Myectomy with secondary chordal resection in hypertrophic obstructive cardiomyopathy: the mid-term outcomes

BACKGROUND: It is not clear whether septal myectomy with secondary chordal resection (SM-SCR) can achieve similar postoperative outcomes among hypertrophic obstructive cardiomyopathy (HOCM) patients exhibiting different severity of septal hypertrophy. METHODS: This was a single-center retrospective cohort study with a nested case-control study. HOCM patients received SM-SCR between 2014 and 2023 were retrospectively included and were grouped based on their septal thickness. The main outcome was the relief of the left ventricular outflow tract (LVOT) obstruction. Besides, predictors for recurrent mitral regurgitation (MR) were also explored. RESULTS: A total of 88 patients were included, with 63 in the significant hypertrophy group (SH group) and 25 in the mild hypertrophy group (MH group). The overall median follow-up time was 54.0 (33.0-79.0) months. Before adjusting the covariates, The LVOT gradients at the last follow-up were similar between groups SH group vs. MH group: 10.0 (6.0-14.0) mmHg vs. 8.0 (6.0-11.5) mmHg, P = 0.556, while the interventricular septum (IVS) was thicker for the SH group 15.0 (12.0-17.0) mm vs. 13.0 (11.0-14.0) mm, P = 0.016. In the fully adjusted model, both the LVOT gradients and the IVS thickness were comparable (P = 0.606 and 0.520 respectively). The risk of recurrent MR was similar between groups (7.9% vs. 8.0%, log-rank P = 0.879), while no predictors for recurrent MR were identified. CONCLUSION: According to our single-center data, the mid-term outcomes after SM-SCR were comparable for HOCM patients with different severity of septal hypertrophy. However, further investigations with larger sample sizes and longer follow-up durations are needed. TRIAL REGISTRATION: The study was approved by the Institutional Review Board 2023(2408), and patients' consents were waived due to the retrospective nature of the study.