Ongoing clinical outcome studies of calcium antagonists.
Calcium antagonists continue to have a place in the treatment of hypertension, despite recent concerns regarding their safety and long-term capacity to alter the natural history of cardiovascular disease. Results of a well-designed cohort study concerning a very elderly population suggested that administration of shorft-acting nifedipine is linked to an increase in mortality, particularly when a high dose is administered and when the initiaol blood pressure is below 160/90 mmHg. The risk of using short-acting verapamil, however, was no greater than that of beta-blockade. These differences can be attributed at least in part to the low catecholamine profile of verapamil and to the marked rapid adrenergic activation with short-acting nifedipine. Current evidence sujggests that less catecholamine activation occurs during the chronic use of long-acting dihydropyridine agents. Two recent studies have shown that the combination of verapamil and an angiotensin converting enzyme inhibitor reduces numbers of cardiovascular disease events among postinfarct patients with heart failure, and that the dihydropyridine nitrendipine reduces poor outcome measures, such as stroke incidence, in treating systolic hypertension in the elderly. In my view, apparent hazards such as the precipitation of myocardial infarction and cancer are discounted by the available evidence. While we await further major trials concerning outcomes, general safety can be related to a preference for administering those long-acting agents that do not stimulate and may even inhibit adrenergic responses, and the avoidance of possible adverse effects through the use of combination therapies, such as verapamil plus an angiotensin converting enzyme inhibitor or nifedipine plus a beta-blocker.
Opie
LH
Heart Research Unit, Cape Heart Centre, University of Cape Town Medical School, Cape Town, Republic of South Africa.