Flow Normalization and Left Ventricular Ejection Fraction Improvement After Transcatheter Aortic Valve Replacement Across Low-Flow Aortic Stenosis Phenotypes

Low-flow aortic stenosis (AS) is a high-risk subgroup of severe AS occurring with either reduced or preserved left ventricular ejection fraction (LVEF). Flow normalization (measured by stroke volume index [SVi]) and LVEF improvement are associated with improved outcomes after transcatheter aortic valve replacement (TAVR), yet whether these changes occur similarly across subtypes and concordantly remains unclear. To evaluate flow normalization and LVEF improvement across low-flow AS subtypes, assess concordance, and identify predictors. Patients with severe low-flow AS (SVi <35 ml/m²; aortic valve area ≤1 cm²) who underwent TAVR with 1-year echocardiographic follow-up were classified as low-flow, low-gradient (LFLG) AS with reduced LVEF, LFLG AS with preserved LVEF, or low-flow, high-gradient (LFHG) AS. Flow normalization and LVEF improvement ≥5% at 1 year were assessed. Among 174 patients (mean age 79 ± 8 years; 36% female), 18.4% had LFLG with reduced LVEF, 60.9% LFLG with preserved LVEF, and 20.7% LFHG. Flow normalization occurred in 38.5% overall at similar rates across phenotypes respectively (40.6%, 34.9%, and 47.2%; p = 0.407). LVEF improvement ≥5% occurred in 35.6% overall but was most frequent in LFLG with reduced LVEF (65.6%) versus preserved LVEF (29.2%) and LFHG (30.6%; p <0.001). Only 16% showed concordant improvement; 40.8% showed neither. Lower baseline LVEF independently predicted LVEF improvement; no independent predictors of flow normalization were identified. Flow normalization after TAVR occurred at similar rates across low-flow AS subtypes, while LVEF improvement was most frequent in LFLG AS with reduced LVEF. These changes frequently occurred discordantly, though prognostic implications remain unclear.