Effectiveness of upgrade left bundle branch area pacing for right ventricular pacing-induced cardiomyopathy: Extra QRS shortening matters

Background and ObjectivesLeft bundle branch area pacing (LBBAP) has developed as a strategy for patients with pacing-induced cardiomyopathy (PICM). We aimed to compare the upgrade effectiveness between LBBAP and traditional biventricular pacing (BVP) in PICM patients. MethodsConsecutive PICM patients with successful device upgrades were enrolled. The primary outcome was the echocardiographic response, defined as absolute left ventricular ejection fraction (LVEF) improvement >= 5% at 6-month follow up. ResultsA total of 92 patients were included. 61 underwent BVP and 31 underwent LBBAP. The median RVP burden was 96.8% (IQR: 93.0-99.0%). LBBAP achieved a shorter paced QRS duration (QRSd) compared with BVP (145.9 +/- 22.4 ms vs. 157.5 +/- 26.5 ms; p =.031). At 6 months, LBBAP had a higher echocardiographic response rate than BVP (67.7% vs. 39.3%, p =.019). LVEF increased from 37.8% +/- 9.2% to 44.8% +/- 10.2% (p <.001) in LBBAP compared with an improvement from 35.7% +/- 8.9% to 38.2% +/- 12.1% (p <.01) in BVP, with significantly greater change from baseline in LBBAP (7.0% +/- 7.0% vs. 2.5% +/- 8.7%; p =.024). Narrower pacing QRS after upgrade was associated with better echocardiographic response only in LBBAP but not in BVP. (P for interaction <.05). Both groups had similar rates of composite clinical outcome. ConclusionLBBAP improved echocardiographic response compared with BVP in PICM patients. The superior efficacy of LBBAP in reverse remodeling was dependent on improved electrical synchrony.