Chest sensors allow remote 6-minute walk testing for patients with pulmonary hypertension

Chest sensors that measured heart rate and accelerometry enabled patients with pulmonary artery hypertension to undergo 6-minute walk tests remotely with similar data as those collected in clinic, according to study results in CHEST.

Measuring cardiac effort rather than distance walked can overcome prior limitations of exercise tolerance home assessment, according to researchers.

“We think this home 6-minute walk test could complement telemedicine or help when assessing clinical status or titrating a drug,” Daniel J. Lachant, DO, assistant professor of medicine at University of Rochester Medical Center, told Healio.

In a single-center, prospective observational study, Lachant and colleagues evaluated 20 patients (median age, 59 years; 80% women) with PAH to see if a chest-based accelerometer (BioStamp nPoint, MC10 Inc.) that collects ECG heart rate data can accurately and safely estimate 6-minute walk test (6MWT) distance at home. Researchers also evaluated if cardiac effort — measured as the total number of heart beats during the test divided by the total distance walked — served as a better remote measure than distance walked.

In the span of 2 weeks, patients took two 6MWTs in the clinic (first and last) and two to four 6MWTs remotely on their own schedules while wearing the sensors.

Researchers compared the clinic and remote data using Wilcoxon matched-pairs signed rank tests, Spearman correlation coefficients and Bland-Altman plots.

Of the patients, 30% had idiopathic PAH, 60% had connective tissue disease-related PAH and 10% had repaired congenital heart disease-related PAH.

Based on data from 38 clinic 6MWTs, researchers found a strong correlation between walk distance estimated by the accelerometer-derived count of laps and directly measured distance (r = 0.99; P < .0001).

Similarly, researchers observed a strong correlation between both estimated and reported remote 6MWTs distances (r = 0.81; P < .0001), with an average difference between the two of 2.8% (± 12.9%), which researchers wrote could reflect patient counting error or premature turns.

When comparing median sensor-estimated walk test distances, the remote 6MWT was shorter compared with the clinic 6MWT (389 m vs. 405 m; P = .002).

In terms of cardiac effort, researchers observed no difference between clinic measurements and remote measurements (1.75 beats/m; 95% CI, 1.48-2.2 vs. 1.85 beats/m; 95% CI, 1.57-2.14), which they said suggests cardiac effort is a less variable measure than distance walked and can correct for several factors such as more turns taken in smaller walking spaces or having no staff.

“We started this in the first year of the COVID-19 pandemic when there was still a lot of uncertainties,” Lachant told Healio. “Our patients were very creative in the places they chose to complete the home 6-minute walk test. We were happy to find out that after adjusting for heart rate there was a similar measurement obtained in the clinic and home setting.

“[In terms of future studies,] this data opens the idea of doing decentralized clinical trial with physiologic assessment remotely,” Lachant added.

For more information:

Daniel J. Lachant, DO, can be reached at daniel_lachant@urmc.rochester.edu.