Minimally invasive electro septal myectomy for hypertrophic obstructive cardiomyopathy via right infra-axillary incision

Abstract Purpose This study aimed to assess the short-term outcomes of minimally invasive electro septal myectomy (MESM) for hypertrophic obstructive cardiomyopathy (HOCM) performed through a right infra-axillary incision. Methods We conducted a retrospective observational study at a single center, including patients diagnosed with HOCM between November 2023 and December 2024. Results The cohort consisted of 263 patients (mean age 47.9 ± 14.2 years; 61.6% male). All procedures were successfully completed using MESM via a 4-5 cm right infra-axillary incision, without conversion to sternotomy. The average cross-clamp time was 62.8±16.9 minutes. Transthoracic echocardiography demonstrated a significant reduction in maximum septal thickness from 20.7±4.0 mm to 13.3±1.9 mm (paired difference PD: 7.3±3.2 mm; 95% CI: 6.5-8.2; p＜0.001), and in left ventricular outflow tract gradient from 99.4±41.3 mmHg to 7.4±4.6 mmHg (real-time heart rate from 63±11 to 82±13 beats per minute) (PD: 92.0±41.5 mmHg; 95% CI: 79.5-104.5; p＜0.001). The systolic anterior motion phenomenon was completely eliminated, with no severe mitral regurgitation observed postoperatively. No iatrogenic ventricular septal defects and in-hospital mortality occurred. Conclusions This novel method of minimally invasive electro septal myectomy for hypertrophic obstructive cardiomyopathy is feasible and safe.