Hypertrophic Cardiomyopathy With Elongated Mitral Valve Leaflets: Clinical Characteristics and Surgical Results

Background: Hypertrophic cardiomyopathy (HCM) is commonly associated with mitral valve pathology. A large majority of patients with HCM have elongated anterior and posterior mitral leaflets. There remains debate regarding the necessity and role of concomitant mitral valve surgery at the time of septal myectomy. We aimed to describe the characteristics and share our surgical experiences with this specific group of patients.Methods: This retrospective single-center study investigates adult patients with HCM, with or without elongated mitral valve leaflets (MVLs), who underwent elective septal myectomy with or without concomitant mitral valve intervention, between January 1, 2016, and June 30, 2020. Clinical data were obtained from institutional medical records as well as the Society of Thoracic Surgeons data registry. The clinical characteristics and in-hospital surgical outcomes were compared between patients with an elongated MVL and those without.Results: In total, 379 patients underwent septal myectomy, and 22 patients with intrinsic mitral valve disease were excluded. In addition, 23 patients were excluded due to missing data. Of the remaining 334 patients, 131 (39.2%) had elongated MVL and concomitant MVL plication. Patients with elongated MVL had higher rates of preoperative mitral valve systolic anterior motion (SAM) (94.7% vs. 86.7%, p=0.019) and higher preoperative provoked left ventricular outflow tract gradient (LVOTG) (134.5 mmHg versus 125.3 mmHg, p=0.046). Post septal myectomy and mitral valve plication, they had lower rates of postoperative residual mitral regurgitation (3.8% vs. 12.8%, p=0.006), comparable rates of residual SAM (28.2% vs. 31.5%, p = 0.524), postoperative provoked LVOTG (15.4 mmHg vs. 14.0 mmHg, p=0.317), 30-day major adverse cardiopulmonary events (2.3% vs. 3.9%, p=0.409), and mortality (0% vs. 1.0%, p=0.255).Conclusions: Elongated MVLs contribute more significantly to dynamic LVOT obstruction, as evidenced during provocative testing. Concomitant mitral valve intervention during septal myectomy can be performed safely and may provide an effective strategy to resolve SAM and stress-induced LVOTG.