Long-term results after excision of fixed subaortic stenosis

Forty-nine patients underwent surgical excision of fixed subaortic stenosis (discrete fibrous ring and tunnel) between 1968 and 1984 and were followed up for 1 to 16 years (5.8 +/- 4). Twenty-six patients (Group I) had isolated subaortic stenosis and 23 (Group II) had subaortic stenosis and associated cardiac defects. Discrete fibrous ring was present in 46 and tunnel type of obstruction in three patients. For the discrete ring, excision alone was done in 32 patients (four recurrences) and excision with myotomy in 17 (three recurrences). In Group I, there were no operative deaths and one late death from a noncardiac cause. In Group II, one early and two late deaths occurred. The actuarial survival rate for 10 years is 88%. Reoperations were performed in 10 patients, seven for recurrence and three for aortic valve replacement for preexisting aortic regurgitation that had progressed since the primary operation. Cardioplegia was used in 28 patients (one recurrence) and was not used in 21 patients (six recurrences). An operative residual gradient of less than 15 mm Hg was achieved in 25 of 28 patients in whom cardioplegia was used compared to 12 of 21 patients in whom cardioplegia was not used (p = 0.017). These results indicate that complete excision of the ring with the aid of cardioplegia has significantly reduced the recurrence rate of subaortic stenosis (p = 0.033), elimination of the residual gradient at the initial operation has been a significant factor in reducing the recurrence rate (p = 0.017), and addition of myotomy in this series has not altered the outcome.