Ventricular pacing burden in patients with left bundle branch block after transcatheter aortic valve replacement therapy

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. INTRODUCTION: Electrophysiological (EP) testing has been proposed in the latest ESC guidelines for cardiac pacing to identify LBBB patients with infrahisian conduction delay (IHCD) after transcatheter aortic valve replacement (TAVR). While in general IHCD is defined by a His-ventricular (HV) interval of > 55ms, a cut-off of ≥ 70ms to trigger pacemaker (PM) implantation has been proposed in the latest ESC guidelines. The ventricular pacing (VP) burden during follow-up in such patients is largely unknown. PURPOSE: To assess the VP burden during follow-up of patients receiving PM therapy for LBBB after TAVR based on an HV interval > 55 ms and ≥ 70ms. METHODS: All patients with new-onset or pre-existing LBBB after undergoing TAVR at a tertiary referral center underwent EP testing the day after TAVR. In patients with a prolonged HV interval (>55 ms), PM implantation was performed by a trained electrophysiologist in a standardized fashion. All devices were programmed to avoid unnecessary VP by specific algorithms (e.g., AAI-DDD). RESULTS: 701 patients underwent TAVR at our university hospital between October 2014 and November 2021. 177 patients presented with new-onset or pre-existing LBBB the day following TAVR and underwent EP testing. An HV interval > 55 ms was found in 58 patients (33%) and an HV interval ≥ 70 ms in 21 patients (12%). 51 patients (mean age 84 ± 6.2 years, 45% women) agreed to receive a PM, out of which 20 (39%) patients had an HV Interval over 70 ms. Atrial fibrillation was present in 53% of the patients. A dual chamber PM was implanted in 39 (77%), and a single chamber pacemaker in 12 (23%) patients, respectively. Median FU was 21 months (IQR 11-41). The median VP burden overall was 3%. The median VP burden was numerically higher in patients with an HV ≥70 ms (6.5% [0.8 - 52]) than in those with an HV between 55 and 69 ms (2% [0 – 17], p = 0.23). 31% of patients had a VP burden <1%, 27% 1-5% and 41% > 5% (Figure). The median HV intervals in patients with VP burden <1%, 1-5% and >5% were 66 (IQR 62 -70) ms, 66 (IQR 63 – 74) ms and 68 (IQR 60 – 72) ms respectively, p= 0.52. When only assessing patients with an HV interval 55-69 ms, 36% demonstrated a VP burden of <1%, 29% of 1-5% and 35% of >5 %. In patients with an HV Interval ≥ 70ms, 25% demonstrated a VP burden <1%, 25% of 1-5% and 50% of >5 %, p=0.64 (Table). CONCLUSION: VP burden can be significant in patients with LBBB after TAVR and an HV interval of > 55 ms. Further studies are warranted to define the optimal cut-off to trigger PM implantation in patients with LBBB after TAVR. [Figure: see text] [Figure: see text]