Effect of Pharmacologic Stress Test Results on Outcomes in Obese versus Nonobese Subjects Referred for Stress Perfusion Echocardiography

Background Real-time contrast stress echocardiography (RTCSE) permits the simultaneous analysis of myocardial perfusion and wall motion during stress echocardiography, which has resulted in improved coronary artery disease detection. Although several studies have confirmed a protective effect of obesity in coronary artery disease, it is unclear whether this benefit is dependent on the functional significance of the disease. The objective of this study was to compare outcomes in obese versus nonobese subjects referred for pharmacologic RTCSE. Methods A retrospective comparison of wall motion and myocardial perfusion with RTCSE was assessed in 481 obese and 961 nonobese patients matched for age and gender without known coronary artery disease referred for either dobutamine (n = 1,056) or dipyridamole (n = 386) stress echocardiography at two separate institutions. Outcomes (death or nonfatal infarction) were determined over a median follow-up period of 1,195 days. Results Abnormal myocardial perfusion and/or wall motion was seen in 207 (20%) dobutamine and 61 (16%) dipyridamole studies. Abnormal rates were similar in obese (17%) and nonobese (19%) subjects. Event-free survival was significantly worse only for nonobese subjects referred for dobutamine RTCSE, with obesity (not test result) being an independent predictor of event-free survival on multivariate analysis (P = .001). No protective effect of obesity was observed following dipyridamole RTCSE. Conclusions Obese subjects in the United States referred for demand stress testing have better outcomes when directly compared with age- and gender-matched nonobese subjects with similar degrees of inducible ischemia.