Typical BBB morphology and implantation depth of 3830 electrode predict QRS correction by left bundle branch area pacing

Aim Strict criteria of typical left bundle branch block (LBBB) can help with the prediction for cardiac resynchronization therapy response. The aim of this study is to determine whether the use of strict criteria for both LBBB and right bundle branch block (RBBB) predicts successful QRS correction (<= 130 ms) by left bundle branch area pacing (LBBAP). Methods Consecutive patients with pacemaker indications according to the present guideline who also underwent LBBAP implantation were retrospectively assessed. Inclusion criteria were patients with BBB and the baseline QRSd > 130 ms. Baseline characteristics and pacing parameters were compared between typical and atypical BBB groups. Multivariate logistic regression was used to adjust for covariates that were found in univariate analyses for successful QRS correction by LBBAP. Results Seventy-three patients were enrolled. Among them, 10 (13.6%) had atypical BBB (5 LBBB and 5 RBBB) and 63 (86.4%) had typical BBB (30 LBBB and 33 RBBB). The rate of successful QRS correction was higher in typical-BBB patients (52/63; 82.5%) than that in atypical-BBB patients (3/10; 30%), P < .001. Paced QRSd was obviously narrower in patients with typical BBB than that in patients with atypical-BBB (118 +/- 14 vs 133 +/- 14 ms, P = .003). In multivariate logistic regression, only typical BBB morphology and the implantation depth of 3830 pacing electrode in the ventricular septum were independent predictors for successful QRS correction. Conclusion This study demonstrates that patients with typical-BBB morphology benefit more from LBBAP for QRS correction. Typical BBB morphology together with deep penetration of 3830 ventricular electrode in the interventricular septum predicts the success of QRS correction by LBBAP.