Correlation of 6-minute-walking test with echocardiographic pulmonary arterial stiffness in patients with pulmonary hypertension

Introduction: Pulmonary arterial stiffness (PAS) has been shown to be related to pulmonary artery pressure (PAP) in patients with pulmonary artery hypertension (PAH). The aim of this study was to determine the correlation between functional capacity and echocardiographic indices of PAS in patients with PAH. Materials and methods This cross sectional study was performed on patients with PAH were confirmed by right heart catheterization who referred to Imam Reza PAH clinic for routine follow up between November 2019 and January 2020. All patients underwent echocardiography and the maximum Doppler frequency shift, pulmonary acceleration time, peak velocity of the pulmonary flow and velocity time integral, as well as PAS were measured. All patients performed 6-minute walk test. Results Fifty patients with the mean age of 41.90 ± 14.73 years old participated in this study. Majority of the patients were female (74%). The most common cause of PAH was idiopathic (74%). There was a significant correlation between PAS and PASP (r = 0.302, P = 0.041), V2 (r=-0.461, P = 0.003), T2/V1 (r=-0.311, P = 0.037) and Z3 ratio (r=-0.346, P = 0.023). There was no significant correlation between PAS and 6MWT, PVR and TAPSE (P > 0.05). There was a significant correlation between V2 and PVR (r = 0.359, P = 0.049). Conclusions PAS and V1 are simple, non-invasive, available tools for evaluation of pulmonary vascular bed and early diagnosis of pre-symptomatic clinical status in patients with PAH.