Supplementary Material for: The Utility of Flow Rate Compared with Left Ventricular Stroke Volume Index in the Hemodynamic Classification of Severe Aortic Stenosis with Preserved Ejection Fraction

Objectives: To substitute the stroke volume index (SVi) with flow rate (FR) in the hemodynamic classification of severe aortic stenosis (AS) with preserved ejection fraction (EF), in order to evaluate its prognostic value. Methods: A total of 529 patients (78.8 ± 9.8 years old, 44.1% males) with isolated severe AS (aortic valve area, AVA < 1 cm²), EF ≥50%, in sinus rhythm, who underwent transthoracic echocardiography, were stratified by FR (≥/< 200 mL/s) and mean pressure gradient (MG) (≥/< 40 mm Hg): FR_normal/MG_high, FR_low/MG_high, FR_normal/MG_low, and FR_low/MG_low. Results: Aortic valve replacement was more frequently performed in the FR_normal/MG_high than in the FR_low/MG_low group (69.3 vs. 47%, respectively, p < 0.0001), yielding a similar survival benefit across all four groups. Over a median follow-up of 51 ± 29 months, there were 249 deaths. In highly adjusted models, the FR_low/MG_low group had a higher all-cause mortality (HR = 1.7, 95% CI: 1.1–2.6, p = 0.02) than patients with FR_normal/MG_high. FR had a stronger association with AVA than SVi (r = 0.51 vs. 0.41, respectively, p = 0.0002), and a similar predictive value for death (AUC = 0.57 and 0.58, respectively, p = 0.88). Conclusions: The FR_low/MG_low subset of AS is associated with the worst prognosis, and FR is not superior to SVi in the hemodynamic classification of severe AS.