<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Publishing DTD v1.1 20151215//EN" "https://jats.nlm.nih.gov/publishing/1.1/JATS-journalpublishing1.dtd">
<article xmlns:xlink="http://www.w3.org/1999/xlink" specific-use="sps-1.9" dtd-version="1.1" xml:lang="pt" article-type="rapid-communication">
  <front>
    <journal-meta>
      <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-loc>S&#227;o Paulo, SP, Brazil</publisher-loc>
      </publisher>
    </journal-meta>
    <article-meta>
      <article-id pub-id-type="publisher-id" specific-use="scielo-v3">3WyJ3jPbcvTWXwM5cx8CmJR</article-id>
      <article-id pub-id-type="other">00010</article-id>
      <article-id pub-id-type="publisher-id" specific-use="scielo-v2">S0066-782X2007001300010</article-id>
      <article-id pub-id-type="publisher-id" specific-use="scielo-v1">S0066-782X(07)08900110</article-id>
      <article-id pub-id-type="doi">10.1590/S0066-782X2007001300010</article-id>
      <article-categories>
        <subj-group subj-group-type="heading">
          <subject>Comunica&#231;&#227;o Breve</subject>
        </subj-group>
      </article-categories>
      <title-group>
        <article-title>Betabloqueador t&#243;pico pode determinar resultados inconclusivos no ecocardiograma sob estresse com dobutamina em pacientes com glaucoma</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <name>
            <surname>Cordovil</surname>
            <given-names>Adriana</given-names>
          </name>
          <xref ref-type="aff" rid="aff01"/>
          <xref ref-type="aff" rid="aff02"/>
          <xref ref-type="aff" rid="aff03"/>
          <xref ref-type="aff" rid="aff04"/>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Matos</surname>
            <given-names>Fernando Q.</given-names>
          </name>
          <xref ref-type="aff" rid="aff01"/>
          <xref ref-type="aff" rid="aff02"/>
          <xref ref-type="aff" rid="aff03"/>
          <xref ref-type="aff" rid="aff04"/>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Campos Filho</surname>
            <given-names>Orlando</given-names>
          </name>
          <xref ref-type="aff" rid="aff01"/>
          <xref ref-type="aff" rid="aff02"/>
          <xref ref-type="aff" rid="aff03"/>
          <xref ref-type="aff" rid="aff04"/>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Paranhos Jr.</surname>
            <given-names>Augusto</given-names>
          </name>
          <xref ref-type="aff" rid="aff01"/>
          <xref ref-type="aff" rid="aff02"/>
          <xref ref-type="aff" rid="aff03"/>
          <xref ref-type="aff" rid="aff04"/>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Rodrigues</surname>
            <given-names>Ana Clara T.</given-names>
          </name>
          <xref ref-type="aff" rid="aff01"/>
          <xref ref-type="aff" rid="aff02"/>
          <xref ref-type="aff" rid="aff03"/>
          <xref ref-type="aff" rid="aff04"/>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Albernaz</surname>
            <given-names>M&#225;rcia V.</given-names>
          </name>
          <xref ref-type="aff" rid="aff01"/>
          <xref ref-type="aff" rid="aff02"/>
          <xref ref-type="aff" rid="aff03"/>
          <xref ref-type="aff" rid="aff04"/>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Paola</surname>
            <given-names>Angelo A. V. de</given-names>
          </name>
          <xref ref-type="aff" rid="aff01"/>
          <xref ref-type="aff" rid="aff02"/>
          <xref ref-type="aff" rid="aff03"/>
          <xref ref-type="aff" rid="aff04"/>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Carvalho</surname>
            <given-names>Antonio Carlos C.</given-names>
          </name>
          <xref ref-type="aff" rid="aff01"/>
          <xref ref-type="aff" rid="aff02"/>
          <xref ref-type="aff" rid="aff03"/>
          <xref ref-type="aff" rid="aff04"/>
        </contrib>
      </contrib-group>
      <aff id="aff03">
        <institution content-type="orgname">Hospital S&#237;rio-Liban&#234;s</institution>
      </aff>
      <aff id="aff04">
        <addr-line>
          <named-content content-type="city">S&#227;o Paulo</named-content>
          <named-content content-type="state">S&#227;o Paulo</named-content>
        </addr-line>
        <institution content-type="orgname">Universidade de S&#227;o Paulo</institution>
        <institution content-type="orgdiv1">FM </institution>
        <institution content-type="orgdiv2">Hospital das Cl&#237;nicas</institution>
        <country country="BR">Brazil</country>
      </aff>
      <aff id="aff01">
        <addr-line>
          <named-content content-type="state">S&#227;o Paulo</named-content>
        </addr-line>
        <institution content-type="orgname">Universidade Federal de S&#227;o Paulo</institution>
        <institution content-type="orgdiv1">EPM </institution>
        <country country="BR">Brazil</country>
      </aff>
      <aff id="aff02">
        <institution content-type="orgname">Hospital Israelita Albert Einstein</institution>
      </aff>
      <pub-date date-type="collection" publication-format="electronic">
        <month>07</month>
        <year>2007</year>
      </pub-date>
      <volume>89</volume>
      <issue>1</issue>
      <fpage>60</fpage>
      <lpage>63</lpage>
      <history>
        <date date-type="accepted">
          <day>08</day>
          <month>02</month>
          <year>2007</year>
        </date>
        <date date-type="received">
          <day>06</day>
          <month>09</month>
          <year>2006</year>
        </date>
      </history>
      <permissions>
        <license license-type="open-access" xlink:href="http://creativecommons.org/licenses/by-nc/4.0/" xml:lang="en">
          <license-p>This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.</license-p>
        </license>
      </permissions>
      <abstract>
        <p>O ecocardiograma sob estresse com dobutamina &#233; um m&#233;todo bem estabelecido para avaliar doen&#231;a arterial coron&#225;ria, cuja sensibilidade tem sido potencializada pela adi&#231;&#227;o de atropina no final do protocolo. Indiv&#237;duos com glaucoma, doen&#231;a com alta preval&#234;ncia em pacientes cardiopatas com mais de 40 anos, n&#227;o podem se beneficiar do uso de atropina por ser contra-indicada neste grupo. Al&#233;m disso, estes indiv&#237;duos s&#227;o tratados freq&#252;entemente com betabloqueadores t&#243;picos (col&#237;rios), que podem exercer efeitos sist&#234;micos diminuindo a freq&#252;&#234;ncia card&#237;aca, press&#227;o arterial e capacidade pulmonar. O objetivo do nosso trabalho foi verificar se a ocorr&#234;ncia de um poss&#237;vel efeito sist&#234;mico causado por estes col&#237;rios, causando baixa resposta cronotr&#243;pica, poderia determinar resultados inconclusivos no ecocardiograma sob estresse pela dobutamina nestes pacientes com glaucoma.</p>
