Concomitant Septal Myectomy at the Time of Aortic Valve Replacement for Severe Aortic Stenosis

Background: Left ventricular outflow tract obstruction may be unmasked after a successful aortic valve replacement (AVR) for severe aortic stenosis in the setting of asymmetrical basal septal hypertrophy (ABSH). The quantitative assessment of the obstructive potential of ABSH adjacent to a severely stenotic valve can be challenging. We reviewed our experience with patients who underwent concomitant septal myectomy at the time of AVR for severe aortic stenosis. Methods: During the 10-year period ending January 2009, 3,523 patients underwent AVR for the primary indication of severe aortic stenosis. Forty-seven of these patients underwent concomitant septal myectomy. Preoperative and postoperative echocardiograms, operative data, hospital course, morbidity, and mortality were assessed. Results: The mean age of the group was 73 ± 11 years. The mean aortic valve area was 0.74 cm² preoperatively. On preoperative transthoracic echocardiography, only 28% of the patients were considered to be at risk for possible left ventricular outflow tract obstruction. The mean left ventricular mass index decreased from 113.7 ± 24.3 g preoperatively to 90.0 ± 17.2 g at 1 year after the surgery (p < 0.001). The operative mortality was 2%. Complete heart block was observed in 2 patients (4.2%), and no iatrogenic ventricular septal defect was noted. Conclusions: A quantitative assessment of the obstructive ABSH in the setting of severe aortic stenosis may be difficult preoperatively. Surgeons should inspect left ventricular outflow tract for possible obstructive ABSH at the time of AVR. Concomitant myectomy is a safe and effective procedure without additional complications and should be considered for patients with a preoperative or intraoperative diagnosis of ABSH even though dynamic obstruction was not demonstrated.