A prospective multicenter study of left bundle branch area pacing using stylet-driven lead: insights into capture types, delivery curve selection, and procedural failure

BACKGROUND: Stylet-driven lead (SDL)-based left bundle branch area pacing (LBBAP) is increasingly adopted, but detailed characterization of capture types, anatomic predictors of optimal sheath selection, and procedural challenges remains limited. METHODS: In this multicenter prospective pilot study, 100 patients undergoing SDL-LBBAP were enrolled. Electrical parameters including paced left ventricular activation time (LVAT) and QRS duration (QRSd) were systematically compared across capture types. Capture types were classified as left bundle branch pacing (LBBP), left bundle fascicular pacing (LBFP), and left ventricular septal pacing (LVSP). Anatomic predictors of sheath-curve selection were evaluated. Detailed procedural features were reviewed for unsuccessful implantations. RESULTS: Successful LBBAP was achieved in 94% of patients. Direct left bundle conduction system capture (LBBP/LBFP) showed shorter LVAT (LBBP: 68.9 ± 6.6ms; LBFP: 72.9 ± 8.2ms) compared to LVSP (86.3 ± 14.5ms); however, no significant differences in LVAT were observed between LBBP and LBFP or among LBFP subtypes. Left atrial (LA) diameter significantly correlated with final sheath curve used in successful procedures (P = 0.022). Patients requiring large-curve sheath had the largest median LA diameter (43.1 mm), followed by those requiring medium- (40.2 mm) and small-curve (33.5 mm) sheaths. Failed implantations (6%) predominantly occurred in patients with enlarged chambers and atrial fibrillation. CONCLUSION: Targeting broader LBFP area and considering LA size during sheath selection may represent feasible procedural consideration in SDL-LBBAP. Dedicated sheath designs may be beneficial in patients with enlarged cardiac chambers and atrial fibrillation. Given the pilot nature of this study, the findings are exploratory and intended to inform future larger-scale investigations.