Peak longitudinal strain delay is superior to TDI in the selection of patients for resynchronisation therapy

Background. Mechanical dyssynchrony has proven to be superior to QRS duration in predicting response to cardiac resynchronisation therapy (CRT). Whether time to peak longitudinal strain delay between the mid-septum and mid-lateral left ventricular wall better predicts CRT response than tissue Doppler imaging (TDI) is unclear. This study compares the value of the two methods for the assessment of mechanical dyssynchrony and prediction of CRT responders. Methods. 66 clinical responders and 17 nonresponders to CRT with severe systolic heart failure (LVEF <35%), New York Heart Association classification III or IV and a wide QRS >130 ms with left bundle branch block were evaluated by peak longitudinal strain and TDI. Doppler echocardiograms and electromechanical time delay (EMD) intervals were acquired before and after pacemaker implantation. Results. In all responders EMD measured by peak longitudinal strain was >60 ms before implantation, compared with 76% of the patients measured by TDI. Nonresponders had EMD <60 ms measured by both techniques. Only peak longitudinal strain delay showed shortened values in every responder postimplantation and demonstrated the most significant reduction and could predict responders to CRT. However, EMD measured by TDI did not diminish in 30% of the positive clinical responders. Nonresponders showed worsening of the EMD with peak longitudinal strain, but not with TDI. Conclusions. Responders to CRT can be excellently predicted if EMD before implantation determined by peak longitudinal strain delay is >60 ms. Peak longitudinal strain delay appears to be superior to TDI to predict the response to CRT.