<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Publishing DTD v1.1 20151215//EN" "http://jats.nlm.nih.gov/publishing/1.1/JATS-journalpublishing1.dtd">
<article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article" dtd-version="1.1" specific-use="sps-1.9" xml:lang="en">
  <front>
    <journal-meta>
      <journal-id journal-id-type="publisher-id">ijcs</journal-id>
      <journal-title-group>
        <journal-title>International Journal of Cardiovascular Sciences</journal-title>
        <abbrev-journal-title abbrev-type="publisher">Int. J. Cardiovasc. Sci.</abbrev-journal-title>
      </journal-title-group>
      <issn pub-type="ppub">2359-4802</issn>
      <issn pub-type="epub">2359-5647</issn>
      <publisher>
        <publisher-name>Sociedade Brasileira de Cardiologia</publisher-name>
      </publisher>
    </journal-meta>
    <article-meta>
      <article-id specific-use="scielo-v3" pub-id-type="publisher-id">JbQGWZkFDZVVkwfmthgXKrt</article-id>
      <article-id specific-use="previous-pid" pub-id-type="publisher-id">S2359-56472022005001203</article-id>
      <article-id specific-use="scielo-v2" pub-id-type="publisher-id">S2359-56472022000400530</article-id>
      <article-id pub-id-type="publisher-id">ijcs.20200242</article-id>
      <article-id pub-id-type="doi">10.36660/ijcs.20200242</article-id>
      <article-categories>
        <subj-group subj-group-type="heading">
          <subject>Original Article</subject>
        </subj-group>
      </article-categories>
      <title-group>
        <article-title>Epicardial Fat Tissue Thickness and Omentin in Patients with Atrial Fibrillation</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">0000-0003-4005-4858</contrib-id>
          <name>
            <surname>Dural</surname>
            <given-names>Ibrahim Etem</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">
            <sup>1</sup>
          </xref>
          <xref ref-type="corresp" rid="c1"/>
        </contrib>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">0000-0002-2215-6570</contrib-id>
          <name>
            <surname>Onrat</surname>
            <given-names>Ersel</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">
            <sup>1</sup>
          </xref>
        </contrib>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">0000-0002-5187-378X</contrib-id>
          <name>
            <surname>&#199;elik</surname>
            <given-names>Sefa</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">
            <sup>1</sup>
          </xref>
        </contrib>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">0000-0001-7268-178X</contrib-id>
          <name>
            <surname>Gokaslan</surname>
            <given-names>Serkan</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">
            <sup>1</sup>
          </xref>
        </contrib>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">0000-0002-1840-2900</contrib-id>
          <name>
            <surname>Vurmaz</surname>
            <given-names>Ayhan</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">
            <sup>1</sup>
          </xref>
        </contrib>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">0000-0002-7652-1123</contrib-id>
          <name>
            <surname>Emren</surname>
            <given-names>Sad&#305;k Volkan</given-names>
          </name>
          <xref ref-type="aff" rid="aff2">
            <sup>2</sup>
          </xref>
        </contrib>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">0000-0001-7736-0205</contrib-id>
          <name>
            <surname>Yal&#305;m</surname>
            <given-names>Zafer</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">
            <sup>1</sup>
          </xref>
        </contrib>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">0000-0001-7865-3915</contrib-id>
          <name>
            <surname>Av&#351;ar</surname>
            <given-names>Alaeddin</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">
            <sup>1</sup>
          </xref>
        </contrib>
        <aff id="aff1">
          <institution content-type="orgname">Afyonkarahisar Health Sciences University</institution>
          <addr-line>
            <named-content content-type="state">Afyonkarahisar</named-content>
          </addr-line>
          <country country="TR">Turkey</country>
          <institution content-type="original">Afyonkarahisar Health Sciences University, Afyonkarahisar &#8211; Turkey</institution>
        </aff>
        <aff id="aff2">
          <institution content-type="orgname">Izmir Katip Celebi University</institution>
          <addr-line>
            <named-content content-type="state">Izmir</named-content>
          </addr-line>
          <country country="TR">Turkey</country>
          <institution content-type="original">Izmir Katip Celebi University, Izmir &#8211; Turkey</institution>
        </aff>
      </contrib-group>
      <author-notes>
        <corresp id="c1"><bold>Mailing Address: Ibrahim Etem Dural</bold> , Afyonkarahisar Health Sciences University, Faculty of Medicine, Department of Cardiology, Zafer Sa&#287;l&#305;k K&#252;lliyesi, 3. Postal Code: <postal-code>2078</postal-code> , D&#246;rtyol Mahallesi, Sokak, Afyonkarahisar &#8211; Turkey. E-mail: <email>iedural@hotmail.com</email> </corresp>
        <fn fn-type="con">
          <p>
            <bold>Author contributions</bold>
          </p>
          <p>Conception and design of the research: Onrat E. Acquisition of data: Dural &#304;E. Analysis and interpretation of the data: Emren SV. Statistical analysis: Vurmaz A. Writing of the manuscript: Dural &#304;E. Critical revision of the manuscript for intellectual content: Av&#351;ar A.</p>
        </fn>
        <fn fn-type="conflict">
          <p>
            <bold>Potential Conflict of Interest</bold>
          </p>
          <p>No potential conflict of interest relevant to this article was reported.</p>
        </fn>
      </author-notes>
      <pub-date date-type="pub" publication-format="electronic">
        <day>11</day>
        <month>02</month>
        <year>2022</year>
      </pub-date>
      <pub-date date-type="collection" publication-format="electronic">
        <year>2022</year>
      </pub-date>
      <volume>35</volume>
      <issue>4</issue>
      <fpage>530</fpage>
      <lpage>536</lpage>
      <history>
        <date date-type="received">
          <day>13</day>
          <month>08</month>
          <year>2020</year>
        </date>
        <date date-type="accepted">
          <day>25</day>
          <month>11</month>
          <year>2021</year>
        </date>
        <date date-type="rev-recd">
          <day>26</day>
          <month>10</month>
          <year>2021</year>
        </date>
      </history>
      <permissions>
        <license license-type="open-access" xlink:href="https://creativecommons.org/licenses/by/4.0/" xml:lang="en">
          <license-p>This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.</license-p>
        </license>
      </permissions>
      <related-article related-article-type="correction-forward" id="ra1" xlink:href="10.36660/ijcs.20230133" ext-link-type="doi"/>
      <abstract>
        <title>Abstract</title>
        <sec>
          <title>Background:</title>
          <p>Although electrical and structural remodeling has been recognized to be important in the pathophysiology of atrial fibrillation, the mechanisms underlying remodeling process are unknown. There has been increasing interest in the involvement of inflammatory molecules and adipokines released from the epicardial fat tissue in the pathophysiology of atrial fibrillation.</p>
        </sec>
        <sec>
          <title>Objectives:</title>
          <p>In our study, we aimed to investigate the relationship of atrial fibrillation with increased epicardial adipose tissue, inflammatory molecules released from this tissue and omentin.</p>
        </sec>
        <sec>
          <title>Methods:</title>
          <p>Thirty-six patients who were followed up with a diagnosis of permanent AF at the cardiology outpatient clinic 33 individuals without atrial fibrillation (controls) were included in the study. Epicardial adipose tissue thickness of patients was measured by echocardiography. Serum omentin, IL 6, IL 1 beta, TNF alpha and CRP levels were measured. Man-Whitney U test was performed for comparisons and significance was established at 5% (p&lt;0.05).</p>
        </sec>
        <sec>
          <title>Results:</title>
          <p>Epicardial adipose tissue thickness was significantly greater in the patient group (6mm [4-5.5]) than controls (4mm [3-5.5]) (p &lt;0.001). No significant difference was found in the concentrations of omentin or inflammatory molecules between the groups.</p>
        </sec>
        <sec>
          <title>Conclusion:</title>
          <p>No relationship was found between atrial fibrillation and serum levels or omentin or inflammatory markers. A relationship between epicardial adipose tissue thickness measured by echocardiography and atrial fibrillation was determined.</p>
        </sec>
      </abstract>
      <kwd-group xml:lang="en">
        <title>Keywords:</title>
        <kwd>Atrial Fibrillation</kwd>
        <kwd>Omentin</kwd>
        <kwd>Inflammation</kwd>
        <kwd>Intelectin 1</kwd>
        <kwd>Pericardium</kwd>
