Discrete subaortic stenosis: surgical outcomes and follow-up results

Discrete subaortic stenosis, which is an obstructing lesion of the left ventricular outflow tract, remains a surgical challenge. The recurrence rate is high despite sufficient conventional resection. We retrospectively reviewed the results of surgery for discrete subaortic stenosis at our institution from September 1995 through March 2001. Twenty-one patients with this lesion underwent surgical treatment during this period. Excision of the fibromuscular membrane with myectomy was performed in all of the patients. Follow-up in all patients ranged from 7 to 67 months (mean follow-up period, 39.57 +/- 15.46 months). The mean systolic gradient between the left ventricle and the aorta decreased from 59.23 +/- 35.38 mmHg preoperatively to 9.47 +/- 9.91 mmHg postoperatively. There was no instance of heart block that required a permanent pacemaker, nor of bacterial endocarditis. There was no early or late postoperative death. A 22nd patient, who had 3+ aortic regurgitation, required aortic valve replacement and was excluded from the study. Two of the patients (9.5%) underwent reoperation because of recurrent gradient and residual ventricular septal defect. Our results suggest that fibromuscular membrane excision combined with myectomy in patients with discrete subaortic stenosis produces sufficient relief of obstruction with low morbidity.