Abstract 9333: Prognostic Value of Stress Echocardiography In Patients Achieving a High Exercise Workload (=10 Metabolic Equivalents) and Submaximal Heart Rate Response

Abstract

Background: High exercise capacity (≥10 metabolic equivalents, METS) is a predictor of favorable prognosis. Submaximal studies (<85% maximum predicted heart rate, MPHR) may lead to non-diagnostic results and indeterminate outcomes. The purpose of this study was to examine the prognostic value of stress echocardiography (SEcho) in patients achieving high exercise capacity and submaximal heart rate response. Methods: We evaluated 81 patients (50 ± 13 years; 62% male) achieving nine minutes (≥10 METS) and <85% MPHR with treadmill SEcho. Resting left ventricular ejection fraction and regional wall motion were assessed. The left ventricle was divided into 16 segments and scored on 5-point scale of wall motion. Abnormal SEcho was defined as stress-induced ischemia (wall-motion score of ≥1 grade). Followup (3.4 ± 1.5 years) for non-fatal myocardial infarction and cardiac death (n = 2) were obtained. Results: By univariate analysis, the number of new ischemic wall motion abnormalities (hazard ratio = 2.5, confidence interval 1.2 - 5.3, p = 0.02) was the most significant predictor of cardiac events. Cumulative survival in patients achieving nine minutes (≥10 METS) and <85% MPHR was significantly worse in patients with abnormal (ischemic) vs. normal (nonischemic) SEcho (1.1%/year vs. 0.2%/year, p = 0.02)[Graph]. Conclusions: The ability to achieve nine minutes (≥10 METS), despite <85% MPHR by treadmill SEcho was associated with a benign prognosis (~1.0%/year). In the setting of high achieved exercise capacity and <85% MPHR, SEcho results (presence or absence of ischemia) were further able to sub-stratify this low risk group.