Preoperative Three-Dimensional Strain Imaging Identifies Reduction in Left Ventricular Function and Predicts Outcomes After Cardiac Surgery

BACKGROUND: Echocardiography-based speckle-tracking strain imaging is an emerging modality to assess left ventricular function. The aim of this study was to investigate the change in left ventricular systolic function after cardiac surgery with 3-dimensional (3D) speckle-tracking strain imaging and to determine whether preoperative 3D strain is an independent predictor of acute and long-term clinical outcomes after aortic valve, mitral valve, and coronary artery bypass grafting operations. METHODS: In total, 163 adult patients undergoing aortic valve, mitral valve, and coronary artery bypass surgeries were enrolled prospectively and had complete data sets. Demographic, operative, and outcome data were collected. 3D transthoracic echocardiograms were preformed preoperatively and on second to fourth postoperative day. Blinded off-line analysis was performed for left ventricular 2-dimensional (2D) ejection fraction (EF2D) and 3D ejection fraction (EF3D) and global peak systolic area, longitudinal, circumferential, and radial strain. RESULTS: 3D global strain correlated well with EF3D. Ventricular function as measured by strain imaging decreased significantly after all types of cardiac surgery. When preoperative EF3D was used, receiver operating characteristic curves identified reference values for 3D global strain corresponding to normal, mildly reduced, and severely reduced ventricular function. Normal ventricular function (EF3D ≥ 50%) corresponded to 3D global area strain -25%, with area under curve = 0.86 (0.81-0.89). Patients with reduced preoperative 3D global area strain had worse postoperative outcomes, including length of intensive care unit stay (4 vs 3 days, P = .001), major adverse events (27% vs 11%, P = .03), and decreased 1-year event-free survival (69% vs 88%, P = .005). After we controlled for baseline preoperative risk models including European System for Cardiac Operative Risk Evaluation score and surgery type, preoperative strain was an independent predictor of both short- and long-term outcomes, including length of intensive care unit stay, postoperative inotrope score, and 1-year event-free survival. CONCLUSIONS: This study shows that cardiac surgery was associated with an acute reduction in postoperative left ventricular function, when evaluated with 3D strain imaging. In addition, preoperative 3D strain was demonstrated to be an independent predictor of acute and long-term clinical outcomes after cardiac surgery. The use of noninvasive 3D transthoracic echocardiogram strain imaging before cardiac surgery may provide added information to aid in perioperative risk stratification and management for these high-risk patients.