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  <front>
    <journal-meta>
      <journal-id journal-id-type="nlm-ta">Arq Bras Cardiol</journal-id>
      <journal-id journal-id-type="publisher-id">abc</journal-id>
      <journal-title-group>
        <journal-title>Arquivos Brasileiros de Cardiologia</journal-title>
        <abbrev-journal-title abbrev-type="publisher">Arq. Bras. Cardiol.</abbrev-journal-title>
      </journal-title-group>
      <issn pub-type="ppub">0066-782X</issn>
      <issn pub-type="epub">1678-4170</issn>
      <publisher>
        <publisher-name>Sociedade Brasileira de Cardiologia - SBC</publisher-name>
      </publisher>
    </journal-meta>
    <article-meta>
      <article-id specific-use="scielo-v3" pub-id-type="publisher-id">MZwJY38qz9QtxXr5d5fHvfs</article-id>
      <article-id specific-use="scielo-v2" pub-id-type="publisher-id">S0066-782X2021000900146</article-id>
      <article-id pub-id-type="publisher-id">abc.20201076</article-id>
      <article-id pub-id-type="doi">10.36660/abc.20201076</article-id>
      <article-categories>
        <subj-group subj-group-type="heading">
          <subject>Carta Cient&#237;fica</subject>
        </subj-group>
      </article-categories>
      <title-group>
        <article-title>Teofilina para o Al&#237;vio da Dispneia Relacionada ao Ticagrelor</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">0000-0001-5469-4579</contrib-id>
          <name>
            <surname>Sanmartin-Fernandez</surname>
            <given-names>Marcelo</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">
            <sup>1</sup>
          </xref>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Zamorano</surname>
            <given-names>Jose Luis</given-names>
          </name>
          <xref ref-type="aff" rid="aff1">
            <sup>1</sup>
          </xref>
        </contrib>
      </contrib-group>
      <aff id="aff1">
        <label>1</label>
        <institution content-type="orgname">Hospital Universitario Ramon y Cajal</institution>
        <addr-line>
          <named-content content-type="city">Madri</named-content>
        </addr-line>
        <country country="ES">Espanha</country>
        <institution content-type="original">Hospital Universitario Ramon y Cajal - Servi&#231;o de Cardiologia,Madri - Espanha</institution>
      </aff>
      <author-notes>
        <corresp id="c01"><bold>Correspond&#234;ncia: Marcelo Sanmartin Fernandez &#8226; </bold>Servicio de Cardiologia - Hospital Universitario Ramon y Cajal - Carretera de Colmenar Viejo 9100, 28034. Madri &#8211; Espanha. E-mail: <email>msanfer@me.com</email> </corresp>
        <fn fn-type="con">
          <p>Contribui&#231;&#227;o dos autores</p>
          <p>Concep&#231;&#227;o e desenho da pesquisa, Obten&#231;&#227;o de dados, An&#225;lise estat&#237;stica e Reda&#231;&#227;o do manuscrito: Sanmartin-Fernandez M; An&#225;lise e interpreta&#231;&#227;o dos dados e Revis&#227;o cr&#237;tica do manuscrito quanto ao conte&#250;do intelectual importante: Sanmartin-Fernandez M, Zamorano JL.</p>
        </fn>
        <fn fn-type="conflict">
          <p>Potencial conflito de interesse</p>
          <p>N&#227;o h&#225; conflito com o presente artigo</p>
        </fn>
      </author-notes>
      <pub-date date-type="pub" publication-format="electronic">
        <day>26</day>
        <month>07</month>
        <year>2021</year>
      </pub-date>
      <pub-date publication-format="electronic" date-type="collection">
        <month>07</month>
        <year>2021</year>
      </pub-date>
      <volume>117</volume>
      <issue>1</issue>
      <fpage>146</fpage>
      <lpage>148</lpage>
      <history>
        <date date-type="received">
          <day>05</day>
          <month>10</month>
          <year>2020</year>
        </date>
        <date date-type="rev-recd">
          <day>17</day>
          <month>01</month>
          <year>2021</year>
        </date>
        <date date-type="accepted">
          <day>24</day>
          <month>02</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>
      <kwd-group xml:lang="pt">
        <kwd>Ticagrelor</kwd>
        <kwd>Teofilina</kwd>
        <kwd>S&#237;ndrome Coronariana Aguda</kwd>
      </kwd-group>
      <counts>
        <fig-count count="2"/>
        <table-count count="2"/>
        <equation-count count="0"/>
        <ref-count count="7"/>
        <page-count count="3"/>
      </counts>
    </article-meta>
  </front>
  <body>
    <sec sec-type="intro">
      <title>Introdu&#231;&#227;o</title>
