Aims: Approximately 40% of severe aortic stenosis (AS) patients have a low-gradient (<40 mmHg) AS (LG-AS). The aim of this study was to investigate the invasively measured haemodynamic changes and long-term outcome after transcatheter aortic valve replacement (TAVR) in the subgroups of LG-AS.
Methods and results: A total of 600 LG-AS patients with haemodynamic assessment by left and right heart catheterisation were divided into three groups: normal-flow (NFLG-AS; n=296), paradoxical low-flow (PLFLG-AS; n=153), and classic low-flow (CLFLG-AS; n=151). Post TAVR, PLFLG-AS and CLFLG-AS showed a significant reduction in global afterload (p<0.005), as well as a significant elevation of stroke volume index (SVI), and left and right ventricular stroke work index (p<0.001). NFLG-AS was associated with an elevation of global afterload and a decrease of SVI (p<0.05). Overall survival was highest in NFLG-AS, followed by PLFLG-AS and CLFLG-AS. All subgroups experienced similar symptomatic improvement.
Conclusions: NFLG-AS was the most prevalent form of LG severe AS and was associated with adequate left ventricular compensation and good prognosis. On the other hand, CLFLG-AS represents the heart failure with reduced ejection fraction (HFrEF) form of AS and was associated with the worst prognosis, whereas PLFLG-AS represents the heart failure with preserved ejection fraction (HFpEF) form of AS with intermediate prognosis. Both groups showed early haemodynamic reverse response after TAVR.