P291 subvalvular mitral apparatus remodeling during hypertrophic obstructive cardiomyopathy surgery: a 15–years of experience

Abstract Background and Aims To assess the role of the mitral valve apparatus (leaflets, chordae and papillary muscles (PM) in left ventricle outflow tract (LVOT) obstruction, and results of the surgical treatment for hypertrophic obstructive cardiomyopathy (HOCM) in a retrospective observational study. Methods Seventy consecutive patients (58±12 years, M/F ratio: 41/29) undergoing HOCM surgery from 2007 to 2021 at our institute were reviewed. End points included the involvement of the mitral valve in LVOT obstruction, mortality, and change in clinical and echocardiographic characteristics after HOCM surgery. Results Secondary chordae tendineae tractioning the anterior mitral leaflet to the interventricular septum were detected in the majority of the patients. Anomalous, hypertrophied, and fused PM with muscularis trabeculae hypertrophy were a common findings. Four patients had posterior leaflet redundancy. Secondary chordae (90%), PM and muscularis trabeculae resection and PM splitting and elongation (77%) were added variably to septal myectomy (100%). Nine procedures (6%) on mitral valve leaflets were performed, involving 6 posterior and 3 anterior mitral leaflets. Long–term follow up was 4.6±3.7 years. There was no hospital mortality, and NYHA was reduced from 3±0.6 to 1±0.7 (p < 0.0001), the LVOT gradient from 91±35 to 21±17 mmHg (p < 0.0001), mitral valve regurgitation from grade 3±1 to 1±0.6 (p < 0.0001), and septum thickness from 19±3 to 14±2 mm (p < 0.0001). Conclusions The mitral valve apparatus with all its components contribute variably to LVOT dynamic obstruction thus, surgical correction in addition to extended myectomy is recommended to achieve the best outcome.