Six-minute walk test reflects neurohormonal activation and right ventricular function in systemic sclerosis patients

Heart and pulmonary involvement is a leading cause of systemic sclerosis (SSc)-related deaths. The six-minute walk test (6MWT) is a simple and reproducible test commonly used to evaluate exercise capacity. We tried to assess a potential relationship between exercise capacity assessed by 6MWT, echocardiographic parameters of right ventricular function and serum levels of endothelin-1 and NTproBNP. We prospectively studied 111 consecutive patients (101F, 10M, age 54.2±13.8 years) with diagnosed SSc (mean disease duration 9±12.4 years) and a group of 21 age-matched subjects (18F, 3M, age 49.3±10.5 years). In addition to routine evaluation, 6MWT and transthoracic echocardiography (Phillips iE 33) were performed. We also measured serum endothelin-1 (Human Endothelin-1 immunoassay R & D Systems) and NT-proBNP levels (Elecsys pro-BNP immunoassay; Roche Diagnostics). The mean 6MWT distance was significantly shorter in the SSc group than in the controls (562.8±60.3 vs. 514.7±102.5 m, p=0.03). In the SSc group 6MWT distance correlated with ET-1 (r=-0.5, p