INDEPENDENT PROGNOSTIC-SIGNIFICANCE OF ISCHEMIC ST-SEGMENT RESPONSE LIMITED TO RECOVERY FROM TREADMILL EXERCISE IN ASYMPTOMATIC SUBJECTS

Background-Although exercise-induced ST depression is an independent p redictor of future coronary events in asymptomatic populations, the pr edictive value of ST depression beginning after exercise cessation is unknown. Methods and Results-We analyzed the treadmill exercise tests of 825 healthy volunteers who were 22 to 89 years of age from the Balt imore Longitudinal Study of Aging. All subjects were foe from coronary heart disease by history, physical examination, and resting EGG. From 825 participants, 611 (group 0) had no ischemic ST-segment changes du ring or after treadmill exercise, while 214 subjects developed greater than or equal to 1-mm flat or downsloping ST depression: 151 (group 1 ) had ST changes starting during exercise, and 63 (group 2) had change s limited to recovery. Groups 1 and 2 were similar in age, sex, smokin g status, hypertension prevalence, fasting plasma glucose, and serum c holesterol (CHOL). However, both groups were older and had higher CHOL and prevalence of hypertension than group 0. Treadmill exercise durat ion, peak oxygen consumption, and maximal heart rate were similar betw een groups 1 and 2 but were lower than in group 0 (each P<0.05). Durin g a mean follow-up time of 9 years, 55 subjects developed coronary eve nts (angina pectoris, myocardial infarction, or coronary death): 21 of 611 (3.4%) in group 0, 22 of 151 (14.6%) in group 1, and 12 of 63 (19 %) in group 2 (P=0.001). By survival analysis, the risk of coronary ev ents was similar in groups 1 and 2 but significantly higher than in gr oup 0 (P<0.0001). Multiple logistic regression showed that age (odds r atio [OR]=1.07 per year, P=0.00001), CHOL (OR=1.02 per 1 mg, P=0.0001) , and presence of ST-segment depression (OR=2.59, P=0.007 and OR=2.38, P=0.04 for groups 1 and 2, respectively) were independent predictors of events. Conclusions-Thus, ischemic ST-segment changes developing du ring recovery from treadmill exercise in apparently healthy individual s have adverse prognostic significance similar to those appearing duri ng exercise.