title: Prevalence, clinical and echocardiographic characteristics of various flow and gradient patterns in mild or moderate aortic stenosis with normal left ventricular ejection fraction.
abstract: OBJECTIVE
  Paradoxical low-flow aortic stenosis (AS) with preserved left ventricular ejection fraction (LVEF) has only been described in severe AS. Controversy surrounds prognosis and management but no studies have reported this phenomenon in mild or moderate AS. We investigated the prevalence of flow and gradient patterns in this population, characterising their clinical and echocardiographic profile.
  
  
  METHODS
  Consecutive subjects (n=1362) with isolated AS: mild (n=462, aortic valve area≥1.5cm(2), 2.5m/s<aortic jet velocity≤3m/s) or moderate (n=900, 1cm(2)≤aortic valve area<1.5cm(2)) and normal LVEF (≥50%) were studied. Subjects with low-flow (stroke volume index<35ml/m(2)) were identified. Univariate and multivariate analyses were employed to compare the flow and gradient patterns.
  
  
  RESULTS
  In mild AS, 130 (28%) had low-flow. Lower left ventricular mass index (LVMI) (97.0±28.5vs116.4±2.3g/m(2),p<0.001), higher percentage of concentric remodelling (40%vs6%,p<0.001) and hypertrophy (43%vs40%,p<0.001) and lower end-systolic wall stress (ESWS) (57.6±1.60vs67.7±19.6dyn/cm(2),p=0.014) were independently associated with low-flow. Similarly, in moderate AS, 297 (33%) had low-flow. Older age (73.4±14.8vs69.5±16.5,p=0.027), lower LVMI (88.6±25.9vs118.0±36.5,p<0.001), higher percentage of concentric remodelling (46%vs8%,p<0.001) and lower ESWS (59.9±18.3vs70.5±19.7,p<0.001) were independently associated with low-flow. Despite moderate AS, most had lower mean pressure gradients, especially subjects with concentric remodelling. In the entire cohort, low-flow patients had more concentric remodelling (43%vs7%,p<0.001) and less eccentric hypertrophy (2%vs27%,p<0.001) compared to normal flow.
  
  
  CONCLUSIONS
  Low-flow AS with normal LVEF is observed in mild or moderate AS, in up to a third of the cases. These patients had different LV structure compared to normal-flow, with more concentric remodelling. Further studies are warranted.
authors.affiliation: Department of Medicine, National University Health System, Singapore.
authors.forename: Yong-Qiang Benjamin
authors.initials: YQ
authors.lastname: Tan
authors.affiliation: Department of Medicine, National University Health System, Singapore.
authors.forename: Jinghao Nicholas
authors.initials: JN
authors.lastname: Ngiam
authors.affiliation: Department of Cardiology, National University Heart Centre, National University Health System, Singapore.
authors.forename: William K F
authors.initials: WK
authors.lastname: Kong
authors.affiliation: Department of Cardiology, National University Heart Centre, National University Health System, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
authors.forename: Tiong-Cheng
authors.initials: TC
authors.lastname: Yeo
authors.affiliation: Department of Cardiology, National University Heart Centre, National University Health System, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, Singapore. Electronic address: kian_keong_poh@nuhs.edu.sg.
authors.forename: Kian-Keong
authors.initials: KK
authors.lastname: Poh
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000503:physiopathology*; D001024:Aortic Valve Stenosis / Q000175:diagnosis / Q000453:epidemiology / Q000503:physiopathology; D018618:Echocardiography, Doppler, Color / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D015995:Prevalence; D011379:Prognosis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012846:Singapore / Q000453:epidemiology; D013318:Stroke Volume / Q000502:physiology*; D020257:Ventricular Remodeling / Q000502:physiology*
keywords: Aortic stenosis; Echocardiography; Left ventricular ejection fraction; Low-flow; Mild–moderate