        <kwd>Adipose Tissue</kwd>
        <kwd>Molecules</kwd>
      </kwd-group>
      <counts>
        <fig-count count="2"/>
        <table-count count="2"/>
        <equation-count count="0"/>
        <ref-count count="27"/>
      </counts>
    </article-meta>
  </front>
  <body>
    <sec sec-type="intro">
      <title>Introdu&#231;&#227;o</title>
      <p>Atrial fibrillation (AF) is a severe arrhythmic condition with high mortality and morbidity. AF may have serious complications, and its incidence is increasing day by day. According to current guidelines, there are five types of AF &#8211; first diagnosed AF, paroxysmal AF, persistent AF, long-standing persistent AF, and permanent AF.<sup><xref ref-type="bibr" rid="B1">1</xref></sup> Permanent AF is used when a joint decision by the patient and clinician has been made to no longer pursue a rhythm control strategy.<sup><xref ref-type="bibr" rid="B1">1</xref></sup> Because of its long duration, permanent AF is more suitable for pathophysiological studies than other types of the disease. <sup><xref ref-type="bibr" rid="B2">2</xref></sup></p>
      <p>Due to the increasing incidence of AF, new treatment modalities have been developed and implemented. However, the pathophysiology of the disease has not been fully elucidated.<sup><xref ref-type="bibr" rid="B3">3</xref></sup> In recent years, it has been suggested that that epicardial fat tissue, adipokines and inflammatory molecules released from this tissue may play a role in the pathophysiology of AF.<sup><xref ref-type="bibr" rid="B4">4</xref> - <xref ref-type="bibr" rid="B6">6</xref></sup></p>
      <p>Epicardial adipose tissue is a visceral adipose tissue where molecules associated with inflammation and atherosclerosis are released.<sup><xref ref-type="bibr" rid="B7">7</xref></sup> As the epicardial adipose tissue thickness increases, the levels of proinflammatory molecules such as interleukin-6 (IL-6 ) and tumor necrosis factor alfa (TNF alpha ) also increase in the tissue.<sup><xref ref-type="bibr" rid="B8">8</xref></sup> We also know that adipokines such as adiponectin, leptin, and omentin are also released from epicardial adipose tissue like other visceral adipose tissues.<sup><xref ref-type="bibr" rid="B9">9</xref> , <xref ref-type="bibr" rid="B10">10</xref></sup> These proinflammatory molecules and adipokines are thought to be related to AF.</p>
      <p>There are many studies on the relationship of inflammation and inflammatory molecules with AF and the contribution of the inflammatory process to the formation of AF.<sup><xref ref-type="bibr" rid="B11">11</xref></sup> Atrial fibrosis, which is an important factor in the formation of AF, is thought to develop as a result of inflammation in the atrial myocardium. Especially in patients with persistent and permanent AF, higher C-reactive protein (CRP) levels indicate this inflammatory process as compared with patients with paroxysmal AF and individuals with sinus rhythm.<sup><xref ref-type="bibr" rid="B12">12</xref></sup> High detection of IL-1, IL-6, and TNF alpha in patients with AF supports this view. In addition, the higher levels of TNF alpha in patients with chronic AF and valvular AF compared to patients with paroxysmal AF indicates its relationship with chronic inflammation and atrial fibrosis.<sup><xref ref-type="bibr" rid="B13">13</xref></sup></p>
      <p>Omentin is an adipokine mostly released from visceral adipose tissue.<sup><xref ref-type="bibr" rid="B14">14</xref></sup> Its anti-inflammatory effects have been shown in experimental studies, and the adipokine has also been detected in epicardial adipose tissue.<sup><xref ref-type="bibr" rid="B10">10</xref> - <xref ref-type="bibr" rid="B13">13</xref></sup> The relationship of omentin released from epicardial adipose tissue with cardiovascular diseases has been shown in various studies.<sup><xref ref-type="bibr" rid="B15">15</xref></sup> Serum levels of omentin, which suppresses the inflammatory process by multiple pathways, are low in some cardiovascular diseases.<sup><xref ref-type="bibr" rid="B16">16</xref></sup> Omentin is thought to play a role in the pathophysiology of AF, although there are few studies on this topic.<sup><xref ref-type="bibr" rid="B17">17</xref></sup></p>
      <p>Thus, in the presen study, we aimed to show the relationship of AF with inflammatory molecules and omentin.</p>
    </sec>
    <sec sec-type="methods">
      <title>Methods</title>
      <sec>
        <title>Study population</title>
        <p>Thirty-six patients who were followed up with a diagnosis of permanent AF at the cardiology outpatient clinic were included in the study. In addition, diagnosis of permanent AF was applied to those cases when both physician and patient decided to accept the presence of AF at least one year before. Thirty-three individuals attending the cardiology outpatient clinic, who had sin&#252;s rhythm (electrocardiography, ECG) were included in the control group. They didn&#8217;t have atrial fibrillation in the ECG Holter monitoring.</p>
        <p>Patients with mitral stenosis, moderate or severe mitral insufficiency, mechanical mitral valve, hyperthyroidism, and those who underwent AF ablation were excluded. Patients with cancer, autoimmune disease, connective tissue, and inflammatory bowel disease were also excluded because of the association of these conditions with elevated inflammatory biomarkers.</p>
        <p>All subjects underwent conventional echocardiography. Left ventricular end-diastolic and end-systolic diameters, posterior wall and septal thickness, aortic root, left atrial dimension, ejection fraction, aortic and mitral valve maximum and mean gradients, systolic pulmonary artery pressure, and epicardial fat tissue thickness were measured. Ejection fraction was calculated with the Teichholz M-mode formula: (EDV-ESV)/EDVx100. EDV:[7/(2.4+End diastolic diameter(EDd))]xEDd<sup>3</sup>; ESV:[7/(2.4+ End systolic diameter (ESd))]xESd<sup>3</sup></p>
        <p>EDV = end-diastolic volume; ESV = end-systolic volume; EDd = end-diastolic diameter; Esd = end-systolic diameter</p>
        <p>The local ethics committee approved the study protocol (approval date and number 01/29/2015 and 2015/02-30). The study complies with the Declaration of Helsinki.</p>
      </sec>
      <sec>
        <title>Measurement of epicardial fat thickness</title>
        <p>Echocardiographic examinations of all patients and the control group were performed with the help of the GE M5Sc-D probe of the General Electric Medical Systems Vivid E9 Xdclear device.</p>
        <p>Transthoracic echocardiographic images of the patients were obtained with a 2.5-3.5 MHz transducer from parasternal and apical windows. Echocardiographically, epicardial fat thickness was mesaured on the parasternal long-axis and parasternal short-axis images while the patient was lying in the left lateral decubitus position. The area and thickness of epicardial fat between the outer layer of the free wall of the right ventricle and the visceral layer of the pericardium was measured at the end of the systole. Echocardiographic fat tissue thickness measurements were taken in three separate cycles to obtain more accurate values. All echocardiographic and Doppler studies were carried out by the same observer.</p>
      </sec>
      <sec>
        <title>Statistical analysis</title>
        <p>Statistical analysis was conducted using the SPSS software version 18.0 (SPSS, Inc., Chicago, Illinois). Continuous variables with normal distribution were described as mean and standard deviation, and median and interquartile ranges were used for continuous variables not normally distributed. Categorical variables were presented as percentage.</p>
        <p>The Kolmogorov-Smirnov test was used to test the normality of these data distribution. The chi-square test was used to compare nominal and categorical variables. Parametric data were compared using the Student's t-test and non-parametric data were compared using the Mann-Whitney U test. A two-sided p-value &lt;0.05 was considered statistically significant. We calculated the sample size based on a statistical power of 0.95, two-sided alpha error of 0.05, with an odds ratio (OR) of l,<sup><xref ref-type="bibr" rid="B17">17</xref></sup> using the Gpower software v3.1.9.4 (Erdfelder, Faul, &amp; Buchner, 1996).</p>
      </sec>
    </sec>
    <sec sec-type="results">
      <title>Results</title>
      <p>Mean age was 68.5 &#177; 15 years in the patient group and 62.8 &#177; 10.1 years in the control group. In addition, 58% (21) of the patient group and 51% (17) of the control group were women. The use of antiplatelet agents was different in the patient and control groups. Demographic characteristics of individuals in the study are summarized in <xref ref-type="table" rid="t1">Table 1</xref> .</p>
      <table-wrap id="t1">
        <label>Table 1</label>
        <caption>
          <title>Baseline clinical characteristics of the study participants</title>
        </caption>
        <table frame="hsides" rules="rows">
          <colgroup width="24%">
            <col width="1%"/>
            <col/>
            <col/>
            <col/>
            <col/>
          </colgroup>
          <thead style="border-top: thin solid; border-bottom: thin solid; border-color: #000000">
