Long-Term Outcome of Patients With Isolated Thin Discrete Subaortic Stenosis Treated by Balloon Dilatation: A 25-Year Study

Study Questions:

What are the long-term outcomes of patients with discrete subaortic stenosis (DSS) treated with transluminal balloon dilatation?


A retrospective review was performed at a single center. Inclusion criteria required the presence of isolated DSS with a thin (<3 mm) subaortic membrane with a significant gradient, left ventricular strain on electrocardiogram, or symptoms. During the procedure, balloons were inflated to a diameter size 1-2 mm larger than the aortic annulus. The balloon was stabilized in the left ventricular outflow tract with either administration of adenosine or rapid ventricular pacing.


A total of 76 patients (mean age 19 ± 16 years, range 2-67 years) underwent the procedure. The mean left ventricular outflow tract gradient decreased from 70 ± 27 to 18 ± 12 mm Hg (p < 0.001). One patient died after emergency surgery for wall perforation, which occurred at the time of the procedure. Over the course of the follow-up period (mean 16 ± 6 years), 11 patients (15%) developed restenosis, three patients (4%) progressed to muscular obstructive disease, and one patient (1.3%) developed a new distant obstructive membrane. Twelve patients (16%) underwent repeat balloon dilatation at a mean of 5 ± 3 years after their first procedure, and four patients (5%) underwent surgery at a mean of 3 ± 2 years after their initial procedure. One patient was found to have significant progression of aortic insufficiency at follow-up. Larger aortic annulus diameter and thinner subaortic membrane were independently associated with better long-term results.


In a majority of patients, transluminal balloon tearing of a discrete subaortic membrane is associated with sustained relief without restenosis, need for surgery, progression to muscular obstructive disease, or an increase in the degree of aortic regurgitation.


Although first reported almost 30 years ago, percutaneous treatment of DSS is not widely used, with most centers favoring surgical intervention. This study reports quite reasonable short- and long-term results of balloon tearing of discrete subaortic membrane at a single center. The primary limitation of this study is its retrospective design and potential for selection bias. Additionally, the study was performed at a single, highly experienced center, and there is the potential that the results may not be generalizable to other centers. However, this study does suggest that a percutaneous approach to DSS may be reasonable for some patients.

Clinical Topics: Valvular Heart Disease

Keywords: Discrete Subaortic Stenosis, Heart Diseases, Follow-Up Studies, Catheterization, Dilatation, Electrocardiography, Heart Ventricles

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