EFFICACY OF METOPROLOL AND DILTIAZEM IN TREATING SILENT-MYOCARDIAL-ISCHEMIA

Recent studies strongly support the prognostic importance of transient silent ischemia. Because patients with silent ischemia are at higher risk of a cardiac event, they are likely to benefit not only from cont rol of symptoms, but also from treatment directed at prevention of isc hemia. The efficacy of controlled-release metoprolol 200 mg once dairy and diltiazem 60 mg 4 times daily was assessed in a randomized, doubl e-blind, crossover study in 32 patients with proven coronary artery di sease, predominantly asymptomatic myocardial ischemia, positive bicycl e exercise test results, and greater than or equal to 5 minutes of asy mptomatic ST-segment depression on a 24-hour screening ambulatory elec trocardiogram (ECG). At the beginning and at the end of both 3-week tr eatment periods, an exercise test was performed and 72-hour ambulatory ECG was recorded. Both active treatment periods were preceded by a 2- week placebo phase. Both treatments effectively reduced and postponed exercise-induced ST depression and reduced the total ischemic integral on the ambulatory ECG. Only metoprolol significantly reduced the mean number of ischemic episodes (54%, p = 0.0003, vs 31% for diltiazem, p = NS) and the mean duration of ischemia (51%, p = 0.012, vs 27% for d iltiazem, p NS) compared with baseline values. Metoprolol strongly blu nted the morning and afternoon peak in the circadian distribution of i schemia, whereas diltiazem did not change the circadian distribution o f ischemia at all.