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Predictors of the Six-Minute Walk Distance (6MWD) in Pulmonary Arterial Hypertension (PAH)

A. Boyer

Murali Chakinala

J. Zheng


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Conference: 2012 International PHA Conference and Scientific Sessions

Release Date: 06.22.2012

Presentation Type: Abstracts

Boyer A, Chakinala M, Zheng J.

Washington University School of Medicine, United States of America

BACKGROUNDThe Six-Minute Walk Test (6MWT) is often used in PAH patients to risk stratify and judge treatment response. In a group of healthy individuals, Enright predicted 6MWD based on age, gender, and body mass index (BMI). We aimed to identify predictors of the 6MWD in a PAH cohort and determine if the same demographic and anthropometric measurements were relevant.

METHODSRetrospective chart review was performed of treatment-naive patients enrolled in the Washington University Pulmonary Hypertension Clinic between January 1, 2004 and January 31, 2010. Data was recorded from the baseline visit including anthropometric measurements, absolute 6MWD (obtained as per ATS guidelines), WHO functional classification, pulmonary function testing, and key measurements from transthoracic echocardiography (TTE) and right heart catheterization (RHC). Univariable and multivariable linear regression identified significant predictors of the 6MWD.

RESULTS86 subjects were included in the analysis (mean age 50 +/- 13, female 73%, WHO functional class III/IV 73%). Hemodynamic variables were consistent with WHO Group I Pulmonary Hypertension. Multivariable analysis revealed DLCO (21.2 +/- 6.2 m for every 10% increase, p<0.001), BNP (-6 +/- 2 m for every 100 pg/dl increase, p=0.001), and WHO functional classification (-124 +/- 25 m class III/IV vs. I/II, p<0.001) to be significant predictors of the 6MWD. Presence of a pericardial effusion, presence of a right to left shunt, and hemodynamic variables (cardiac index, right atrial pressure, and pulmonary vascular resistance) were significant factors associated with the 6MWD but only in univariable analysis. Age, gender, and BMI were not predictive of the 6MWD.

CONCLUSIONSWHO functional classification, DLCO, and BNP were significant predictors of the 6MWD in a cohort of treatment-naïve PAH patients. Interestingly, the three determinants (age, gender, and BMI) of the 6MWD from a large cohort of healthy.