Discrete subaortic stenosis: long-term prognosis on the progression of the obstruction and of the aortic insufficiency.

Background: We sought to determine the long-term rate of progression of left ventricular outflow tract (LVOT) obstruction and aortic insufficiency (AI) in adult patients operated on for discrete subaortic stenosis (DSS). Methods: Between 1975 and 1995, 52 patients underwent surgery for DSS; their mean age was 25.4 ± 14.8 years. Mean preoperative LVOT gradient was 72.8 ± 25.7 mm Hg. Excision of the subaortic membrane was carried out in all patients, myectomy of the interventricular septum was additionally carried out in 8 patients (15.4 %), and aortic valve replacement (AVR) was performed in 15 patients (28.8 %). Results: There were 2 operative deaths (3.8 %). Early postoperative LVOT gradient was 9.7 ± 6.5 mm Hg. Follow-up ranged from 8.1 to 26.6 years. There were 8 late deaths (16.3 %), and mean LVOT gradient was 13.3 ± 10.7 mm Hg. Five patients required reoperation for recurrent obstruction; 4 patients had a gradient of more than 30 mm Hg. The AI, in patients who did not undergo aortic valve replacement, did not substantially change during follow-up. Conclusions: DSS is a variable, unpredictable and progressive disease; recurrent obstruction may reappear despite the adequacy of surgical excision, and is not related to preoperative gradient. Mild AI remains substantially unchanged and AVR is indicated in severe AI.