[Critical analysis of beta blockers in heart failure: certainty and incompleteness].
Heart failure is one of the commonest debilitating conditions of industrialized society, with mortality and morbidity comparable with that of the common neoplastic diseases. The role of beta-blockers in heart failure has been the subject of debate for many years. The results of recent prospective, placebo-controlled studies of the addition of beta-blockers to standard therapy in patients with chronic heart failure have confirmed a significant beneficial effect on ventricular function, clinical status, morbidity and mortality. The importance of these trials suggests that beta-adrenergic blocker therapy can save one life out of every 35 patients treated with mild-to-moderate heart failure. These major trials have used one of four beta-blockers (metoprolol, bisoprolol, carvedilol, or bucindolol) in varying study designs with different patient populations. Beta-blockers improve function of the failing left ventricle, prevent or reverse progressive left ventricular dilation, chamber sphericity, and hypertrophy, and consequently have a positive impact on cardiac remodeling. Beta-blockers also reduce heart rate and left ventricular wall stress, leading to reduced myocardial oxygen consumption, a clear benefit to the failing heart. Moreover, beta-blockers can improve the intrinsic contractile function of cardiomyocytes and have been shown to improve myocardial energetics in heart failure, possibly through desirable changes in substrate utilization. Many important clinical questions still remain unanswered. These questions include whether beta-blockers are of benefit in patients with severe NYHA functional class (IIIB-IV), in patients with asymptomatic left ventricular dysfunction, in the extreme elderly, in patients with diabetes mellitus and renal impairment. Furthermore, it is not clear whether beta-blockade by itself is the real mechanism of clinical benefit. Although certain effects of beta-blockers may be considered class effects, it is not yet clear whether there are differences between beta 1-selective antagonists and nonselective agents. Major studies are currently being undertaken to address the above questions.
Rapezzi
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Istituto di Cardiologia, Università degli Studi, Bologna. crapezzi@orsola-malpighi.med.unibo.it
Branzi
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D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D018849:Controlled Clinical Trials as Topic; D005260:Female; D006333:Heart Failure / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged
D000319:Adrenergic beta-Antagonists