Dimensionless Index in Patients With Low-Gradient Severe Aortic Stenosis and Preserved Ejection Fraction

Abstract

Background Risk stratification of patients with low-gradient (LG) severe aortic stenosis (AS) despite preserved left ventricular ejection fraction remains challenging. We sought to evaluate the relationship between the dimensionless index (DI)—the ratio of the left ventricular outflow tract time-velocity integral to that of the aortic valve jet—and mortality in these patients. Methods Seven hundred fifty-five patients with LG severe AS (defined by aortic valve area ≤1 cm 2 or aortic valve area indexed to body surface area ≤0.6 cm 2 /m 2 and mean aortic pressure gradient <40 mm Hg) and preserved left ventricular ejection fraction ≥50% were studied. Flow status was defined according to stroke volume index <35 mL/m 2 (low flow, LF) or ≥35 mL/m 2 (normal flow, NF). Results After adjustment for age, sex, body mass index, Charlson comorbidity index, history of hypertension, history of atrial fibrillation, AS-related symptoms, left ventricular ejection fraction, indexed left ventricular ventricular mass, aortic valve area, and aortic valve replacement as a time-dependent covariate, patients with LG-LF and DI<0.25 exhibited a considerable increased risk of death compared with patients with LG-NF and DI≥0.25 (adjusted hazard ratio, 2.41 [95% CI, 1.61–3.62]; P <0.001), LG-NF and DI<0.25 (adjusted hazard ratio, 1.84 [95% CI, 1.24–2.73]; P =0.003), and LG-LF and D≥0.25 (adjusted hazard ratio, 2.27 [95% CI, 1.42–3.63]; P <0.001). In contrast, patients with LG-LF and DI≥0.25, LG-NF and DI<0.25, and LG-NF and DI≥0.25 had similar outcome. DI<0.25 showed incremental prognostic value in patients with LG-LF severe AS but not in patients with LG-NF severe AS. Conclusions Among patients with LG severe AS and preserved left ventricular ejection fraction, decreased DI<0.25 is a reliable parameter in patients with LF to identify a subgroup of patients at higher risk of death who may derive benefit from aortic valve replacement.