Exercise-induced silent myocardial ischemia and future cardiac events in healthy, sedentary, middle-aged and older men

OBJECTIVES: Before men older than age 45 participate in vigorous exercise p rograms, the American Heart Association and the American College of Sports Medicine recommend they undergo a screening maximal exercise treadmill test . We examined the predictive value for subsequent cardiac events of exercis e-induced silent myocardial ischemia (SI) during the exercise treadmill tes t in healthy, sedentary, obese, middle-aged and older men recruited for res earch studies. DESIGN: A cohort study with 7 years of follow-up SETTING: Out-patient research at a tertiary hospital PARTICIPANTS: 170 healthy, sedentary, obese, middle-aged and older (ages 45 -79 years) men with no prior history of coronary artery disease (CAD) recru ited for research studies MEASUREMENTS: Cardiac risk factors, exercise-induced SI (ST segment depress ion on the electrocardiogram during a maximal exercise treadmill test), max imal aerobic capacity ((V) over dot O(2)max), and 7 - year follow-up data o n incident CAD RESULTS: At baseline, 37 of the men (22%) had exercise-induced SI on their treadmill tests. Seven-year follow-up data was obtained in 97% of the patie nts. In the interim, 31 men had cardiac endpoints (sudden cardiac death, my ocardial infarction, angioplasty, coronary artery bypass graft surgery, ang ina), and four had noncardiac deaths. Seventeen of the 37 men (46%) with ex ercise-induced SI on their baseline exercise tests had cardiac endpoints co mpared with 14 of 133 (11%) men with normal exercise tests (P <.001). Compa red with the men with no cardiac endpoints, the men with subsequent cardiac endpoints were older (63 +/- 1 vs 58 +/- 1 years, mean +/- SEM, P <.001) a nd had a lower maximal aerobic capacity ((V) over dot O(2)max) (24 +/- 1 vs 29 +/- 1 mL/kg/min, P < .001). In Cox proportional hazards analysis, exerc ise-induced SI and a low (V) over dot O(2)max were independent predictors o f subsequent cardiac endpoints. CONCLUSION: In a healthy population of obese, sedentary, middle-aged and ol der men, exercise-induced SI and low (V) over dot O(2)max were predictors o f incident CAD. This suggests that exercise treadmill testing is beneficial in assessing risk for future cardiac events in obese, sedentary individual s.