Predictive implications of stress testing. Follow up of 2700 subjects after maximum treadmill stress testing

Abstract

Follow up data on 2700 subjects who had had maximum stress tests were assembled in life tables. A positive test, characterized by ST segment depression of 1.5 mm, 0.08 sec from the J point, predicted an incidence of some new coronary event of 9.5%/yr, as compared with 1.7% in those with a negative test. The incidence of infarction and death was also significantly higher than in the negative responders. Early onset of ischemia occurring at moderate exercise (4 metabolic equivalents METS) resulted in an incidence of all coronary events of 15%/yr, while ischemia first manifested at the 7th minute of exercise (approximately 8 METS) results in an incidence of only 4%/yr. The magnitude of ST depression and the age of onset of ischemia failed to influence the incidence of coronary events. A myocardial infarction previous to the test increased the incidence of events in both positive and negative responders. The positives with a previous infarction had more than double the incidence of coronary events than the positive responders with no pre existing infarction. Those with chronotropic incompetence had a high incidence of coronary events even though the ECG response to exercise was normal.