Reduction of QRS amplitude correlates with decrease in left-ventricular pre-ejection time after cardiac resynchronisation therapy

Introduction Left ventricular pre-ejection time (LVPET) is associated with myocardial efficiency. LVPET increases in patients with heart failure and decreases after cardiac resynchronisation therapy (CRT) with variation according to pacing site. The objective of this study was to evaluate the relationship between electrocardiogram (ECG) parameters and LVPET in patients with CRT. Methods It was an observational, prospective, and monocentric study. From May 2017 to October 2017, all patients who underwent CRT with left quadripolar lead in Rouen University Hospital were included. LVPET was evaluated by echocardiography and defined as the time between the beginning of the QRS and the beginning of pulsed Doppler signal positioned in left ventricular outflow tract in apical view. The following parameters on 12-leads ECG were assessed: QRS width in V3, sum of QRS amplitude in all lead. Measures were performed during bi-ventricular pacing (at each pacing electrode of the quadripolar lead called D1, M2, M3, P4, for distal to proximal ones), left-ventricular pacing alone, right-ventricular pacing alone, and spontaneous rhythm. Partial correlation test was used. Results Seventeen patients were included. In each patient, LVPET was correlated with QRS width (P = 0.02, R = 0.194) and QRS amplitude (P  Fig. 1 ). It was observed that the lower the LVPET, the lower the QRS amplitude and the narrower the QRS width. In each patient, mean variation of QRS width was equal to 64.7 ± 29.4%, mean variation of LVPET was equal to 37.1 ± 16.4% and mean variation of QRS amplitude was equal to 53.2 ± 27.4%. Conclusion QRS width, but also QRS amplitude varies according to the pacing site after CRT and are correlated with left ventricular pre-ejection time. These ECG parameters could be helpful to optimize CRT.