      </abstract>
      <kwd-group xml:lang="pt" kwd-group-type="author-generated">
        <kwd>Dobutamina</kwd>
        <kwd>ecocardiograma</kwd>
        <kwd>beta-antagonistas adren&#233;rgicos</kwd>
        <kwd>glaucoma</kwd>
      </kwd-group>
      <pub-date publication-format="electronic" date-type="pub">
        <day>28</day>
        <month>08</month>
        <year>2007</year>
      </pub-date>
    </article-meta>
  </front>
  <body>
    <p>
      <bold>COMUNICA&#199;&#195;O BREVE</bold>
    </p>
    <p>
      <bold>Betabloqueador t&#243;pico pode determinar resultados inconclusivos no ecocardiograma sob estresse com dobutamina em pacientes com glaucoma</bold>
    </p>
    <p>
      <bold>Topical betablocker use can result in inconclusive dobutamine stress echocardiography in patients with glaucoma</bold>
    </p>
    <p>
      <bold>Adriana Cordovil; Fernando Q. Matos; Orlando Campos Filho; Augusto Paranhos Jr.; Ana Clara T. Rodrigues; M&#225;rcia V. Albernaz; Angelo A. V. de Paola; Antonio Carlos C. Carvalho</bold>
    </p>
    <p>Universidade Federal de S&#227;o Paulo - Unifesp/EPM, Hospital Israelita Albert Einstein, Hospital S&#237;rio-Liban&#234;s, Instituto do Cora&#231;&#227;o do Hospital das Cl&#237;nicas - FMUSP - S&#227;o Paulo, SP - Brasil</p>
    <p>
      <xref ref-type="corresp" rid="back">Correspond&#234;ncia</xref>
    </p>
    <p>
      <bold>RESUMO</bold>
    </p>
    <p>O ecocardiograma sob estresse com dobutamina &#233; um m&#233;todo bem estabelecido para avaliar doen&#231;a arterial coron&#225;ria, cuja sensibilidade tem sido potencializada pela adi&#231;&#227;o de atropina no final do protocolo. Indiv&#237;duos com glaucoma, doen&#231;a com alta preval&#234;ncia em pacientes cardiopatas com mais de 40 anos, n&#227;o podem se beneficiar do uso de atropina por ser contra-indicada neste grupo. Al&#233;m disso, estes indiv&#237;duos s&#227;o tratados freq&#252;entemente com betabloqueadores t&#243;picos (col&#237;rios), que podem exercer efeitos sist&#234;micos diminuindo a freq&#252;&#234;ncia card&#237;aca, press&#227;o arterial e capacidade pulmonar. O objetivo do nosso trabalho foi verificar se a ocorr&#234;ncia de um poss&#237;vel efeito sist&#234;mico causado por estes col&#237;rios, causando baixa resposta cronotr&#243;pica, poderia determinar resultados inconclusivos no ecocardiograma sob estresse pela dobutamina nestes pacientes com glaucoma.</p>
    <p><bold>Palavras-chave:</bold> Dobutamina, ecocardiograma, beta-antagonistas adren&#233;rgicos, glaucoma.</p>
    <p>
      <bold>SUMMARY</bold>
    </p>
    <p>Dobutamine stress echocardiography is a well-established method to assess coronary artery disease, of which sensitivity has been enhanced by adding atropine at the end of the protocol. Individuals with glaucoma, a disease with a high prevalence in patients with cardiac diseases older than 40 years, cannot benefit from the use of atropine as it is contraindicated for this group of patients. Additionally, these individuals are often treated with topical betablockers (eye drops), which can have systemic effects by decreasing cardiac frequency, blood pressure and pulmonary capacity. The aim of our study was to verify whether a possible systemic effect caused by the use of these eye drops, yielding a low chronotropic response, could result in inconclusive dobutamine stress echocardiography in patients with glaucoma.</p>
    <p><bold>Key words:</bold> Dobutamine; echocardiography; adrenergic beta-antagonists; glaucoma.</p>
    <p>
      <bold>Introdu&#231;&#227;o</bold>
    </p>
    <p>O ecocardiograma sob estresse pela dobutamina-atropina &#233; um m&#233;todo diagn&#243;stico para doen&#231;a arterial coronariana amplamente difundido e bem estabelecido<sup>1</sup>. &#201; de conhecimento que betabloqueadores utilizados na forma sist&#234;mica podem interferir nos resultados dos exames diminuindo a resposta cronotr&#243;pica e reduzindo a acur&#225;cia diagn&#243;stica do m&#233;todo<sup>2</sup>. A adi&#231;&#227;o de atropina no final do protocolo de infus&#227;o da dobutamina aumenta a freq&#252;&#234;ncia card&#237;aca e, conseq&#252;entemente, a sensibilidade do teste, especialmente em pacientes que utilizam betabloqueadores orais<sup>3,4</sup>, e tem sido utilizada sistematicamente, exceto em pacientes com prostatismo e com glaucoma de &#226;ngulo fechado, contra-indica&#231;&#245;es ao seu uso<sup>5</sup>.</p>
    <p>O glaucoma &#233; uma doen&#231;a com alta preval&#234;ncia ap&#243;s os 40 anos, &#233; comumente observado em pacientes com doen&#231;a cardiovascular e seu tratamento consiste em uso t&#243;pico de col&#237;rios &#224; base de v&#225;rios f&#225;rmacos, entre eles betabloqueadores<sup>6</sup>. Estudos anteriores j&#225; registraram que betabloqueadores t&#243;picos podem exercer efeitos sist&#234;micos, diminuindo a freq&#252;&#234;ncia card&#237;aca, press&#227;o arterial e a capacidade pulmonar, e s&#227;o potencialmente capazes de atenuar o incremento da freq&#252;&#234;ncia card&#237;aca induzida pelo esfor&#231;o f&#237;sico em esteira ergom&#233;trica<sup>7,8</sup>. At&#233; o momento, n&#227;o h&#225; refer&#234;ncias sobre a influ&#234;ncia dessa medica&#231;&#227;o no ecocardiograma sob estresse com dobutamina.</p>
    <p>O objetivo do nosso trabalho foi verificar se a ocorr&#234;ncia de um poss&#237;vel efeito sist&#234;mico de betabloqueadores t&#243;picos causando baixa resposta cronotr&#243;pica poderia determinar resultados inconclusivos no ecocardiograma sob estresse pela dobutamina em pacientes com glaucoma<sup>9</sup>.</p>
    <p>
      <bold>M&#233;todos</bold>
    </p>