      <p>A dispneia &#233; uma das rea&#231;&#245;es mais comuns ao ticagrelor, levando &#224; sua descontinua&#231;&#227;o prematura em 15 a 20% dos pacientes.<sup><xref rid="B1" ref-type="bibr">1</xref></sup> O mecanismo n&#227;o &#233; claro, mas acredita-se que esteja relacionado ao aumento da concentra&#231;&#227;o de adenosina no tecido ou &#224; inibi&#231;&#227;o reversiva e direta dos receptores P2Y<sub>12 </sub>nos neur&#244;nios sensoriais.<sup><xref rid="B2" ref-type="bibr">2</xref></sup></p>
      <p>A teofilina tem sido usada como broncodilatador desde 1922, e seus efeitos aparentam ser parcialmente mediados por meio do bloqueio n&#227;o-seletivo dos receptores de adenosina.<sup><xref rid="B3" ref-type="bibr">3</xref></sup></p>
      <p>A hip&#243;tese dos autores &#233; a de que a teofilina poderia atenuar a dispneia causada pela administra&#231;&#227;o do ticagrelor, e reportaram sua experi&#234;ncia cl&#237;nica inicial com 10 pacientes.</p>
    </sec>
    <sec sec-type="methods">
      <title>M&#233;todos</title>
      <p>Os crit&#233;rios de inclus&#227;o foram: 1) presen&#231;a de dispneia moderada ou grave ap&#243;s pelo menos uma dose de ticagrelor, n&#227;o explicada por causas card&#237;acas ou pulmonares; 2) Acompanhamento em uma unidade de terapia intensiva do cora&#231;&#227;o; 3) Concord&#226;ncia formal do paciente pelo uso compassivo da teofilina.</p>
      <p>Uma &#250;nica dose de 200 mg de teofilina foi administrada por infus&#227;o salina, dilu&#237;da em 100ml-0,9%, ap&#243;s 20 minutos. Todos os pacientes fizeram um exame cl&#237;nico completo, eletrocardiograma e ecocardiograma antes da administra&#231;&#227;o do medicamento, al&#233;m do monitoramento cont&#237;nuo da satura&#231;&#227;o do O<sub>2</sub>, eletrocardiograma e medi&#231;&#227;o de press&#227;o arterial n&#227;o-invasiva. O eletrocardiograma e o ecocardiograma foram realizados &#224; beira do leito, com a &#250;nica inten&#231;&#227;o de excluir causas alternativas da dispneia, como isquemia continua, insufici&#234;ncia card&#237;aca ou broncoespasmo.</p>
      <p>A avalia&#231;&#227;o dos sintomas e o exame f&#237;sico foram realizados antes e imediatamente ap&#243;s a infus&#227;o. Cada paciente forneceu autoriza&#231;&#227;o espec&#237;fica e verbal para o uso compassivo da teofilina nesta situa&#231;&#227;o. Todos os pacientes deram consentimento para publica&#231;&#227;o de dados an&#244;nimos.</p>
    </sec>
    <sec sec-type="results">
      <title>Resultados</title>
      <p>De janeiro de 2017 a dezembro de 2019, 1.437 pacientes foram internados no hospital com s&#237;ndromes coronarianas agudas, dos quais 29 (3,1%) apresentaram dispneia moderada a grave durante a hospitaliza&#231;&#227;o, presumidamente relacionada &#224; administra&#231;&#227;o do ticagrelor. Um total de 10 pacientes foram tratados empiricamente com 200 mg de teofilina intravenosa, j&#225; que seus sintomas foram considerados suficientemente consider&#225;veis para requerer manobras terap&#234;uticas (<xref rid="t1" ref-type="table">Tabela 1</xref>). A idade mediana foi 75 anos (intervalo interquartil 61-80 anos), seis pacientes tiveram infartos do mioc&#225;rdio pr&#233;vios, cinco tinham diabetes mellitus tipo 2, quatro eram fumantes e nenhum tinha doen&#231;a pulmonar obstrutiva cr&#244;nica pr&#233;via. Em seis pacientes, os sintomas come&#231;aram ap&#243;s a administra&#231;&#227;o oral de uma dose de 180 mg em bolus, incluindo dois pacientes que j&#225; tinham recebido o clopidogrel.</p>
      <p>
        <table-wrap id="t1">
          <label>Tabela 1</label>
          <caption>
            <title>&#8211; Caracter&#237;sticas dos pacientes. Todos os pacientes receberam ticagrelor como agente antiplaquet&#225;rio inicial, com uma dose oral de 180 mg em bolus, exceto os pacientes #8 e #9, que receberam clopidogrel antes e depois mudaram para o ticagrelor 90 mg bid.</title>
          </caption>
          <table frame="hsides" rules="groups">
            <colgroup width="10%">
              <col/>
              <col/>
              <col/>
              <col/>
              <col/>
              <col/>
              <col/>
              <col/>
              <col/>
              <col/>
            </colgroup>
            <thead>
              <tr>
                <th align="left">Paciente</th>
                <th>Idade (anos)</th>
                <th>Peso (kg)</th>
                <th>Sexo</th>
                <th>S&#237;ndrome coronariana aguda</th>
                <th>Satura&#231;&#227;o O<sub>2</sub> de base (%)</th>
                <th>Inibidor P2Y<sub>12</sub> inicial</th>
                <th>In&#237;cio da dispneia (horas depos da dose de 180 mg em bolus)</th>
                <th>Ameniza&#231;&#227;o da dispneia</th>
                <th>Libera&#231;&#227;o do inibidor P2Y<sub>12</sub></th>
              </tr>
            </thead>
            <tbody>
              <tr>
                <td>1</td>
                <td align="center">56</td>
