The role of beta-blockers in left ventricular dysfunction and heart failure

Abstract

It was first reported by our group in 1975 that heart failure due to idiopathic dilated cardiomyopathy (IDC) could be improved by long term treatment with a beta-blocker, starting at a low dose and continuing with a stepwise up-titration. Since then, many studies have been performed in patients with heart failure of various aetiologies and the beneficial effects of long term beta-blockade have been confirmed. About 3000 patients have been included in randomised studies in which beta-blockade, given for more than 2 months, mostly elicited significant improvements in functional class, exercise capacity, cardiac function, quality of life and/or morbidity. When started at a very low dose (one-tenth to one-twentieth of the doses generally used in angina or hypertension), the treatment is well tolerated in most patients. In these studies, various types of beta-blockers were used, including beta1-selective blockers and nonselective blockers with additional properties (vasodilator and antioxidative) such as metoprolol, bisoprolol, bucindolol and carvedilol. Several large studies have also reported benefits on mortality and morbidity. In the Metoprolol in Dilated Cardiomyopathy (MDC) trial, metoprolol treatment in patients with IDC resulted in a 34% reduction of the primary combined endpoint, total number of deaths and need for cardiac transplantation. In the Cardiac Insufficiency Bisoprolol Study (CIBIS), in patients with idiopathic as well as ischaemic cardiomyopathy, there was a nonsignificant 20% reduction in mortality. In the US carvedilol studies (n = 1094), also in patients with ischaemic and idiopathic cardiomyopathy, carvedilol reduced mortality by 65%, which was highly significant. A nonsignificant reduction in mortality was observed in the Australia-New Zealand (ANZ) Heart Failure Study with carvedilol. In all these studies there was a reduction in hospitalisations, with all drugs being generally well tolerated. It can thus be concluded that the beneficial effects of beta-blockers on cardiac function and morbidity have been documented in a large number of studies in selected groups of patients. The treatment has been accepted in some countries by the regulatory authorities. Larger, placebo-controlled studies are needed to convincingly demonstrate a reduction in total mortality as observed in the pooling of the 4 US carvedilol studies. Such studies are in progress for various beta-blockers, which may lead to acceptance of their routine clinical use in patients with congestive heart failure.