Transmitral Septal Myectomy for Hypertrophic Obstructive Cardiomyopathy

BACKGROUND: Intrinsic abnormalities of the mitral valve are common in patients with hypertrophic cardiomyopathy and may need to be addressed at operation.

METHODS: Consecutive patients undergoing transmitral septal myectomy were retrospectively reviewed. The ventricular septum was exposed through a left atriotomy, and the anterior leaflet of the mitral valve was detached from its annulus. An extended myectomy was performed to the base of the papillary muscles. After myectomy, the anterior leaflet was reattached and concomitant mitral valve repair or replacement was performed. In some cases, we performed a modified anterolateral commissural closure suture, which served to reposition the lateral aspect of the anterior leaflet out of the left ventricular outflow tract ("curtain stitch").

RESULTS: Twenty patients who underwent this procedure were identified (70% women; mean age 63 years). Mitral regurgitation was moderate in 55% and severe in 40%. Preoperative peak left ventricular outflow tract gradient was 92 ± 43 mm Hg. Mitral valve repair (n = 11) or replacement (n = 9) was performed. Predischarge transthoracic echocardiography demonstrated a left ventricular outflow tract gradient of 10 ± 5 mm Hg. There was no operative mortality. Follow-up was 100% complete and averaged 22 ± 25 months. No patient required reoperation, and there was no recurrence of left ventricular outflow tract obstruction or mitral regurgitation greater than mild.

CONCLUSIONS: Potential advantages of transmitral myectomy include a panoramic view of the septum and mitral subvalvular apparatus and the ability to simultaneously address mitral valve pathology. Consideration should be given to using the transmitral approach to septal myectomy as the preferred approach for the surgical treatment of hypertrophic cardiomyopathy.