                <td align="center">75</td>
                <td align="center">Masculino</td>
                <td align="center">STEMI</td>
                <td align="center">98</td>
                <td align="center">Ticagrelor</td>
                <td align="center">48</td>
                <td align="center">Completa</td>
                <td align="center">Prasugrel</td>
              </tr>
              <tr>
                <td>2</td>
                <td align="center">80</td>
                <td align="center">54</td>
                <td align="center">Masculino</td>
                <td align="center">STEMI</td>
                <td align="center">99</td>
                <td align="center">Ticagrelor</td>
                <td align="center">36</td>
                <td align="center">Parcial</td>
                <td align="center">Clopidogrel</td>
              </tr>
              <tr>
                <td>3</td>
                <td align="center">76</td>
                <td align="center">80</td>
                <td align="center">Feminino</td>
                <td align="center">STEMI</td>
                <td align="center">93</td>
                <td align="center">Ticagrelor</td>
                <td align="center">2</td>
                <td align="center">Completa</td>
                <td align="center">Clopidogrel</td>
              </tr>
              <tr>
                <td>4</td>
                <td align="center">57</td>
                <td align="center">83</td>
                <td align="center">Masculino</td>
                <td align="center">STEMI</td>
                <td align="center">99</td>
                <td align="center">Ticagrelor</td>
                <td align="center">40</td>
                <td align="center">Completa</td>
                <td align="center">Prasugrel</td>
              </tr>
              <tr>
                <td>5</td>
                <td align="center">78</td>
                <td align="center">68</td>
                <td align="center">Masculino</td>
                <td align="center">NSTEMI</td>
                <td align="center">97</td>
                <td align="center">Ticagrelor</td>
                <td align="center">2</td>
                <td align="center">Completa</td>
                <td align="center">Clopidogrel</td>
              </tr>
              <tr>
                <td>6</td>
                <td align="center">48</td>
                <td align="center">85</td>
                <td align="center">Masculino</td>
                <td align="center">STEMI</td>
                <td align="center">95</td>
                <td align="center">Ticagrelor</td>
                <td align="center">12</td>
                <td align="center">Parcial</td>
                <td align="center">Clopidogrel</td>
              </tr>
              <tr>
                <td>7</td>
                <td align="center">71</td>
                <td align="center">100</td>
                <td align="center">Masculino</td>
                <td align="center">NSTEMI</td>
                <td align="center">97</td>
                <td align="center">Ticagrelor</td>
                <td align="center">2</td>
                <td align="center">Completa</td>
                <td align="center">Prasugrel</td>
              </tr>
              <tr>
                <td>8</td>
                <td align="center">82</td>
                <td align="center">75</td>
                <td align="center">Masculino</td>
                <td align="center">STEMI</td>
                <td align="center">95</td>
                <td align="center">Clopidogrel</td>
                <td align="center">2</td>
                <td align="center">Completa</td>
                <td align="center">Clopidogrel</td>
              </tr>
              <tr>
                <td>9</td>
                <td align="center">73</td>
                <td align="center">68</td>
                <td align="center">Feminino</td>
                <td align="center">NSTEMI</td>
                <td align="center">98</td>
                <td align="center">Clopidogrel</td>
                <td align="center">3</td>
                <td align="center">Completa</td>
                <td align="center">Clopidogrel</td>
              </tr>
              <tr>
                <td>10</td>
                <td align="center">83</td>
                <td align="center">72</td>
                <td align="center">Masculino</td>
                <td align="center">NSTEMI</td>
                <td align="center">97</td>
                <td align="center">Ticagrelor</td>
                <td align="center">1</td>
                <td align="center">Completa</td>
                <td align="center">Clopidogrel</td>
              </tr>
            </tbody>
