Background and Aims: Left bundle branch area pacing (LBBAP) promotes physiological synchronous activation of the left ventricle and may be particularly beneficial in patients with atrioventricular block (AVB), but its mortality benefit remains unclear. This study aims to compare long-term survival in AVB patients receiving either LBBAP or right ventricular pacing (RVP) and to analyse predictors of mortality during LBBAP. Methods: MELOS RELOADED, a multicentre European collaboration, was a registry-based study of pacemaker patients with AVB, left ventricular ejection fraction (LVEF) >40% and ventricular pacing >20%. The primary outcome was all-cause mortality based on national registries. A 1:1 propensity score matching was performed between the RVP and LBBAP groups. Kaplan–Meier curves and multivariable Cox proportional hazards models were used to estimate survival. Results: In total, 3382 patients receiving LBBAP or RVP were matched. At 4-year follow-up, the Kaplan–Meier curve showed an absolute difference in survival of 11.8% in favour of LBBAP (P < .001). LBBAP was a robust predictor of reduced mortality with a hazard ratio (HR) of 0.53 (95% confidence interval 0.42–0.65, P < .001). Within the LBBAP group, the following independent predictors of increased mortality were identified: lack of confirmed left bundle branch capture (HR 1.85, P < .001), lower percentage of ventricular pacing (HR 1.12), and age. Conclusions: This is the first large study demonstrating the long-term survival benefit of LBBAP. This strengthens the use of LBBAP in AVB patients with preserved/mildly reduced LVEF while awaiting the results of randomized trials. Confirmation of left bundle branch capture seems advisable to achieve optimal results with LBBAP.

Background: Atrial high‐rate episodes (AHRE) detected by cardiac implanted electronic devices are known markers for adverse cardiac events. Previous studies have shown that the incidence of new‐onset AHREs in patients with right ventricular pacing reaches 50%. At the same time, His bundle pacing (HBP) and left bundle branch area pacing (LBBAP) were associated with significantly fewer AHRE. This study aimed to compare the incidence of new‐onset AHRE between HBP and LBBAP in patients with atrioventricular block and no history of atrial fibrillation. Methods: One hundred and forty‐two patients, fifty‐nine with HBP and eighty‐three with LBBAP for advanced atrioventricular block, were prospectively followed for new‐onset AHRE. Results: The mean follow‐up period was 624 ± 148.6 days for the HBP patients and 663.4 ± 157.4 days for the LBBAP patients. New‐onset AHRE was encountered in 8 of 59 patients (13.5%) with HBP and 14 of 83 (16.8%) with LBBAP (hazard ratio—0.91, log rank p = .84). In the multivariate Cox regression model, HBP and LBBAP had similar predictive values, while only age and diabetes mellitus were significantly associated with new‐onset AHRE occurrence. Conclusion: HBP and LBBAP were associated with a similar incidence of device‐detected new‐onset AHRE during a medium‐term follow‐up period in patients with atrioventricular block and no history of atrial fibrillation.

Compared with conventional right ventricular septal pacing (RVSP), several studies have shown a net clinical benefit of left bundle branch area pacing (LBBAP) in terms of ejection fraction preservation and reduced hospitalizations for heart failure. The purpose of this study was to compare acute depolarization and repolarization electrocardiographic parameters between LBBAP and RVSP in the same patients during the LBBAP implant procedure. We prospectively included 74 consecutive patients subjected to LBBAP from 1 January to 31 December 2021 at our institution in the study. After the lead was placed deep into the ventricular septum, unipolar pacing was performed and 12-lead ECGs were recorded from the distal (LBBAP) and proximal (RVSP) electrodes. QRS duration (QRSd), left ventricular activation time (LVAT), right ventricular activation time (RVAT), QT and JT intervals, QT dispersion (QTd), T-wave peak-to-end interval (Tpe), and Tpe/QT were measured for both instances. The final LBBAP threshold was a 0.7 ± 0.31 V at 0.4 ms duration with a sensing threshold of 10.7 ± 4.1 mV. RVSP produced a significantly larger QRS complex than the baseline QRS (194.88 ± 17.29 ms vs. 141.89 ± 35.41 ms, p < 0.001), while LBBAP did not significantly change the mean QRSd (148.10 ± 11.52 ms vs. 141.89 ± 35.41 ms, p = 0.135). LVAT (67.63 ± 8.79 ms vs. 95.89 ± 12.02 ms, p < 0.001) and RVAT (80.54 ± 10.94 ms vs. 98.99 ± 13.80 ms, p < 0.001) were significantly shorter with LBBAP than with RVSP. Moreover, all the repolarization parameters studied were significantly shorter in LBBAP than in RVSP (QT—425.95 ± 47.54 vs. 487.30 ± 52.32; JT—281.85 ± 53.66 vs. 297.69 ± 59.02; QTd—41.62 ± 20.07 vs. 58.38 ± 24.44; Tpe—67.03 ± 11.19 vs. 80.27 ± 10.72; and Tpe/QT—0.158 ± 0.028 vs. 0.165 ± 0.021, p < 0.05 for all), irrespective of the baseline QRS morphology. LBBAP was associated with significantly better acute depolarization and repolarization electrocardiographic parameters compared with RVSP.

