[Calcium antagonists in cardiovascular disease. Clinical evidence from morbidity and mortality trials]

Calcium antagonists, particularly the newer, longer-acting agents, are clearly effective in reducing elevated blood pressure with minimal to modest adverse effect profiles, and are therefore used extensively. The goal of antihypertensive therapy, however, is not simply to reduce blood pressure, but also to reduce vascular injury due to hypertension. Prospective controlled clinical trials evaluating cardiovascular morbidity and mortality are needed to test calcium antagonists in patients with hypertension. This review summarises the design and, in some cases, the results of 7 trials (5 of them still ongoing) that have provided insight into the effects of moderate- to long-acting calcium antagonists on mortality and target-organ damage in patients with hypertension. The Systolic Hypertension in Europe (Syst-Eur) trial studied 4695 elderly patients with isolated systolic hypertension, and demonstrated significant reductions in stroke and all fatal and nonfatal cardiac end-points in patients randomised to nitrendipine versus placebo. The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) compares the effects of standard diuretic treatment with 3 alternatives (amlodipine, lisinopril, and doxazosin) on the incidence of fatal coronary artery disease and nonfatal myocardial infarction in more than 42,000 hypertensive patients with additional cardiovascular risk factors. The Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT) compares the effects of amlodipine +/- perindopril with atenolol +/- bendrofluazide on fatal coronary artery disease and nonfatal myocardial infarction in 18,000 high risk patients. The Controlled ONset Verapamil INvestigation of Cardiovascular End-points (CONVINCE) study is assessing the incidence of fatal or nonfatal myocardial infarction and stroke, and cardiovascular disease-related death in patients on controlled-onset extended-release verapamil compared with a standard regimen of hydrochlorothiazide or atenolol. The Nordic Diltiazem Study (NORDIL) also compares a calcium antagonist (diltiazem) with conventional antihypertensive drug treatment (diuretics or beta-blockers) with add-on therapy as needed, in preventing cardiovascular mortality or morbidity. The Prospective Randomized Evaluation of the Vascular Effects of Norvasc Trial (PREVENT) tests a similar hypothesis, examining the effects of amlodipine on atherosclerotic lesions. The African-American Study of Kidney Disease (AASK) trial is evaluating the effects of amlodipine in hypertensive patients with renal disease. These important clinical trials of different classes of antihypertensive agents are critical for optimising the treatment of hypertensive patients in order to prevent coronary artery disease and other vascular diseases in this new millennium. Importantly, these randomised trials are free of the major problems of observational studies, i.e., confounding by indication, and should fully address the concerns raised by observational studies and small, under-powered, randomised trials that calcium antagonists may have adverse effects on myocardial infarction, bleeding and cancer. To date, these trials in progress have provided no evidence to support these concerns.