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.

Automated summary

In patients with HOCM and moderate septal thickness with SAM-related MR, addressing abnormalities of the MV apparatus may become necessary as septal hypertrophy decreases. However, performing myectomy alone appears to be associated with a better postoperative course and a trend towards lower cardiac mortality at follow-up, despite a higher rate of residual moderate MR.