    <p>Estudamos 42 pacientes que foram submetidos ao ecocardiograma sob estresse farmacol&#243;gico para diagn&#243;stico ou avalia&#231;&#227;o de doen&#231;a arterial coronariana conhecida. Dos 42 pacientes, 21 tinham glaucoma. Os outros 21 pacientes constitu&#237;ram o grupo controle (GC). Entre os 21 pacientes com glaucoma, 14 faziam uso de betabloqueador t&#243;pico (BB) e sete faziam uso de col&#237;rios a base de outros medicamentos (NB). Os pacientes foram pareados pela idade, e nenhum fazia uso de betabloqueador oral no momento do exame. Aqueles que faziam uso pr&#233;vio dessa medica&#231;&#227;o foram orientados a interromp&#234;-la sete dias antes do teste.</p>
    <p>Todos os pacientes foram submetidos &#224; avalia&#231;&#227;o da freq&#252;&#234;ncia card&#237;aca e press&#227;o arterial em repouso a cada tr&#234;s minutos durante e ap&#243;s a infus&#227;o. De acordo com as normas padronizadas, foi realizado o exame ecocardiogr&#225;fico completo com captura em sistema digital das imagens em repouso e no pico da infus&#227;o<sup>5</sup>. A dobutamina foi administrada em infus&#227;o cont&#237;nua, em doses escalares de 10, 20, 30, at&#233; 40 <italic>u</italic>g/kg/min. A atropina, entretanto, n&#227;o foi administrada em nenhum paciente. Os objetivos do exame foram atingir a freq&#252;&#234;ncia card&#237;aca subm&#225;xima (85% da freq&#252;&#234;ncia m&#225;xima), ou o final do protocolo com a dose m&#225;xima de infus&#227;o, ou a presen&#231;a de isquemia observada pela altera&#231;&#227;o de contratilidade mioc&#225;rdica regional. O teste foi interrompido previamente aos objetivos caso houvesse arritmia ventricular grave, presen&#231;a de supradesnivelamento do segmento ST &gt; 2 mm ao eletrocardiograma, aumento da press&#227;o sist&#243;lica acima de 210 mmHg ou diast&#243;lica acima de 110 mmHg, ou hipotens&#227;o acentuada. O teste foi considerado inconclusivo quando n&#227;o atingida a freq&#252;&#234;ncia card&#237;aca alvo ou quando houvesse interrup&#231;&#227;o precoce do teste pela presen&#231;a de efeitos colaterais limitantes como arritmia, hipertens&#227;o e suas conseq&#252;&#234;ncias, como cefal&#233;ia, n&#225;usea, v&#244;mitos.</p>
    <p><italic>An&#225;lise estat&#237;stica</italic> - As vari&#225;veis qualitativas foram determinadas em freq&#252;&#234;ncia absoluta e relativa, enquanto as quantitativas pela m&#233;dia e desvio-padr&#227;o. As compara&#231;&#245;es entre os grupos foram feitas pelo teste de qui-quadrado ou Fisher. Foram utilizados os testes ANOVA para vari&#226;ncias homog&#234;neas, e Tukey para compara&#231;&#245;es m&#250;ltiplas. Compara&#231;&#245;es entre os grupos em momentos diferentes foram feitas pela an&#225;lise univariada. O valor de <italic>p</italic> &lt; 0,05 foi considerado significante.</p>
    <p>
      <bold>Resultados</bold>
    </p>
    <p>N&#227;o houve diferen&#231;a estat&#237;stica entre os grupos em rela&#231;&#227;o &#224;s caracter&#237;sticas demogr&#225;ficas como sexo, presen&#231;a de hipertens&#227;o, diabetes, tabagismo, dislipidemia e hist&#243;ria pregressa de infarto agudo do mioc&#225;rdio (<xref ref-type="table" rid="t1">tab. 1</xref>). Todos os pacientes foram pareados pela idade.</p>
    <table-wrap id="t1">
      <graphic xlink:href="1678-4170-abc-89-01-0060-00010-gt01.jpg"/></table-wrap>
    <p>A an&#225;lise da press&#227;o arterial sist&#243;lica revelou que os grupos apresentaram press&#245;es semelhantes no repouso e que o aumento da press&#227;o no pico da infus&#227;o ocorreu de forma equivalente, sem diferen&#231;a estat&#237;stica entre eles (<italic>p</italic>=ns).</p>
    <p>Apesar de o BB ter apresentado press&#227;o diast&#243;lica mais alta tanto no repouso quanto no pico em rela&#231;&#227;o aos outros grupos, essa diferen&#231;a n&#227;o foi estatisticamente significativa (<italic>p</italic> =ns).</p>
    <p>Observou-se, ainda, que a freq&#252;&#234;ncia card&#237;aca em repouso foi similar em todos os grupos (<italic>p</italic>=ns), mas no pico da infus&#227;o foi significativamente menor no BB do que nos outros grupos (<italic>p</italic> &lt;0,05). Esse resultado confirma o efeito sist&#234;mico do betabloqueador no incremento da freq&#252;&#234;ncia card&#237;aca induzida pela dobutamina. Os dados sobre press&#227;o e freq&#252;&#234;ncia card&#237;aca est&#227;o resumidos na <xref ref-type="table" rid="t2">tabela 2</xref>.</p>
    <p content-type="asset">
      <table-wrap id="t2">
        <graphic xlink:href="1678-4170-abc-89-01-0060-00010-gt02.jpg"/></table-wrap>
    </p>
    <p>Todos os testes do NB e do GC foram conclusivos. Entretanto, entre os 14 pacientes do BB, observaram-se apenas tr&#234;s testes conclusivos. Onze pacientes apresentaram testes inconclusivos pela falta de resposta cronotr&#243;pica isolada (n=1), e/ou associada a efeitos colaterais limitantes como hipertens&#227;o e cefal&#233;ia (n=8) ou arritmia ventricular (n=2) (<xref ref-type="table" rid="t2">tab. 2</xref>).</p>
    <p>A fra&#231;&#227;o de eje&#231;&#227;o foi equivalente nos tr&#234;s grupos, sem diferen&#231;a estat&#237;stica entre eles (<italic>p</italic>=ns) (<xref ref-type="table" rid="t1">tab. 1</xref>). Entre os 31 testes conclusivos, 11 foram positivos para isquemia e 20 negativos para isquemia. Dos 11 testes positivos, sete foram no GC, tr&#234;s do NB e um do BB (<italic>p</italic>=ns) (<xref ref-type="table" rid="t2">tab. 2</xref>).</p>
    <p>
      <bold>Discuss&#227;o</bold>
    </p>
    <p>Nossos resultados demonstram que o uso de betabloqueadores t&#243;picos em pacientes com glaucoma pode interferir nos resultados do ecocardiograma sob estresse com dobutamina, resultando em uma resposta cronotr&#243;pica ineficaz e, conseq&#252;entemente, em testes inconclusivos. Esse efeito j&#225; havia sido observado por autores que utilizaram o teste ergom&#233;trico como agente estressor<sup>8,9</sup>. Entretanto, n&#227;o h&#225; nenhum trabalho indicando o mesmo efeito em pacientes submetidos ao ecocardiograma sob estresse farmacol&#243;gico.</p>
