Prevalence and patterns of silent myocardial ischemia during daily life in stable angina patients receiving conventional antianginal drug therapy.

The prevalence and patterns of silent myocardial ischemia were evaluated in 105 stable angina patients receiving conventional antianginal drug therapy. During 2,520 hours of electrocardiographic monitoring, silent ischemia was detected in 45 (43%) patients. A total of 188 ischemic episodes was observed; 163 (87%) were silent and accounted for a total ischemic duration of 5,771 minutes. There was no difference in the baseline clinical characteristics between the patients with and without ambulatory silent ischemia. However, patients with silent ischemia on ambulatory electrocardiographic monitoring had earlier onset of ischemia during exercise testing. The highest density of silent ischemic events occurred between 6 A.M. and 6 P.M. Comparison of the class or combination of antianginal agents used by the 2 groups revealed no difference. However, in patients with silent ischemia the mean duration per event was shorter for those receiving 2 (p less than 0.05) or more (p = 0.001) antianginal agents compared to those receiving monotherapy. The average duration of silent ischemia per event was significantly less (p less than 0.001) in patients receiving beta blockers. These results demonstrate that silent ischemia during ordinary daily activities occurs frequently despite conventional antianginal drugs prescribed for control of symptoms.