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.

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.

Introduction. Recently published data suggested significantly lower pacing-induced cardiomyopathy (PICM) incidence with conduction system pacing (CSP). Because most data evaluated only the impact on the left ventricle, this study aimed to assess changes in echocardiographic parameters of morphology and function for all heart chambers in patients with baseline preserved and mid-range LVEF over a medium-term follow-up period after CSP. Methods. A total of 128 consecutive patients with LVEF > 40% and successful CSP for bradyarrhythmic indication were prospectively enrolled. A complete 2D echocardiographic examination was performed at baseline and the last follow-up. Results. In total, 38 patients received His bundle pacing (HBP) and 90 received left bundle branch area pacing (LBBAP). The mean follow-up period was 699.2 ± 177.2 days, with 23 patients lost during this period. The ventricular pacing burden for the entire group was 97.2 ± 4.2%. Only three patients (2.9%) met the criteria for PICM. CSP led to a significant increase in LVEF (from 54.2 ± 7.9 to 56.7 ± 7.8%, p = 0.01) and a significant decrease in LV diastolic (from 107.2 ± 41.8 to 91.3 ± 41.8 mL, p < 0.001) and systolic (from 49.7 ± 21.4 to 39.5 ± 18.2 mL, p < 0.001) volumes. There were no significant changes in E/e′, mitral regurgitation, atrial volumes, and right ventricle (RV) diameter. There was a significant improvement in RV function. Tricuspid regurgitation was the only parameter that worsened. There were no differences in evolution for each echocardiographic parameter between the HBP and the LBBAP groups. Conclusions. HBP and LBBAP are equally protective for harmful changes in both atria and ventricles. The prevalence of PICM, defined as a decrease in LVEF, is very low with CSP.