Longitudinal Remote 6-Minute Walk Distance and Cardiac Effort Using Wearable Sensors in Pulmonary Hypertension

Remote 6-min walk testing (6MWT) has been shown to be safe in pulmonary hypertension, but limited data exist on its longitudinal durability and relationship to supervised in-clinic testing. Cardiac Effort (CE), defined as total heartbeats divided by walk distance, provides physiologic context beyond distance alone. We evaluated the longitudinal performance of a home-based 6MWT and CE performed on a modified indoor walking space using a wearable chest sensor and compared results with in-clinic testing over 8 weeks. This single-center prospective study was conducted with institutional review board approval. Participants with PH performed supervised in-clinic and unsupervised home 6MWTs at baseline and Week 8. A chest-based wearable sensor recorded acceleration and heart rate data to estimate walk distance and calculate CE. Mixed-effects repeated-measures models were used to compare sensor-estimated and directly observed walk distance and CE in the clinic and at home over time. Agreement was assessed using Bland-Altman analyses, intraclass correlation coefficients (ICC), and Spearman correlations. Twenty-nine participants were enrolled, and no adverse events occurred. Sensor-estimated 6MWT distance and CE demonstrated minimal bias and excellent agreement with directly observed in-clinic measurements (6MWD bias 0.04%, ICC 0.995; CE bias -0.04%, ICC 0.995). Home-based 6MWD was approximately 40 m lower than supervised clinic testing. Mixed-effects models showed similar longitudinal changes between home and clinic testing. Changes in home 6MWD and CE correlated with corresponding in-clinic changes (6MWD: r = 0.40, p = 0.045; CE: r = 0.42, p = 0.03). Home-based 6MWT and CE obtained using a wearable chest sensor provide a safe, feasible method for remote functional assessment in PH that tracks with in-clinic testing. Frequent home assessment may facilitate earlier detection of clinical change, support therapeutic titration, and expand access to standardized physiologic monitoring.