Calcium channel blockers: The jury is still out on whether they cause heart attacks and suicide

Calcium antagonists are used extensively for treating high blood pressure and angina. Since 1995 they have been accused of causing myocardial infarcts, cerebrovascular events, cancer, bleeding, depression, and suicide by mechanisms that include pro-ischaemic, pro-arrhythmic, negative inotropic, hypotensive, and reflex sympathetic effects (cardiovascular events); inhibition of apoptosis (cancer); inhibition of platelet aggregation and the normal vasocontrictive response to bleeding (bleeding); excess hypotension or interference with neurones and receptors involved in mood regulation (depression). A recent review of the evidence recommended no change to current guidelines and clinical practice,1 but since then a report of raised suicide rates among patients taking calcium antagonists has been published,2 together with three randomised controlled trials suggesting that myocardial infarcts might be increased in diabetics on calcium antagonists.3–5 Much of the evidence concerning risk of cardiovascular events, cancer, and bleeding, both published and unpublished, was reviewed in 1996-7 by an ad hoc subcommittee of the Liaison Committee of the World Health Organisation and the International Society of Hypertension.1 The principal conclusions were that the available evidence did not prove the existence of either beneficial or harmful effects of calcium antagonists on the risks of major coronary heart disease events and that there was no good evidence for adverse effects of calcium antagonists on either cancer or bleeding risks. The committee commented that the bulk of the evidence for adverse effects was derived from observational studies or small randomised clinical trials and pointed to a “clear failure of pharmaceutical companies, regulatory authorities, and clinical researchers to ensure the timely conduct of studies, involving both large numbers of cases and random assignment of treatments.” Many such large randomised clinical trials are now in progress, but reliable detection of any modest adverse or beneficial effect of calcium antagonists is not expected until …