Low-flow and normal-flow low-gradient aortic stenosis with reduced left ventricular ejection fraction. Insights from the CURRENT AS Registry-2.

The term “classical low-flow low-gradient (LG) aortic stenosis (AS)” is widely used, with the conventional assumption that reduced left ventricular ejection fraction (LVEF) implies low flow (stroke volume index [SVi] < 35 ml/m2). This study included 285 patients with LG AS and LVEF < 50% from a prospective registry of 3369 patients with severe AS. The primary outcome was a composite of death or heart failure hospitalization. Among 285 patients, 133 (47%) had normal flow (SVi ≥ 35 ml/m2) despite reduced LVEF, while 152 (53%) had low flow. The low-flow group more often had non-paroxysmal atrial fibrillation, active malignancy, frailty, AS-related symptoms. With a median follow-up period of 624 days, cumulative 3-year incidence of the primary outcome was significantly higher in the low-flow group than in the normal-flow group (74.8% versus 56.4%, P = 0.005). After adjustment for confounders, the excess risk of low flow relative to normal flow was no longer significant in the entire study population (hazard ration [HR]: 1.43; 95% confidence interval [CI]: 0.97–2.09; P = 0.07). However, in the conservative management, low flow relative to normal flow remained significant (HR: 1.81; 95% CI: 1.18–2.79; P = 0.01), but not in the initial aortic valve replacement stratum (HR: 1.55; 95% CI: 0.74–3.26; P = 0.25). This study demonstrated that nearly half of the patients with LG AS and reduced LVEF had normal flow, and that flow status was associated with prognosis under the conservative management. The normal-flow LG AS with reduced LVEF group was highly heterogeneous, highlighting the importance of incorporating both flow status and precise AS severity in patient assessment.