Tissue Doppler Derived Mechanical Dyssynchrony Does Not Change after Cardiac Resynchronization Therapy

Background: Mechanical left ventricular (LV) dyssynchrony, as determined by tissue Doppler imaging (TDI), predicts response to cardiac resynchronization therapy (CRT). However, changes in TDI mechanical dyssynchrony after CRT implantation have only limited investigation. Our objective was to detect changes in the extent and location of TDI mechanical dyssynchrony pre- and post-CRT, and to explore their relationship in response to CRT. Methods: Thirty-nine consecutive patients undergoing CRT implantation for chronic heart failure underwent TDI analysis pre-CRT and up to 12 months post-CRT. Regional dyssynchrony was determined by the time to systolic peak velocity of opposing LV walls. Dyssynchrony was defined as a difference in time to peak contraction of >105 msec. Two patients were excluded, as suitable coronary venous access was not available. Results: Of the 37 patients, 28 (76%) had significant mechanical dyssynchrony pre-CRT. Of those with dyssynchrony, 18 (64%) had septal delay and 10 (36%) had LV free wall delay. Post-CRT, 29 (78%) patients had significant mechanical dyssynchrony, 17 (59%) with septal delay, and 12 (41%) with LV free wall delay. There was no difference in both the amount of dyssynchrony (P = 0.8) or the location of the dyssynchrony (P = 0.5), before and after CRT, even though 28 (76%) were considered responders based on symptomatic and echocardiographic parameters. Conclusion: The TDI-derived dyssynchrony does not change with CRT despite significant symptomatic and echocardiographic improvement in cardiac function. The TDI is of limited utility for monitoring response to CRT. (Echocardiography 2011;28:961-967)