In these patients, the primary cardiac abnormality leading to heart failure is an abnormality of ventricular filling. Possibly as many as one third of patients with heart failure have normal ventricular systolic function. Beta blockers are also effective in slowing the ventricular rate, and rarely worsen the situation providing ventricular systolic function is reasonably well preserved. Digoxin is usually effective in this situation. In this situation, controlling the ventricular response alone can produce a major improvement in heart failure. In some patients, atrial fibrillation with rapid ventricular response is a major factor which worsens the severity of their heart failure. There are two other types of heart failure where use of beta blockers provides clear benefits and little risk. Indications other than systolic heart failure We will not know if the additional properties of carvedilol are important, and whether carvedilol actually produces a larger benefit than standard beta blockers, until the results of current head-to-head comparisons are reported. Based on the unequivocal treatment benefits seen in the CIBIS2 and MERIT3 studies, the principal mechanism by which these drugs improve outcome in heart failure is likely to be via their beta-1 receptor blocking action. By comparison, carvedilol is a non-selective beta blocker with additional alpha-receptor blocking and antioxidant properties. Metoprolol and bisoprolol are both cardio selective beta blockers acting primarily on beta-1 receptors. Possible mechanisms for beta receptor blockade improving survival include: This action is consistent with the large body of data documenting high plasma catecholamines in severe heart failure, and more sophisticated studies demonstrating increased cardiac sympathetic activity and catecholamine release. The benefit of beta blockers almost certainly depends on blockade of beta-1 receptors.
†† Number of patients who must be treated with beta blocker for one year to prevent one death † New York Heart Association functional class * Not yet published, data preliminary and incomplete Summary of beta blocker trials in chronic systolic heart failure 1 The overall reduction of total mortality from chronic beta blockade was 32%, with a 41% reduction in sudden deaths and a 37% reduction in hospitalisation. In 1998 there was a meta-analysis of 18 double-blind placebo-controlled trials of beta blockers in chronic systolic heart failure (see Table 1).
#Beta blockers ok to take as needed trial
The MDC trial of Metoprolol in Dilated Cardiomyopathy in 1985 failed to show either harm or benefit. A number of relatively small trials showed benefits, primarily in patients with non-ischaemic dilated cardiomyopathy. The Scandinavians have been promoting the use of beta blockers in systolic heart failure since the mid-1970s. – improved left ventricular ejection fraction In patients with primarily severe systolic heart failure (low ejection fraction) beta blockade has the following long-term benefits which must be balanced against the short-term risks. The risks remain, but now need to be balanced against the major long-term benefits of beta blockade in chronic systolic heart failure (see box). Recent trials have seriously challenged this conventional wisdom. To remove this by using a beta blocker would risk precipitating or exacerbating heart failure. The rationale was that the sympathetic nervous system was overactive and provided a crucial level of compensation for the failing heart. Traditional teaching was that beta blockers should be avoided in patients with heart failure.
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