            <tr style="background-color:#BCBDC0;">
              <th align="left" colspan="2" valign="middle">Characteristics</th>
              <th align="center" valign="middle">AF group (n=36)</th>
              <th align="center" valign="middle">Control group (n=33)</th>
              <th align="center" valign="middle">p</th>
            </tr>
          </thead>
          <tbody style="border-bottom: thin solid; border-color: #000000">
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Age, years</td>
              <td align="center" valign="bottom">68.5&#177;15</td>
              <td align="center" valign="bottom">62.8&#177;10,1</td>
              <td align="center" valign="bottom">0.068</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Male, n (%)</td>
              <td align="center" valign="bottom">21 (%58)</td>
              <td align="center" valign="bottom">17 (%51)</td>
              <td align="center" valign="bottom">0.666</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Body mass index (kg/m2)</td>
              <td align="center" valign="bottom">28.6&#177;6.4</td>
              <td align="center" valign="bottom">27.8&#177;4,1</td>
              <td align="center" valign="bottom">0.535</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Coronary artery disease n (%)</td>
              <td align="center" valign="bottom">10 (%28)</td>
              <td align="center" valign="bottom">12 (%36)</td>
              <td align="center" valign="bottom">0.445</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Heart Failure n (%)</td>
              <td align="center" valign="bottom">4 (%11)</td>
              <td align="center" valign="bottom">5 (%15)</td>
              <td align="center" valign="bottom">0.728</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Hypertension n (%)</td>
              <td align="center" valign="bottom">19 (%53)</td>
              <td align="center" valign="bottom">18 (%54)</td>
              <td align="center" valign="bottom">0.883</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Diabetes mellitus n (%)</td>
              <td align="center" valign="bottom"> 9 (%25)</td>
              <td align="center" valign="bottom">7 (%21)</td>
              <td align="center" valign="bottom">0.710</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Dyslipidemia n (%)</td>
              <td align="center" valign="bottom">9 (%25)</td>
              <td align="center" valign="bottom">15 (%45)</td>
              <td align="center" valign="bottom">0.075</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Stroke n (%)</td>
              <td align="center" valign="bottom">1 (%3</td>
              <td align="center" valign="bottom">0</td>
              <td align="center" valign="top"/>
            </tr>
            <tr>
              <td align="left" colspan="5" valign="top">
                <bold>Drugs</bold>
              </td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Beta blocker n (%)</td>
              <td align="center" valign="bottom">18 (%50)</td>
              <td align="center" valign="bottom">12 (%36)</td>
              <td align="center" valign="bottom">0.254</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">ACEi/ARB n (%)</td>
              <td align="center" valign="bottom">21 (%64)</td>
              <td align="center" valign="bottom">20 (%56)</td>
              <td align="center" valign="bottom">0.495</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Statin n (%)</td>
              <td align="center" valign="bottom">10 (%28)</td>
              <td align="center" valign="bottom">5 (%45)</td>
              <td align="center" valign="bottom">0.127</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">ASA n (%)</td>
              <td align="center" valign="bottom">0</td>
              <td align="center" valign="bottom">13 (%39)</td>
              <td align="center" valign="top"/>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Oral anticoagulant n (%)</td>
              <td align="center" valign="bottom">35 (%97)</td>
              <td align="center" valign="bottom">0</td>
              <td align="center" valign="top"/>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Oral antidiabetic n (%)</td>
              <td align="center" valign="bottom">8 (%22)</td>
              <td align="center" valign="bottom">8 (%24)</td>
              <td align="center" valign="bottom">0.843</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">MRA n (%)</td>
              <td align="center" valign="bottom">6 (%17)</td>
              <td align="center" valign="bottom">4 (%12)</td>
              <td align="center" valign="bottom">0.592</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Diuretic n (%)</td>
              <td align="center" valign="bottom">10 (%28)</td>
              <td align="center" valign="bottom">15 (%45)</td>
              <td align="center" valign="bottom">0.127</td>
            </tr>
          </tbody>
        </table>
        <table-wrap-foot>
          <fn id="TFN1">
            <p>P value &lt; 0.05</p>
          </fn>
          <fn id="TFN2">
            <p>ACEi: angiotensin converting enzyme inhibitors, ARB: angiotensin receptor blockers, ASA: acetylsalicylic acid, MRA: mineralocorticoid receptor antagonist</p>
          </fn>
        </table-wrap-foot>
      </table-wrap>
      <p>Epicardial adipose thickness and center atrial size were significantly greater in patients with AF than in the control group. <xref ref-type="fig" rid="f1">Figure 1</xref> shows the graph comparing epicardial adipose thickness.</p>
      <fig id="f1">
        <label>Figure 1</label>
        <caption>
          <title>Measurement of epicardial fat tissue thicknesses in patients (n=36) and controls (n=33).</title>
        </caption>
        <graphic xlink:href="2359-5647-ijcs-35-04-0530-00242-gf01.tif"/></fig>
      <p>Serum TNF-alpha, high-sensitivity CRP, IL-1 beta, IL-6 and omentin levels were not statistically different between the two groups ( <xref ref-type="fig" rid="f2">Figure 2</xref> and <xref ref-type="table" rid="t2">Table 2</xref> ).</p>
      <fig id="f2">
        <label>Figure 2</label>
        <caption>
          <title>Serum omentin levels in patients (n=36) and controls (n=33).</title>
        </caption>
        <graphic xlink:href="2359-5647-ijcs-35-04-0530-00242-gf02.tif"/></fig>
      <table-wrap id="t2">
        <label>Table 2</label>
        <caption>
          <title>Serum inflammatory molecules and serum omentin levels in the study groups</title>
        </caption>
        <table frame="hsides" rules="rows">
          <colgroup width="24%">
            <col width="1%"/>
            <col/>
            <col/>
            <col/>
            <col/>
          </colgroup>
          <thead style="border-top: thin solid; border-bottom: thin solid; border-color: #000000">
            <tr style="background-color:#BCBDC0;">
              <th align="left" colspan="2" valign="middle">Characteristics</th>
              <th align="center" valign="middle">AF group (n=36)</th>
              <th align="center" valign="middle">Control group (n=33)</th>
              <th align="center" valign="middle">p</th>
            </tr>
          </thead>
          <tbody style="border-bottom: thin solid; border-color: #000000">
            <tr>
              <td align="left" colspan="5" valign="top">
                <bold>Inflammatory molecules</bold>
              </td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">TNF-alfa (pg/mL)</td>
              <td align="center" valign="bottom">27.635 (20.658-30.813)</td>
              <td align="center" valign="bottom">27.935 (21.723-27.935)</td>
              <td align="center" valign="bottom">0.959</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Hs-CRP (mg/mL)</td>
              <td align="center" valign="bottom">6.69 (2.34-15.21)</td>
              <td align="center" valign="bottom">6.53 (3.2025-11.52)</td>
              <td align="center" valign="bottom">0.498</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">IL-1 beta (pg/mL)</td>
              <td align="center" valign="bottom">8.61 (6.26-12.22)</td>
              <td align="center" valign="bottom">9.6 (7.145-11.735)</td>
              <td align="center" valign="bottom">0.556</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">IL-6 (pg/mg)</td>
              <td align="center" valign="bottom">3.64 (2-8.955)</td>
              <td align="center" valign="bottom">2.37 (1.4825-4.2575)</td>
              <td align="center" valign="bottom">0.343</td>
            </tr>
            <tr>
              <td align="left" valign="top"/>
              <td align="left" valign="bottom">Omentin (ng/mL)</td>
              <td align="center" valign="bottom">13.51 (6.785-20.413)</td>
              <td align="center" valign="bottom">11.8 (7.425-18.145)</td>
              <td align="center" valign="bottom">0.555</td>
            </tr>
          </tbody>
        </table>
        <table-wrap-foot>
          <fn id="TFN3">
            <p>P value &lt; 0.05</p>
          </fn>
          <fn id="TFN4">
            <p>TNF-alfa: tumor necrosis factor alpha, Hs-CRP: high-sensitive c-reactive protein, IL-1 beta: interleukin 1 beta, IL 6: interleukin 6</p>
          </fn>
        </table-wrap-foot>
      </table-wrap>
    </sec>
    <sec sec-type="discussion">
