Prediction of Outcomes in Patients with Chronic Ischemic Cardiomyopathy by Layer-Specific Strain Echocardiography: A Proof of Concept

Abstract

Cardiac magnetic resonance imaging (CMR) has been established as a powerful tool for predicting mortality. However, its application is limited by availability and various contraindications. The aim of this study was to evaluate the predictive value of layer-specific myocardial deformation analysis as assessed by strain echocardiography for cardiac events in patients with chronic ischemic left ventricular dysfunction in comparison with CMR. Three hundred ninety patients (mean age, 63±4years; 69% men; mean left ventricular ejection fraction [LVEF], 41±7%) with chronic ischemic cardiomyopathy were prospectively enrolled and underwent strain echocardiography and CMR within 3±1days. LVEF, wall motion score index, and circumferential strain (CS), longitudinal strain, and radial strain for total wall thickness and for three myocardial layers (endocardial, midmyocardial, and epicardial) were determined by echocardiography. The extent of total myocardial scar (TMS) was determined by CMR. Follow-up was obtained for a mean of 4.9±2.2years. Cardiac events were defined as readmission for worsening of heart failure, ventricular arrhythmias, or death of any cause. The incremental value of LVEF, strain parameters, and TMS to relevant clinical variables was determined in nested Cox models. There were 133 cardiac events (34%). Baseline clinical data associated with outcomes were age (hazard ratio [HR], 1.27; P=.04), diabetes mellitus (HR, 1.52; P=.001), and renal insufficiency (HR, 1.77; P=.001) by multivariate analysis. The addition of LVEF, global and endocardial strain parameters, and TMS increased the predictive power, but endocardial CS (HR, 1.52; P<.01) caused the greatest increment in model power (χ(2)=39.2, P<.001). Endocardial CS<-20% was found to be the optimal predictor of prognosis. Endocardial CS is a powerful predictor of cardiac events and appears to be a better parameter than LVEF, TMS by CMR, and other strain variables by echocardiography.