Safety and Efficacy of His Bundle Area (Para-Hisian) Pacing Using a Mathematical Cross-Correlation Cardiac Synchrony Index

Abstract

Background: The deleterious effects of right ventricular (RV) apical pacing promoted the need for more physiological pacing techniques, such as conduction system, His bundle area, and mid-septal ventricular pacing. We aimed to compare permanent mid-septal and His bundle area pacing (HBAP) vs RV apical pacing to determine which is more physiological and to assess lead stability and pacing thresholds. Methods: We retrospectively analyzed 137 consecutive patients undergoing permanent pacing (63% men, mean age 61 ± 24 years). Seventy-one (52%) had a baseline QRS of < 120 ms, with no evidence of intraventricular conduction abnormalities, 37 (27%) had right bundle branch block, and 29 (21%) had left bundle branch block. The ventricular lead was implanted at the RV apex in 54 patients, at the His bundle area in 66, and at the mid interventricular septum in 17. Twelve-lead electrocardiogram was recorded, and electrical synchrony was assessed using the Synchromax® crosscorrelation cardiac synchrony index (CSI). Results: QRS duration was prolonged in all pacing sites. There was no correlation between QRS duration and the CSI (r = 0.028, p = 0.79). The CSI was significantly improved only in patients undergoing HBAP, despite a slight widening of the QRS complex. There was no difference in pacing thresholds and sensed R wave voltage. Lead dislodgment occurred in only 1 lead implanted at the His bundle area. Conclusions: HBAP successfully captures the conduction system, normalizing the CSI despite producing a wider QRS, meaning that coordination is more important than duration for achieving optimal cardiac synchrony