Outcomes of Surgical Myectomy and Mitral Valve Repair for Hypertrophic Cardiomyopathy With vs Without Marked Septal Hypertrophy

Background This study reports a single institution's clinical and echocardiographic outcomes for septal myectomy with vs without concomitant mitral valve interventions in patients with hypertrophic cardiomyopathy (HCM) and left ventricular outflow tract (LVOT) obstruction. Methods Consecutive patients who underwent transaortic septal myectomy with vs without subvalvular mitral apparatus intervention for HCM between October 2019 and March 2024 were included. All patients underwent transesophageal echocardiography and cardiac magnetic resonance imaging to confirm the pathology, measure intracavitary gradients, and assess mitral valve morphology. Patients were analyzed as an entire cohort and stratified by the presence of marked (> 15 mm) or only mild (≤ 15 mm) septal hypertrophy. Results A total of 61 patients (32 male) were included, of whom 28 (45.9%) had mild septal hypertrophy. The follow-up assessment was 100% complete and averaged 26.9 ± 16.2 months. In addition to septal myectomy, 32 patients (52.5%) underwent concomitant papillary muscle realignment, and aberrant chordae were resected in 40 patients (65.6%). All patients with a septal thickness ≤ 15 mm had a mitral valve repair intervention. The 30-day and 2-year mortality were 1.6% and 3.3%, respectively. No postoperative ventricular septal defects occurred, including in the thin septum subgroup. Peak LVOT gradients were significantly reduced with surgery, both at rest (47.8 ± 34.7 mm Hg preoperatively vs 8.8 ± 12.3 mm Hg postoperatively, P < 0.001) and under stress (114.2 ± 58.7 mm Hg preoperatively vs 17.6 ± 18.5 postoperatively, P < 0.001). Conclusions In patients with symptomatic HCM, even in those without marked septal hypertrophy, septal myectomy with a concomitant mitral valve apparatus intervention is safe and provides excellent relief of LVOT obstruction.