Early Decline in 6-minute Walk Test Distance Predicts Pulmonary Arterial Hypertension Deterioration

Results from a recent study published in the journal Respirology showed that an early decline in 6-minute walk test (6MWT) distance predicts deterioration of disease condition in patients with pulmonary arterial hypertension (PAH). The findings could provide new insights into effectively diagnosing and treating the disease using a completely non-invasive diagnostic approach.

PAH is a condition that causes the pulmonary arteries to constrict abnormally, forcing the heart to work harder and blood pressure within the lungs to rise. PAH worsens over time and is life-threatening because the pressure in a patient’s pulmonary arteries rises to dangerously high levels, putting a strain on the heart.

The six-minute walk distance (6MWD) is normally used to measure pulmonary arterial hypertension (PAH). But the role of 6MWD in predicting clinical outcomes in PAH is debatable.

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Since clinical worsening is considered a clinically important end point in PAH, researchers sought to examine if early longitudinal changes in 6MWD (Δ6MWD) in meters and percent predicted (%pred) from the time of diagnosis were able to predict clinical worsening of PAH. In the study titled “Early Decline in Six-Minute Walk Distance from the Time of Diagnosis Predicts Clinical Worsening in Pulmonary Arterial Hypertension,” Marco Mura from Western University in London, Ontario and his colleagues assessed a total of 100 patients with PAH group I.

The team evaluated 6MWD with the American (%pred US) or Canadian (%pred CAN) reference equations. The research recorded the Δ6MWD at 6 months and clinical worsening included the following variables: hospital admission for PAH, referral for lung transplantation, right heart failure and initiation of prostanoids after oral therapy failed.

The results revealed significant difference in Δ6MWD between patients with clinical disease worsening and those with no disease progression. The most relevant 6MWD declines in a 6 month time period were ≥35 m, ≥8%pred US and ≥6%pred CAN. Declines in 6MWD at 6 months were predictors of disease worsening with a high specificity (94%) but a low sensitivity (33%).

Based on the results, the researchers concluded that an early decline in 6MWD is a predictor of a clinical worsening in patients with PAH. The team indicated that Δ6MWD is already part of a comprehensive assessment of a patient’s clinical status. Nevertheless according to the researchers a decline in 6MWD should be used with other clinical evaluation methods to appropriately assess PAH progression.

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