    <p>&#201; de nosso conhecimento que o uso de betabloqueadores sist&#234;micos pode interferir nos resultados do ecocardiograma sob estresse farmacol&#243;gico, impedindo o aumento da freq&#252;&#234;ncia card&#237;aca, causando hipertens&#227;o arterial e cefal&#233;ia durante o teste<sup>2</sup>. O acr&#233;scimo de atropina ao protocolo de infus&#227;o de dobutamina diminuiu o n&#250;mero de testes inconclusivos, e recentemente tem sido realizado cada vez mais precocemente<sup>10</sup>. Entretanto, desde a proposta de sua inser&#231;&#227;o ao protocolo original e do estabelecimento de suas contra-indica&#231;&#245;es, n&#227;o houve relato na literatura sobre os resultados do ecocardiograma sob estresse farmacol&#243;gico em pacientes com glaucoma, que n&#227;o puderam se beneficiar do uso da atropina. Provavelmente isso se deve ao fato de que muitos pacientes cardiopatas e com glaucoma sejam submetidos a esse exame fazendo uso de betabloqueador oral, e a falta de resposta cronotr&#243;pica seja atribu&#237;da a essa forma, e n&#227;o &#224; forma t&#243;pica. A realiza&#231;&#227;o do nosso trabalho s&#243; foi poss&#237;vel porque suspendemos sistematicamente o uso de betabloqueadores orais, excluindo qualquer possibilidade de "contamina&#231;&#227;o" da amostra.</p>
    <p><italic>Import&#226;ncia cl&#237;nica -</italic> Apesar de a coexist&#234;ncia de doen&#231;a respirat&#243;ria ou cardiovascular ser uma contra-indica&#231;&#227;o ao uso de betabloqueadores t&#243;picos, na pr&#225;tica cl&#237;nica comumente m&#233;dicos cardiologistas n&#227;o valorizam esses efeitos e n&#227;o est&#227;o atentos &#224; poss&#237;veis intera&#231;&#245;es medicamentosas entre esses col&#237;rios e outros f&#225;rmacos. O uso desse tipo de col&#237;rio em nosso meio &#233; muito difundido em raz&#227;o do baixo custo. Portanto, a escolha do tipo de tratamento para a cardiopatia desses pacientes deveria ser realizada com cautela, considerando-se o tipo de col&#237;rio que utilizam. Al&#233;m do mais, possivelmente outros testes diagn&#243;sticos para doen&#231;a arterial coronariana podem apresentar resultados inconclusivos, aumentando o custo do tratamento. Outra quest&#227;o a ser discutida diz respeito &#224; contra-indica&#231;&#227;o da atropina exclusivamente para pacientes com glaucoma de &#226;ngulo fechado. No nosso meio, freq&#252;entemente o paciente n&#227;o tem conhecimento do tipo de glaucoma que o acomete e a comunica&#231;&#227;o com o oftalmologista n&#227;o ocorre. Pelo nosso conhecimento, nos laborat&#243;rios de ecocardiografia a atropina &#233; sistematicamente contra-indicada para pacientes com qualquer tipo de glaucoma. N&#227;o sabemos se o melhor conhecimento sobre essa afec&#231;&#227;o evitaria a contra-indica&#231;&#227;o da atropina, t&#227;o &#250;til para a realiza&#231;&#227;o efetiva do teste. Al&#233;m disso, &#233; necess&#225;rio que seja estudada a possibilidade de suspender o betabloqueador t&#243;pico antes da realiza&#231;&#227;o do ecocardiograma sob estresse e possivelmente de qualquer teste diagn&#243;stico em que seja necess&#225;rio o aumento da freq&#252;&#234;ncia card&#237;aca.</p>
    <p><italic>Limita&#231;&#245;es do estudo -</italic> A amostra de pacientes estudada &#233; pequena, portanto n&#227;o foi poss&#237;vel estabelecer se o efeito delet&#233;rio do betabloqueador t&#243;pico &#233; dose-dependente e/ou tempo-dependente. Al&#233;m disso, em raz&#227;o do formato do estudo n&#227;o sabemos se a suspens&#227;o dessa medica&#231;&#227;o estaria indicada na realiza&#231;&#227;o do ecocardiograma sob estresse pela dobutamina. A coexist&#234;ncia de glaucoma e doen&#231;a arterial coronariana em faixas et&#225;rias mais avan&#231;adas &#233; um fato relevante que justifica a continuidade dessa pesquisa. Portanto, &#233; necess&#225;rio que a amostra seja ampliada, e que se considere a substitui&#231;&#227;o do betabloqueador t&#243;pico por outras medica&#231;&#245;es.</p>
    <p>
      <bold>Agradecimento</bold>
    </p>
    <p>&#192; FAPESP pelo apoio recebido para a realiza&#231;&#227;o deste trabalho.</p>
    <p>
      <bold>Potencial Conflito de Interesses</bold>
    </p>
    <p>Declaro n&#227;o haver conflitos de interesses pertinentes.</p>
    <p>
      <bold>Fontes de Financiamento</bold>
    </p>
    <p>Esse estudo foi financiado com recursos pr&#243;prios do investigador.</p>
    <p>
      <bold>Vincula&#231;&#227;o Acad&#234;mica &#224; P&#243;s-Gradua&#231;&#227;o</bold>
    </p>
    <p>N&#227;o h&#225; vincula&#231;&#227;o desse estudo a programas de p&#243;s-gradua&#231;&#227;o.</p>
    <p>
      <fn id="back" fn-type="corresp">
        <label>
          <bold>Correspond&#234;ncia:</bold>
        </label>
        <p> Adriana Cordovil </p>
        <p> Av. Padre Pereira de Andrade, 545/193D </p>
        <p> 05469-000 - S&#227;o Paulo, SP - Brasil </p>
        <p> E-mail: </p>
        <p>
          <email xlink:href="acordovil@cardiol.br">acordovil@cardiol.br</email>
        </p>
      </fn>
    </p>
    <p>Artigo recebido em 06/09/06; artigo revisado recebido em 05/02/07; aceito em 08/02/07.</p>
  </body>
  <back>
    <ref-list>
      <ref id="B1">
        <mixed-citation>1. Picano E. Stress echocardiography. 4th ed. Heidelberg: Springer-Verlag; 2003.</mixed-citation>
        <element-citation publication-type="book">
          <source>Stress echocardiography</source>
          <date>
            <year>2003</year>
          </date>
          <person-group person-group-type="author">
            <name>
              <surname>Picano</surname>
              <given-names>E</given-names>
            </name>
          </person-group>
        </element-citation>
      </ref>
      <ref id="B2">
        <mixed-citation>2. San Rom&#225;n JA, Vilacosta I, Roll&#225;n MJ, Castillo A, Sanchez-Harguindey L, Avil&#233;s FF. Impact of betablockers on dobutamine-atropine stress echocardiography. Echocardiography. 1996; 13 (4): 373-9.</mixed-citation>
        <element-citation publication-type="journal">
          <article-title>Impact of betablockers on dobutamine-atropine stress echocardiography</article-title>
          <source>Echocardiography</source>
          <date>
            <year>1996</year>
          </date>
          <fpage>373</fpage>
          <lpage>9</lpage>
          <issue>4</issue>
          <volume>13</volume>
          <person-group person-group-type="author">
            <name>
              <surname>San Rom&#225;n</surname>
              <given-names>JA</given-names>
            </name>
            <name>
              <surname>Vilacosta</surname>
              <given-names>I</given-names>
            </name>
            <name>
              <surname>Roll&#225;n</surname>
              <given-names>MJ</given-names>
            </name>
            <name>
              <surname>Castillo</surname>
              <given-names>A</given-names>
            </name>
            <name>
              <surname>Sanchez-Harguindey</surname>
