Six-minute walking test and long term prognosis in patients with asymptomatic aortic valve stenosis

BACKGROUND: Management of asymptomatic patients with aortic valve stenosis is challenging due to the elusive relationship between symptomatic status and hemodynamic parameters in addition to the occurrence of cardiovascular death. The 6-minute walking test (6MWT) reflects overall hemodynamic function and could contribute to risk assessment in such patients.

METHODS AND RESULTS: One hundred sixteen asymptomatic patients (peak velocity>2.5m/s and left ventricular ejection fraction >50% assessed by echocardiographic screening; 85 males; aged 72±8years) underwent clinical workup, transthoracic echocardiography and a 6MWT. The mean distance covered by patients able to perform the 6MWT (n=107) was 422±90m. Patients were grouped in tertiles according to distance covered in the 6MWT: Short, intermediate and long distance patients. During a median follow-up of 5.5years (IQR 4.5-6.3), 29 (25%) patients died, 10 (9%) from cardiovascular causes. Multivariate analysis revealed that short distance patients (≤390m) were at higher risk of all-cause mortality (HR: 2.44; 95% CI: 1.05-5.67; p=0.04) and cardiovascular mortality (HR: 6.12; 95% CI: 1.18-31.83; p=0.03). For every 100m covered, the risk of all-cause mortality decreased by 35% (HR: 0.65; 95% CI: 0.43-0.99; p=0.04). Long distance patients (>465m) did not experience cardiovascular deaths during follow-up.

CONCLUSIONS: In asymptomatic patients with aortic valve stenosis, the 6MWT is an independent predictor of all-cause and cardiovascular mortality. It is of incremental value to the echocardiographic evaluation, suggesting that the 6MWT might be useful to guide clinical follow-up intervals and treatment strategy.