Prevalence and prognostic significance of silent myocardial ischaemia detected by exercise test and continuous ECG monitoring after acute myocardial infarction.

Abstract

The incidence and prognostic significance of silent myocardial ischaemia in 165 patients who survived a first acute myocardial infarction were assessed by means of maximal exercise stress test and 24 h continuous ECG monitoring performed before discharge. During the 1 year follow-up period 10 cardiac deaths occurred; moreover seven patients suffered a fatal myocardial re-infarction and 14 developed unstable angina. Cardiac death occurred in five of 40 patients (12.5%) with ST segment depression on stress test by in only three of 117 (2.6%) without ST segment changes (P less than 0.01). One-hundred-and-three of 117 patients (88.0%) without angina or ST segment depression on stress testing survived 1 year without cardiac events, compared with 24 of 40 patients (60.0%) with ST segment depression whether or not associated with angina (P less than 0.001). Cardiac death occurred in five of 25 patients (20.0%) with ST segment depression on continuous ECG monitoring, compared with five of 140 (3.6%) without (P less than 0.01). One-hundred-and-seventeen out of 140 patients (83.6%) without angina or ST segment depression survived 1 year follow-up without cardiac events, compared with 13 of 25 (52.0%) with ST segment depression with or without angina (P less than 0.01). Classifying patients in a 2 x 5 contingency table according to the occurrence of ST segment depression on exercise testing and/or ECG ambulatory monitoring, the Yates corrected chi-square test showed a significant pattern when cardiac deaths and cardiac events were considered together (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)