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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?
Methods:
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.
Results:
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.
Conclusions:
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.
Perspective:
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.
Keywords: Discrete Subaortic Stenosis, Heart Diseases, Follow-Up Studies, Catheterization, Dilatation, Electrocardiography, Heart Ventricles
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