Shuttling toward Improved Clinic-based Assessment of Exercise Capacity in Pulmonary Arterial Hypertension

Brittain discusses the study of Lewis et al wherein they make noteworthy progress toward introducing a viable alternative to the 6-minute-walk distance (6MWD) that has risk stratification value before and after treatment initiation. The authors assessed the ability of the intermittent shuttle walking test (ISWT) to predict clinical risk in a large cohort of patients with incident pulmonary arterial hypertension (PAH) enrolled in the Assessing the Spectrum of Pulmonary Hypertension Identified at a Referral Centre registry. The findings suggest several key advantages of the ISWT over the 6MWD. First, the test elicits maximal effort as evident in the fact that no patients reached the highest levels and only one reached level 9. Next, the absence of a ceiling effect was demonstrated by showing that even among those who had high baseline ISWT distances, the majority improved their absolute distance after therapy. Finally, changes in ISWT distance after treatment have prognostic value.