No Associations Exist Between 6MWD and Maximum Oxygen Uptake in Pulmonary Arterial Hypertension

Walking down the hall of a hospital.
Walking down the hall of a hospital.
Results indicate that further study of the relationship between the 6-minute walk distance test and functional capacity in PAH is necessary.
The following article is part of conference coverage from the CHEST 2017 in Toronto, Canada. Visit Pulmonology Advisor’s  conference page for more conference news.

TORONTO — No significant associations exist between the 6-minute walk distance (6MWD) or percent predicted 6MWD (PP-6MWD) and peak oxygen uptake (VO2peak) as measured by cardiopulmonary exercise testing (CPET) in patients with pulmonary arterial hypertension (PAH), according to a study presented at CHEST 2017, held October 28-November 1 in Toronto, Ontario, Canada.

“The 6MWD estimated by the 6MW test (6MWT) is used routinely in assessing functional capacity of patients with PAH,” according to the investigators. “VO2peak measured by CPET is the gold standard for assessing functional capacity in PAH but is not routinely used in the follow-up of these patients due to its complexity and cost.”

The objective of this study was to evaluate the relationship between 6MWD and PP-6MWD with VO2peak measured by CPET. A total of 8 patients with PAH (defined as PAH with a mean pulmonary arterial pressure of >25 mm Hg and a pulmonary capillary wedge pressure <15) were included in this study (63% female). Of the patients included in the final analysis, mean pulmonary artery pressure was 56±8 mm Hg.

The mean VO2peak on CPET was 16±2.8 mL/kg/min, whereas the mean 6MWD from 6MWT scores were 480±83 meters vs 68±10 meters for mean PP-6MWD. There was no significant association between the VO2peak and PP-6MWD (r=0.515, P =.20) or VO2peak and 6MWD (r = 0.703; P =.07).

Investigators commented, “The relationship between 6MWD, a commonly used parameter to assess functional capacity, with oxygen uptake, in PAH merits further studies on larger groups of patients.”

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Orr L, Datta D. Percent predicted 6-minute walk distance and VO2 max in pulmonary arterial hypertension. Presented at: CHEST 2017; October 28-November 1, 2017; Toronto, Ontario, Canada. Abstract 2744411.