title: Resting Aortic Valve Area at Normal Transaortic Flow Rate Reflects True Valve Area in Suspected Low-Gradient Severe Aortic Stenosis.
abstract: OBJECTIVE
  This study sought to assess the diagnostic impact of stress echocardiography (SE) in patients with suspected low-flow, low-gradient aortic stenosis but normal resting transvalvular flow rate.
  
  
  BACKGROUND
  SE may help to distinguish between true severe aortic stenosis and pseudosevere aortic stenosis in patients with low aortic valve area (AVA) and mean gradient. However, if rest flow rate is normal, then SE may not confer any additional diagnostic value, irrespective of resting left ventricular ejection fraction (LVEF) and indexed stroke volume (SVi).
  
  
  METHODS
  Sixty-seven patients with suspected low-flow, low-gradient aortic stenosis who underwent SE were retrospectively studied. Following stratification by rest LVEF, SVi, and flow rate-using cutoffs of 50%, 35 ml/m(2), and 200 ml/s, respectively-we tested for significant changes in AVA during SE.
  
  
  RESULTS
  Mean age was 77 ± 9 years and 60% of patients were male. Mean values for rest variables were as follows: AVA: 0.77 ± 0.12 cm(2); mean gradient: 27 ± 7 mm Hg; flow rate: 182 ± 37 ml/s; SVi: 32 ± 8 ml/m(2); and LVEF: 45 ± 15%. During SE, significant increases in AVA were observed regardless of resting LVEF and SVi state. In patients with rest flow rate ≥200 ml/s, AVA did not increase significantly during stress (rest AVA: 0.90 cm(2) vs. stress AVA: 0.97 cm(2); p = 0.11), and positive predictive value for confirming underlying true severe aortic stenosis was 84%. In adjusted analyses, rest flow rate was the only parameter associated with severe AS (odds ratio: 1.05, 95% confidence interval: 1.0 to 1.1; p = 0.002).
  
  
  CONCLUSIONS
  Rest AVA measured under normal flow rate conditions is likely to reflect the true severity of AS and unlikely to change significantly with SE. Flow normalization may only be required in patients with AVA <1 cm(2) and mean gradient <40 mm Hg when the rest flow rate is <200 ml/s.
authors.affiliation: Royal Brompton Hospital, London, United Kingdom; Biomedical Research Unit, National Heart and Lung Institute, Imperial College London, United Kingdom.
authors.forename: Navtej S
authors.initials: NS
authors.lastname: Chahal
authors.affiliation: Royal Brompton Hospital, London, United Kingdom.
authors.forename: Maria
authors.initials: M
authors.lastname: Drakopoulou
authors.affiliation: Royal Brompton Hospital, London, United Kingdom.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Gonzalez-Gonzalez
authors.affiliation: Royal Brompton Hospital, London, United Kingdom.
authors.forename: Ramasamy
authors.initials: R
authors.lastname: Manivarmane
authors.affiliation: Royal Brompton Hospital, London, United Kingdom; Biomedical Research Unit, National Heart and Lung Institute, Imperial College London, United Kingdom.
authors.forename: Rajdeep
authors.initials: R
authors.lastname: Khattar
authors.affiliation: Royal Brompton Hospital, London, United Kingdom; Biomedical Research Unit, National Heart and Lung Institute, Imperial College London, United Kingdom; Northwick Park Hospital, Harrow, United Kingdom. Electronic address: roxysenior@cardiac-research.org.
authors.forename: Roxy
authors.initials: R
authors.lastname: Senior
mesh_terms: D058665:Adrenergic beta-1 Receptor Agonists / Q000008:administration & dosage; D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000000981:diagnostic imaging* / Q000503:physiopathology; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D004280:Dobutamine / Q000008:administration & dosage; D025401:Echocardiography, Stress; D005260:Female; D006439:Hemodynamics; D006801:Humans; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D013318:Stroke Volume; D016277:Ventricular Function, Left
chemical_list: D058665:Adrenergic beta-1 Receptor Agonists; D004280:Dobutamine
keywords: aortic stenosis; flow rate; stress echocardiography