Conduction system pacing for ventricular pacing requirement is feasible and effective on patients with hypertrophic cardiomyopathy and cardiac dysfunction

OBJECTIVE: We aimed to evaluate the feasibility and safety of his-bundle pacing (HBP) and left bundle branch pacing (LBBP) in patients with hypertrophic cardiomyopathy (HCM) and heart failure (HF). METHODS: Patients with HF and interventricular septal thickness (IVST) ≥ 13 mm resulted from HCM, who accepted conduction system pacing (CSP) with a percentage of ventricular pacing > 40% from May 2018 to April 2022 were consecutively enrolled in our center. LBBP was preferred and HBP was the alternative therapy unless IVST ≥ 16 mm or LBBP failed, whereas LBBP would be the alternative therapy if HBP failed in patients with IVST ≥ 16 mm. All patients were followed up for at least one year. Data including clinical, echocardiographic parameters and electrocardiogram measurements, were collected and evaluated in patients with and without left ventricular ejection fraction (LVEF) < 50%. RESULTS: A total of 27 patients (65.93 ± 9.09 years old) were enrolled and only 3 patients failed in CSP (11.11%) via LBBP (6/13) and HBP (18/21) procedures. LVEF (P = 0.521), left ventricular end-diastolic diameter (LVEDD) (P = 0.816), and QRS duration (P = 0.928) did not worsen after CSP, and left atrial diameter (LAD) (49.58 ± 8.99 mm vs.47.04 ± 9.82 mm, P = 0.045) tended to improve slightly after 19.19 ± 7.71 months follow-up. Of note, LVEF (39.22%±7.51% vs. 45.22%±9.59%, P = 0.015), LVEDD (52.11 ± 10.10 mm vs. 48.33 ± 9.07 mm, P = 0.037), LAD (50.33 ± 8.93 mm vs. 46.11 ± 5.97 mm, P = 0.013) and New York Heart Association (NYHA) grade (2.67 ± 0.5 vs. 1.38 ± 1.02, P = 0.029) improved in 9 patients with LVEF < 50%, whereas LVEF (P = 0.372), LVEDD (P = 0.665), LAD (P = 0.093) and NYHA grade (P = 0.452) did not deteriorate in patients with preserved ejection fraction. CONCLUSION: CSP was safe and feasible in patients with HCM and cardiac dysfunction, and did not worsen cardiac performance especially in patients with LVEF < 50%. HBP might be an effective alternative to LBBP in patients with significantly thickened interventricular septum.