ObjectiveTo investigate the effectiveness and safety of totally endoscopic transmitral myectomy (TETM) for hypertrophic obstructive cardiomyopathy (HOCM), comparing with traditional sternotomy modified Morrow procedure (SMMP).MethodsThirty-eight patients with HOCM who needed surgical intervention were selected from our hospital in 2019, including 14 males and 24 females, with an average age of 56 (44-68) years. According to the operation method, they were divided into a TETM group (n=18) and a SMMP group (n=20). Appropriate patients were screened by propensity matching scores. Finally, the clinical data of two matched groups were compared and analyzed.ResultsThere was no death, septal perforation, residual left ventricular outflow tract obstruction or third degree atrioventricular block in either group. After propensity score matching, there was no statistical difference between the two groups in the ICU length of stay (41.5±5.0 h vs. 53.0±24.0 h, P=0.620), ventilation time (19.5±9.2 h vs. 38.0±24.0 h, P=0.463), cardiopulmonary bypass time (190.7±45.6 min vs. 156.0±70.7 min, P=0.627), aortic cross-clamp time (100.1±25.3 min vs. 94.5±57.3 min, P =0.915), left ventricular outflow tract gradient (17.0±1.4 mm Hg vs. 5.0±0.5 mm Hg, P=0.053), left atrial anterior and posterior diameter (37.0±1.3 mm vs. 40.0±0.7 mm, P=0.090), interventricular septum thickness (12.5±0.7 mm vs. 13.0±1.4 mm, P=0.712), left ventricular posterior wall thickness (10.0±1.4 mm vs. 10.5±2.1 mm, P=0.811), left ventricular end-diastolic diameter (43.5±3.5 mm vs. 46.0±4.2 mm, P=0.589), and mitral regurgitation (1.0±0.2 vs. 0.7±0.5, P=0.500). The follow-up time was 6±3 months, and no death occurred. In the TETM group, one patient underwent mitral valvuloplasty again three months after surgery because of a tear in the A3 region of mitral valve..ConclusionTETM is a safe and effective procedure that can well expose the interventricular septum at the basal & middle obstruction site and effectively eliminate the mitral regurgitation associated with systolic anterior motion syndrome caused by left ventricular outflow tract obstruction.