              <given-names>L</given-names>
            </name>
            <name>
              <surname>Avil&#233;s</surname>
              <given-names>FF</given-names>
            </name>
          </person-group>
        </element-citation>
      </ref>
      <ref id="B3">
        <mixed-citation>3. McNeill AJ, Fioretti P, El-Said ES, Salustri A, Forster T, Roelandt J. Enhanced sensitivity for detection of coronary artery disease by addition of atropine to dobutamine stress echocardiography. Am J Cardiol. 1992; 70: 41-6.</mixed-citation>
        <element-citation publication-type="journal">
          <article-title>Enhanced sensitivity for detection of coronary artery disease by addition of atropine to dobutamine stress echocardiography</article-title>
          <source>Am J Cardiol.</source>
          <date>
            <year>1992</year>
          </date>
          <fpage>41</fpage>
          <lpage>6</lpage>
          <volume>70</volume>
          <person-group person-group-type="author">
            <name>
              <surname>McNeill</surname>
              <given-names>AJ</given-names>
            </name>
            <name>
              <surname>Fioretti</surname>
              <given-names>P</given-names>
            </name>
            <name>
              <surname>El-Said</surname>
              <given-names>ES</given-names>
            </name>
            <name>
              <surname>Salustri</surname>
              <given-names>A</given-names>
            </name>
            <name>
              <surname>Forster</surname>
              <given-names>T</given-names>
            </name>
            <name>
              <surname>Roelandt</surname>
              <given-names>J</given-names>
            </name>
          </person-group>
        </element-citation>
      </ref>
      <ref id="B4">
        <mixed-citation>4. Das G. Therapeutic review- Cardiac effects of atropine in man: an update. Int J Clin Pharm. 1989; 27 (10): 473-7.</mixed-citation>
        <element-citation publication-type="journal">
          <article-title>Therapeutic review- Cardiac effects of atropine in man: an update</article-title>
          <source>Int J Clin Pharm.</source>
          <date>
            <year>1989</year>
          </date>
          <fpage>473</fpage>
          <lpage>7</lpage>
          <issue>10</issue>
          <volume>27</volume>
          <person-group person-group-type="author">
            <name>
              <surname>Das</surname>
              <given-names>G</given-names>
            </name>
          </person-group>
        </element-citation>
      </ref>
      <ref id="B5">
        <mixed-citation>5. Stress echocardiography: recommendations for performance and interpretation of stress echocardiography. Stress Echocardiography Task force of the Nomenclature and standard commitee of the American Society of Echocardiography. J Am Soc Echocardiogr. 1998; 11: 97-104.</mixed-citation>
        <element-citation publication-type="journal">
          <article-title>Stress echocardiography: recommendations for performance and interpretation of stress echocardiography: Stress Echocardiography Task force of the Nomenclature and standard commitee of the American Society of Echocardiography</article-title>
          <source>J Am Soc Echocardiogr</source>
          <date>
            <year>1998</year>
          </date>
          <fpage>97</fpage>
          <lpage>104</lpage>
          <volume>11</volume>
        </element-citation>
      </ref>
      <ref id="B6">
        <mixed-citation>6. Frishman WH, Kowalski M, Nagnur S, Warshafsky S, Sica D. Cardiovascular considerations in using topical, oral, and intravenous drugs for the treatment of glaucoma and ocular hypertension: focus on beta-adrenergic blockade. Heart Dis. 2001; 3 (6): 386-97.</mixed-citation>
        <element-citation publication-type="journal">
          <article-title>Cardiovascular considerations in using topical, oral, and intravenous drugs for the treatment of glaucoma and ocular hypertension: focus on beta-adrenergic blockade</article-title>
          <source>Heart Dis.</source>
          <date>
            <year>2001</year>
          </date>
          <fpage>386</fpage>
          <lpage>97</lpage>
          <issue>6</issue>
          <volume>3</volume>
          <person-group person-group-type="author">
            <name>
              <surname>Frishman</surname>
              <given-names>WH</given-names>
            </name>
            <name>
              <surname>Kowalski</surname>
              <given-names>M</given-names>
            </name>
            <name>
              <surname>Nagnur</surname>
              <given-names>S</given-names>
            </name>
            <name>
              <surname>Warshafsky</surname>
              <given-names>S</given-names>
            </name>
            <name>
              <surname>Sica</surname>
              <given-names>D</given-names>
            </name>
          </person-group>
        </element-citation>
      </ref>
      <ref id="B7">
        <mixed-citation>7. Stewart WC, Stewart JA, Crockett S, Kubilus C, Brown A, Shams N. Comparison of the cardiovascular effects of unoprostone 0.15%, timolol 0,5% and placebo in healthy adults during exercise using a treadmill test. Acta Ophthalmol Scand. 2002; 80: 272-6.</mixed-citation>
        <element-citation publication-type="journal">
          <article-title>Comparison of the cardiovascular effects of unoprostone 0.15%, timolol 0,5% and placebo in healthy adults during exercise using a treadmill test</article-title>
          <source>Acta Ophthalmol Scand</source>
          <date>
            <year>2002</year>
          </date>
          <fpage>272</fpage>
          <lpage>6</lpage>
          <volume>80</volume>
          <person-group person-group-type="author">
            <name>
              <surname>Stewart</surname>
              <given-names>WC</given-names>
            </name>
            <name>
              <surname>Stewart</surname>
              <given-names>JA</given-names>
            </name>
            <name>
              <surname>Crockett</surname>
              <given-names>S</given-names>
            </name>
            <name>
              <surname>Kubilus</surname>
              <given-names>C</given-names>
            </name>
            <name>
              <surname>Brown</surname>
              <given-names>A</given-names>
