Usefulness of exercise testing in the prediction of coronary disease risk among asymptomatic persons as a function of the Framingham risk score

Background - The purpose of this study is to determine the usefulness of exercise treadmill testing (ETT) among asymptomatic persons in predicting coronary heart disease (CHD) events over and above the Framingham CHD risk score. Methods and Results - Subjects included 3043 members of the Framingham Heart Study offspring cohort without CHD ( 1431 men and 1612 women; age, 45 +/- 9 years) who underwent ETT and were followed up for 18.2 years. The risk of developing CHD was evaluated relative to 3 exercise test variables: ( 1) ST-segment depression greater than or equal to 1 mm, ( 2) failure to achieve target heart rate (THR) of 85% predicted maximum, and ( 3) exercise capacity. In multivariable analyses that adjusted for age and Framingham CHD risk score, among men, ST-segment depression ( hazard ratio [HR], 1.88; 95% CI, 1.21 to 2.91) and failure to achieve THR (HR, 1.70; 95% CI, 1.18 to 2.45) predicted higher CHD risk, whereas a greater exercise capacity predicted lower CHD risk ( HR per MET, 0.94; 95% CI, 0.89 to 0.99). Although similar HRs were seen in women, those results were not statistically significant. Among men with 10-year predicted risk greater than or equal to20%, failure to reach THR and ST-segment depression both more than doubled the risk of an event ( HR, 2.66 and HR, 2.11, respectively), and each MET increment in exercise capacity reduced risk by 13% ( HR, 0.87). Conclusions - Among asymptomatic men, ST-segment depression, failure to reach THR, and exercise capacity during ETT provided additional prognostic information in age- and Framingham risk score - adjusted models, particularly among those in the highest risk group ( 10-year predicted CHD risk of greater than or equal to 20%). The evaluation of exercise test variables in women is limited, given our sample size and the few CHD events in women.