Abstract 15541: Effect of Stress Perfusion and Wall Motion Response on Outcome of Obese versus Non-Obese Subjects Without Known Coronary Artery Disease

Abstract

Background: Although several studies have demonstrated a protective effect of obesity in coronary artery disease (CAD), it is unclear whether this protective effect is evident in patients referred for stress imaging. Real time contrast echocardiography (RTCE) permits the simultaneous analysis of perfusion and wall motion during different forms of stress echocardiography.The objective of this study was to determine whether a protective effect of obesity is evident in subjects referred for pharmacologic stress RTCE. Methods and Results: Wall motion (WM) and myocardial perfusion (MP) with RTCE (using SonoVue and Definity ultrasound contrast) were assessed in 2106 consecutive patients without known CAD referred for either dobutamine (n=1209) or dipyridamole (n=897) stress echocardiography. Of these, 481 (23%) were obese (body mass index>30 kg/m2). Outcome (death/non-fatal infarction) was determined over a median follow-up of 1022 days. Multivariate Cox Models were created from significant univariate variables to assess hazard ratios (HR) and 95% confidence intervals (CI). Abnormal MP and/ or WM were seen in 246 dobutamine and 169 dipyridamole studies (equally distributed between obese and non-obese). Although event free survival (EFS) was significantly better for obese versus non-obese subjects with normal tests (p=0.01) and in obese patients with abnormal dobutamine stress perfusion/wall motion responses (p=0.009), obesity was not an independent clinical predictor of outcome, while age (HR 1.04 (95% CI 1.03-1.06) and male gender (HR 2.26;(95% CI 1.59-3.21) did independently predict outcome (both p<0.001). Furthermore, abnormal responses to stress (either dobutamine or dipyridamole) were associated with significantly worse prognosis, independent of age, gender, or obesity (HR 2.67;95% CI 1.91-3.77). Conclusions: Although obese subjects with both normal and abnormal responses to pharmacologic stress have improved EFS when compared to non-obese with the same test result, this trait is not independently associated with outcome. Perfusion and wall motion responses determined with RTCE add significant predictive value in this setting irrespective of age, gender, or obesity status.