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Natural History of Discrete Subaortic Stenosis in Adults: A Multicentre Study
Study Questions:
What is the natural history of discrete subaortic stenosis in adults; and are there identifiable risk factors for its progression, for the progression of aortic regurgitation, and for event-free survival?
Methods:
Conservatively managed adult patients with discrete subaortic stenosis were included in a retrospective multicenter cohort study. Mixed-effects and joint models were used to assess the progression of discrete subaortic stenosis and aortic regurgitation, and intervention-free survival.
Results:
Longitudinal natural history data were available for 149 patients (age 20 [interquartile range (IQR), 18-34] years, 48% male). Sixty patients (40.3%) had associated congenital heart defects. The median follow-up duration was 6.3 (IQR, 3.0-12.4) years. The baseline peak left ventricular outflow tract (LVOT) gradient was 32.3 ± 17.0 mm Hg, and increased by 0.8 ± 0.1 mm Hg/year. While neither baseline LVOT gradient (p = 0.89) nor age (p = 0.42) was associated with progression rate, the presence of an associated congenital heart defect was associated with faster progression (p = 0.005). Mild aortic regurgitation was common (58%), but did not significantly progress over time (p = 0.70). The median intervention-free survival was 16 years and associated with the baseline LVOT gradient (hazard ratio [HR], 3.9; 95% confidence interval [CI], 2.0-7.6), discrete subaortic stenosis progression (HR, 2.6; 95% CI, 2.0-3.5), and aortic regurgitation (HR, 6.4; 95% CI, 2.6-15.6).
Conclusions:
In contrast to children, discrete subaortic stenosis progresses slowly in adulthood. However, adult patients with an associated congenital heart defect (especially a ventricular septal defect) were observed to be at risk for faster progression, and the authors recommend closer monitoring. In this analysis, neither baseline LVOT gradient nor age was found to be associated with discrete subaortic stenosis progression. Mild aortic regurgitation was common, but nonprogressive over time.
Perspective:
Discrete subaortic stenosis often is diagnosed early in life. Among children, discrete subaortic stenosis has been associated with sometimes-rapid progression and with the presence of significant aortic regurgitation. This observational multicenter study found generally slow progression of discrete subaortic stenosis among conservatively managed adult patients. This observation might be anticipated, in that patients reaching adulthood without a significant complication might already have been defined to be at low risk for rapid progression or surgical aortic regurgitation.
Keywords: Discrete Subaortic Stenosis, Follow-Up Studies, Risk Factors
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