His bundle pacing is continually relevant for patients with atrial fibrillation and bradycardia without prior atrioventricular nodal ablation, data from mid-term follow-up.

Background: In patients with atrial fibrillation (AF) and symptomatic bradycardia, His Bundle pacing (HBP) is used to achieve an appropriate heart rate and physiological depolarization of the left ventricle (LV).

Aims: We aimed to evaluate the impact of HBP on LV function in two different populations: normal LV ejection fraction (LVEF) and low LVEF (<50%).

Methods: Patients who received HBP as de novo therapy or as an upgrade were divided into two groups based on initial LVEF, followed by echocardiographic and device monitoring.

Results: One hundred and twenty three patients (aged 76.0 [69.2-79.8] years, 74.0% men) with AF and bradycardia received HBP and completed follow-up with a median of 6.2 months (6.0-8.0). LV function remained unchanged in initially normal LV function patients (65 participants, LVEF 59.0% [55.0 - 62.0] vs. 58.0% [55.0-63.0]). In patients with low LVEF (58 participants), there was an increase in LVEF (37.5% [30.0-43.0] vs. 44.0% [35.0-50.0]; p < 0.0001), reduction of indexed LV end-systolic volume (62.4 [20.7] ml vs. 51.5 [21.5] ml; p = 0.001) and indexed LV end-diastolic volume (97.5 [26.2] ml vs. 88.1 [25.1] ml; p = 0.009), and improvement in the New York Heart Association class (2.3 [0.71] to 1.6 [0.9]; p < 0.0001).

Conclusion: With permanent HBP, patients with AF and bradycardia and without prior atrioventricular nodal ablation did not experience LV systolic function deterioration. Those with reduced baseline LVEF experienced improvements in LV function and its reverse remodeling at the mid-term follow-up.