            </name>
            <name>
              <surname>Shams</surname>
              <given-names>N</given-names>
            </name>
          </person-group>
        </element-citation>
      </ref>
      <ref id="B8">
        <mixed-citation>8. Bacon PJ, Brazier DJ, Smith R, Smith SE. Cardiovascular responses to metipranolol and timolol eyedrops in healthy volunteers. Br J Clin Pharmacol. 1989; 27 (1): 1-5.</mixed-citation>
        <element-citation publication-type="journal">
          <article-title>Cardiovascular responses to metipranolol and timolol eyedrops in healthy volunteers</article-title>
          <source>Br J Clin Pharmacol</source>
          <date>
            <year>1989</year>
          </date>
          <fpage>1</fpage>
          <lpage>5</lpage>
          <issue>1</issue>
          <volume>27</volume>
          <person-group person-group-type="author">
            <name>
              <surname>Bacon</surname>
              <given-names>PJ</given-names>
            </name>
            <name>
              <surname>Brazier</surname>
              <given-names>DJ</given-names>
            </name>
            <name>
              <surname>Smith</surname>
              <given-names>R</given-names>
            </name>
            <name>
              <surname>Smith</surname>
              <given-names>SE</given-names>
            </name>
          </person-group>
        </element-citation>
      </ref>
      <ref id="B9">
        <mixed-citation>9. Sica DA. Current concepts of pharmacotherapy in hypertension-ophthalmically administered beta blockers and their cardiopulmonary effects. J Clin Hypertens. (Greenwich) 2001; 3 (3): 175-8.</mixed-citation>
        <element-citation publication-type="journal">
          <article-title>Current concepts of pharmacotherapy in hypertension-ophthalmically administered beta blockers and their cardiopulmonary effects</article-title>
          <source>J Clin Hypertens. (Greenwich)</source>
          <date>
            <year>2001</year>
          </date>
          <fpage>175</fpage>
          <lpage>8</lpage>
          <issue>3</issue>
          <volume>3</volume>
          <person-group person-group-type="author">
            <name>
              <surname>Sica</surname>
              <given-names>DA</given-names>
            </name>
          </person-group>
        </element-citation>
      </ref>
      <ref id="B10">
        <mixed-citation>10. Tsutsui JM,    Osorio AF, Lario FA, Fernandes DR, Sodr&#233; G, Andrade JL, et al. Comparison    of safety and efficacy of the early injection of atropine during dobutamine    stress echocardiography with the conventional protocol. Am J Cardiol. 2004;    94: 1367-72.</mixed-citation>
        <element-citation publication-type="journal">
          <article-title>Comparison of safety and efficacy of the early injection of atropine during dobutamine stress echocardiography with the conventional protocol</article-title>
          <source>Am J Cardiol</source>
          <date>
            <year>2004</year>
          </date>
          <fpage>1367</fpage>
          <lpage>72</lpage>
          <volume>94</volume>
          <person-group person-group-type="author">
            <name>
              <surname>Tsutsui</surname>
              <given-names>JM</given-names>
            </name>
            <name>
              <surname>Osorio</surname>
              <given-names>AF</given-names>
            </name>
            <name>
              <surname>Lario</surname>
              <given-names>FA</given-names>
            </name>
            <name>
              <surname>Fernandes</surname>
              <given-names>DR</given-names>
            </name>
            <name>
              <surname>Sodr&#233;</surname>
              <given-names>G</given-names>
            </name>
            <name>
              <surname>Andrade</surname>
              <given-names>JL</given-names>
            </name>
          </person-group>
        </element-citation>
      </ref>
    </ref-list>
  </back>
  <sub-article article-type="translation" id="TRen" xml:lang="en">
    <front-stub>
      <article-categories>
        <subj-group subj-group-type="heading">
          <subject>Brief Comments</subject>
        </subj-group>
      </article-categories>
      <title-group>
        <article-title xml:lang="en">Topical betablocker use can result in inconclusive dobutamine stress echocardiography in patients with glaucoma</article-title>
      </title-group>
      <abstract xml:lang="en">
        <p>Dobutamine stress echocardiography is a well-established method to assess coronary artery disease, of which sensitivity has been enhanced by adding atropine at the end of the protocol. Individuals with glaucoma, a disease with a high prevalence in patients with cardiac diseases older than 40 years, cannot benefit from the use of atropine as it is contraindicated for this group of patients. Additionally, these individuals are often treated with topical betablockers (eye drops), which can have systemic effects by decreasing cardiac frequency, blood pressure and pulmonary capacity. The aim of our study was to verify whether a possible systemic effect caused by the use of these eye drops, yielding a low chronotropic response, could result in inconclusive dobutamine stress echocardiography in patients with glaucoma.</p>
      </abstract>
      <kwd-group xml:lang="en">
        <kwd>Dobutamine</kwd>
        <kwd>echocardiography</kwd>
        <kwd>adrenergic beta-antagonists</kwd>
        <kwd>glaucoma</kwd>
      </kwd-group>
    </front-stub>
    <body>
      <p>
        <bold>BRIEF COMMENTS</bold>
      </p>
      <p>
        <bold>Topical betablocker use can result in inconclusive dobutamine stress echocardiography in patients with glaucoma </bold>
      </p>
      <p>
        <bold>Adriana Cordovil; Fernando Q. Matos; Orlando Campos Filho; Augusto Paranhos Jr.; Ana Clara T. Rodrigues; M&#225;rcia V. Albernaz; Angelo A. V. de Paola; Antonio Carlos C. Carvalho</bold>
      </p>
      <p>Universidade Federal de S&#227;o Paulo - UNIFESP/EPM, Hospital Israelita Albert Einstein, Hospital S&#237;rio Liban&#234;s, Instituto do Cora&#231;&#227;o do Hospital das Cl&#237;nicas - FMUSP - S&#227;o Paulo, SP - Brazil</p>
      <p>
        <xref ref-type="corresp" rid="back-body2">Mailing address</xref>
      </p>
      <p>
        <bold>SUMMARY</bold>
