Discrete subaortic stenosis. Operative age and gradient as predictors of late aortic valve incompetence.

Between January 1969 and May 1990, 100 patients were operated on for discrete subaortic stenosis. Three patients died in the perioperative period. Patients with intrinsic lesions, prosthetic replacement, or extensive operative remodeling of the aortic valve were excluded from the analysis. The 67 remaining patients had a median follow-up of 62 months. Preoperatively, 8 patients had aortic valve competence, 51 had mild incompetence, and 8 patients moderate aortic valve incompetence. At follow-up mild incompetence persisted in 27 and moderate incompetence in 6 patients. In 1 patient it worsened from no incompetence to mild and in another patient from mild to moderate. The probability of aortic incompetence at follow-up was significantly and simultaneously related (multivariate ordinal logistic model) to (1) older age at operation (logarithm of months, p = 0.007), (2) higher preoperative gradient (third power of milligrams of mercury, p = 0.0004), (3) preoperative cardiomegaly (p = 0.04), and (4) surgical myectomy (p = 0.002). There was an interaction between age and gradient (p = 0.03). Two nomograms are proposed as a generalizable aid to decision making. The data support the policy of early repair of subaortic stenosis.