PARADIGM SHIFT - BETA-BLOCKER TREATMENT FOR HEART-FAILURE

It is well-established that beta-blockers, particularly those without intrinsic sympathomimetic activity (ISA), are cardioprotective and pre vent secondary recurrences of myocardial infarction (MI) when given wi thin hours of onset of symptoms as well as during late intervention. T he reduction in mortality in patients with MI appears significant for those agents without ISA, suggesting that magnitude of reduction in he art rate is an important factor. There is now convincing evidence that beta-blockade also produces beneficial effects in heart failure (HF). In the early stages of HF, adrenergic support mechanisms help to main tain cardiac output but the long-term effects are deleterious; as a re sult increased adrenergic drive in HF is directly related to an advers e outcome. Early studies with beta-blockers mere undertaken primarily in Sweden and subsequently, in the 1980s, the same workers reported be neficial effects of long-term beta-blockade with metoprolol in dilated cardiomyopathy. To date, studies have been undertaken with a variety of different beta-blockers in patients with idiopathic dilated cardiom yopathy, as well as ischaemic HF. Until the 1990s the results of these studies were inconclusive, but showed a trend towards improvement in congestive HF (CHF). In the past 5 years, several placebo-controlled r andomised trials of at least 12 months' duration and involving greater patient numbers have provided more compelling evidence for the use of these agents in CHF. Because cardiac decompensation may occur seconda ry to their negative inotropic effects, beta-blockers are still rarely used in patients with CHF. This has led to the development of beta-bl ockers with vasodilatory effects in an attempt to improve tolerance of these drugs. Initiated gradually, most patients with mild-to-moderate CHF can safely be treated with beta-blockers except for some 10 - 15% who develop hypotension. Treatment should be initiated in a controlle d setting at low doses (carvedilol 6.25 mg twice daily, metoprolol 5 m g twice daily) and titrated upwards gradually. Despite a remarkable re duction in mortality in recent studies with carvedilol, routine manage ment of heart failure with beta-blockade can only be recommended when further confirmatory evidence from large, unconfounded randomised clin ical trials on an intention-to-treat basis becomes available.