Left Bundle Branch Capture During Left Bundle Branch Area Pacing: A Diagnostic Accuracy Systematic Review.

BACKGROUND: Left bundle branch area pacing (LBBAP) does not necessarily achieve true left bundle branch (LBB) capture, and misclassifying left ventricular septal pacing (LVSP) as LBB capture may bias procedural decisions and outcome interpretation. We evaluated the diagnostic accuracy of electrocardiographic (ECG) and electrophysiological criteria for confirming true LBB capture and distinguishing it from LVSP or deep septal pacing. METHODS: Following PRISMA-DTA, we searched PubMed/MEDLINE, CENTRAL, the Cochrane Database of Systematic Reviews, and Google Scholar from inception to July 8, 2026. Eligible studies evaluated V6 R-wave peak time (V6RWPT), V6-V1 interpeak interval, aVL R-wave peak time, morphologic criteria, combined ECG criteria, or ECG/electrogram algorithms against a stated reference standard. Risk of bias was assessed with QUADAS-2, emphasizing circularity. RESULTS: Of 332 records, 15 original studies were included; eight formed the primary diagnostic accuracy evidence set, of which four provided extractable criterion-level 2 × 2 data for exploratory pooling. The V6-V1 interpeak interval and combined ECG criteria showed the most consistent rule-in performance, whereas fixed V6RWPT thresholds were susceptible to baseline conduction disease and pacing-site variability. ECG and electrogram (EGM) stepwise algorithms achieved the highest specificity but had limited applicability owing to heterogeneous reference standards. CONCLUSIONS: The evidence supports a stepwise approach rather than any single ECG cutoff. High-specificity ECG criteria aid rule-in confirmation, whereas dynamic output-dependent transitions and EGM-based adjudication remain essential when ECG criteria are equivocal. Standardized definitions and reference standards are needed for future LBBAP trials.