Interplay of aortic stenosis flow groups and mitral regurgitation aetiology in patients undergoing transcatheter aortic valve replacement

Management of transcatheter aortic valve replacement (TAVR) in aortic stenosis (AS) flow groups—high-gradient (HG-AS), classical low-flow low-gradient (cLFLG-AS), and paradoxical low-flow low-gradient (pLFLG-AS)—is debated. Concomitant mitral regurgitation (MR) worsens outcomes, but the influence of MR aetiology on AS subtypes is unclear. This study aims to evaluate the impact of MR aetiology and severity on outcomes across AS flow groups in TAVR patients.

A retrospective analysis was performed on 2658 patients undergoing TAVR (2013–21). MR was categorized as atrial functional (aFMR), ventricular functional (vFMR), or primary MR (PMR). Outcomes included 3-year mortality, MR improvement, and symptomatic benefit. Out of 2658 TAVR patients, 531 (20.0%) showed at least moderate MR (MR ≥ 2+) (50.1% male, median age 83.1 years). The fraction of patients with MR ≥ 2+ was highest among cLFLG-AS patients (34.2%). MR aetiology varied among AS subtypes, with mostly vFMR in cLFLG-AS (83.0%) and highest rates of aFMR (43%) and PMR (45%) in pLFLG-AS patients. Three-year mortality was significantly affected by MR severity [hazard ratio (HR) for MR2+ vs. MR < 2 1.62 (1.38–1.90)]. Differences in 3-year mortality were found in high-gradient (HG)-AS [HR 1.52 (1.16–1.98)] and pLFLG-AS patients [HR 1.73 (1.24–2.40)], but not in cLFLG-AS patients [HR 1.21 (0.93–1.56)]. MR improvement after TAVR was commonly found in HG-AS (67.2%) and least often among pLFLG-AS (48.7%, P = 0.03 compared with HG-AS). While MR improvement was associated with a lower mortality in HG-AS [HR 0.21 (0.10–0.43)] and cLFLG-AS patients [HR 0.48 (0.29–0.79)], this was not the case in pLFLG-AS patients [1.32 (0.67–2.59)].

MR aetiology and severity influence outcomes after TAVR depending on AS flow groups.