Abstract 3520: A Novel Combined Assessment of Left Ventricular Dyssynchrony and Contractility by Radial Strain Echocardiography Predicts Responders to Cardiac Resynchronization Therapy
Introduction: Mechanical left ventricular (LV) dyssynchrony in patients with reduced LV systolic function is associated with response to cardiac resynchronization therapy (CRT). However approximately 30% of patients who received CRT judged as nonresponders by any dyssynchrony measurements.
Hypothesis: LV contractility index has not been assessed to predict responders in previous reports. We assessed the hypothesis that combined evaluation of LV dyssynchrony and contractility could predict responders more adequately.
Methods: We studied 47 heart failure patients with low ejection fraction (EF) and wide QRS interval by speckle tracking radial strain echocardiography before and 6 months after CRT. We measured the max difference (RD) and the standard deviation (SDt) of time to peak-systolic strains as dyssynchrony measurements, and the mean radial thickening (RS) as contractility measurement. Two indices, RD × RS (d-Index) and SDt × RS (i-Index), were also calculated as combined indices. Definition of responder was a decrease of 15%≥LV end-systolic volume.
Results: Thirty-two (68%) patients were judged as responders after CRT. Novel indices were significantly higher in responders than in nonresponders (d-Index: 8030±3074 vs. 4094±2179, p<0.001, i-Index: 3450±1180 vs. 1481±841, p<0.001). Both indices decreased at 6-month follow-up in responders, but not in nonresponders. Receiver-operating characteristic curve analysis revealed that the area under the curve (AUC) for d-Index was 86% and optimal cut-off value (5000) predicted responders with 84% sensitivity and 73% specificity, and that AUC for i-Index was 92% and optimal cut-off value (2000) predicted with 94% sensitivity and 80% specificity. AUC for RD was 70% and RD predicted responders with a high sensitivity of 81% but with a low specificity of 53% and
Conclusions: Combined assessment of dyssynchrony and contractility could be the most predictive indices for responders after CRT. Assessment of left ventricular contractility by radial strain imaging will be also important in addition to the evaluation of mechanical dyssynchrony.