OBJECTIVE
Recent studies have highlighted the potentially harmful effects of short-acting calcium channel blockers, especially of the dihydropyridine type, in patients with coronary heart disease. Some have argued that long-acting calcium channel blockers are safer, but few outcome data exist. The objective of the study was to compare the occurrence of adverse outcomes among recipients of long-acting versus short-acting calcium channel blockers, with dihydropyridines and non-dihydropyridines compared separately.
SETTING
The New Jersey Medicare population.
DESIGN
A retrospective cohort study using linked Medicare and drug claims data.
PARTICIPANTS
Older survivors of acute myocardial infarction (MI) occurring in 1989 and 1990. Eligible subjects had survived at least 30 days after the MI, participated in Medicare and a drug benefits program, and were prescribed a single type of either a long-acting or a short-acting calcium channel blocker within 90 days after the MI.
MEASUREMENTS
The two outcome measures were rates of all-cause mortality and cardiac rehospitalization. Using separate Cox regression models for dihydropyridines (nifedipine, nicardipine) and non-dihydropyridines (diltiazem, verapamil), we examined these outcomes for recipients of long-acting compared with short-acting calcium channel blockers.
RESULTS
Of the 833 patients eligible for the study, 160 were prescribed long-acting and 673 short-acting calcium channel blockers. Clinical characteristics of long-acting and short-acting users were comparable. During 2 years of follow-up, 221 deaths and 300 rehospitalizations occurred. Controlling for age, sex, race, and indicators of disease severity and comorbidity, the relative risk of dying for recipients of long-acting, compared with short-acting, dihydropyridines was .42 (95% confidence interval (CI), 0.21-0.86). For cardiac rehospitalization, the relative risk was 0.57 (95% CI, 0.34-0.94). For the long-acting versus short-acting nondihydropyridines, the adjusted relative risk of dying was 1.43 (95% CI, 0.88-2.32), and for cardiac rehospitalization, .65 (95% CI, 0.40-1.05).
CONCLUSION
Use of long-acting dihydropyridine calcium channel blockers after acute MI was associated with substantially lower rates of cardiac rehospitalization and death compared with use of their short-acting counterparts. More data are needed to address the possibility that long-acting, compared with short-acting, non-dihydropyridines could decrease rehospitalization rates but increase mortality.