QRS duration shortening predicts left ventricular reverse remodelling in patients with dilated cardiomyopathy after cardiac resynchronization therapy

Objective The relationship between the QRS duration, severity of mechanical dyssynchrony and efficacy of cardiac resynchronization therapy (CRT) is poorly understood. We determined if QRS duration shortening in patients with dilated cardiomyopathy after treatment with CRT was predictive of left ventricular (LV) reverse remodelling. Methods Thirty patients with dilated cardiomyopathy were enrolled. Electrocardiographic and echocardiographic recordings were obtained before and 6 months after CRT. Patients were classified as CRT responders or non-responders based on their echocardiographic parameters 6 months following CRT. Results After 6 months of CRT, 9 patients (30%) were classified as non-responders. Surprisingly, no significant differences in any of the preoperative metrics were found between CRT responders and non-responders. In sharp contrast, the postoperative parameters of the CRT responder group had significantly improved compared to the non-responder group. The average QRS duration of the CRT responders was significantly shorter than that of the non-responders (-37 +/- 23 ms vs 0 +/- 23 ms; P<0.01). The relationships between preoperative parameters, the change in QRS duration and LV end-diastolic diameter were analysed for each patient using multi-linear correlation and regression analyses. We found that the change in QRS duration positively correlated with the change in LV end-diastolic diameter (R=0.583, P=0.001). Furthermore, multi-linear regression analysis suggested that changes in QRS duration had a significant effect on LV end-diastolic diameter (y=9.739+0.272 x, P=0.006). Conclusion CRT-mediated changes in the QRS duration are predictive of LV reverse remodelling in patients with dilated cardiomyopathy.