Left ventricular volumes and function in successful and failed His-BundLe Pacing. A comparative prospective study.

Introduction: Initial data suggest that His Bundle Pacing (HBP) could preserve long-term cardiac structure and function better than Right Ventricular Pacing (RVP), but evidence is limited.

Methods: We studied consecutive patients with baseline ejection fraction (EF) ≥ 50% who underwent HBP attempt, either successful (HBP group) or failed (RVP group). Two-dimensional (2D) and three-dimensional (3D) echocardiography were carried out at baseline and after 6 months of ventricular pacing burden > 20%.

Results: Among 68 patients, 40 underwent successful HBP, and 28 RVP. The HBP and RVP groups did not differ for age, sex and pacing indication. At baseline, the HBP and RVP groups did not differ for 2D EF (62% vs. 62%), 3D EF (60% vs. 63%), 2D (-19% vs. -19%) and 3D global longitudinal strain (GLS) (-15% vs. -16%). After 6 months, 2D EF (-3.86%) and 3D EF (-5.71%) significantly decreased in the RVP group and did not change in the HBP group (p for interaction .006 and <.001, respectively). 2D GLS (3.08%) and 3D GLS (2.22%) significantly increased in the RVP group, but did not change in the HBP group (p for interaction .013 and <.016, respectively). Pacing induced cardiomyopathy (PICM) (EF drop ≥ 10% and EF < 50%) occurred in 14% (RVP) versus 0% (HBP) of patients (p = .025).

Conclusions: Successful HBP was superior to RVP in preserving LV systolic function despite a high ventricular pacing burden, and was less frequently associated with PICM.