EFFECT OF MORNING VERSUS EVENING DOSING OF DILTIAZEM ON MYOCARDIAL-ISCHEMIA DETECTED BY AMBULATORY ELECTROCARDIOGRAPHIC MONITORING IN CHRONIC STABLE ANGINA-PECTORIS

Myocardial ischemia occurs frequently during daily life and has a circ adian pattern similar to that reported for myocardial infarction and s udden death. Because of the increased risk of myocardial ischemia in t he morning hours, it has been suggested that the administration of ant i-ischemic medication before bedtime may be more effective than the tr aditional morning dosing. This randomized, double-blind, placebo-contr olled, crossover study evaluated the effects of 480-mg/day diltiazem ( given either in the A.M. or the P.M.) on myocardial ischemia using amb ulatory electrocardiographic monitoring in 68 patients with chronic st able angina and greater than or equal to 2 minutes of ischemia per 48 hours. During treatment with diltiazem, the duration and number of myo cardial ischemic episodes were reduced by 45% (94 to 52 minutes, p < 0 .004) and by 40% (4.5 to 2.7 episodes, p < 0.003), respectively. The d uration and number of myocardial ischemic episodes during daytime (6 A .M. to 6 P.M.) hours were also reduced by 52% (74 to 36 minutes, p < 0 .002) and by 48% (3.1 to 1.6 episodes, p < 0.001), respectively. There was no significant difference between A,M. and P.M. dosing. Morning i schemia (6 A.M. to noon), considered separately from daytime ischemia, was also significantly reduced by both A,M. and P.M. dosing regimens, with no difference between the regimens. The results of this study sh owed that both A.M. and P.M. dosing of long-acting diltiazem were equa lly effective in suppressing episodes of ambulatory myocardial ischemi a at all times. (C) 1997 by Excerpta Medica, Inc.