Abstract

Objectives: Septal myectomy (SM) is the gold standard treatment option for patients with hypertrophic obstructive cardiomyopathy (HOCM) whose symptoms do not respond to medical therapy. Extended SM adequately relieves left ventricular outflow tract (LVOT) gradients, abolishes systolic anterior motion (SAM) of the mitral valve and improves mitral regurgitation (MR). However, in patients with moderate and severe MR, controversy remains regarding the necessity of mitral intervention at the time of SM. In this study, we investigated short-term outcomes of SM without correction of moderate and severe MR, as well as risk factors for residual MR ≥2+ after SM.

Materials and Methods: From January 2019 to January 2024, 207 adult patients underwent transaortic SM in our Center. Of these, 119 patients who underwent isolated SM were included in the study: group 1 (n=36) consisted of patients with no or mild MR and group 2 (n=83) consisted of patients with moderate to severe MR. The primary endpoint was the severity of MR after SM. Secondary endpoints included postoperative complications, residual LVOT gradient ≥30 mmHg and residual SAM.

Results: There was no residual MR in the group 1, while 9% of patients in group 2 had moderate MR. Only 3.6% of cases in group 2 required repeated aortic cross-clamping and mitral valve intervention. The mortality rate was 1.2% (1 patient) in group 2, with no deaths in group 1. Complete AV-block requiring permanent pacemaker implantation occurred in 2 patients (5.6%) in group 1 and 6 patients (7.2%) in group 2 (p=0.74). There were 2 patients (5.6%) in group 1 and 4 patients (4.8%) in group 2 with a residual LVOT gradient ≥30 mmHg at discharge (p=0.87). Residual SAM was identified in 2 patients (5.6%) in group 1 and 7 patients (8.4%) in group 2 (р=0.58). Multivariate regression analysis identified only residual SAM [odds ratio (OR): 13.994, 95% confidence interval (CI): 2.692-72.744, p=0.02] as a predictor of residual MR ≥2+.

Conclusion: In our study, among patients with moderate and severe MR, only 3.6% required repeated aortic cross-clamping and mitral valve intervention. Before discharge, only 9% of patients had moderate MR. Consequently, in most patients with HOCM and moderate/severe MR not due to organic mitral valve lesion, isolated SM effectively relieves LVOT gradients, SAM of the mitral valve and the associated MR.