          </table>
        </table-wrap>
      </p>
      <p>Ap&#243;s a administra&#231;&#227;o da teofilina, todos os pacientes reportaram a melhora na falta de ar, embora dois pacientes tenham reportado somente um al&#237;vio parcial. Em um dos pacientes com resposta parcial, uma segunda dose de 200 mg em bolus foi administrada uma hora depois, com a completa resolu&#231;&#227;o dos sintomas. Todos os pacientes foram tratados com um diferente inibidor P2Y<sub>12 </sub>ap&#243;s o evento. Um paciente (paciente #3) recebeu tratamento de teofilina de 200-mg bid, oralmente, junto com o ticagrelor, antes de os autores decidirem mudar para o clopidogrel previamente &#224; alta. Nenhum paciente apresentou trombose de stent ou outros eventos tromb&#243;ticos durante a hospitaliza&#231;&#227;o. Um paciente de 82 anos, com infarto do mioc&#225;rdio sem eleva&#231;&#227;o do ST, tratado de forma conservadora e com alta ap&#243;s o clopidogrel, foi readmitido depois de 20 dias com outro infarto do mioc&#225;rdio e choque cardiog&#234;nico, e morreu apesar da revasculariza&#231;&#227;o ter sido bem-sucedida.</p>
    </sec>
    <sec sec-type="discussion">
      <title>Discuss&#227;o</title>
      <p>Pela primeira vez, os efeitos favor&#225;veis da teofilina s&#227;o reportados na resolu&#231;&#227;o da dispneia relacionada ao uso de ticagrelor em pacientes com s&#237;ndromes coronarianas agudas. Embora esta experi&#234;ncia cl&#237;nica inicial tenha sido muito positiva, esses achados devem ser considerados como explorat&#243;rios devido &#224; falta de um grupo controle.</p>
      <p>Embora os mecanismos por tr&#225;s do al&#237;vio da dispneia possam ser multifatoriais, esses achados preliminares fortalecem a hip&#243;tese da adenosina para a dispneia causada pela inibi&#231;&#227;o reversiva dos receptores P2Y<sub>12 </sub>(<xref rid="f01" ref-type="fig">Figura 1</xref>). Em um estudo duplo-cego, controlado com placebo, Wittfeldt et al.<sup><xref rid="B5" ref-type="bibr">5</xref></sup>demonstraram que uma dose de 5 mg/kg de teofilina amenizou os efeitos de uma infus&#227;o incremental de adenosina em 40 volunt&#225;rios tratados com 180 mg de ticagrelor na velocidade do fluxo coron&#225;rio e sintomas de dispneia, medidos pela escala de Borg. Os resultados apresentados estendem esses achados &#224; popula&#231;&#227;o de pacientes com s&#237;ndromes coronarianas agudas, e usando uma dose menor de teofilina.</p>
      <p>
        <fig id="f01">
          <label>Figura 1</label>
          <caption>
            <title>&#8211;<italic> Les&#227;o do tecido e hip&#243;xia estimulam a forma&#231;&#227;o de adenosina no espa&#231;o extracelular pela degrada&#231;&#227;o da adenosina trifosfato (ATP) e da adenosina difosfato (ADP) por meio da a&#231;&#227;o de nucleotidases como CD39 e CD73. A r&#225;pida degrada&#231;&#227;o da adenosina intracelular ocorre pela adenosina quinase e pela adenosina deaminase, depois de serem transportadas com os transportadores de nucleos&#237;deos independentes de s&#243;dio (ENT). Como o ticagrelor inibe a membrana dos ENT, a adenosina se acumula no espa&#231;o extracelular, levando a efeitos mediados pela adenosina, como a estimula&#231;&#227;o dos neuroreceptores no pulm&#227;o, provavelmente ao se ligarem aos receptores da adenosina (A1, A2A, A2B, e A3), e, mais tarde, a intera&#231;&#227;o com o adenilato ciclase e a forma&#231;&#227;o do monofostafo c&#237;clico de adenosina (cAMP). O bloqueio da teofilina em receptores da adenosina provavelmente explica a inibi&#231;&#227;o dos efeitos mediados pela adenosina.<sup>4</sup></italic></title>
          </caption>
          <graphic xlink:href="1678-4170-abc-117-01-0146-01076-gf01.tif"/></fig>
      </p>
      <p>A teofilina &#233; derivada da xantina, muito usada no tratamento da asma por muitas d&#233;cadas, embora seus mecanismos moleculares precisos de a&#231;&#227;o sejam incertos.<sup><xref rid="B3" ref-type="bibr">3</xref>,<xref rid="B6" ref-type="bibr">6</xref></sup> Entre os mecanismos terap&#234;uticos propostos, foi demonstrado que a teofilina promove a inibi&#231;&#227;o n&#227;o-seletiva da fosfodiesterase, o antagonismo dos receptores da adenosina e seus efeitos anti-inflamat&#243;rios, como a libera&#231;&#227;o da interleucina-10, a preven&#231;&#227;o da transloca&#231;&#227;o do fator de transcri&#231;&#227;o do fator nuclear kappa B (FN-kB), e a ativa&#231;&#227;o das histonas desacetilases, que melhoram o efeito anti-inflamat&#243;rio dos corticosteroides. Os autores acreditam que a ameniza&#231;&#227;o da dispneia induzida pelo ticagrelor se deva ao bloqueio n&#227;o-seletivo dos receptores de adenosina, prevenindo a forma&#231;&#227;o intracelular de monofosfato c&#237;clico de adenosina (<xref rid="f01" ref-type="fig">Figura 1</xref>) no tecido intersticial do pulm&#227;o, considerando que n&#227;o h&#225; broncoespasmo ou atividade inflamat&#243;ria local neste cen&#225;rio cl&#237;nico.</p>
