Functional recovery after pulmonary embolism: A pilot study using metabolic monitoring during the 6-minute walk test

Disability after acute pulmonary embolism is common. Functional testing is not routinely performed in early follow-up and typically occurs only when symptoms persist after three months of anticoagulation.

This pilot study was a single center, prospective, observational study as part of a larger rehabilitation clinical trial. We recruited patients hospitalized for intermediate or high risk acute pulmonary embolism. Baseline (within 2 weeks of discharge) and follow up (3 months later) testing included 6-min walk test with metabolic monitoring, Cardiac Effort (number of heart beats used/walk distance), two weeks of actigraphy, and PE-mb Quality of Life Questionnaire. Non-parametric and mixed method repeated measures regression were performed.

Twenty-five participants completed paired 6-min walk testing after acute PE. No safety concerns emerged when performing the walk test. There was significant improvement in walk distance, +58 m (29, 108), and Cardiac Effort, -0.2 beats/m (-0.4, -0.1), at 3-month follow up. Metabolic monitoring showed improvement in oxygen consumption, +1.8 ml/kg/min (0.8, 4.9), and respiratory efficiency, -2.9 (-7.7, -0.5). Actigraphy showed increased moderate activity time, +10 min/day (4, 21), and quality of life improved, -20% (-24, -7). Both 6-min walk distance and actigraphy parameters were associated with metabolic parameters.

For a group of participants that were asymptomatic at 3 months after hospitalization for acute pulmonary embolism, early functional assessments that can be obtained and repeated in an office setting demonstrated recovery in function and physiology (gas exchange and heart rate). Early testing could help better characterize recovery after acute pulmonary embolism.