Exercise-provoked ST-segment depression and prognosis in patients recovering from acute myocardial infarction. Significance and pitfalls.

Abstract

The importance of maximal versus submaximal exercise testing and the significance of heart failure on the prognostic value of exercise-provoked ST-segment depression > or = 0.1 mV was studied in 143 patients recovering from acute myocardial infarction. Patients were exercise tested prior to discharge and follow up lasted for up to 18 months (mean 17 months). End-point was first major event (i.e. first non-fatal reinfarction or death). A symptom-limited exercise test was superior to a heart-rate-limited test in detecting ST-segment depressions (27% vs. 20%: P < 0.5), and patients with ST-segment depression at lower heart rates did not have an increased risk of subsequent events compared with patients with ST-segment depression at higher heart rates (14% vs. 27%; NS). Heart failure surpassed ST-segment depression as a risk predictor (34% vs. 18%). Based on a meta-analysis including 13 studies (1987 patients) exercise-provoked ST-segment depression possessed an increased risk of subsequent major events (P < 0.0001; risk ratio = 1.90; 95% confidence limits 1.43,2.51). Thus, ST-segment depression provoked by a symptom-limited test selects patients with an increased risk of subsequent major events. In patients with a history of heart failure exercise-provoked ST-segment depression is of limited value.