Predictors of procedural failure of left bundle branch pacing in scarred left ventricle

Introduction Presence of scar at the implantation‐site is considered as a major factor in determining the success of left bundle branch pacing (LBBP). We aimed at analyzing the predictors of procedural failure in patients with scarred‐left ventricle (LV) as demonstrated by cardiac‐magnetic resonance‐imaging (CMR). Methods This was a retrospective, observational single‐center‐study that included consecutive cardiomyopathy patients with LV‐scar as demonstrated by late‐gadolinium‐enhancement (LGE) in CMR requiring LBBP. Procedural‐failure was defined as the inability to penetrate the septum to reach the LV subendocardium Results A total of 25 cardiomyopathy patients demonstrated LGE in CMR and were included in the study. LBBP was successful in 16 patients (group‐I; 64% acute‐procedural‐success). In the remaining 9 patients (group‐II) lead could not be penetrated and hence biventricular‐pacing was done. LBBP resulted in reduction in QRS‐duration and improvement in LV ejection fraction in group‐I patients during a mean follow‐up of 11.2 ± 3.7 months. Computed‐tomography‐angiography after LBBP showed the successful lead deployment site (LBBP‐Zone) as the overlapping areas of inferior aspect of antero‐septum and superior aspect of infero‐septum (segment 2/3; AHA‐model) in short‐axis view(figure‐1C). CMR showed LGE in significantly more number of LV‐segments and high scar‐burden in group‐II as compared to group‐I (figure‐1). A total scar score value of >1.0 predicted failure with 100%‐sensitivity and 75%‐specificity. CMR revealed transmural‐scar in the LBBP‐Zone in all patients in group‐II (n = 9; 100%). Transmural scar in LBBP‐Zone by CMR had 100%‐sensitivity and 100%‐specificity for predicting the procedural‐failure. Conclusion CMR helps in predicting the procedural failure of LBBP in patients with scarred LV. Presence of transmural‐LGE in the LBBP‐Zone predicts failure with high sensitivity and specificity.