Study Tests Feasibility of Remote Monitoring in PAH

Researchers tested the feasibility of remote monitoring for patients with pulmonary arterial hypertension via smartphones and smartwatches.

Parallel monitoring of physical activity, heart rate, and iloprost inhalation is feasible among patients with pulmonary arterial hypertension (PAH), according to results of a prospective, multicenter, observational study. However, some challenges remain. Findings were published in Journal of Medical Internet Research.

PAH is a progressive disease that can lead to right-sided heart failure and death, while iloprost is a prostacyclin analog that can be inhaled through a nebulizer that tracks inhalation behavior.

“The impairment of quality of life in patients with PAH is severe, with health-related quality of life scores comparable to those reported for patients with spinal cord injuries or cancer unresponsive to therapy,” the researchers explained.

“The use of vasoactive treatment to address PAH is usually guided by intermittent clinical measurements of the 6-minute walk distance, World Health Organization (WHO) functional class, and levels of B-type natriuretic peptide (BNP) or N-terminal pro–B-type natriuretic peptide (NT-proBNP).” But these clinical measures can only provide a snapshot of a patient’s health status as they are measured at in-person appointments. According to the authors, this creates an opportunity for remote patient monitoring.

Continuous assessment of parameters like physical activity can help researchers better understand the impact of PAH on daily life.

Using a commercially available smartwatch and smartphone, the investigators tracked the daily physical activity of patients with PAH starting treatment with iloprost. They also examined “the association between changes in digital physical activity measures and changes in traditional clinical measures of disease severity and health-related quality of life over a 12-week period.”

Between February 2018 and July 2019, patients aged 18 or older were recruited from 7 PAH centers in Germany. Of the 31 patients screened, 18 individuals followed for a median (IQR) 91.5 (88-92) days were included in final analyses. At baseline, all patients were taking oral PAH therapies.

The researchers found:

  • Changes from baseline in traditional and digital 6-minute walk distance were moderately correlated (r = 0.57)
  • Physical activity (daily distance walked: median 0.4 [–0.2 to 1.9] km; daily step count: median 591 [−509 to 2413]) and clinical measures (traditional 6-minute walk distance: median 26 [0-40] m) changed concordantly from baseline to the end of the observation period
  • Health-related quality of life showed little change
  • Total sleep score and resting heart rate slightly decreased
  • Distance walked and step count showed short-term increases after each iloprost inhalation

No new safety signals were identified (safety analysis set: n = 30)

“The results demonstrate the feasibility of using digital parameters as digital biomarkers for long-term activity levels in patients with PAH,” the authors wrote, adding “although correlations between changes in digital and traditional clinical outcome measures were few, the overall directions of those changes were generally concordant.”

A lack of available patients and a subsequent small study size mark a limitation to the investigation, in addition to the fact the digital 6-minute walk distance algorithm was based on healthy individuals’ step length as opposed to those with PAH.

Overall, further research in this area, including studies with longer-term follow-ups, is warranted. “Digital measures of daily physical activity and traditional clinical measures showed concordant changes from baseline after addition of inhaled iloprost to oral PAH therapies,” the authors concluded. “The data indicate that activity tracking algorithms validated for healthy people require adaptation for patients with PAH.”


Stollfuss B, Richter M, Drömann D, et al. Digital tracking of physical activity, heart rate, and inhalation behavior in patients with pulmonary arterial hypertension treated with inhaled iloprost: observational study (VENTASTEP). J Med Internet Res. Published online August 10, 2021. doi:10.2196/25163