Comparison of Speckle Tracking Echocardiography During Different Pacing Modalities for Cardiac Resynchronization Therapy Response Prediction

Background : The aim of this study was to evaluate left ventricular mechanical activation pattern by speckle tracking echocardiography (STE) as a predictor of response to cardiac resynchronization therapy (CRT) in patients with heart failure. Methods : Echocardiography was performed during no pacing, right ventricular pacing (RVP), biventricular pacing (BVP) and multipolar pacing (MPP) immediately after CRT implantation in 16 patients at a single centre. Seven patients were diagnosed as responders and 9 patients as non-responders after 6 months of standard CRT pacing. All had adequate short axis views, and 1 CRT responder and 2 CRT non-responders had limited longitudinal views. Results : Longitudinal and circumferential global strain (GS) and global strain rate (GSR) or their change analysis, did not yield any CRT response prediction. However, the longitudinal BVP/RVP GS ratio was significantly higher in the responder group (1.32 ± 0.2%, 2.0 ± 0.4% and 1.9 ± 0.4%), compared with the non-responder group (1.06 ± 0.2%, 1.1 ± 0.4% and 1.2 ± 0.4%) in the apical two-chamber, APLAX and four-chamber views, respectively. Similarly, the longitudinal BVP/RVP GSR at active systolic phase (GSRs) was significantly higher in the responder group (1.9 ± 0.9% and 1.7 ± 0.4%) compared with the non-responder group (1.0 ± 0.4% and 1.1 ± 0.2%) in the apical APLAX and four-chamber views, respectively. Measurements of the strain delay index showed predictive power regarding CRT response in non-paced patients. Conclusion : Post implantation, longitudinal BVP/RVP GS and GSRs ratios of 1.4% and above may be useful as a CRT response prediction tool. Furthermore, our findings support the usefulness of strain delay index prior to CRT implantation in non-paced patients.