Wearable Devices in Pulmonary Arterial Hypertension: What Are We Trying to Learn?

Wearable technologies (accelerometers) are currently being evaluated as an alternative to the 6-minute walk test as an objective measure of functional status in pulmonary arterial hypertension (PAH). Multiple observational studies incorporating accelerometers have shown patients with PAH have low physical activity (PA) time. Despite widespread use of accelerometers, PA has not been shown to increase after adding vasodilator therapy, which suggests a behavioral component influencing activity. A decrease in PA from baseline may identify clinical worsening and someone at risk for future hospitalization. Cardiac Effort, the number of heart beats used during the 6-minute walk test/6-minute walk distance (beats per meter), has less variability than 6-minute walk distance and provides a comparable clinic measurement in the home setting. Cardiac Effort may provide a better remote measurement than changes in total daily activity when evaluating for clinical improvement. The amount and duration of PA achieved in patients with PAH is likely related to a combination of right ventricular (RV) function, deconditioning, and environmental factors. Strategies to target all aspects are needed to improve PA. Further studies are needed to determine the optimal remote measure and monitoring period.