[Surgical treatment for obstructive hypertrophic cardiomyopathy: a five-year single-center experience of 421 cases]

Objectives: To examine the short-term and mid-term effects of surgical treatment of obstructive hypertrophic cardiomyopathy (HCM) in one center. Methods: The perioperative data and short-term follow-up outcomes of 421 patients with obstructive HCM who received surgical treatment at Department of Cardiac Surgery, Zhongshan Hospital, Fudan University from January 2017 to December 2021 were analyzed retrospectively. There were 207 males and 214 females, aged (56.5±11.7) years (range: 19 to 78 years). Preoperative New York Heart Association (NYHA) classification included 45 cases of class Ⅱ, 328 cases in class Ⅲ, and 48 cases in class Ⅳ. Fifty-eight patients were diagnosed with latent obstructive HCM and 257 patients had moderate or more mitral regurgitation with 56 patients suffering from intrinsic mitral valve diseases. All procedures were completed by a multidisciplinary team, including professional echocardiologists involving in preoperative planning for proper mitral valve management strategies and intraoperative monitoring. A total of 338 patients underwent septal myectomy alone, and 59 patients underwent mitral valve surgery along with myectomy. A single transaortic approach was used in 355 patients, and a right atrial-atrial septal/atrial sulcus approach was used in 51 other patients. Long-handled minimally invasive surgical instruments were used for the procedures. Student t test, Wilcoxon rank sum test, χ² test or Fisher exact test were used to compare the data before and after surgery. Results: The aortic cross-clamping time of septal myectomy alone was (34.3±8.5) minutes (range: 21 to 94 minutes). Eighteen patients had intraoperative adverse events and underwent immediate reoperation, including residual obstruction (10 patients), left ventricular free wall rupture (4 patients), ventricular septal perforation (3 patients), and aortic valve perforation (1 patient). Four patients died during hospitalization, and 11 patients developed complete atrioventricular block requiring permanent pacemaker implantation. After discharge, 384 (92.1%) patients received a follow-up visit with a median duration of 9 months. All follow-up patients survived with significantly improved NYHA classifications: 216 patients in class Ⅰ and 168 patients in class Ⅱ (χ²=662.73, P<0.01 as compared to baseline). At 6 months after surgery, follow-up echocardiography showed that the thickness of the ventricular septum ((13.6±2.5) mm vs. (18.2±3.0) mm, t=23.51, P<0.01) and the peak left ventricular outflow tract gradient ((12.0±6.3) mmHg vs. (93.4±19.8) mmHg, 1 mmHg=0.133 kPa, t=78.29, P<0.01) were both significantly lower than baseline values. Conclusion: The construction of the surgical team (including echocardiography experts), proper mitral valve management strategies, identification and management of sub-mitral-valve abnormalities, and application of long-handled minimally invasive surgical instruments are important for the successful implementation of septal myectomy with satisfactory short-and medium-term outcomes.