Introduction: There is an increasing interest in the past decade for more physiological pacing strategies due to detrimental long-term right ventricular pacing. His bundle pacing is the most physiological one, but it has some drawbacks, mainly an increased pacing threshold. Left bundle branch area pacing (LBBAP) emerged in the recent years as the next step in conduction system pacing. We present our initial experience and learning curve with this latter procedure. Material and methods: During January 2019 and February 2021, 20 patients with pacing indications that failed initial permanent His bundle pacing underwent successful LBBAP. Results: The mean age was 65.9 ± 12.7 years. The indications for cardiac pacing were AV block in 14 patients (70%) and cardiac resynchronization therapy in 6 patients (30%). At baseline, normal QRS complex was noted in 9 patients, a left bundle branch block pattern in 10 patients and a right bundle branch block in one patient. A total of 18 dual-chamber and one single chamber pacemakers were implanted and a cardiac resynchronization therapy defibrillator (CRT-D) device. The acute pacing threshold was 0.56±0.2 V at 0.4ms, the sensing threshold was 10.3±3.9 mV and the impedance was 684.9±112.2 Ω. The overall QRS duration decreased after LBBAP from 128.5 ± 27ms to 103.6 ± 17.4ms (p= 0.001). In patients with baseline wide QRS complex there was a highly significant decrease from 148.2 ± 11.6 ms to 104.7 ± 19.4 ms (p<0.001). The fluoroscopy time, including the time spent for His bundle location, was 13.8 ± 8.5 minutes. The pacing thresholds remained constant after three-months (0.6 ± 0.2 V vs. 0.56 ± 0.2 V at 0.4 ms). We had two intraprocedural septal perforations without any consequences and three micro dislodgements at follow-up with pure left septal capture. Conclusion: Left bundle branch area pacing is a feasible physiological pacing technique with a high success rate and the potential to overcome the limits of permanent His bundle pacing. It can be successfully performed virtually in all types of pacing indications, including cardiac resynchronization therapy as provides a rapid and synchronous activation of the left ventricle.

Purpose: Although feasibility studies have included older patients, specific data for His bundle pacing (HBP) in this population is scarce. The aim of this study was to evaluate the feasibility and mid-term performance of HBP in the elderly (70 to 79 years old) versus the very elderly (80 years old and above) patients with conventional indications for pacing. Patients and Methods: About 105 patients older than 70 years of age with attempted HBP from the 1st of January 2019 to the 31st of December 2021 were reviewed. Clinical and procedural characteristics were recorded at baseline, and after a mid-term follow-up period. Results: The procedural success rate was similar in both age groups (68.49% vs 65.62%). There was no significant difference in pacing or sensing thresholds, impedance, and fluoroscopy times. For both age intervals, patients with a baseline narrow QRS maintained a similar QRS duration after pacing, while in patients with a wide QRS, the paced QRS was significantly shorter. Baseline QRS duration, left bundle branch block morphology, and ejection fraction, were significantly associated with HBP procedural failure. The mean follow-up period was 830.34 days for the elderly and 722.76 days for the very elderly. After the follow-up period, both sensing and pacing thresholds were similar between the groups. Compared to the baseline values, there were no significant changes in both pacing and sensing parameters, irrespective of the age interval. During follow-up, no lead dislodgements were recorded. There were two cases of significant pacing threshold rise in the elderly (4%) and three cases in the very elderly group (14.2%) which were managed conservatively, without lead revision. Conclusion: In elderly and very elderly patients, HBP is a feasible procedure associated with constant pacing and sensing parameters and with low complication rates over mid-term follow-up.

His bundle pacing (HBP) has several pitfalls, such as the inability to identify the His bundle and lack of capture at acceptable thresholds. The majority of data regarding HBP were obtained using a dedicated non-deflectable delivery system. This study aimed to evaluate the impact of cardiac chamber dimensions on permanent HBP procedural outcomes when using this type of fixed-curve catheter. Seventy-two patients subjected to HBP from the 1st of January to the 31st of December 2021 at our institution were retrospectively reviewed. The baseline clinical characteristics and echocardiographic measurements of all the cardiac chambers were recorded, as well as procedural outcomes (HB electrogram identification and overall procedural success). During the procedure, the HB electrogram was recorded in 59 patients (81.9%) and successful permanent HBP was achieved in 33 patients, representing 45.8% of all the studied patients. Left atrial (LA) and right atrial (RA) volumes were significantly higher in patients without HB electrogram identification. Only LA and RA volumes were statistically associated with HB electrogram localization, while there was no significant association between the echocardiographic parameters and procedural success. LA volumes above 93 mL and RA volumes above 60 mL had an 8.81 times higher chance of failure to localize the HB electrogram compared with patients with lower volumes (p < 0.001). When considering non-deflectable delivery catheters for HBP, careful preprocedural echocardiographic analysis of the atrial volumes could help in the proper selection of implanting tools, thus optimizing the procedural outcomes and costs.