title: Comparing characteristics and clinical and echocardiographic outcomes in low-flow vs normal-flow severe aortic stenosis with preserved ejection fraction in an Asian population.
abstract: OBJECTIVE
  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.
authors.affiliation: University Medicine Cluster, National University Health System, Singapore.
authors.forename: Jinghao Nicholas
authors.identifier: http://orcid.org/0000-0002-3339-7281
authors.initials: JN
authors.lastname: Ngiam
authors.affiliation: University Medicine Cluster, National University Health System, Singapore.
authors.forename: Benjamin Yong-Qiang
authors.initials: BY
authors.lastname: Tan
authors.affiliation: University Medicine Cluster, National University Health System, Singapore.
authors.forename: Ching-Hui
authors.initials: CH
authors.lastname: Sia
authors.affiliation: University Medicine Cluster, National University Health System, Singapore.
authors.forename: Glenn K M
authors.initials: GKM
authors.lastname: Lee
authors.affiliation: Department of Cardiology, National University Heart Center Singapore, Singapore.
authors.forename: William K F
authors.initials: WKF
authors.lastname: Kong
authors.affiliation: Biostatistics Unit, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Yiong-Huak
authors.initials: YH
authors.lastname: Chan
authors.affiliation: Department of Cardiology, National University Heart Center Singapore, Singapore.|Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Kian-Keong
authors.initials: KK
authors.lastname: Poh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging* / Q000208:ethnology*; D044466:Asian People; D015331:Cohort Studies; D003937:Diagnosis, Differential; D004452:Echocardiography / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012016:Reference Values; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D012846:Singapore / Q000453:epidemiology; D013318:Stroke Volume; D015996:Survival Rate; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging*
keywords: left ventricular ejection fraction; low-flow; normal-flow; severe aortic stenosis