Exercise versus recovery electrocardiography for predicting outcome in hypertensive patients with chest pain

BACKGROUND: Exercise electrocardiography has limited prognostic accuracy in hypertensives because of unsatisfactory specificity. We prospectively used comparative stress-recovery heart rate-adjusted ST (ST/HR) analysis to predict mortality in a consecutive population of hypertensives with chest pain. METHODS: The stress-recovery index (SRI), defined as the difference between ST/HR areas during exercise and recovery, was derived in 460 hypertensive with known (n=360, 78%) or suspected (n=100, 22%) coronary artery disease. To assess whether it added prognostic information to routinely obtained information, clinical data, the resting ejection fraction, and exercise testing data were entered into a sequential Cox's model; the SRI was entered last. Model validation was performed by bootstrap adjusted by the degree of optimism in estimates. Survival analysis was performed using the product-limit Kaplan-Meier method. RESULTS: During a median follow-up of 28 months (interquartile range, 13-44 months), 32 (7%) patients died, 23 (5%) suffered from acute myocardial infarction and 60 (13%) underwent late (> 3 months) revascularization. Male gender (hazard ratio, 1.53; 95% confidence interval, 1.01-2.34), peak double product (hazard ratio, 0.70; 95% confidence interval, 0.54-0.90) and the SRI (hazard ratio, 0.69; 95% confidence interval, 0.59-0.81 for interquartile difference) were independent predictors of outcome. The SRI increased the prognostic power of the model on top of clinical and exercise testing variables (concordance index, + 10%; discrimination index, + 32%) and showed the widest area under the ROC curve to predict outcome as compared with exercise-only ST analysis and the ST/HR index. Moreover, it provided a significant discrimination of survival. CONCLUSIONS: The SRI predicts all-cause mortality in hypertensive patients with chest pain and provides additional prognostic information over clinical and standard exercise testing data.