      <p>N&#227;o houve efeitos adversos da administra&#231;&#227;o da teofilina, mas as doses selecionadas foram menores do que aquelas recomendadas para asma aguda (5 mg/kg). N&#227;o h&#225; relatos de resposta pr&#243;-tromb&#243;tica &#224; teofilina. Na verdade, alguns estudos sugerem maior inibi&#231;&#227;o de plaquetas com esta droga.<sup><xref rid="B7" ref-type="bibr">7</xref></sup></p>
      <p>Embora esses achados requeiram confirma&#231;&#227;o por meio de ensaios cl&#237;nicos, uma combina&#231;&#227;o fixa de teofilina e ticagrelor poderia representar um importante passo para evitar frequentes descontinua&#231;&#245;es do tratamento com ticagrelor.</p>
    </sec>
  </body>
  <back>
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      <fn fn-type="other">
        <p>Vincula&#231;&#227;o acad&#234;mica</p>
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      <fn>
        <p>N&#227;o h&#225; vincula&#231;&#227;o deste estudo a programas de p&#243;s-gradua&#231;&#227;o.</p>
      </fn>
      <fn fn-type="other">
        <p>Aprova&#231;&#227;o &#233;tica e consentimento informado</p>
      </fn>
      <fn>
        <p>Este artigo n&#227;o cont&#233;m estudos com humanos ou animais realizados por nenhum dos autores.</p>
      </fn>
      <fn fn-type="supported-by">
        <p>Fontes de financiamento</p>
        <p>O presente estudo n&#227;o teve fontes de financiamento externas.</p>
      </fn>
    </fn-group>
  </back>
  <sub-article article-type="translation" id="TRen" xml:lang="en">
    <front-stub>
      <article-categories>
        <subj-group subj-group-type="heading">
          <subject>Research Letter</subject>
        </subj-group>
      </article-categories>
      <title-group>
        <article-title>Theophylline for Attenuating Ticagrelor-Related Dyspnea</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">0000-0001-5469-4579</contrib-id>
          <name>
            <surname>Sanmartin-Fernandez</surname>
            <given-names>Marcelo</given-names>
          </name>
          <xref ref-type="aff" rid="aff1001">
            <sup>1</sup>
          </xref>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Zamorano</surname>
            <given-names>Jose Luis</given-names>
          </name>
          <xref ref-type="aff" rid="aff1001">
            <sup>1</sup>
          </xref>
        </contrib>
      </contrib-group>
      <aff id="aff1001">
        <label>1</label>
        <country country="ES">Spain</country>
        <institution content-type="original">Hospital Universitario Ramon y Cajal - Servi&#231;o de Cardiologia, Madri - Spain</institution>
      </aff>
      <author-notes>
        <corresp id="c01001"><bold>Mailing Address: Marcelo Sanmartin Fernandez &#8226; </bold>Servicio de Cardiologia - Hospital Universitario Ramon y Cajal - Carretera de Colmenar Viejo 9100, 28034. Madri &#8211; Spain. E-mail: msanfer@me.com </corresp>
        <fn fn-type="con">
          <p>Author Contributions</p>
          <p>Conception and design of the research, Acquisition of data, Statistical analysis e Writing of the manuscript: Sanmartin-Fernandez M; Analysis and interpretation of the data and Critical revision of the manuscript for intellectual content: Sanmartin-Fernandez M, Zamorano JL.</p>
        </fn>
        <fn fn-type="conflict">
          <p>Potential Conflict of Interest</p>
          <p>No potential conflict of interest relevant to this article was reported.</p>
        </fn>
      </author-notes>
      <kwd-group xml:lang="en">
        <kwd>Ticagrelor</kwd>
        <kwd>Theophylline</kwd>
        <kwd>Acute Coronary Syndrome</kwd>
      </kwd-group>
    </front-stub>
    <body>
      <sec sec-type="intro">
        <title>Introduction</title>
        <p>Dyspnea is one of the most frequent adverse reaction of ticagrelor, leading to premature discontinuation in 15-20% of the patients.<sup><xref rid="B1" ref-type="bibr">1</xref></sup> The mechanism is unclear, but it is thought to be related to increased tissue adenosine concentrations or to the direct reversible inhibition of P2Y<sub>12</sub> receptors on sensory neurons.<sup><xref rid="B2" ref-type="bibr">2</xref></sup></p>
        <p>Theophylline has been used as a bronchodilator since 1922, and its effects seem to be partly mediated through nonselective adenosine receptors blockade.<sup><xref rid="B3" ref-type="bibr">3</xref></sup></p>
        <p>The authors hypothesized that theophylline could attenuate the dyspnea caused by ticagrelor administration and reported their initial clinical experience with 10 patients.</p>