      </p>
      <p>Dobutamine stress echocardiography is a well-established method to assess coronary artery disease, of which sensitivity has been enhanced by adding atropine at the end of the protocol. Individuals with glaucoma, a disease with a high prevalence in patients with cardiac diseases older than 40 years, cannot benefit from the use of atropine as it is contraindicated for this group of patients. Additionally, these individuals are often treated with topical betablockers (eye drops), which can have systemic effects by decreasing cardiac frequency, blood pressure and pulmonary capacity. The aim of our study was to verify whether a possible systemic effect caused by the use of these eye drops, yielding a low chronotropic response, could result in inconclusive dobutamine stress echocardiography in patients with glaucoma.</p>
      <p><bold>Key words:</bold> Dobutamine; echocardiography; adrenergic beta-antagonists; glaucoma.</p>
      <p>
        <bold>Introduction</bold>
      </p>
      <p>The dobutamine-atropine stress echocardiography is a broadly disseminated and well&#150;established diagnostic method for coronary artery disease<sup>1</sup>. It is known that the use of systemic betablockers can interfere with the test result by decreasing the chronotropic response and reducing the diagnostic accuracy of the method<sup>2</sup>. The addition of atropine at the end of the dobutamine infusion protocol increases heart rate (HR) and consequently, the test sensitivity, especially in patients who use oral betablockers<sup>3,4</sup>, and has been systematically used, except in patients with prostatism and closed-angle glaucoma, which are contraindications to its use<sup>5</sup>.</p>
      <p>Glaucoma is a disease with a high prevalence after 40 years of age; it is commonly observed in patients with cardiovascular disease and its treatment consists in the topic use of eye drops with several drugs, and among them betablockers, as their base<sup>6</sup>. Prior studies have reported that topic betablockers can have systemic effects, decreasing HR, blood pressure (BP) and pulmonary capacity, and that they are potentially capable of attenuating the stress-induced HR increase at the ergometric stress test (EST)<sup>8,9</sup>. To date, there have been no references regarding the influence of this drug on dobutamine-stress echocardiography.</p>
      <p>The aim of our study was to verify whether the occurrence of a possible systemic effect of topic betablockers, resulting in low chronotropic response, could yield inconclusive results at the dobutamine-stress echocardiography in patients with glaucoma.</p>
      <p>
        <bold>Methods</bold>
      </p>
      <p>Forty-two patients who were submitted to pharmacological-stress echocardiography for diagnosis or evaluation of known coronary artery disease were studied. Of the 42 patients, 21 had glaucoma. The control group (CG) consisted of the other 21 patients. Among the 21 patients with glaucoma, 14 used topic betablocker (BB group) and 7 used eye drops based on other drugs (NB group). The patients were age-paired and none of them were using oral betablocker at the time of the examination. Those who had previously used this type of medication were advised to interrupt it 7 days before the test.</p>
      <p>All of the patients were submitted to at-rest HR and BP assessment every three minutes during and after the infusion. According to the standardized norms, a complete echocardiography was carried out and a digital system captured images at rest and at the infusion peak <sup>5</sup>. Dobutamine was administered as a continuous infusion, in progressive doses of 10, 20, 30 up to 40 <italic>u</italic>g/kg/min. Atropine, however, was not administered to any of the patients. The aims of the examination were to attain submaximal HR (85% of the maximum HR) or the end of the protocol with the maximum dose of infusion, or the presence of ischemia observed by the alteration of the regional myocardial contractility.</p>
      <p>The test was interrupted earlier in case of severe ventricular arrhythmia, presence of supra-unleveling of the ST segment &gt; 2 mm at the electrocardiogram, increase of systolic pressure &gt; 210 mmHg or diastolic pressure &gt; 110 mmHg, or accentuated hypotension. The test was considered inconclusive when the target HR was not reached or when was premature interruption due to the presence of limiting side effects such as arrhythmia, hypertension and its consequences, such as headache, nausea and vomiting.</p>
      <p><italic>Statistical analysis -</italic> The qualitative variables were determined as absolute and relative frequency, whereas the quantitative variables were determined as means and standard deviation (SD). The comparisons between the groups were performed by the chi-square test or Fisher's test. The ANOVA (analysis of variance) was used for homogenous variance. Tukey's test was used for multiple comparisons. Comparisons between the groups at different moments were carried out by univariate analysis. A value of <italic>p</italic> &lt; 0.05 was considered to be statistically significant.</p>
      <p>
        <bold>Results</bold>
      </p>
      <p>There was no statistical difference between the groups regarding the demographical characteristics such as gender, presence of hypertension, diabetes, smoking, dyslipidemia and previous history of acute myocardial infarction (<xref ref-type="table" rid="t1-body2">Table 1</xref>). All patients were paired by age.</p>
      <table-wrap id="t1-body2">
        <graphic xlink:href="1678-4170-abc-89-01-0060-00010-gt01-en.jpg"/></table-wrap>
      <p>The analysis of the systolic arterial pressure (SAP) showed that the groups presented similar SAP at rest and that the pressure increase at the infusion peak occurred equivalently, with no statistical difference among them (<italic>p</italic>=ns).</p>
      <p>Although the BB group presented a higher diastolic arterial pressure (DAP) at rest, as well as at the peak when compared to the other groups, this difference was not statistically significant (<italic>p</italic>=ns).</p>
      <p>On the other hand, the heart rate (HR) at rest was similar in all groups (<italic>p</italic>=ns), but it was significantly lower in the BB group at the infusion peak when compared to the other groups (<italic>p</italic>&lt;0.05). This result confirms the systemic effect of the betablocker on the dobutamine-induced HR increment. The data on pressure and HR are summarized in <xref ref-type="table" rid="en_10t2-body2">Table 2</xref>.</p>
