Pulmonary arterial hypertension (PAH) patients with better right ventricular systolic function have increased levels of daily physical activity, which are linked with longer 6-minute walk test distances (6MWD) and better health-related quality of life (HRQoL).

The findings, published in the Annals of the American Thoracic Society, were part of a multicenter study to investigate the relationships between right ventricular function, levels of daily activity, and HRQoL in patients with PAH.

The study also showed that activity-based phenotypes created using accelerometer data from patients in the multicenter Pulmonary Hypertension and Anastrozole Trial (PHANTOM) could be generalized to patients in a separate single-site cohort. Increased 6MWD and decreased emPHasis-10 (E-10) scores, indicating improvements in HRQoL, were found when looking across the 3 phenotypes identified (low, medium, and high activity).


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“Distinct activity-based phenotypes may be helpful in risk stratification of PAH patients or provide novel endpoints for clinical trials,” the study authors suggested.

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Patients with higher tricuspid annular plane systolic excursion (TAPSE), indicating better right ventricular function, were found to have higher levels of activity as measured by vector magnitude counts recorded by hip-worn accelerometers. Researchers found that a 0.4 cm or 1 standard deviation increase in TAPSE was associated with an increase of 34,000 counts (95% CI, 900–67,000 counts; P =.004).

Higher levels of daily physical activity were correlated with longer 6MWDs and lower E-10 scores. An increase of 1 standard deviation in vector magnitudes increased 6MWD by 56.1 m (95% CI, 28.6 – 83.7 m; P <.001) and was correlated with a decrease of 3.3 points in E-10 scores (95% CI, 0.3–6.4; P =.03).

Fifty-five patients with PAH (67% female) from the PHANTOM trial participated in the study and wore the accelerometers for 13.6 hours per day on average. A subset of 4 patients had days where they wore the accelerometer for less than 5 hours and were consequently excluded from the analysis. Median values of 7 accelerometer features from the remaining patients were used, with principal component analysis and K-means clustering to group patients into the 3 phenotypes.

The phenotypes identified from the PHANTOM cohort of patients were then applied to a cohort of 60 female patients with PAH from the University of Pennsylvania in Philadelphia. Four patients were again excluded for having days with less than 5 hours of accelerometer wear. The 3 clusters identified had similar distributions of activity to the PHANTOM cohort and were significantly associated with 6MWD (P =.04). No differences were observed in E-10 scores between clusters, however (P =.62).

Reference

Minhas J, Shou H, Hershman S, et al. Physical activity and its association with traditional outcome measures in pulmonary arterial hypertension. Ann Am Thorac Soc. Published online September 2, 2021. doi:10.1513/annalsats.202105-560oc