      </sec>
      <sec sec-type="methods">
        <title>Methods</title>
        <p>Inclusion criteria were: 1) Presence of moderate or severe dyspnea after at least one dose of ticagrelor, not explained by cardiac or pulmonary causes; 2) Follow-up in a Cardiac Intensive Care unit; 3) Patient&#8217;s formal agreement to the compassionate use of theophylline.</p>
        <p>A single dose of 200-mg theophylline was administered, diluted in 100 ml-0.9% saline infusion over 20 min. All patients had a thorough clinical exam, electrocardiogram and echocardiogram performed before drug administration, and continuous monitoring of O<sub>2</sub> saturation, electrocardiogram, and noninvasive blood pressure. Electrocardiogram and echocardiograms were performed at bedside, with the sole intention of excluding alternative causes of dyspnea such as ongoing ischemia, heart failure, or bronchospasm.</p>
        <p>Assessment of symptoms and physical exam was performed before and immediately after infusion. Each patient provided specific verbal authorization for compassionate use of theophylline in this situation. All patients granted consent for publication of anonymous data.</p>
      </sec>
      <sec sec-type="results">
        <title>Results</title>
        <p>From January/2017 to December/2019, 1,437 patients were admitted to the hospital with acute coronary syndromes, of whom 29 (3.1%) had moderate to severe dyspnea during admission presumably related to ticagrelor administration. A total of 10 patients were empirically treated with 200-mg IV theophylline because their symptoms were deemed to be sufficiently important to require therapeutic maneuvers (<xref rid="t1001" ref-type="table">Table 1</xref>). The median age was 75 years (IQ range 61-80 years), six patients had previous myocardial infarctions, five patients had type 2 diabetes mellitus, four patients were smokers, and none had previous pulmonary obstructive chronic disease. In six patients, symptoms begun after orally receiving the 180-mg bolus dose, including two patients with previous administration of clopidogrel.</p>
        <p>
          <table-wrap id="t1001">
            <label>Table 1</label>
            <caption>
              <title>&#8211; Patients&#8217; characteristics. All patients received ticagrelor as the initial antiplatelet agent with an oral bolus dose of 180 mg, except patients #8 and #9, who received clopidogrel first and then switched to ticagrelor 90 mg bid</title>
            </caption>
            <table frame="hsides" rules="groups">
              <colgroup width="10%">
                <col/>
                <col/>
                <col/>
                <col/>
                <col/>
                <col/>
                <col/>
                <col/>
                <col/>
                <col/>
              </colgroup>
              <thead>
                <tr>
                  <th align="left">Patient</th>
                  <th>Age (years)</th>
                  <th>Weight (kg)</th>
                  <th>Sex</th>
                  <th>Acute Coronary Syndrome</th>
                  <th>Baseline O<sub>2</sub> Saturation (%)</th>
                  <th>Initial P2Y<sub>12</sub> inhibitor</th>
                  <th>Dyspnea onset (hours after 180 mg bolus dose)</th>
                  <th>Attenuation of dyspnea</th>
                  <th>Discharge P2Y<sub>12</sub> inhibitor</th>
                </tr>
              </thead>
              <tbody>
                <tr>
                  <td>1</td>
                  <td align="center">56</td>
                  <td align="center">75</td>
                  <td align="center">Male</td>
                  <td align="center">STEMI</td>
                  <td align="center">98</td>
                  <td align="center">Ticagrelor</td>
                  <td align="center">48</td>
                  <td align="center">Complete</td>
                  <td align="center">Prasugrel</td>
                </tr>
                <tr>
                  <td>2</td>
                  <td align="center">80</td>
                  <td align="center">54</td>
                  <td align="center">Male</td>
                  <td align="center">STEMI</td>
                  <td align="center">99</td>
                  <td align="center">Ticagrelor</td>
                  <td align="center">36</td>
                  <td align="center">Partial</td>
                  <td align="center">Clopidogrel</td>
                </tr>
                <tr>
                  <td>3</td>
                  <td align="center">76</td>
                  <td align="center">80</td>
                  <td align="center">Female</td>
                  <td align="center">STEMI</td>
                  <td align="center">93</td>
