Surgical treatment of subaortic stenosis: a seventeen-year experience

The aim of the study was to analyze the long-term results of subaortic stenosis relief and the risk factors associated with recurrence and reoperation.

One hundred sixty patients with subaortic stenosis underwent biventricular repair. Before the operation the mean left ventricle-aorta gradient was 80 +/- 35 mm Hg, 57 patients had aortic regurgitation, and 34 were in New York Heart Association functional class III or IV. Median age at repair was 10 years. For discrete subaortic stenosis (n = 120), 39 patients underwent isolated membranectomy, 67 underwent membranectomy with associated septal myotomy, and 14 underwent septal myectomy. Tunnel subaortic stenosis (n = 34) was treated by myotomy in 10 cases, myectomy in 12, septoplasty in 7, Konno procedure in 3, and apical conduit in 2. Aortic valve replacement was performed in 6 cases, mitral valve replacement in 2 cases, and mitral valvuloplasty in 4 cases.

There were 5 early (3.1%) and 4 late (4.4%) deaths. Within 3.6 +/- 3.3 years a recurrent gradient greater than 30 mm Hg was found in 42 patients (27%), 20 of whom had 26 reoperations. According to multivariable Cox regression analysis survival was influenced by hypoplastic aortic anulus (P =.01) and mitral stenosis (P =.048); recurrence and reoperation were influenced by coarctation and immediate postoperative left ventricular outflow tract gradients. At a median follow-up of 13.3 years, mean left ventricle-aorta gradient was 20 +/- 13 mm Hg. Relief of the subaortic stenosis improved the degree of aortic regurgitation in 86% of patients with preoperative aortic regurgitation. Actuarial survival and freedom from reoperation rates at 15 years were 94% +/- 1.3% and 85% +/- 6%, respectively.

Although surgical treatment provides good results, recurrence and reoperation are significantly influenced by previous coarctation repair and by the quality of initial relief of subaortic stenosis.