      <p content-type="asset">
        <table-wrap id="en_10t2-body2">
          <graphic xlink:href="1678-4170-abc-89-01-0060-00010-gt02-en.jpg"/></table-wrap>
      </p>
      <p>All of the tests from the NB and CG groups were conclusive. However, only 3 tests were conclusive among the 14 patients from the BB group. Eleven patients presented inconclusive tests due to the lack of isolated chronotropic response (n=1) and/or associated to limiting side effects such as hypertension and headache (n=8) or ventricular arrhythmia (n=2) (<xref ref-type="table" rid="en_10t2-body2">Table 2</xref>).</p>
      <p>The ejection fraction (EF) was equivalent in the three groups, with no statistical difference among them (<italic>p</italic>=ns) (<xref ref-type="table" rid="t1-body2">Table 1</xref>). Among the 31 conclusive tests, 11 were positive and 20 were negative for ischemia. Of the 11 positive tests, 7 were from the CG, 3 from the NG group and 1 was from the BB group (<italic>p</italic>=ns) (<xref ref-type="table" rid="en_10t2-body2">Table 2</xref>).</p>
      <p>
        <bold>Discussion</bold>
      </p>
      <p>Our results show that the use of topic betablockers in patients with glaucoma can interfere with the results of the dobutamine-stress echocardiography test, resulting in an ineffective chronotropic response and, consequently, in inconclusive tests. This effect had been previously observed by authors who used the ergometric test as the stressor agent<sup>8,9</sup>. However, there are no studies indicating the same effect in patients submitted to pharmacological-stress echocardiography.</p>
      <p>It is known that the use of systemic betablockers can interfere with the results of the pharmacological-stress echocardiography by preventing HR increase, causing arterial hypertension and headache during the test<sup>2</sup>. The addition of atropine to the dobutamine infusion protocol decreased the number of inconclusive tests and is now currently performed as early as possible<sup>10</sup>. However, since the proposal of its inclusion in the original protocol and the establishment of its contraindications, there have been no reports in the literature on the results of pharmacological-stress echocardiography in patients with glaucoma, who could not benefit from the use of atropine. This is probably due to the fact that many patients with cardiac disease and glaucoma are submitted to this test under the use of oral betablocker, and the lack of chronotropic response is attributed to the oral medication, instead of the topic presentation. The present study was only possible because the use of betablockers was systematically withdrawn, excluding any possibility of sample "contamination".</p>
      <p><italic>Clinical significance -</italic> Although the coexistence of respiratory or cardiovascular disease is a contraindication to the use of topical betablockers, cardiologists do not commonly take these effects into account in clinical practice and do not pay special attention to the possible drug interactions between these eye drops and other pharmaceuticals. The use of this kind of eye drops is very disseminated in our country due to its low cost. Therefore, the choice of treatment for these patients' cardiopathy should be considered with caution, considering the type of eye drops used by these patients.</p>
      <p>Additionally, other diagnostic tests for coronary artery disease can possibly present inconclusive results, increasing the cost of treatment. Another question to be considered is the contraindication of atropine for patients with closed-angle glaucoma, exclusively. In our country, patients frequently do not know what type of glaucoma they have and the communication with the ophthalmologist does not take place. To our knowledge, atropine is systematically contraindicated for patients with any type of glaucoma in echocardiography laboratories. We do not know whether further knowledge about this affection would prevent the contraindication of atropine, which is so useful for the effective test performance. Additionally, it is necessary to study the possibility of withdrawing the topic betablocker before carrying out the stress echocardiography and possibly any diagnostic test during which it is necessary to increase heart rate.</p>
      <p><italic>Study limitations -</italic> The present study sample size is small and thus, it is not possible to establish whether the deleterious effect of the topic betablocker is dose-dependent and/or time-dependent. Furthermore, due to the study design, we do not know whether this drug withdrawal would be indicated during the performance of dobutamine stress echocardiography. The coexistence of glaucoma and coronary artery disease at older age ranges is a relevant fact that justifies further research. Therefore, it is necessary to increase the sample size and to consider the substitution of the topic betablocker for other types of medication.</p>
      <p>
        <bold>Acknowledgment</bold>
      </p>
      <p>The author gratefully acknowledge the support provided for this project by FAPESP.</p>
      <p>
        <bold>Potential Conflict of Interest</bold>
      </p>
      <p>No potential conflict of interest relevant to this article was reported.</p>
      <p>
        <bold>Sources of Funding</bold>
      </p>
      <p>This study was funded with the investigator&#180;s own resources.</p>
      <p>
        <bold>Study Association with Graduate Work</bold>
      </p>
      <p>This study is not associated with any graduation program.</p>
      <p>
        <bold>References</bold>
      </p>
      <p>
        <fn id="back-body2" fn-type="corresp">
          <label>
            <bold>Mailing address:</bold>
          </label>
          <p> Adriana Cordovil</p>
          <p> Av. Padre Pereira de Andrade, 545/193D</p>
          <p> 05469-000 - S&#227;o Paulo, SP - Brazil</p>
          <p> E-mail: </p>
          <p>
            <email xlink:href="acordovil@cardiol.br">acordovil@cardiol.br</email>
          </p>
        </fn>
      </p>
      <p>Manuscript received September 6, 2006; revised received February 5, 2007; accepted February 8, 2007.</p>
    </body>
  </sub-article>
</article>
