Transapical Beating-Heart Septal Myectomy to Relieve Residual Obstruction and Mitral Regurgitation After Failed Septal Reduction Therapies for Hypertrophic Obstructive Cardiomyopathy

J. Li¹, Y. Chen¹, J. Fang¹, Y. Wei¹, S. Wan¹, X. Wei^2
1Department of Cardiovascular Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei ²Tongji Hospital affiliated to Tongji Medical College of Huazhong University of Science & Technology, Wuhan, Hubei

Purpose: To report our experience of transapical beating-heart septal myectomy (TA-BSM) in patients with hypertrophic obstructive cardiomyopathy after failed septal reduction therapies (SRTs).

Methods: Patients with drug-refractory disabling symptoms after failed SRTs underwent reoperation via the TA-BSM approach at our institution. Using a novel myectomy device, the TA-BSM procedure (Figure) was carried out under real-time echocardiographic guidance through a mini-thoracotomy, as recently described (JACC 2023;82:575-86). Repetitive tailored resections were performed, following echo guidance, to achieve an ideal surgical result. The primary outcome measure was procedural success, which was defined as resting/provoked left ventricular outflow tract gradient < 30/50 mmHg and residual mitral regurgitation ≤ grade 1+ (of 4+) at 3-month follow-up.

Results: In 40 patients enrolled from August 2022 through April 2024, their previous SRTs included conventional septal myectomy (n=5), alcohol septal ablation (n=15), endocardial radiofrequency ablation (n=18), percutaneous intramyocardial septal radiofrequency ablation (n=1), and coil embolization of septal artery (n=1). Preoperative residual obstructions were categorized into subaortic obstruction (n=16) or mixed subaortic and mid-ventricular obstruction (n=4). Systolic anterior motion of the mitral valve secondary to insufficient septal reduction was the main reason for residual mitral regurgitation. By TA-BSM, the median weight of the resected septal myocardium was 3.8 g (IQR: 2.6-5.2 g). All patients survived well with 100% follow-up at 3 months. The median (IQR) resting left ventricular outflow tract gradient reduced from preoperative 79 (64-107) mmHg to 17 (10-23) mmHg at 3 months. Mitral regurgitation grade was ≤ 1+ in 8 patients at baseline and in 36 patients at 3 months. Procedural success was achieved in 34 out of 40 patients. One patient underwent sternotomy conversion to repair chordae tendineae due to iatrogenic mitral valve injury during TA-BSM. Two patients with prior alcohol septal ablation-induced right bundle branch block received permanent pacemaker implantation for new-onset atrioventricular block after TA-BSM.

Conclusion: The timing to gauge the performance of SRT was advanced to real-time by TA-BSM. Residual obstruction and mitral regurgitation could be precisely and reliably addressed due to the immediate feedback and enhanced visualization in TA-BSM, which could serve as a safe remedial option for failed SRTs.

Identify the source of the funding for this research project: This study was funded by a research grant of the National Key Research and Development Program (2019YFC0121600), Ministry of Science and Technology of the People’s Republic of China.