                  <td align="center">Ticagrelor</td>
                  <td align="center">2</td>
                  <td align="center">Complete</td>
                  <td align="center">Clopidogrel</td>
                </tr>
                <tr>
                  <td>4</td>
                  <td align="center">57</td>
                  <td align="center">83</td>
                  <td align="center">Male</td>
                  <td align="center">STEMI</td>
                  <td align="center">99</td>
                  <td align="center">Ticagrelor</td>
                  <td align="center">40</td>
                  <td align="center">Complete</td>
                  <td align="center">Prasugrel</td>
                </tr>
                <tr>
                  <td>5</td>
                  <td align="center">78</td>
                  <td align="center">68</td>
                  <td align="center">Male</td>
                  <td align="center">NSTEMI</td>
                  <td align="center">97</td>
                  <td align="center">Ticagrelor</td>
                  <td align="center">2</td>
                  <td align="center">Complete</td>
                  <td align="center">Clopidogrel</td>
                </tr>
                <tr>
                  <td>6</td>
                  <td align="center">48</td>
                  <td align="center">85</td>
                  <td align="center">Male</td>
                  <td align="center">STEMI</td>
                  <td align="center">95</td>
                  <td align="center">Ticagrelor</td>
                  <td align="center">12</td>
                  <td align="center">Partial</td>
                  <td align="center">Clopidogrel</td>
                </tr>
                <tr>
                  <td>7</td>
                  <td align="center">71</td>
                  <td align="center">100</td>
                  <td align="center">Male</td>
                  <td align="center">NSTEMI</td>
                  <td align="center">97</td>
                  <td align="center">Ticagrelor</td>
                  <td align="center">2</td>
                  <td align="center">Complete</td>
                  <td align="center">Prasugrel</td>
                </tr>
                <tr>
                  <td>8</td>
                  <td align="center">82</td>
                  <td align="center">75</td>
                  <td align="center">Male</td>
                  <td align="center">STEMI</td>
                  <td align="center">95</td>
                  <td align="center">Clopidogrel</td>
                  <td align="center">2</td>
                  <td align="center">Complete</td>
                  <td align="center">Clopidogrel</td>
                </tr>
                <tr>
                  <td>9</td>
                  <td align="center">73</td>
                  <td align="center">68</td>
                  <td align="center">Female</td>
                  <td align="center">NSTEMI</td>
                  <td align="center">98</td>
                  <td align="center">Clopidogrel</td>
                  <td align="center">3</td>
                  <td align="center">Complete</td>
                  <td align="center">Clopidogrel</td>
                </tr>
                <tr>
                  <td>10</td>
                  <td align="center">83</td>
                  <td align="center">72</td>
                  <td align="center">Male</td>
                  <td align="center">NSTEMI</td>
                  <td align="center">97</td>
                  <td align="center">Ticagrelor</td>
                  <td align="center">1</td>
                  <td align="center">Complete</td>
                  <td align="center">Clopidogrel</td>
                </tr>
              </tbody>
            </table>
          </table-wrap>
        </p>
        <p>After theophylline administration, all patients reported attenuation of the shortness of breath, although two patients only reported a partial relief. In one of the patients with partial response, a second 200-mg bolus dose was administered one hour later with complete resolution of symptoms. All patients were treated with a different P2Y<sub>12</sub> inhibitor after the event. One patient (patient #3) further received 200-mg bid theophylline treatment, orally, along with ticagrelor, before the authors decided to switch to clopidogrel prior to discharge. No patient presented stent thrombosis or other thrombotic events during admission. An 82-year-old patient, with non-ST elevation myocardial infarction conservatively treated and discharged with clopidogrel, was readmitted after 20 days with a repeated myocardial infarction and cardiogenic shock and died despite successful revascularization.</p>
      </sec>
