Comparison of three walking tests to cardiopulmonary exercise tests in the assessment of exercise tolerance in individuals with pulmonary arterial hypertension

Abstract

Background: The clinical utility of walking tests to evaluate the exercise capacity of patients with pulmonary arterial hypertension (PAH) is in need of further investigation.Very few studies have compared the clinical utility of field walking tests (The 6-min walk test -6MWT); Incremental Shuttle Walk Test (ISWT)) to CPET to assess exercise tolerance in patients with PAH.

Objectives: To compare three field tests: 6MWT, ISWT and Endurance Shuttle Walk Test (ESWT)to CPET in patients with PAH.

Methods and Results: 20 PAH patients (49.8±14.6 years old), WHO functional class II-III, mean pulmonary artery pressure (PAPm): 45 mmHg, were subjected to the three field tests and CPET. The ISWT reached maximum levels of effort and no significant differences in any variable when compared to CPET results. However,the 6MWT and ESWT achieved submaximal levels when compared to CPET results. A higher correlation was observed between ISWT walk distance (WD) and peak oxygen consumption (pVO2) of CPET than between 6MWT distance and pVO₂(r=0.89versus0.52, respectively;p<0.05). Furthermore, strong negative correlations were observed between the PAPm and (1) WD during the ISWT and ESWT (r=-0.83versus-0.66,respectively) and (2)CPET pVO₂and workload (r=-0.80versus-0.87, respectively). There was no significant correlation between PAPm with the WD during the 6MWT.

Conclusion: The ISWT is an effective and safe alternative to CPET with the advantage of being simple and inexpensive, and capable of capturing the functional status of patients with PAH.