Beta-blockers in cardiac failure.

Abstract

The use of beta-blocking agents in patients with heart failure is still controversial. An activated sympatho-adrenal system in heart failure may support blood pressure and cardiac index, on the other hand, it increases cardiac load and myocardial oxygen consumption, reduces myocardial oxygen supply and may contribute to the high incidence of arrhythmias and sudden death. Today there is a certain awareness about the important role of the sympatho-adrenal system in CHF. Short-term studies failed to demonstrate a benefit of beta-blockers while long-term studies have proved major haemodynamic benefit and functional improvement in most patients. The haemodynamic benefit consists of a reduction of heart rate and left ventricular filling pressure and an improvement in exercise capacity. The mechanism of these actions of beta-blockers, with the exception of lowering heart rate, remains unclear. Energy metabolism of the failing heart, which is considered to be deficient, may beneficially be influenced by chronic beta-blocker treatment. Effects of beta-blockers on prognosis in patients with heart failure are also still controversial. Most recent trials (MDC Trial, CIBIS Trial) were inconclusive concerning mortality. Aetiology of heart failure may be important; however, observations on secondary prevention post-myocardial infarction also contradict heart failure studies. Thus, further efforts are urgently needed to define the mechanism of action of beta-blockers in patients with cardiac failure and to identify more clearly patients who benefit from this type of therapy.