      <sec sec-type="discussion">
        <title>Discussion</title>
        <p>For the first time, the favorable effects of theophylline are reported in the resolution of ticagrelor-related dyspnea in patients with acute coronary syndromes. Although this initial clinical experience was strikingly positive, these findings should be considered exploratory due to the lack of a control group.</p>
        <p>Although mechanisms behind dyspnea alleviation may be multifactorial, these preliminary findings represent a strong case for the adenosine hypothesis of dyspnea caused by reversible P2Y<sub>12</sub> inhibition (<xref rid="f01001" ref-type="fig">Figure 1</xref>). In an elegant double-blind, placebo-controlled study, Wittfeldt et al.<sup><xref rid="B5" ref-type="bibr">5</xref></sup>showed that a 5-mg/kg dose of theophylline attenuated the effects of an incremental adenosine infusion of 40 volunteers treated with 180-mg ticagrelor on coronary blood flow velocity and dyspnea symptoms, measured by the Borg scale. The present results extend these findings to a population of patients with acute coronary syndromes and using a smaller dose of theophylline.</p>
        <p>
          <fig id="f01001">
            <label>Figure 1</label>
            <caption>
              <title>
                <italic>Tissue damage and hypoxia stimulates adenosine formation in extracellular space by degradation of adenosine triphosphate (ATP) and adenosine diphosphate (ADP) through the action of nucleotidases such as CD39 and CD73. Rapid degradation of adenosine intracellularly occurs by adenosine kinase and adenosine deaminase, after being taken up through sodium-independent nucleoside transporters (equilibrative nucleoside transporter (ENT)). As ticagrelor inhibits the ENT membrane, adenosine accumulates in the extracellular space, leading to adenosine-mediated effects, such as stimulation of lung neuroreceptors, probably through binding to adenosine membrane receptors (A1, A2A, A2B, and A3), and later to interaction with adenylyl cyclase and formation of cyclic adenosine monophosphate (cAMP). Theophylline blockade of adenosine receptors probably explains inhibition of adenosine-mediated effects.<sup>4</sup></italic>
              </title>
            </caption>
            <graphic xlink:href="1678-4170-abc-117-01-0146-01076-gf01-en.tif"/></fig>
        </p>
        <p>Theophylline is a xanthine derivative that has been commonly used in the treatment of asthma for several decades, although its precise molecular mechanism of action is uncertain.<sup><xref rid="B3" ref-type="bibr">3</xref>,<xref rid="B6" ref-type="bibr">6</xref></sup> Among the proposed therapeutical mechanisms, it has been shown that theophylline promotes nonselective phosphodiesterase inhibition, antagonism of adenosine receptors and anti-inflammatory effects, such as interleukin-10 release, prevention of translocation of nuclear factor kappa B (NF-&#120523;B) transcription factor, and activation of histone deacetylases, which enhances the anti-inflammatory effect of corticosteroids. The authors believe that the attenuation of ticagrelor-induced dyspnea occurs through nonselective blockade of adenosine membrane receptors, preventing intracellular formation of cyclic adenosine monophosphate (<xref rid="f01001" ref-type="fig">Figure 1</xref>) in the interstitial lung tissue, considering that there is no objective bronchospasm or local inflammatory activity in this clinical setting.</p>
        <p>There were no adverse effects from the theophylline administration, but the selected doses were smaller than those recommended for acute asthma (5 mg/kg). There are no reports of a prothrombotic response to theophylline. In fact, some studies suggest enhanced platelet inhibition with this drug.<sup><xref rid="B7" ref-type="bibr">7</xref></sup></p>
        <p>Although the present findings require confirmation in clinical trials, a fixed combination of theophylline and ticagrelor could represent an important step for avoiding frequent discontinuations of ticagrelor treatment.</p>
      </sec>
    </body>
    <back>
      <fn-group>
        <fn fn-type="other">
          <p>Study Association</p>
          <p>This study is not associated with any thesis or dissertation work.</p>
        </fn>
        <fn fn-type="other">
          <p>Ethics approval and consent to participate</p>
          <p>This article does not contain any studies with human participants or animals performed by any of the authors.</p>
        </fn>
      </fn-group>
      <fn-group>
        <fn fn-type="supported-by">
          <p>Sources of Funding</p>
          <p>There were no external funding sources for this study.</p>
        </fn>
      </fn-group>
    </back>
  </sub-article>
</article>