      <title>Discussion</title>
      <p>In recent years, new risk factors for AF have been identified. Some of these new risk factors are obesity, and increased epicardial fat tissue, cytokines and inflammatory factors. Epicardial fat tissue is thought to be more specific than obesity in determining AF risk. Therefore, the relation of inflammatory molecules released from epicardial adipose tissue and adipokines with AF will provide a better understanding of the pathophysiology of the disease.<sup><xref ref-type="bibr" rid="B18">18</xref> , <xref ref-type="bibr" rid="B19">19</xref></sup> In our study, we investigated serum levels of inflammatory molecules thought to be released from epicardial adipose tissue and of omentin, which has been poorly addressed.</p>
      <p>The thickness of the epicardial fat tissue is related to the biological activity of the tissue, with greater release of cytokines from thick tissues.<sup><xref ref-type="bibr" rid="B20">20</xref></sup> There is strong evidence that cytokines released from epicardial fat tissue are effective in the pathogenesis of heart disease. Tissue studies have shown that epicardial fat tissue of patients with ischemic heart disease secretes high levels of interleukin 6, tumor necrosis factor-alpha and monocyte chemotactic factor 1, and local concentrations of these cytokine are significantly higher than in systemic circulation. These results suggest that cytokines released from epicardial fat tissue act in the cardiac region.<sup><xref ref-type="bibr" rid="B21">21</xref> - <xref ref-type="bibr" rid="B25">25</xref></sup></p>
      <p>Our finding of increased epicardial adipose thickness in patients with AF was consistent with the literature, and supports the relationship between epicardial adipose tissue and AF.</p>
      <list list-type="bullet">
        <list-item>
          <p>Inflammation is one of the new risk factors for AF, and the source of inflammatory cytokines secreted in cardiac diseases seems to be the epicardial fat tissue.<sup><xref ref-type="bibr" rid="B19">19</xref></sup> This is supported by the increased frequency of AF in conditions of intense myocardial inflammation, such as pericarditis, myocarditis and cardiac surgery. It is known that atrial fibrosis, which occurs at the end of inflammation, plays an important role in the development of AF. Increased B-type natriuretic peptide (BNP) due to myocyte stretch and increasing high-sensitive troponin levels due to myocyte damage caused by inflammation and fibrosis supports this pathophysiological pathway. High BNP levels have been associated with ischemic complications, and high troponin levels have been associated with cardiovascular mortality in patients with AF.<sup><xref ref-type="bibr" rid="B22">22</xref> , <xref ref-type="bibr" rid="B23">23</xref></sup></p>
        </list-item>
        <list-item>
          <p>Inflammatory biomarkers detected in the atrial tissue reinforce the idea of the relationship between inflammation and AF.<sup><xref ref-type="bibr" rid="B19">19</xref></sup> In atrial biopsies taken during cardiac surgery, high-sensitive CRP, IL-1, IL-6 and TNF alpha levels indicated an inflammatory process. H&#305;gh serum levels of these molecules, especially in patients with permanent AF, have been reported in previous studies.<sup><xref ref-type="bibr" rid="B11">11</xref> , <xref ref-type="bibr" rid="B18">18</xref> , <xref ref-type="bibr" rid="B19">19</xref></sup> In addition, these biomarkers have been investigated in disease prediction and evaluation of prognosis,<sup><xref ref-type="bibr" rid="B11">11</xref> , <xref ref-type="bibr" rid="B20">20</xref></sup> and in treatment response in patients receiving beta-blocker therapy.<sup><xref ref-type="bibr" rid="B24">24</xref></sup></p>
        </list-item>
        <list-item>
          <p>We could not find a significant difference in the levels of inflammatory markers between patients&#8217; and control groups in our study. The most important reason for this may be the inclusion of patients with inflammation-related diseases such as coronary artery disease, diabetes and hypertension. Thus, the inclusion of patients from the general population rather than selected patients may have affected the outcomes in this direction. This is supported by the fact that inflammatory molecule levels were not normally distributed.</p>
        </list-item>
        <list-item>
          <p>Omentin is an anti-inflammatory adipokine released substantially from the epicardial and omentum fat tissues.<sup><xref ref-type="bibr" rid="B14">14</xref></sup> Although omentin is secreted from the omentum, blood levels of this cytokine fall in obesity. In contrast, the relationship between epicardial fat tissue and blood omentin level are not fully clarified. Omentin has anti-inflammatory properties and suppresses inflammation through several biochemical pathways in experimental studies.<sup><xref ref-type="bibr" rid="B25">25</xref></sup></p>
        </list-item>
        <list-item>
          <p>We thought that the decisive effect of inflammation and increased epicardial fat tissue in the development of AF was by means of omentin release. Epicardial adipose tissue, which is increased in patients with AF, gradually progresses to adipose tissue dysfunction called adiposopathy. This, in turn, reduces the release of the anti-inflammatory cytokine omentin,<sup><xref ref-type="bibr" rid="B26">26</xref></sup> resulting in inflammation.<sup><xref ref-type="bibr" rid="B27">27</xref></sup> This inflammation is thought to be one of the causes of AF.<sup><xref ref-type="bibr" rid="B18">18</xref></sup></p>
        </list-item>
        <list-item>
          <p>In our study, there was no significant difference between the two groups for omentin. We confirmed our hypothesis that increased epicardial fat tissue is the basis of AF, with involvement of inflammation and adipokines; however, we could not demonstrate the implication of omentin or biomarkers in it. We have shown that high body mass index is associated with increased epicardial fat tissue thickness, which may explain the association between obesity and AF.</p>
        </list-item>
        <list-item>
          <p>Our study is the second in the literature to examine the association of serum omentin levels with AF. Tao et al.,<sup><xref ref-type="bibr" rid="B17">17</xref></sup> showed a negative correlation between serum omentin levels and AF; the adipokine levels were significantly lower in patients with AF. However, in our study, this significant difference was not observed. One of the reasons for this can be that the larger sample size in their study. Also, Tao et al.,<sup><xref ref-type="bibr" rid="B17">17</xref></sup> did not include patients with chronic diseases. In our study, patients with coronary artery disease, diabetes mellitus, hypertension, and heart failure were included, with no statistical difference in the two groups.</p>
        </list-item>
        <list-item>
          <p>We also believed that adiposopathy, related to increased epicardial fat tissue, may cause AF through inflammation and omentin. However, in our study, adiposopathy was not detected in patients with increased epicardial fat tissue. We suggest that further studies be done to elucidate the pathophysiology of adiposopathy by different imaging and laboratory techniques.</p>
        </list-item>
      </list>
      <sec>
        <title>Study limitations</title>
        <p>The small numbers of patients and control subjects is the most important limitation of our study. Another limitation is the presence of diseases that could affect omentin and inflammatory biomarker levels.</p>
      </sec>
    </sec>
    <sec sec-type="conclusions">
      <title>Conclusion</title>
      <p>Our study showed that increased epicardial fat tissue played an important role in AF, and that it had a positive relationship with body mass index. We could not establish the relationship of omentin and inflammation with AF.</p>
    </sec>
  </body>
  <back>
    <fn-group>
      <fn fn-type="supported-by" id="fn1">
        <p>
          <bold>Sources of Funding</bold>
        </p>
        <p>This study was funded by Turkish Society of Cardiology.</p>
      </fn>
      <fn fn-type="other" id="fn2">
        <p>
          <bold>Study Association</bold>
        </p>
        <p>This study is not associated with any thesis or dissertation work.</p>
      </fn>
      <fn fn-type="other" id="fn3">
        <p>
          <bold>Ethics approval and consent to participate</bold>
        </p>
        <p>This study was approved by the Ethics Committee of the Afyon Health Science University under the protocol number 2015/02-30. All the procedures in this study were in accordance with the 1975 Helsinki Declaration, updated in 2013. Informed consent was obtained from all participants included in the study.</p>
      </fn>
    </fn-group>
    <ref-list>
      <title>References</title>
      <ref id="B1">
        <label>1</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>January</surname>
              <given-names>CT</given-names>
            </name>
            <name>
              <surname>Wann</surname>
              <given-names>LS</given-names>
            </name>
            <name>
              <surname>Alpert</surname>
              <given-names>JS</given-names>
