Surgical outcome for hypertrophic cardiomyopathy patients with extreme interventricular septal thickness: a propensity score matched study

Background: Hypertrophic cardiomyopathy (HCM) with extreme interventricular septal thickness (IVST) is associated with a higher incidence of adverse cardiovascular events. However, the results of these patients who underwent septal myectomy are unclear. Methods: We studied 47 HCM patients with IVST ≥30 mm who underwent septal myectomy between 2011 and 2018 in Anzhen Hospital. After a 2:1 propensity score matching, the study cohort included 141 patients and 94 patients with IVST <30 mm. Results: Patients with IVST ≥30 mm had a longer clinical course of disease, high incidence of syncope, palpitation, and moderate or severe mitral regurgitation. After a mean follow-up of 34.0±21.3 months, 6 patients died, including 5 with IVST ≥30 mm and 1 with IVST <30 mm. The 5-year survival free of all-cause mortality was significantly higher in patients with IVST ≥30 mm than in those with IVST <30 mm (98.9% vs. 85.7%, P=0.03). Multivariable Cox analysis revealed that IVST ≥30 mm (HR: 1.12, 95% CI: 1.01–1.25, P=0.028) was an independent risk factor for all-cause mortality. Meanwhile, left ventricular end diastole diameter (HR: 0.72, 95% CI: 0.54–0.97, P=0.031) and age (HR: 0.91, 95% CI: 0.83–0.99, P=0.025) were also independent risk factors for all-cause mortality in this special cohort. Furthermore, the incidence of NYHA class III or IV was significantly higher in patients with IVST ≥30 mm. Conclusions: The surgical outcome was poor in a matched cohort of HCM patients with IVST ≥30 mm, which was mainly reflected by mortality and the incidence of NYHA class III or IV.