Improvement in Left Ventricular Function of the Resected Myocardium after Septal Myectomy in Patients with Aortic Valve Replacement

Background: Some surgeons have previously advocated for a more aggressive concomitant septal myectomy to address left ventricular outflow tract obstruction; however, concerns about the surgical complications of post-septal myectomy remain. Here, we aimed to assess the clinical, echocardiographic, and pathological findings following concomitant septal myectomy with surgical aortic valve replacement. Methods: We reviewed 21 patients who underwent surgical aortic valve replacement and concomitant septal myectomy from April 2014 to September 2019. The global and regional left ventricular ejection fraction changes between the perioperative periods were analyzed using two-dimensional speckle-tracking echocardiography. The resected myocardium was pathologically assessed. Results: No operative mortality was observed during the study period. Transthoracic echocardiography showed no significant differences in preoperative and postoperative left ventricular ejection fraction (68.1 ± 9.9% vs. 68.6 ± 6.0%, p = 0.82) or interventricular septum thickness (11.9 ± 1.4 mm vs. 11.5 ± 1.5 mm, p = 0.23). Interventricular septum thickness at the end-systolic phase, which is the maximum septal wall thickness, was significantly reduced postoperatively (27.7 ± 9.3 mm vs. 22.6 ± 5.5 mm, p < 0.05). The basal, mid, and apical septal areas improved with septal myectomy by 80%, 230%, and 27%, respectively, compared to perioperative echocardiography (basal septal, 80 ± 23%; mid septal, 230 ± 830%; apical septal, 27 ± 350%). Pathological examination of the resected myocardium revealed marked endocardial thickness (mean, 914 µm) with focal fibrosis. Conclusions: In aortic valve stenosis patients with septal hypertrophy, concomitant septal myectomy with surgical aortic valve replacement improved regional myocardial function and eliminated left ventricular outflow tract obstruction by removing thickened endocardium and prominent fibrosis.