title: Low-flow, low-gradient aortic stenosis: from evaluation to treatment.
abstract: OBJECTIVE
  Valve replacement improves symptoms and survival in symptomatic severe aortic stenosis. Low-flow, low-gradient aortic stenosis, however, is an especially challenging subset as valve replacement has a significant risk, and may fail to alleviate symptoms or improve left ventricular function. This article reviews the potential problems in evaluating aortic stenosis severity in low-flow, low-gradient aortic stenosis, the utility of dobutamine challenge to identify patients most likely to benefit from surgery, and the factors predicting patient outcome.
  
  
  RESULTS
  Low-flow, low-gradient aortic stenosis consists of a heterogeneous group of patients with 'true' severe aortic stenosis, in whom afterload mismatch results from a severely stenotic valve; and 'pseudo-severe' aortic stenosis, where the valve is only mildly or moderately stenotic, but appears severe due to limitations in determining disease severity under low-flow conditions. Valve replacement is likely to benefit the former group, but may have little benefit to the latter. Dobutamine challenge can distinguish 'true' and 'pseudo-severe' aortic stenosis, and can evaluate contractile reserve, one of the strongest predictors of patient outcome. Strategies to avoid prosthesis-patient mismatch should be considered to optimize postoperative outcome.
  
  
  CONCLUSIONS
  Dobutamine challenge can identify low-flow, low-gradient aortic stenosis patients most likely to benefit from valve replacement and provides important prognostic information on the operative risks and long-term outcome.
authors.affiliation: Department of Medicine, Division of Cardiology, University of Ottawa Heart Institute, University of Ottawa, Ontario, Canada. iburwash@ottawaheart.ca
authors.forename: Ian G
authors.initials: IG
authors.lastname: Burwash
mesh_terms: D001024:Aortic Valve Stenosis / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D001783:Blood Flow Velocity; D025401:Echocardiography, Stress; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D011379:Prognosis; D012039:Regional Blood Flow; D012720:Severity of Illness Index; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000209:etiology / Q000503:physiopathology / Q000628:therapy