Calcium Antagonists for Secondary Prevention of Myocardial Infarction Is There a Need to Shift From Short-Acting to Long-Acting Types?

Abstract

Although short-acting nifedipine does not prevent myocardial infarction (MI), calcium antagonists with a long half-life may be effective. The present study was a retrospective analysis of the incidences of cardiac events among patients with a healed MI treated with 3 times-a-day type nifedipine (half-life 1.8 h; n=617), twice-a-day type nifedipine (half-life 4.0 h; n=527) and those not taking calcium antagonists (n=1,593) from 1986 to 1993, and the incidences of those on once-a-day type calcium antagonists (half-life 11.0 h; n=903) and those not taking calcium antagonists (n=2,788) from 1994 to 2001. Cardiac events included cardiac death and nonfatal recurrent MI. Single and multivariate analyses using the Cox-Hazard model were performed. From 1986 to 1993 cardiac events occurred in 38 patients with 3-times-a-day nifedipine (6.2%, hazard ratio and 95% confidence interval: 1.45 and 0.93-2.27), in 18 patients with twice-a-day nifedipine (3.4%: 0.68 and 0.39-1.20), 57 patients without calcium antagonists (3.6%). Cardiac events also occurred in 11 patients with once-a-day type nifedipine (1.2%: 0.72 and 0.37-1.42) and 48 patients without calcium antagonists (1.7%). Of the once-a-day type calcium antagonists, cardiac events were the lowest (2 patients, 0.6%: 0.32 and 0.08-1.31) in patients with amlodipine (half-life 39.0 h; n=334), which has the longest half-life. None of these drugs were a significant factor in the increase or decrease in the incidence of cardiac events. However, there was a good correlation between the half-life of the calcium antagonist and the hazard ratio for reducing cardiac events. Although there was a tendency toward a reduction in cardiac events using calcium antagonists with long half-life, none of these drugs could significantly reduce the incidence of cardiac events in patients with a healed MI.