            </name>
            <name>
              <surname>Calkins</surname>
              <given-names>H</given-names>
            </name>
            <name>
              <surname>Cleveland</surname>
              <given-names>JC</given-names>
              <suffix>Jr</suffix>
            </name>
            <name>
              <surname>Cigarroa</surname>
              <given-names>JE</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society</article-title>
          <source>J Am Coll Cardiol</source>
          <year>2014</year>
          <volume>64</volume>
          <issue>21</issue>
          <fpage>e1</fpage>
          <lpage>e76</lpage>
          <pub-id pub-id-type="doi">10.1016/j.jacc.2014.03.022</pub-id>
        </element-citation>
        <mixed-citation>1 January CT, Wann LS, Alpert JS, Calkins H, Cleveland JC Jr, Cigarroa JE. et al. AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2014;64(21):e1-76. doi: 10.1016/j.jacc.2014.03.022.</mixed-citation>
      </ref>
      <ref id="B2">
        <label>2</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Heijman</surname>
              <given-names>J</given-names>
            </name>
            <name>
              <surname>Voigt</surname>
              <given-names>N</given-names>
            </name>
            <name>
              <surname>Nattel</surname>
              <given-names>S</given-names>
            </name>
            <name>
              <surname>Dobrev</surname>
              <given-names>D</given-names>
            </name>
          </person-group>
          <article-title>Cellular and molecular electrophysiology of atrial fibrillation initiation, maintenance, and progression</article-title>
          <source>Circ Res</source>
          <year>2014</year>
          <volume>114</volume>
          <issue>9</issue>
          <fpage>1483</fpage>
          <lpage>1489</lpage>
          <pub-id pub-id-type="doi">10.1161/CIRCRESAHA.114.302226</pub-id>
        </element-citation>
        <mixed-citation>2 Heijman J, Voigt N, Nattel S, Dobrev D. Cellular and molecular electrophysiology of atrial fibrillation initiation, maintenance, and progression.Circ Res. 2014;114(9):1483-9. doi:10.1161/CIRCRESAHA.114.302226</mixed-citation>
      </ref>
      <ref id="B3">
        <label>3</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Alpert</surname>
              <given-names>J.S.</given-names>
            </name>
            <name>
              <surname>Petersen</surname>
              <given-names>P</given-names>
            </name>
            <name>
              <surname>Godtfredsen</surname>
              <given-names>J</given-names>
            </name>
          </person-group>
          <article-title>Atrial fibrillation: natural history, complications, and management</article-title>
          <source>Ann Rev Med</source>
          <year>1988</year>
          <volume>39</volume>
          <fpage>41</fpage>
          <lpage>52</lpage>
          <pub-id pub-id-type="doi">10.1146/annurev.me.39.020188.000353</pub-id>
        </element-citation>
        <mixed-citation>3 Alpert, J.S. Petersen, P. Godtfredsen, J. Atrial fibrillation: natural history, complications, and management. Ann Rev Med. 1988;39:41-52. DOI: 10.1146/annurev.me.39.020188.000353</mixed-citation>
      </ref>
      <ref id="B4">
        <label>4</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Venteclef</surname>
              <given-names>N</given-names>
            </name>
            <name>
              <surname>Guglielmi</surname>
              <given-names>V</given-names>
            </name>
            <name>
              <surname>Balse</surname>
              <given-names>E</given-names>
            </name>
            <name>
              <surname>Gaborit</surname>
              <given-names>B</given-names>
            </name>
            <name>
              <surname>Cotillard</surname>
              <given-names>A</given-names>
            </name>
            <name>
              <surname>Atassi</surname>
              <given-names>F</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>Human epicardial adipose tissue induces fibrosis of the atrial myocardium through the secretion of adipo-fibrokines</article-title>
          <source>Eur Heart J</source>
          <year>2015</year>
          <volume>36</volume>
          <issue>13</issue>
          <fpage>795a</fpage>
          <lpage>805a</lpage>
          <pub-id pub-id-type="doi">10.1093/eurheartj/eht099</pub-id>
        </element-citation>
        <mixed-citation>4 Venteclef N, Guglielmi V, Balse E, Gaborit B , Cotillard A, Atassi F, et al. Human epicardial adipose tissue induces fibrosis of the atrial myocardium through the secretion of adipo-fibrokines. Eur Heart J. 2015;36(13):795-805a. DOI: 10.1093/eurheartj/eht099</mixed-citation>
      </ref>
      <ref id="B5">
        <label>5</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Leggio</surname>
              <given-names>M</given-names>
            </name>
            <name>
              <surname>Severi</surname>
              <given-names>P</given-names>
            </name>
            <name>
              <surname>D&#8217;emidio</surname>
              <given-names>S</given-names>
            </name>
            <name>
              <surname>Mazza</surname>
              <given-names>A</given-names>
            </name>
          </person-group>
          <article-title>Epicardial adipose tissue and atrial fibrillation: The other side of the coin</article-title>
          <source>Anatol J Cardiol</source>
          <year>2017</year>
          <volume>17</volume>
          <issue>5</issue>
          <fpage>415</fpage>
          <lpage>416</lpage>
          <pub-id pub-id-type="doi">10.14744/AnatolJCardiol.2017.7752</pub-id>
        </element-citation>
        <mixed-citation>5 Leggio M, Severi P, D&#8217;emidio S, Mazza A. Epicardial adipose tissue and atrial fibrillation: The other side of the coin. Anatol J Cardiol. 2017; 17(5):415-6. DOI: 10.14744/AnatolJCardiol.2017.7752</mixed-citation>
      </ref>
      <ref id="B6">
        <label>6</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Hatem</surname>
              <given-names>SN</given-names>
            </name>
          </person-group>
          <article-title>Is epicardial adipose tissue an epiphenomenon or a new player in the pathophysiology of atrial fibrillation?</article-title>
          <source>Arch Cardiovasc Dis</source>
          <year>2014</year>
          <volume>107</volume>
          <issue>6-7</issue>
          <fpage>349</fpage>
          <lpage>352</lpage>
          <pub-id pub-id-type="doi">10.1016/j.acvd.2014.06.002</pub-id>
        </element-citation>
        <mixed-citation>6 Hatem SN. Is epicardial adipose tissue an epiphenomenon or a new player in the pathophysiology of atrial fibrillation?. Arch Cardiovasc Dis. 2014;107(6-7):349-52. DOI: 10.1016/j.acvd.2014.06.002</mixed-citation>
      </ref>
      <ref id="B7">
        <label>7</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Al Chekakie</surname>
              <given-names>MO</given-names>
            </name>
            <name>
              <surname>Welles</surname>
              <given-names>CC</given-names>
            </name>
            <name>
              <surname>Metoyer</surname>
              <given-names>R</given-names>
            </name>
            <name>
              <surname>Ibrahim</surname>
              <given-names>A</given-names>
            </name>
            <name>
              <surname>Shapira</surname>
              <given-names>AR</given-names>
            </name>
            <name>
              <surname>Cytron</surname>
              <given-names>J</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>Pericardial fat is independently associated with human atrial fibrillation</article-title>
          <source>J Am Coll Cardiol</source>
          <year>2010</year>
          <month>08</month>
          <day>31</day>
          <volume>56</volume>
          <issue>10</issue>
          <fpage>784</fpage>
          <lpage>788</lpage>
          <pub-id pub-id-type="doi">10.1016/j.jacc.2010.03.071</pub-id>
        </element-citation>
        <mixed-citation>7 Al Chekakie MO, Welles CC, Metoyer R, Ibrahim A, Shapira AR, Cytron J, et al. Pericardial fat is independently associated with human atrial fibrillation. J Am Coll Cardiol. 2010 Aug 31;56(10):784-8. DOI: 10.1016/j.jacc.2010.03.071</mixed-citation>
      </ref>
      <ref id="B8">
        <label>8</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Mazurek</surname>
              <given-names>T</given-names>
            </name>
            <name>
              <surname>Kiliszek</surname>
              <given-names>M</given-names>
            </name>
            <name>
              <surname>Kobylecka</surname>
              <given-names>M</given-names>
            </name>
            <name>
              <surname>Skubisz-G&#322;uchowska</surname>
              <given-names>J</given-names>
            </name>
            <name>
              <surname>Kochman</surname>
              <given-names>J</given-names>
            </name>
            <name>
              <surname>Filipiak</surname>
              <given-names>K</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>Relation of proinflammatory activity of epicardial adipose tissue to the occurrence of atrial fibrillation</article-title>
