Hypertrophic cardiomyopathy with moderate septal thickness and mitral regurgitation: long-term surgical results.

OBJECTIVES The aim of this study was to assess the long-term outcomes of different surgical strategies in patients with hypertrophic obstructive cardiomyopathy (HOCM) with septal thickness ≤18 mm and systolic anterior motion (SAM)-related moderate-to-severe mitral regurgitation (MR). METHODS Seventy-six HOCM patients with septal thickness 17 [16; 18] mm, resting left ventricle outflow tract gradient 60 [41; 85] mmHg and SAM-related MR ≥2+/4+, underwent septal myectomy alone (54%) or mitral valve (MV) surgery ± myectomy (46%). RESULTS No hospital death and no ventricular septal defect occurred. Patients undergoing MV surgery ± myectomy had longer cardiopulmonary bypass and X-clamp times (77 [60-106] vs 51 [44-62] min, P < 0.001 and 56 [45-77] vs 32 [28-41] min, P < 0.001) and higher incidence of low output syndrome (11% vs 0%, P = 0.04). Follow-up was 98.6% complete, median 8 years [3-11]. There were no statistically significant differences in overall survival (P = 0.069) with survival rates at 9 years of 96 ± 4% in the myectomy alone group and 81 ± 8% in the MV surgery ± myectomy one. At 9 years, cumulative incidence function of cardiac death was 12 ± 6% in the MV surgery ± myectomy group vs 0% in the myectomy one, P = 0.06. Multivariable analysis identified age and previous septal alcoholization as predictors of cardiac death (hazard ratio (HR) = 1.1, 95% confidence interval (CI) 1.0-1.1, P = 0.004 and HR = 2.9, 95% CI 1.0-8.3, P = 0.042). The 9-year cumulative incidence function of recurrence of MR ≥2+, with death as competing risk, was 3 ± 2.8% in the MV surgery ± myectomy group vs 25 ± 6.9% in the myectomy one, P = 0.005. CONCLUSIONS In HOCM patients with moderate septal thickness and SAM-related MR, as the degree of septal hypertrophy decreases, addressing the abnormalities of the MV apparatus may become necessary to provide a durable resolution of left ventricle outflow tract obstruction and SAM-related MR. However, performing myectomy alone, whenever possible, seems to be associated to a better postoperative course and a trend towards lower cardiac mortality at follow-up, despite a higher rate of residual moderate MR.