Evaluation of cardiac energetics in left bundle branch area pacing using noninvasive pressure-volume loops.

Background: Conduction system pacing, particularly left bundle branch area pacing (LBBAP), is emerging as the preferred strategy for bradyarrhythmias and cardiac resynchronization therapy because of its clinical benefits. However, the differences in the impact of LBBAP vs right ventricular pacing (RVP) on cardiac energetics remain unclear. Objective: The purpose of this study was to compare the effects of LBBAP and RVP on cardiac energetics using a novel noninvasive pressure-volume (PV) loop algorithm derived from cardiac magnetic resonance (CMR). Methods: We included patients who underwent permanent pacemaker implantation with LBBAP or RVP between January 2021 and October 2024, followed by CMR imaging. Noninvasive PV loops were calculated using volumes derived from CMR and a time-varying elastance model. The parameters obtained from the PV loop analysis were compared between the LBBAP and RVP groups. Sensitivity analyses were performed by varying the left ventricular end-diastolic pressure (3-40 mm Hg) and excluding anodal pacing cases. Results: Of the 235 patients, 15 were analyzed (LBBAP group, n = 7; RVP group, n = 8). The end-systolic PV relationship was significantly higher in the LBBAP group (2.25 mm Hg/mL [1.85-2.55]) compared to the RVP group (1.39 mm Hg/mL [1.33-1.69]; Conclusion: LBBAP reduces myocardial energy consumption and improves ventricular efficiency compared with RVP, suggesting its advantages in pacing-associated cardiac energetics.