Prognostic Usefulness of the 6-Minute Walk Test in Patients With Severe Aortic Stenosis

Abstract

The 6-minute walk test distance (6MWD) has been shown to predict prognosis in selected cohorts of patients with heart failure and outcomes after surgical or transcatheter aortic valve implantation (AVI) in patients with symptomatic severe aortic stenosis (AS). Our objective was to evaluate the association between the 6MWD and outcome in patients with severe AS while remaining under medical treatment. In a prospective observational cohort study, a total of 149 patients diagnosed with severe AS by Doppler echocardiography underwent a 6-minute walk test. The single end point was a composite of all-cause death or hospitalization for heart failure. Patients receiving an AVI were censored from follow-up at the time of their AVI, so that only the events that occurred while the patients remained under medical treatment were included in the analysis. During follow-up (median 12.9 months), the end point occurred in 65 patients (43.6%). Univariate analysis showed an association between the 6MWD and the end point (p <0.001). After adjustment for symptoms, left ventricular ejection fraction, aortic valve area, Charlson co-morbidity score, and anemia, the 6MWD independently predicted the end point (adjusted hazard ratio 0.63; 95% confidence interval 0.45 to 0.89; p = 0.010). The incidence of the composite end point was 12 per 100 patient-years in patients with a 6MWD >331 m compared to 86 per 100 patient-years in those with a 6MWD ≤331 m (p <0.001). In conclusion, although patients with severe AS remain under medical treatment, the 6MWD is independently associated with all-cause death or hospitalization for heart failure.