          <source>Am J Cardiol</source>
          <year>2014</year>
          <volume>113</volume>
          <issue>9</issue>
          <fpage>1505</fpage>
          <lpage>1508</lpage>
          <pub-id pub-id-type="doi">10.1016/j.amjcard.2014.02.005</pub-id>
        </element-citation>
        <mixed-citation>8 Mazurek T, Kiliszek M, Kobylecka M, Skubisz-G&#322;uchowska J, Kochman J, Filipiak K, et al. Relation of proinflammatory activity of epicardial adipose tissue to the occurrence of atrial fibrillation. Am J Cardiol. 2014;113(9):1505-8. doi: 10.1016/j.amjcard.2014.02.005.</mixed-citation>
      </ref>
      <ref id="B9">
        <label>9</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Ermakov</surname>
              <given-names>S</given-names>
            </name>
            <name>
              <surname>Azarbal</surname>
              <given-names>F</given-names>
            </name>
            <name>
              <surname>Stefanick</surname>
              <given-names>ML</given-names>
            </name>
            <name>
              <surname>La Monte</surname>
              <given-names>MJ</given-names>
            </name>
            <name>
              <surname>Li</surname>
              <given-names>W</given-names>
            </name>
            <name>
              <surname>Tharp</surname>
              <given-names>KM</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>The associations of leptin, adiponectin and resistin with incident atrial fibrillation in women</article-title>
          <source>Heart</source>
          <year>2016</year>
          <month>09</month>
          <day>01</day>
          <volume>102</volume>
          <issue>17</issue>
          <fpage>1354</fpage>
          <lpage>1362</lpage>
          <pub-id pub-id-type="doi">10.1136/heartjnl-2015-308927</pub-id>
        </element-citation>
        <mixed-citation>9 Ermakov S, Azarbal F, Stefanick ML, LaMonte MJ, Li W, Tharp KM,et al. The associations of leptin, adiponectin and resistin with incident atrial fibrillation in women. Heart. 2016 Sep 1;102(17):1354-62. doi: 10.1136/heartjnl-2015-308927.</mixed-citation>
      </ref>
      <ref id="B10">
        <label>10</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Fain</surname>
              <given-names>JN</given-names>
            </name>
            <name>
              <surname>Sacks</surname>
              <given-names>HS</given-names>
            </name>
            <name>
              <surname>Buehrer</surname>
              <given-names>B</given-names>
            </name>
            <name>
              <surname>Bahouth</surname>
              <given-names>SW</given-names>
            </name>
            <name>
              <surname>Garrett</surname>
              <given-names>E</given-names>
            </name>
            <name>
              <surname>Wolf</surname>
              <given-names>RY</given-names>
            </name>
          </person-group>
          <article-title>e al. Identification of omentin mRNA in human epicardial adipose tissue: comparison to omentin in subcutaneous, internal mammary artery periadventitial and visceral abdominal depots</article-title>
          <source>Int J Obes (Lond)</source>
          <year>2008</year>
          <volume>32</volume>
          <issue>5</issue>
          <fpage>810</fpage>
          <lpage>815</lpage>
        </element-citation>
        <mixed-citation>10 Fain JN, Sacks HS, Buehrer B, Bahouth SW, Garrett E, Wolf RY, e al. Identification of omentin mRNA in human epicardial adipose tissue: comparison to omentin in subcutaneous, internal mammary artery periadventitial and visceral abdominal depots. Int J Obes (Lond). 2008;32(5):810-5</mixed-citation>
      </ref>
      <ref id="B11">
        <label>11</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Scott</surname>
              <given-names>L</given-names>
              <suffix>Jr</suffix>
            </name>
            <name>
              <surname>Li</surname>
              <given-names>N</given-names>
            </name>
            <name>
              <surname>Dobrev</surname>
              <given-names>D</given-names>
            </name>
          </person-group>
          <article-title>Role of inflammatory signaling in atrial fibrillation</article-title>
          <source>Int J Cardiol</source>
          <year>2019</year>
          <month>07</month>
          <volume>15</volume>
          <issue>287</issue>
          <fpage>195</fpage>
          <lpage>200</lpage>
          <pub-id pub-id-type="doi">10.1016/j.ijcard.2018.10.020</pub-id>
        </element-citation>
        <mixed-citation>11 Scott L Jr, Li N, Dobrev D. Role of inflammatory signaling in atrial fibrillation. Int J Cardiol. 2019 Jul 15;287:195-200. doi: 10.1016/j.ijcard.2018.10.020.</mixed-citation>
      </ref>
      <ref id="B12">
        <label>12</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Chung</surname>
              <given-names>MK</given-names>
            </name>
            <name>
              <surname>Martin</surname>
              <given-names>DO</given-names>
            </name>
            <name>
              <surname>Sprecher</surname>
              <given-names>D</given-names>
            </name>
            <name>
              <surname>Wazni</surname>
              <given-names>O</given-names>
            </name>
            <name>
              <surname>Kanderian</surname>
              <given-names>A</given-names>
            </name>
            <name>
              <surname>Carnes</surname>
              <given-names>CA</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>C-reactive protein elevation in patients with atrial arrhythmias: inflammatory mechanisms and persistence of atrial fibrillation</article-title>
          <source>Circulation</source>
          <year>2001</year>
          <volume>104</volume>
          <issue>24</issue>
          <fpage>2886</fpage>
          <lpage>2891</lpage>
          <pub-id pub-id-type="doi">10.1161/hc4901.101760</pub-id>
        </element-citation>
        <mixed-citation>12 Chung MK, Martin DO, Sprecher D, Wazni O, Kanderian A, Carnes CA, et al. C-reactive protein elevation in patients with atrial arrhythmias: inflammatory mechanisms and persistence of atrial fibrillation. Circulation. 2001;104(24):2886-91. doi: 10.1161/hc4901.101760.</mixed-citation>
      </ref>
      <ref id="B13">
        <label>13</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Wang</surname>
              <given-names>CH</given-names>
            </name>
            <name>
              <surname>Hu</surname>
              <given-names>DY</given-names>
            </name>
            <name>
              <surname>Tang</surname>
              <given-names>CZ</given-names>
            </name>
            <name>
              <surname>Wu</surname>
              <given-names>MY</given-names>
            </name>
            <name>
              <surname>Mei</surname>
              <given-names>YQ</given-names>
            </name>
            <name>
              <surname>Zhao</surname>
              <given-names>JG</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>Changes of interleukin-1beta and tumor necrosis factor-alpha of right atrial appendages in patients with rheumatic valvular disease complicated with chronic atrial fibrillation</article-title>
          <source>Zhonghua Xin Xue Guan Bing Za Zhi</source>
          <year>2005</year>
          <month>06</month>
          <volume>33</volume>
          <issue>6</issue>
          <fpage>522</fpage>
          <lpage>525</lpage>
          <comment>Chinese</comment>
          <pub-id pub-id-type="pmid">16053785</pub-id>
        </element-citation>
        <mixed-citation>13 Wang CH, Hu DY, Tang CZ, Wu MY, Mei YQ, Zhao JG, et al. Changes of interleukin-1beta and tumor necrosis factor-alpha of right atrial appendages in patients with rheumatic valvular disease complicated with chronic atrial fibrillation. Zhonghua Xin Xue Guan Bing Za Zhi. 2005 Jun;33(6):522-5. Chinese. PMID: 16053785.</mixed-citation>
      </ref>
      <ref id="B14">
        <label>14</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Yang</surname>
              <given-names>R</given-names>
            </name>
            <name>
              <surname>Xu</surname>
              <given-names>A</given-names>
            </name>
            <name>
              <surname>Pray</surname>
              <given-names>J</given-names>
            </name>
            <name>
              <surname>Hu</surname>
              <given-names>H</given-names>
            </name>
            <name>
              <surname>Jadhao</surname>
              <given-names>S</given-names>
            </name>
            <name>
              <surname>Hansen</surname>
              <given-names>B</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>Cloning of omentin, a new adipocytokine from omental fat tissue in humans</article-title>
          <source>Diabetes</source>
          <year>2003</year>
          <volume>52</volume>
          <supplement>Suppl 1</supplement>
          <fpage>A1</fpage>
          <lpage>A730</lpage>
        </element-citation>
