Surgical Myectomy with Anterior Mitral Leaflet Extension Versus Isolated Myectomy in Patients with Hypertrophic Obstructive Cardiomyopathy

Background This study evaluated the echocardiographic parameters and complication rates of surgical myectomy with concomitant anterior mitral leaflet extension (SM + AMLE) and isolated SM in hypertrophic obstructive cardiomyopathy (HOCM) patients. Methods All HOCM patients undergoing SM + AMLE (2006-2015) and isolated SM (2015-2020) in our centre were analysed. The primary outcome was left ventricular outflow tract (LVOT)-gradient and surgical reoperation (SM/mitral surgery). Secondary outcomes were aortic cross-clamping (ACC) time, iatrogenic ventricular septal defect (VSD), and mortality at 30-day and 3-year follow-up. Mixed-effects models assessed postoperative changes in LVOT-gradient measurements over time until a 3-year follow-up. Results This cohort (n = 59) consisted of 34 (58%) SM + AMLE and 25 (42%) isolated SM procedures. There were 32 (54%) males and 27 (46%) females with a mean age of 55 ± 13 years at the time of the intervention. Postoperatively, no differences were observed over time in the median LVOT-gradient (p = 0.34). In the SM + AMLE group, 6% (n = 2) required surgical reoperation (due to patch dehiscence) versus 0% in the SM group. In the SM + AMLE group, the ACC time was significantly higher (86 minutes [interquartile range [IQR]: 74-103]) than in the isolated SM group (48 minutes [IQR: 39-57]; p < 001). In both groups, the VSD complication rate was 0%, and neither procedure led to death at 3-year follow-up. Conclusion HOCM-patients who underwent SM + AMLE had comparable clinical and echocardiographic outcomes to patients who underwent isolated SM. This suggests that increasing procedural complexity may not improve outcomes. However, given potential confounding, this should be interpreted with caution, future prospective randomised controlled trials are necessary.