Long-term effects of diltiazem and verapamil on mortality and cardiac events in non–Q-wave acute myocardial infarction without pulmonary congestion: post hoc subset analysis of the multicenter diltiazem postinfarction trial and the second danish verapamil infarction trial studies

Abstract

The main objective of this retrospective analysis was to evaluate the long-term effect of the heart rate–lowering calcium antagonists verapamil and diltiazem on the incidence of combined cardiac events and all-cause mortality in patients who had experienced a non–Q-wave acute myocardial infarction (AMI), but who did not also have pulmonary congestion. In addition, factors having an independent association with these 2 outcomes were identified. Of 817 non–Q-wave patients, 81 (9.9%) died during 12 to 52 months of follow-up. The unadjusted mortality rate was 42% lower in patients randomized to calcium antagonist therapy than placebo (7.2% vs 12.4%, p = 0.010). Non–Q-wave patients who died during follow-up were older than patients who survived (62 vs 58 years, p = 0.001). Other factors found to have an independent association with all-cause mortality included diuretic use (RR 2.79), diabetes mellitus (RR 2.86), and New York Heart Association class >I (RR 1.73). The covariate adjusted all-cause mortality risk ratio associated with randomization to calcium antagonist therapy was 0.65 (95% confidence interval [0.40 to 1.05, p = 0.079]). Overall, 153 patients (18.7%) died or had nonfatal reinfarction. The unadjusted combined event rate was 31% lower in patients randomized to calcium antagonist therapy than to placebo (15.2% vs 21.9%, p <0.006). Factors found to have an independent association with cardiac events included age, diabetes (RR 2.82), diuretic use (RR 2.04), and previous AMI (RR 1.71). In addition, randomization to the calcium antagonist group had a significant independent association with reduced cardiac events (p = 0.031). The covariate adjusted event rate RR associated with randomization to the calcium antagonist group was 0.69 (95% confidence interval [0.49 to 0.97]). In conclusion, the heart rate–lowering calcium antagonists diltiazem and verapamil may play an important role in reducing long-term mortality and reinfarction in non–Q-wave AMI without pulmonary congestion.