Two new studies have shown that the newer style calcium antagonists given to heart patients are no more effective or safe than older style drugs.

In the first, the Nordic Diltiazem (NORDIL) study, more than 10,000 patients were randomised to receive either the calcium antagonist diltiazem, or diuretics, beta blockers or both. The purpose of the study was to determine the rate of fatal and non fatal stroke, heart attack and other cardiovas cular deaths. The researchers found a marginally significantly lower risk of stroke with diltiazem (despite a lesser reduction in blood pressure), but no clear difference in stroke or heart failure risk among the regimes (Lancet, 2000; 356: 359-65).

In the second, Intervention as a Goal in Hypertension Treatment (INSIGHT) trial, more than 6000 patients aged 55 to 80 years with hypertension were randomised to receive either the calcium antagonist nifedipine or the diuretic combination co-ami-lozide, again to assess rates of cardiovascular death, heart attacks and stroke. INSIGHT researchers found no difference in stroke rate between the regimes, but there was a marginally significant excess of heart failure with nifedipine. Heart attacks were also more common in the nifedipine group (Lancet, 2000; 356; 366-72).

Withdrawals from both studies due to adverse events were also high. In NORDIL, 23 per cent of the patients withdrew from the diltiazem group while only 7 per cent withdrew from both diuretic and beta blocker groups. In INSIGHT, 40 per cent of the patients withdrew from the nifedipine group due to adverse events compared with a third of the patients taking diuretics.

Both sets of authors tried to put a positive spin on their findings, with the INSIGHT authors even suggesting that the choice of heart drugs can now be based on tolerability and blood pressure response, rather than long term safety.

Another interpretation would be that heart drugs have yet to prove that they are the most effective way to manage heart disease.

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Written by What Doctors Don't Tell You

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