title: Predictors of outcomes in low-flow, low-gradient aortic stenosis: results of the multicenter TOPAS Study.
abstract: BACKGROUND
  Patients with low-flow, low-gradient aortic stenosis have a poor prognosis with conservative therapy but a high operative mortality if treated surgically. Recently, we proposed a new index of aortic stenosis severity derived from dobutamine stress echocardiography, the projected aortic valve area at a normal transvalvular flow rate, as superior to other conventional indices to differentiate true-severe from pseudosevere aortic stenosis. The objective of this study was to identify the determinants of survival, functional status, and change in left ventricular ejection fraction during follow-up of patients with low-flow, low-gradient aortic stenosis.
  
  
  RESULTS
  One hundred one patients with low-flow, low-gradient aortic stenosis (aortic valve area </=1.2 cm(2), left ventricular ejection fraction </=40%, and mean gradient </=40 mm Hg) underwent dobutamine stress echocardiography and an assessment of functional capacity using the Duke Activity Status Index. A subset of 72 patients also underwent a 6-minute walk test. Overall survival was 70+/-5% at 1 year and 57+/-6% at 3 years. After adjusting for age, gender, and the type of treatment (aortic valve replacement versus no aortic valve replacement), significant predictors of mortality during follow-up were a Duke Activity Status Index </=20 (P=0.0005) or 6-minute walk test distance </=320 m (P<0.0001, in the subset of 72 patients), projected aortic valve area at a normal transvalvular flow rate </=1.2 cm(2) (P=0.03), and peak dobutamine stress echocardiography left ventricular ejection fraction </=35% (P=0.03). More severe stenosis, defined as projected aortic valve area </=1.2 cm(2), was a predictor of mortality only in the no aortic valve replacement group. The Duke Activity Status Index, 6-minute walk test, and left ventricular ejection fraction improved significantly during follow-up in the aortic valve replacement group, but remained unchanged or decreased in the no aortic valve replacement group.
  
  
  CONCLUSIONS
  In patients with low-flow, low-gradient aortic stenosis, the most significant risk factors for poor outcome were (1) impaired functional capacity as measured by Duke Activity Status Index or 6-minute walk test distance; (2) more severe valve stenosis as measured by projected aortic valve area at a normal transvalvular flow rate; and (3) reduced peak stress left ventricular ejection fraction, a composite measure accounting for both resting left ventricular function and contractile reserve.
authors.affiliation: Laval Hospital Research Center/Québec Heart Institute, Laval Hospital, 2725 Chemin Sainte-Foy, Québec, Quebec, Canada.
authors.forename: Marie-Annick
authors.initials: MA
authors.lastname: Clavel
authors.forename: Christina
authors.initials: C
authors.lastname: Fuchs
authors.forename: Ian G
authors.initials: IG
authors.lastname: Burwash
authors.forename: Gerald
authors.initials: G
authors.lastname: Mundigler
authors.forename: Jean G
authors.initials: JG
authors.lastname: Dumesnil
authors.forename: Helmut
authors.initials: H
authors.lastname: Baumgartner
authors.forename: Jutta
authors.initials: J
authors.lastname: Bergler-Klein
authors.forename: Rob S
authors.initials: RS
authors.lastname: Beanlands
authors.forename: Patrick
authors.initials: P
authors.lastname: Mathieu
authors.forename: Julien
authors.initials: J
authors.lastname: Magne
authors.forename: Philippe
authors.initials: P
authors.lastname: Pibarot
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015906:Angioplasty, Balloon, Coronary; D001011:Aorta / Q000503:physiopathology; D001021:Aortic Valve; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy*; D015331:Cohort Studies; D001026:Coronary Artery Bypass; D025401:Echocardiography, Stress; D017079:Exercise Tolerance; D005260:Female; D005500:Follow-Up Studies; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012039:Regional Blood Flow; D012720:Severity of Illness Index; D015607:Stents; D013318:Stroke Volume; D016277:Ventricular Function, Left