Supplementary Material
Figure S1. Quadripolar left ventricular lead (Quartet™, model 1458Q, Abbott). We first chose one of the two distal electrodes (D1 or M2). Subsequently, we chose one of the two proximal electrodes (M3 or P4), prioritizing the maximum distance between LV1 and LV2: D1/P4 > D1/M3 or M2/P4.
Figure S2 Description of the fusion-optimized atrioventricular (AV) interval method. During atrial sensing, the AV interval was progressively shortened by 20 ms during left ventricular (LV) pacing alone, from intrinsic conduction with a long AV interval (second left ) to only LV activation with a short AV interval (right ). The AV interval that provided the narrowest QRS was selected and considered the fusion-optimized AV interval (AV FOI). QRSd, QRS duration.
Figure S3 Evaluation of cardiac asynchrony at several levels using echocardiography. A Left intraventricular: septal flash on M-mode imaging (yellow arrows ). B Atrioventricular: diastolic filling ratio (diastolic filling time [DFT]/RR interval duration). C, D Interventricular: the difference between the left (D, orange ) and right (C, blue ) ventricular pre-ejection times using pulsed-wave Doppler.