Contemporary Clinical Characteristics, Imaging, Management, and Surgical and Nonsurgical Outcomes of Adult Patients With Subaortic Stenosis

BACKGROUND: Subaortic stenosis (SAS) is characterized by a fibromuscular membrane located just below the aortic valve, causing fixed outflow tract obstruction. There is a paucity of studies evaluating this condition. This cohort study reviewed the contemporary characteristics and outcomes of SAS in adult patients in a single large referral center. METHODS AND RESULTS: We retrospectively studied adult patients with SAS evaluated at our center during 2011 to 2022. The primary outcome was all-cause mortality and heart failure hospitalizations during follow-up, with secondary end points including recurrence of SAS and repeat surgery after initial SAS surgery. Among 484 patients with SAS, key characteristics included mean age 55±18 years, 67.5% female, left ventricular outflow tract peak velocity 352±140 cm/s and gradient 57±40 mm Hg, left ventricular ejection fraction 60%±14%, 54.8% had prior SAS surgery, and 45.1% had surgery during follow-up. Over a median follow-up of 5.5 (1.5-12.3) years, 11.5% (n=56) died, 6.8% (n=33) had heart failure hospitalizations, 8.0% (n=39) experienced SAS recurrence, and 14 (5.9%) underwent repeat SAS surgery. Multivariable analyses identified older age per 10-years (hazard ratio HR, 1.37 95% CI, 1.12-1.68) and baseline New York Heart Association class (HR, 2.48 95% CI, 1.54-3.99) to be statistically significantly associated with the primary end point; higher body mass index, New York Heart Association class, and peak left ventricular outflow tract gradient were also statistically significantly associated with SAS recurrence and redo surgery. CONCLUSIONS: Almost half of patients with SAS had surgery in the past or during follow-up, and a significant minority had mortality or morbidity events during follow-up. Identified prognosticators warrant further research to guide management.