Incremental Value of Speckle Tracking Echocardiography to Predict Cardiac Resynchronization Therapy (CRT) Responders

BACKGROUND Speckle tracking echocardiography (STE) is reported as a useful method to predict cardiac resynchronization therapy (CRT) responders. This study aimed to identify the incremental value of a STE parameter to predict CRT responders. METHODS AND RESULTS We enrolled 171 patients from the Speckle Tracking imaging for the Assessment of cardiac Resynchronization Therapy (START) study. CRT responders were defined as patients with ≥15% reduction of left ventricular (LV) end-systolic volume at 6 months post-CRT. Based on multivariable logistic regression analysis, incremental values of STE were assessed by c-statistics, net reclassification improvement (NRI)/integrated discrimination improvement (IDI), and decision curve analysis. Six parameters (left bundle branch block or right ventricular pacing, use of beta-blocker, blood urea nitrogen ≤3.0 mg/dL, LV end-systolic diameter ≤50 mm, mitral regurgitation index ≤40%, and STE parameter standard deviation of time from QRS onset to first peak on the circumferential strain curves [TSD] ≥116 ms) were identified as the determinants. Compared to the multivariable logistic regression model without TSD (model 1), that with TSD (model 2) showed significant improvement to predict CRT responders: c-statistic (0.86 vs 0.77; P<0.001), NRI=0.19, P<0.001, and IDI=0.17, P<0.001. The decision curve of model 2 was higher than that of model 1 at threshold probabilities ≥0.2. Based on model 2, a START score was constructed. Compared to the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT) score, the decision curve of the START score was higher than that of the MADIT-CRT score at threshold probabilities ≥0.2. CONCLUSIONS Based on various statistical methods, this study revealed that STE had an incremental value to predict CRT responders.