Thoracoscopic trans-mitral myectomy for hypertrophic obstructive cardiomyopathy: a retrospective single-centre study

OBJECTIVES: Transaortic myectomy is a common procedure for patients with hypertrophic obstructive cardiomyopathy. Thoracoscopic trans-mitral myectomy has been described in a few small-sample studies and has been recommended as preferable. We herein report our clinical outcomes using the thoracoscopic trans-mitral approach with 76 patients. METHODS: This is a retrospective single-centre analysis of the safety and efficacy of thoracoscopic trans-mitral myectomy by comparing the clinical outcomes with that of transaortic myectomy. RESULTS: Between April 2019 and October 2021, 132 patients underwent either a transaortic (n = 56) or a thoracoscopic trans-mitral myectomy (n = 76). Compared with those in the transaortic group, patients in the trans-mitral group were more likely to be weaned off the ventilator within 24 h after surgery (80.3% vs 60.7%, P < 0.05) and to require a shorter duration of ventilation [29.01 (43.91) vs 51.12 (94.96) h, P = 0.08] and lower transfusion rate (26.3% vs 48.2%, P < 0.05). The in-hospital mortality rate of the transaortic and trans-mitral groups was 3.6% (n = 2) and 1.3% (n = 1), respectively. No significant inter-group differences were observed regarding in-hospital mortality, the incidence of low cardiac output syndrome or permanent pacemaker implantations. In the trans-mitral group, the thickness of the interventricular septum was significantly reduced postoperatively, with resultant relief of the left ventricular outflow tract obstruction [89.37 (27.5) vs 10.51 (0.65) mmHg, P < 0.01]. Transaortic myectomy also resulted in a significant reduction in left ventricular outflow tract gradient [90.41 (33.31) vs 11.35 (9.43) mmHg, P < 0.01]. And the incidence of residual systolic anterior motion of the trans-mitral group and the transaortic group was 2.67% and 1.9%, respectively. CONCLUSIONS: The thoracoscopic trans-mitral approach provides excellent exposure to the septum and anomalies of the mitral valve and papillary muscle. It relieves obstruction effectively, without increasing the incidence of major complications.