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(Circulation. 2008;118:S234-S242.)
© 2008 American Heart Association, Inc.

Surgery for Valvular Heart Disease

Predictors of Outcomes in Low-Flow, Low-Gradient Aortic Stenosis

Results of the Multicenter TOPAS Study

Marie-Annick Clavel, DVM; Christina Fuchs, MD; Ian G. Burwash, MD; Gerald Mundigler, MD; Jean G. Dumesnil, MD, FRCPC, FACC; Helmut Baumgartner, MD; Jutta Bergler-Klein, MD; Rob S. Beanlands, MD; Patrick Mathieu, MD; Julien Magne, MSc; Philippe Pibarot, DVM, PhD, FACC, FAHA

From the Laval Hospital Research Center/Québec Heart Institute (M.A.C., C.F., J.M., J.G.D., P.M., P.P.), Laval University, Québec, Canada; Vienna General Hospital (C.F., G.M., H.B., J.B.K.), Medical University of Vienna, Vienna, Austria; and the University of Ottawa Heart Institute (I.G.B., R.B.), Ottawa, Ontario, Canada.

Correspondence to Philippe Pibarot, DVM, PhD, FACC, FAHA, Laval Hospital, 2725 Chemin Sainte-Foy, Québec, Quebec, Canada, G1V-4G5. E-mail philippe.pibarot{at}med.ulaval.ca

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.

Methods and Results— One hundred one patients with low-flow, low-gradient aortic stenosis (aortic valve area 1.2 cm², 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 cm² (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 cm², 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.

Conclusion— 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.

Key Words: aortic stenosis • Doppler echocardiography • hemodynamics • LV dysfunction • survival