Comparing characteristics and clinical and echocardiographic outcomes in low‐flow vs normal‐flow severe aortic stenosis with preserved ejection fraction in an Asian population

• Published in: Echocardiography (Mount Kisco, N.Y.) Vol. 34; no. 5; pp. 638 - 648
• Main Authors: Ngiam, Jinghao Nicholas, Tan, Benjamin Yong‐Qiang, Sia, Ching‐Hui, Lee, Glenn K.M., Kong, William K.F., Chan, Yiong‐Huak, Poh, Kian‐Keong
• Format: Journal Article
• Language: English
• Published: United States 01.05.2017
• Subjects: Aged; Aged, 80 and over; Aortic Valve Stenosis - diagnostic imaging; Aortic Valve Stenosis - ethnology; Asian Continental Ancestry Group; Cohort Studies; Diagnosis, Differential; Echocardiography - statistics & numerical data; Female; Humans; left ventricular ejection fraction; Longitudinal Studies; low‐flow; Male; Middle Aged; normal‐flow; Prevalence; Reference Values; Reproducibility of Results; Risk Factors; Sensitivity and Specificity; severe aortic stenosis; Severity of Illness Index; Singapore - epidemiology; Stroke Volume; Survival Rate; Ventricular Dysfunction, Left - diagnostic imaging; low-flow; severe aortic stenosis; normal-flow; left ventricular ejection fraction
• ISSN: 0742-2822; 1540-8175
• DOI: 10.1111/echo.13525

Background/Objectives In severe aortic stenosis (AS), deterioration of left ventricular ejection fraction (LVEF) to <50% is an AHA/ACC class I indication for valve replacement, regardless of symptoms. Controversy surrounds prognosis of low‐flow AS compared to normal‐flow, and no study has examined LVEF deterioration. We compared factors associated with LVEF deterioration (to <50%) and clinical outcomes. Methods Consecutive subjects with low‐flow (stroke volume index <35 mL/m2, n=56) and normal‐flow (n=72) severe AS (aortic valve area <1 cm2) with preserved LVEF (>50%) and with paired echocardiography were studied. Univariate and multivariate analyses identified factors associated with LVEF deterioration. Clinical outcomes were determined on follow‐up for more than 5 years. Results Significant LVEF deterioration (to <50%) was seen in 18% of low‐flow (initial LVEF 63±8% to 32±9%) and 18% of normal‐flow AS (61±7% to 31±12%). Independent factors in low‐flow AS were hypertension (OR: 30.7, 95% CI: 2.0–467.6, P=.014) and higher end‐systolic wall stress (OR: 1.086, 95% CI: 1.022–1.153, P=.008), compared to normal‐flow, which were hypertension (OR: 15.9, 95% CI: 3.1–81.9, P=.001), higher septal E/E′ ratio (OR: 1.16, 95% CI: 1.01–1.35, P=.043), lower septal S′ velocity (OR: 0.204, 95% CI: 0.061–0.682, P=.010), and higher end‐systolic wall stress (OR: 1.051, 95% CI: 1.001–1.104, P=.047). Overall, a third of the cohort experienced MACE, regardless of flow (log‐rank 0.048, P=.827). However, aortic valve replacement (AVR) rates were lower in low‐flow AS (20% vs 43%, P=.005). Conclusions Low‐flow AS despite normal LVEF appears similar to normal‐flow in terms of LVEF deterioration and clinical outcomes in our Asian population. AVR rate was lower even though low‐flow may not reflect less severe disease.