Incremental Value of the Preoperative Echocardiogram to Predict Mortality and Major Morbidity in Coronary Artery Bypass Surgery
Background—Although echocardiography is commonly performed before coronary artery bypass surgery (CABG), there has yet to be a study examining the incremental prognostic value of a complete echocardiogram.
Methods and Results—Patients undergoing isolated CABG at two hospitals were divided into derivation and validation cohorts. A panel of quantitative echocardiographic parameters was measured. Clinical variables were extracted from the STS database. The primary outcome was in-hospital mortality or major morbidity, and the secondary outcome was long-term all-cause mortality. The derivation cohort consisted of 667 patients with a mean age of 67.2±11.1 years and 22.8% females. The following echocardiographic parameters were found to be optimal predictors of mortality or major morbidity: severe diastolic dysfunction as evidenced by restrictive filling (OR 2.96; 95% CI 1.59,5.49), RV dysfunction as evidenced by fractional area change <35% (OR 3.03; 95% CI 1.28,7.20) or myocardial performance index >0.40 (OR 1.89; 95% CI 1.13,3.15). These results were confirmed in the validation cohort of 187 patients. When added to the STS risk score, the echocardiographic parameters resulted in a net improvement in model discrimination and reclassification with a change in c-statistic from 0.68 to 0.73 and an integrated discrimination improvement of 5.9% (95% CI 2.8%, 8.9%). In the Cox proportional hazards model, RV dysfunction and pulmonary hypertension were independently predictive of mortality over 3.2 years of follow-up.
Conclusions—Preoperative echocardiography, in particular RV dysfunction and restrictive LV filling, provides incremental prognostic value in identifying patients at higher risk of mortality or major morbidity after CABG.
- Received June 28, 2012.
- Accepted November 9, 2012.
- Copyright © 2012, American Heart Association, Inc. All rights reserved. Unauthorized use prohibited