Two new studies show that the beta blockers bucindolol and carvedilol have little or no effect in cases of severe heart failure.

In one study, the effect of bucindolol on survival was studied in 2708 patients diagnosed with class III or IV heart failure. Patients were randomised to receive either bucindolol at 3 mg twice daily which was gradually increased to as much as 100 mg twice daily for those weighing 75 kg or more or placebo.

The trial was halted after two years because it showed no significant differences in mortality between the two groups (N Engl J Med, 2001; 344: 1659-67).

In the other study, 1133 patients were randomised to receive placebo and 1156 to receive carvedilol, at dosages up to 25 mg twice daily. Patients carried on taking their other medications, which included diuretics, ACE inhibitors and angiotensin II receptor antagonists.

Over a period of about 10 months, there were 190 deaths in the placebo group and 130 deaths in the carvedilol group a 35 per cent reduction in mortality, which seems encouraging.

However, the researchers put their findings into context by noting that 1000 patients would have to be treated for one year to prevent around 70 deaths. The reduction in the combined risk of death or hospitalisation in the carvedilol group was even smaller at just 24 per cent (N Engl J Med, 2001; 344: 1711-2).