[Isosorbide dinitrate treatment of silent myocardial ischemia in patients after myocardial infarction].

In a group of 17 men and women aged 38-65 years (means = 51.1) three months after the first myocardial infarction we studied changes in silent ischemic ST segment depression by using Holter monitoring and exercise stress testing before and after 120 mg/daily of oral isosorbide dinitrate (Isoket). Repeated ECG monitoring and exercise stress test were performed after two weeks. It was found that before isosorbide dinitrate therapy 16 out of 17 patients had 56 episodes of ST segment depression of 1-5 mm including 6 (37.5%) symptomatic episodes and 10 (62.5%) asymptomatic episodes. The number of asymptomatic episodes after isosorbide dinitrate therapy decreased more than five times (p less than 0.001), their duration was three times shorter (p less than 0.01). ST segment depressions were also significantly smaller. During isosorbide dinitrate therapy the duration of stress test was almost doubled and the achievable heart rate increased (p less than 0.02; p less than 0.05). The magnitude of ST segment depression during exercise testing also decreased significantly (p less than 0.01) and at heart rate below 100 beats/min ischemic ST segment depression were not observed, in contrast to pre-treatment period. Thus it may be concluded that silent myocardial ischemia is a frequent event in patients after the first myocardial infarction and isosorbide dinitrate significantly decreases the number of symptomatic and asymptomatic episodes detected by Holter monitoring.