        <mixed-citation>14 Yang R, Xu A, Pray J, Hu H, Jadhao S, Hansen B, et al. Cloning of omentin, a new adipocytokine from omental fat tissue in humans. Diabetes 2003;52(Suppl 1):1-A730.</mixed-citation>
      </ref>
      <ref id="B15">
        <label>15</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Shibata</surname>
              <given-names>R</given-names>
            </name>
            <name>
              <surname>Ouchi</surname>
              <given-names>N</given-names>
            </name>
            <name>
              <surname>Murohara</surname>
              <given-names>T</given-names>
            </name>
          </person-group>
          <article-title>Omentin and cardiovascular disease]</article-title>
          <source>Nihon Yakurigaku Zasshi</source>
          <year>2016</year>
          <month>03</month>
          <volume>147</volume>
          <issue>3</issue>
          <fpage>139</fpage>
          <lpage>142</lpage>
          <comment>Japanese</comment>
          <pub-id pub-id-type="doi">10.1254/fpj.147.139</pub-id>
        </element-citation>
        <mixed-citation>15 Shibata R, Ouchi N, Murohara T. [Omentin and cardiovascular disease]. Nihon Yakurigaku Zasshi. 2016 Mar;147(3):139-42. Japanese. doi: 10.1254/fpj.147.139.</mixed-citation>
      </ref>
      <ref id="B16">
        <label>16</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Du</surname>
              <given-names>Y</given-names>
            </name>
            <name>
              <surname>Ji</surname>
              <given-names>Q</given-names>
            </name>
            <name>
              <surname>Cai</surname>
              <given-names>L</given-names>
            </name>
            <name>
              <surname>Huang</surname>
              <given-names>F</given-names>
            </name>
            <name>
              <surname>Lai</surname>
              <given-names>Y</given-names>
            </name>
            <name>
              <surname>Liu</surname>
              <given-names>Y</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>Association between omentin-1 expression in human epicardial adipose tissue and coronary atherosclerosis</article-title>
          <source>Cardiovasc Diabetol</source>
          <year>2016</year>
          <volume>28</volume>
          <fpage>15</fpage>
          <lpage>90</lpage>
          <pub-id pub-id-type="doi">10.1186/s12933-016-0406-5</pub-id>
        </element-citation>
        <mixed-citation>16 Du Y, Ji Q, Cai L, Huang F, Lai Y, Liu Y, et al. Association between omentin-1 expression in human epicardial adipose tissue and coronary atherosclerosis. Cardiovasc Diabetol. 2016 28;15:90 doi: 10.1186/s12933-016-0406-5.</mixed-citation>
      </ref>
      <ref id="B17">
        <label>17</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Tao</surname>
              <given-names>S</given-names>
            </name>
            <name>
              <surname>Huang</surname>
              <given-names>YQ</given-names>
            </name>
            <name>
              <surname>Cai</surname>
              <given-names>AP</given-names>
            </name>
            <name>
              <surname>Huang</surname>
              <given-names>C</given-names>
            </name>
            <name>
              <surname>Zhang</surname>
              <given-names>Y</given-names>
            </name>
            <name>
              <surname>Tang</surname>
              <given-names>ST</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>Association of Serum Omentin-1 Concentrations with the Presence of Atrial Fibrillation</article-title>
          <source>Med Sci Monit</source>
          <year>2016</year>
          <volume>22</volume>
          <fpage>4749</fpage>
          <lpage>4754</lpage>
          <pub-id pub-id-type="doi">10.12659/msm.898202</pub-id>
        </element-citation>
        <mixed-citation>17 Tao S, Huang YQ, Cai AP, Huang C, Zhang Y, Tang ST, et al. Association of Serum Omentin-1 Concentrations with the Presence of Atrial Fibrillation. Med Sci Monit. 2016;22:4749-4754. doi: 10.12659/msm.898202.</mixed-citation>
      </ref>
      <ref id="B18">
        <label>18</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Mazurek</surname>
              <given-names>T</given-names>
            </name>
            <name>
              <surname>Kiliszek</surname>
              <given-names>M</given-names>
            </name>
            <name>
              <surname>Kobylecka</surname>
              <given-names>M</given-names>
            </name>
            <name>
              <surname>Skubisz-G&#322;uchowska</surname>
              <given-names>J</given-names>
            </name>
            <name>
              <surname>Kochman</surname>
              <given-names>J</given-names>
            </name>
            <name>
              <surname>Filipiak</surname>
              <given-names>K</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>Relation of proinflammatory activity of epicardial adipose tissue to the occurrence of atrial fibrillation</article-title>
          <source>Am J Cardiol</source>
          <year>2014</year>
          <volume>113</volume>
          <issue>9</issue>
          <fpage>1505</fpage>
          <lpage>1508</lpage>
          <pub-id pub-id-type="doi">10.1016/j.amjcard.2014.02.005</pub-id>
        </element-citation>
        <mixed-citation>18 Mazurek T, Kiliszek M, Kobylecka M, Skubisz-G&#322;uchowska J, Kochman J, Filipiak K, et al. Relation of proinflammatory activity of epicardial adipose tissue to the occurrence of atrial fibrillation. Am J Cardiol. 2014;113(9):1505-8. doi: 10.1016/j.amjcard.2014.02.005.</mixed-citation>
      </ref>
      <ref id="B19">
        <label>19</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Guo</surname>
              <given-names>Y</given-names>
            </name>
            <name>
              <surname>Lip</surname>
              <given-names>GY</given-names>
            </name>
            <name>
              <surname>Apostolakis</surname>
              <given-names>S</given-names>
            </name>
          </person-group>
          <article-title>Inflammation in atrial fibrillation</article-title>
          <source>J Am Coll Cardiol</source>
          <year>2012</year>
          <volume>60</volume>
          <issue>22</issue>
          <fpage>2263</fpage>
          <lpage>2270</lpage>
          <pub-id pub-id-type="doi">10.1016/j.jacc.2012.04.063</pub-id>
        </element-citation>
        <mixed-citation>19 Guo Y, Lip GY, Apostolakis S. Inflammation in atrial fibrillation. J Am Coll Cardiol. 2012;60(22):2263-70. doi: 10.1016/j.jacc.2012.04.063.</mixed-citation>
      </ref>
      <ref id="B20">
        <label>20</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Kremen</surname>
              <given-names>J</given-names>
            </name>
            <name>
              <surname>Dolinkova</surname>
              <given-names>M</given-names>
            </name>
            <name>
              <surname>Krajickova</surname>
              <given-names>J</given-names>
            </name>
            <name>
              <surname>Blaha</surname>
              <given-names>J</given-names>
            </name>
            <name>
              <surname>Anderlova</surname>
              <given-names>K</given-names>
            </name>
            <name>
              <surname>Lacinova</surname>
              <given-names>Z</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>Increased subcutaneous and epicardial adipose tissue production of proinflammatory cytokines in cardiac surgery patients: possible role in postoperative insulin resistance</article-title>
          <source>J Clin Endocrinol Metab</source>
          <year>2006</year>
          <volume>91</volume>
          <issue>11</issue>
          <fpage>4620</fpage>
          <lpage>4627</lpage>
          <pub-id pub-id-type="doi">10.1210/jc.2006-1044</pub-id>
        </element-citation>
        <mixed-citation>20 Kremen J, Dolinkova M, Krajickova J, Blaha J, Anderlova K, Lacinova Z, et al. Increased subcutaneous and epicardial adipose tissue production of proinflammatory cytokines in cardiac surgery patients: possible role in postoperative insulin resistance. J Clin Endocrinol Metab. 2006;91(11):4620-7. doi: 10.1210/jc.2006-1044.</mixed-citation>
      </ref>
      <ref id="B21">
        <label>21</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Mazurek</surname>
              <given-names>T</given-names>
            </name>
            <name>
              <surname>Zhang</surname>
              <given-names>L</given-names>
            </name>
            <name>
              <surname>Zalewski</surname>
              <given-names>A</given-names>
            </name>
            <name>
              <surname>Mannion</surname>
              <given-names>JD</given-names>
            </name>
            <name>
              <surname>Diehl</surname>
              <given-names>JT</given-names>
            </name>
            <name>
              <surname>Arafat</surname>
              <given-names>H</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>Human epicardial adipose tissue is a source of inflammatory mediators</article-title>
          <source>Circulation</source>
          <year>2003</year>
          <volume>108</volume>
          <issue>20</issue>
