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

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.

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.

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.