Subvalvular aortic stenosis in adults: clinical course and long-term outcomes

This study investigates the clinical course and long-term outcomes of adults with subvalvular aortic stenosis (SAS).

Adults with SAS, prospectively registered in the Dutch Congenital Cor Vitia (CONCOR) registry between 2001-2019, were included. All-cause mortality, SAS (re-) operation, and cardiovascular events, including arrhythmias, heart failure, (re-)operation for aortic regurgitation (AR), were assessed. Longitudinal changes in echocardiographic peak velocity, interventricular septal thickness (IVST), and left ventricular posterior wall thickness (LVPW) were analysed using linear mixed-effects models. Differences in the history of SAS repair (operated/unoperated patients), isolated/non-isolated SAS, and sex were explored.

Overall, 312 patients were included [age: 26.0 (interquartile range, IQR: 20.0-35.3) years, 68.3% history of SAS repair] with a median follow-up of 16 (IQR: 10-20) years (4423 patient-years). Unadjusted survival at 15 years was lower in the operated group compared to the unoperated group (P = .009) and no significant differences were observed between sexes (P = .083) or isolated/non-isolated SAS (P = .810). The cumulative incidence of (re-)operation for AR at 15 years was 7.6% (95% CI 4.7%-11.0%). The hazard of SAS repair during follow-up was higher in the unoperated group compared to the operated group [HR 0.2 (95% CI 0.1-0.5), P < .001], after correction for covariates. Peak velocity progression was 0.1 m/s (P = .357) during the first period and 0.3 m/s (P = .032) during the second (after ±10 years). No patient showed fast progression (≥0.3 m/s/year) in peak velocity. At baseline no evidence of left ventricular hypertrophy was observed, following IVST/LVPW criteria.

Survival of adult SAS patients with a history of SAS repair was substantially lower compared to the unoperated group, reflecting a potentially more severe SAS phenotype. Nevertheless, long-term clinical event rates were considerable. SAS remained stable, suggesting less echocardiographic follow-up may suffice, particularly in mild phenotypes without AR. Additionally, follow-up should focus on the clinical sequelae of SAS.