          <fpage>2460</fpage>
          <lpage>2466</lpage>
          <pub-id pub-id-type="doi">10.1161/01.CIR.0000099542.57313.C5</pub-id>
        </element-citation>
        <mixed-citation>21 Mazurek T, Zhang L, Zalewski A, Mannion JD, Diehl JT, Arafat H,et al. Human epicardial adipose tissue is a source of inflammatory mediators. Circulation. 2003;108(20):2460-6 doi: 10.1161/01.CIR.0000099542.57313.C5.</mixed-citation>
      </ref>
      <ref id="B22">
        <label>22</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Fan</surname>
              <given-names>Y</given-names>
            </name>
            <name>
              <surname>Zhao</surname>
              <given-names>X</given-names>
            </name>
            <name>
              <surname>Li</surname>
              <given-names>X</given-names>
            </name>
            <name>
              <surname>Li</surname>
              <given-names>N</given-names>
            </name>
            <name>
              <surname>Hu</surname>
              <given-names>X</given-names>
            </name>
          </person-group>
          <article-title>Cardiac troponin and adverse outcomes in atrial fibrillation: A meta-analysis</article-title>
          <source>Clin Chim Acta</source>
          <year>2018</year>
          <month>02</month>
          <volume>477</volume>
          <fpage>48</fpage>
          <lpage>52</lpage>
          <pub-id pub-id-type="doi">10.1016/j.cca.2017.11.040</pub-id>
        </element-citation>
        <mixed-citation>22 Fan Y, Zhao X, Li X, Li N, Hu X. Cardiac troponin and adverse outcomes in atrial fibrillation: A meta-analysis. Clin Chim Acta. 2018 Feb;477:48-52. doi: 10.1016/j.cca.2017.11.040.</mixed-citation>
      </ref>
      <ref id="B23">
        <label>23</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Roever</surname>
              <given-names>L</given-names>
            </name>
            <name>
              <surname>Resende</surname>
              <given-names>ES</given-names>
            </name>
            <name>
              <surname>Roerver-Borges</surname>
              <given-names>AS</given-names>
            </name>
          </person-group>
          <article-title>Impact of pro-atrial natriuretic peptide in atrial fibrillation and stroke</article-title>
          <source>Eur J Prev Cardiol</source>
          <year>2017</year>
          <month>08</month>
          <volume>24</volume>
          <issue>12</issue>
          <fpage>1239</fpage>
          <lpage>1241</lpage>
          <pub-id pub-id-type="doi">10.1177/2047487317707832</pub-id>
        </element-citation>
        <mixed-citation>23 Roever L, Resende ES, Roerver-Borges AS. Impact of pro-atrial natriuretic peptide in atrial fibrillation and stroke. Eur J Prev Cardiol. 2017 Aug;24(12):1239-1241. doi: 10.1177/2047487317707832.</mixed-citation>
      </ref>
      <ref id="B24">
        <label>24</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Pan</surname>
              <given-names>J</given-names>
            </name>
            <name>
              <surname>Wang</surname>
              <given-names>W</given-names>
            </name>
            <name>
              <surname>Wu</surname>
              <given-names>X</given-names>
            </name>
            <name>
              <surname>Kong</surname>
              <given-names>F</given-names>
            </name>
            <name>
              <surname>Pan</surname>
              <given-names>J</given-names>
            </name>
            <name>
              <surname>Lin</surname>
              <given-names>J</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>Inflammatory cytokines in cardiac pacing patients with atrial fibrillation and asymptomatic atrial fibrillation</article-title>
          <source>Panminerva Med</source>
          <year>2018</year>
          <month>09</month>
          <volume>60</volume>
          <issue>3</issue>
          <fpage>86</fpage>
          <lpage>91</lpage>
          <pub-id pub-id-type="doi">10.23736/S0031-0808.18.03452-3</pub-id>
        </element-citation>
        <mixed-citation>24 Pan J, Wang W, Wu X, Kong F, Pan J, Lin J,et al. Inflammatory cytokines in cardiac pacing patients with atrial fibrillation and asymptomatic atrial fibrillation. Panminerva Med. 2018 Sep;60(3):86-91. doi: 10.23736/S0031-0808.18.03452-3.</mixed-citation>
      </ref>
      <ref id="B25">
        <label>25</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Fain</surname>
              <given-names>JN</given-names>
            </name>
            <name>
              <surname>Sacks</surname>
              <given-names>HS</given-names>
            </name>
            <name>
              <surname>Buehrer</surname>
              <given-names>B</given-names>
            </name>
            <name>
              <surname>Bahouth</surname>
              <given-names>SW</given-names>
            </name>
            <name>
              <surname>Garrett</surname>
              <given-names>E</given-names>
            </name>
            <name>
              <surname>Wolf</surname>
              <given-names>RY</given-names>
            </name>
            <etal/>
          </person-group>
          <article-title>Identification of omentin mRNA in human epicardial adipose tissue: comparison to omentin in subcutaneous, internal mammary artery periadventitial and visceral abdominal depots</article-title>
          <source>Int J Obes (Lond)</source>
          <year>2008</year>
          <volume>32</volume>
          <issue>5</issue>
          <fpage>810</fpage>
          <lpage>815</lpage>
          <pub-id pub-id-type="doi">10.1038/sj.ijo.0803790</pub-id>
        </element-citation>
        <mixed-citation>25 Fain JN, Sacks HS, Buehrer B, Bahouth SW, Garrett E, Wolf RY, et al. Identification of omentin mRNA in human epicardial adipose tissue: comparison to omentin in subcutaneous, internal mammary artery periadventitial and visceral abdominal depots. Int J Obes (Lond). 2008;32(5):810-5. doi: 10.1038/sj.ijo.0803790.</mixed-citation>
      </ref>
      <ref id="B26">
        <label>26</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Bays</surname>
              <given-names>H.E</given-names>
            </name>
          </person-group>
          <article-title>Adiposopathy is "sick fat" a cardiovascular disease?</article-title>
          <source>J Am Coll Cardiol</source>
          <year>2011</year>
          <volume>57</volume>
          <issue>25</issue>
          <fpage>2461</fpage>
          <lpage>2473</lpage>
          <pub-id pub-id-type="doi">10.1016/j.jacc.2011.02.038</pub-id>
        </element-citation>
        <mixed-citation>26 Bays, H.E. Adiposopathy is "sick fat" a cardiovascular disease?. J Am Coll Cardiol. 2011;57(25):2461-2473. doi: 10.1016/j.jacc.2011.02.038.</mixed-citation>
      </ref>
      <ref id="B27">
        <label>27</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name>
              <surname>Yamawaki</surname>
              <given-names>H</given-names>
            </name>
            <name>
              <surname>Kuramoto</surname>
              <given-names>J</given-names>
            </name>
            <name>
              <surname>Kameshima</surname>
              <given-names>S</given-names>
            </name>
            <name>
              <surname>Usui</surname>
              <given-names>T</given-names>
            </name>
            <name>
              <surname>Okada</surname>
              <given-names>M</given-names>
            </name>
            <name>
              <surname>ve Hara</surname>
              <given-names>Y</given-names>
            </name>
          </person-group>
          <article-title>Omentin, a novel adipocytokine inhibits TNF-induced vascular inflammation in human endothelial cells</article-title>
          <source>Biochem Biophys Res Commun</source>
          <year>2011</year>
          <volume>408</volume>
          <issue>2</issue>
          <fpage>339</fpage>
          <lpage>343</lpage>
          <pub-id pub-id-type="doi">10.1016/j.bbrc.2011.04.039</pub-id>
        </element-citation>
        <mixed-citation>27 Yamawaki, H. Kuramoto, J. Kameshima, S. Usui, T. Okada, M. ve Hara Y. Omentin, a novel adipocytokine inhibits TNF-induced vascular inflammation in human endothelial cells. Biochem Biophys Res Commun. 2011;408(2): 339-343. doi: 10.1016/j.bbrc.2011.04.039</mixed-citation>
      </ref>
    </ref-list>
    <fn-group>
      <fn fn-type="other">
        <label>ERRATUM</label>
        <p>
          <bold>Int J Cardiovasc Sci. 2022; 35(4), 530-536</bold>
        </p>
        <p>In Original Article &#8220;Epicardial Fat Tissue Thickness and Omentin in Patients with Atrial Fibrillation&#8221;, with DOI number: <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.36660/ijcs.20200242">https://doi.org/10.36660/ijcs.20200242</ext-link>, published in International Journal of Cardiovascular Science, 35(4). Correct the Orcid of the author Alaeddin Av&#351;ar from "<ext-link ext-link-type="uri" xlink:href="https://orcid.org/0000-0001-7865-3915">https://orcid.org/0000-0001-7865-3915</ext-link>" to "<ext-link ext-link-type="uri" xlink:href="https://orcid.org/0000-0003-0759-0165">https://orcid.org/0000-0003-0759-0165</ext-link>".</p>
      </fn>
    </fn-group>
  </back>
</article>
