Combined Assessment of Left Ventricular Dyssynchrony and Contractility by Speckled Tracking Strain Imaging: A Novel Index for Predicting Responders to Cardiac Resynchronization Therapy

Abstract

Background: Mechanical dyssynchrony is an important factor in the response to cardiac resynchronization therapy (CRT). However, no echocardiographic measure can improve prediction of case selection for CRT.Objective: The purpose of this study was to assess the efficacy of a newly combined echocardiographic index for ventricular dyssynchrony and contractility using speckled tracking strain analysis to predict responders to CRT.Methods: Forty-seven patients with severe heart failure in New York Heart Association functional class III/IV, left ventricular ejection fraction ≤35%, and QRS duration ≥130 ms were included in the study. Echocardiography was performed, and a novel index (i-Index), the product of radial dyssynchrony and radial strain, was calculated. Responder to CRT was defined as a patient with a ≥15% decrease in left ventricular end-systolic volume at 6-month follow-up.Results: Thirty-two patients (68%) were classified as responders. The i-Index was significantly higher in responders than in nonresponders (3,450±1,180 vs 1,481±841, P 2,000 predicted responders with 94% sensitivity and 80% specificity. The index using only radial dyssynchrony had 81≤% sensitivity and 53% specificity. Furthermore, i-Index decreased in responders (1,985±1,261, P<.001) but not in nonresponders (1,684±866, P=.48).Conclusion: Our findings suggest that a novel combined index by radial strain echocardiography might be a predictor of response to CRT. The value of this novel echocardiographic index requires further assessment in larger studies.