Calcium channel antagonists: friend or foe in postinfarction patients?

Calcium antagonists represent a diverse group of therapeutic agents with heterogenous pharmacologic, pharmacokinetic, and pharmacodynamic properties. It seems clear that the role of these agents in the management of patients with ischemic heart disease and hypertension is, in part, predicated on the subclass of calcium antagonists (dihydropyridine versus nondihydropyridine [heart rate-lowering]) that are used. The reports by Psaty and Furberg are important in that they remind clinicians of the fact that use of short-acting dihydropyridine agents may be associated with increased cardiac event rates in patients with ischemic heart disease and hypertension. It is our opinion, however, that there are no data that support the extrapolation of these untoward effects to the more contemporary, long-acting dihydropyridines (eg, amlodipine) or, especially, to the non-dihydropyridine (heart rate-lowering) calcium antagonists, such as diltiazem or verapamil. On the contrary, data pooled from homogeneous populations of post-MI patients from DRS, MDPIT, DAVIT-I, and DAVIT-II indicate that clinical outcomes are favorably influenced in patients recovering from non-Q wave MI, and in hypertensive post-MI patients with preserved left ventricular function. These findings support the belief that the deleterious effects observed in certain studies with short-acting dihydropyridine calcium antagonists represent a "selective" rather than a "class action" effect of these agents. Psaty and Furberg have assailed the absence of "evidence-based medicine" regarding, the utility of calcium antagonists as the most compelling argument to call for a moratorium on this broad class of therapy, pending the completion of several prospective, randomized, controlled clinical trials that are presently underway or planned. However, a large body of scientific evidence provides no sound basis for physicians to discontinue therapy in patients who are being treated with long acting calcium antagonists, particularly those that lower heart rate. Moreover, the available data support the use of heart rate lowering calcium antagonists in selected patients, such as those recovering from acute non-Q wave MI, who may experience long-term benefit from diltiazem or verapamil. Until the results of controlled trials are completed, these data suggest that a generic moratorium of all calcium antagonists is ill-advised.