A 21-year old woman presents to an emergency department with symptoms of worsening congestive heart failure. She was operated on an anomalous origin of left coronary artery from the ascending aorta at the age of 15. She was diagnosed unusually late as for this lesion, and she had experienced left ventricle anterior wall myocardial infarction by her teens. She reports taking her medicines, which include beta-blockers, spironolactone and occasionally furosemide for a long time. An echocardiogram reveals reduced contractility of the left ventricle with ejection fraction estimated at 30%. It is well known that beta-blockers depress myocardial contractility._x000D_
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Patient: those who show worsening congestive heart failure while taking beta-blockers. Intervention: the exposure interested in is giving a beta-blocker – a drug of concern to apply for this patient. Comparator: alternatively, one may withdraw the beta-blocker, which might have negative impacts. Outcome: the expected consequences are improving compliance to the drug in a remote time. PICO question: In deteriorating on beta-blockers, will the drug (as compared to withdrawal) improve the compliance in the future?_x000D_
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CLINICAL PROBLEM_x000D_
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The use of beta-blockers to treat heart failure had been abandoned for years. The rationale for avoidance was due to their negative inotropic effect, while adrenergic support is required for circulatory support. However, further observations came to a conclusion, that might myocardial exposure to adrenaline reduce, the energy storage is preserved, thus providing a positive longtime effect. Today beta-blockers are considered to be the first-line medicine to treat ventricular systolic dysfunction._x000D_
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AN ARTICLE_x000D_
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I chose free database PubMed, which is enlisted into Palmer Health Sciences Library Databases. PubMed of The National Center for Biotechnology Information provides the direct link to the manuscript at the keywords “blocker continuation decompensation”. The only result displayed is a B-CONVINCED trial. In this randomized, controlled, open-labeled, non-inferiority trial a group of investigators from France provide an answer to the challenging question, how to manage patients who become worse while in treatment with b-blocker. Their results were published in the European Heart Journal in 2009, free full-text of which is open to preview on the official website of the Journal._x000D_
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In a randomized trial held by Jondeau and others, 147 patients were evaluated for a randomisation to find out what to do with patients who deteriorate on beta-blocker therapy. The study follows the clinical course of those patients who are hospitalized for heart failure with reduced contractility of the left ventricle (ejection fraction less than 40%), receiving an uninterrupted beta-blocker therapy for more than a month. The authors found that keeping on taking beta-blockers was not associated with any risks as compared to withdrawing. Whatever scenario chosen, there was a clinical improvement within a week of in-hospital treatment. What is more important, keeping treatment results in a significantly higher rate of b-blocker prescription 3 months after discharge._x000D_
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The article provides strong preliminary support in favor of continuation of the beta-blocker therapy. However, it does not detect some critical endpoints, such as death or re-admission as it would demand a much larger survey cohort. Some patients were withdrawn from the study design because of beta-blocker’s side effects in spite of the fact that the aim of the trial was to validate the attitude of pursuing beta-blocker therapy._x000D_
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The results of the trial are rather valid because the patients were randomized, all patients underwent strict requirements (low ejection fraction, beta-blockers more than one month, pulmonary oedema at admission etc). But it should be noted that the randomization was not blind. The prognostic balance was relatively poor – this is an open labeled trial, so both patients, and clinicians new about treatment regimen. However, it is not directly noted whether data collectors, adjudicators of outcome or data analysts were aware of the protocol proceeding details. At the study conclusion the groups were followed-up almost completely (up to 92% in control and treatment groups), and the trial was not stopped prematurely. Nevertheless, it is not clear wether the patients were analyzed in the groups to which they were randomized. The results were remarkable – the treatment effect showed no major adverse outcomes, but patients receiving a beta-blocker after 3 months was lower in patients discontinuating beta-blocker therapy during the hospitalization (90 vs. 76%)._x000D_
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This study is exactly what the patient needs. Beta-blockers have previously shown to be the basic drug class to make survival longer, so this is the most important outcome to study. The potential costs of a long-life prescription of a beta-blocker are a minority to compare with the potential benefits of survival improvement._x000D_
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STATISTICS (one of the reported results)_x000D_
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“The percentage of patients receiving beta-blockade at 3 months were compared using the Fisher exact test”, the paper states. Fisher exact test is statistical significance test primarily designed to appreciate small sample sizes. It explores significance of the relationship between the two variables in the factor dimension table 2 x 2. In this case the patients were divided according to beta-blocker affection at admission, on one hand, and rate of remote beta-blocker prescription, on the other hand. The test reveals whether there is any difference between the groups._x000D_
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The question the test answers is: knowing that a+c of these a+b+c+d patients had beta-blockers during in-hospital treatment, and a+b continued on beta-blockers, what is significance that these a+c patients would be distributed in this way not accidently? If the result is of statistical power, the general conclusions of B-CONVINCED trial are evidence-based._x000D_
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In conclusion, it is noteworthy that withdrawal of b-blocker therapy in patients with worsening heart failure caused by left ventricular depression should be safely avoided.