Right bundle branch pacing: Criteria, characteristics, and outcomes

BACKGROUND Targets for right-sided conduction system pacing (CSP) include His bundle and right bundle branch. Electrocardio-graphic patterns, diagnostic criteria, and outcomes of right bundle branch pacing (RBBP) are not known.OBJECTIVE Our aims were to delineate electrocardiographic and electrophysiological characteristics of RBBP and to compare out-comes between RBBP and His bundle pacing (HBP).METHODS Patients with confirmed right CSP were divided accord-ing to the conduction system potential to QRS complex interval at the pacing lead implantation site. Six hypothesized RBBP criteria as well as pacing parameters, echocardiographic outcomes, and all-cause mortality were analyzed.RESULTS All analyzed criteria discriminated between HBP and RBBP: double QRS complex transition during the threshold test, se-lective paced QRS complex different from conducted QRS complex, stimulus to selective-QRS complex > potential-QRS complex, small increase in V6 R-wave peak time (V6RWPT) during QRS complex tran-sition, equal capture thresholds of CSP and myocardium, and stimulus-V6RWPT > potential-V6RWPT (adopted as the diagnostic standard). According to the last criterion, RBBP was observed in 19.2% of patients (64 of 326) who had been targeted for HBP, present mainly among patients with potential to QRS complex interval ,35 ms (90.6% [48 of 53]) and occasionally among the remaining patients (5.6% [16 of 273]). RBBP was characterized by longer QRS complex (by 10.5 ms), longer V6RWPT (by 11.6 ms), and better sensing (by 2.6 mV) compared with HBP. During a median follow-up duration of 29 months, no differences in capture threshold, echocardiographic outcomes, or mortality were found.CONCLUSION RBBP has distinct features that separate it from HBP and is observed in approximately a fifth of patients in whom HBP is intended.

Automated summary

This study compared two methods of right-sided conduction system pacing, right bundle branch pacing (RBBP) and His bundle pacing (HBP). The results showed that RBBP has distinct features separate from HBP, and approximately one-fifth of patients are suitable for RBBP.