The purpose of this study was to compare the efficacy of three standard antianginal agents,
nitrate, Ca antagonist, and beta blocker on
myocardial ischemia in patients with effort angina (EA) using ambulatory electrocardiographic monitoring (
AEM). Forty-three patients, mean age 57 +/- 11 years, with positive exercise tests were studied.
AEM was performed for 24-hours, initially with the patients off all antianginal medication and then after 1-2 weeks treatment with each agent. Antianginal drugs used were long-acting
isosorbide dinitrate 40-80 mg/day for
nitrate (17 patients),
diltiazem 90-180 mg/day for Ca antagonist (13 patients), and
propranolol 30-60 mg/day or
metoprolol 60-120 mg/day for beta blocker (13 patients). The following results were obtained: 1) The severity of
ischemia (total magnitude and duration of ST depression) was improved with each three agent. 2) Although the number of total ischemic episodes was reduced significantly with each three agent, the number of asymptomatic episodes was reduced significantly only with beta blocker. 3) Circadian variation of ischemic episodes displayed a pattern with a peak frequency in daytime. In addition,
nitrate and Ca antagonist did not reduce ischemic episodes in daytime (especially asymptomatic episodes), while beta blocker reduced both symptomatic and asymptomatic episodes in daytime resulting in change in the pattern of circadian variation of
ischemia. Thus, it was concluded that beta blocker was the most effective means of reducing
myocardial ischemia, including silent
ischemia, in patients with EA.