• Michael Insel, Tammer El Aini, Gregory Woodhead, Rebecca Wig, Saad Kubba, Guido Claessen, Erin Howden, and Franz Rischard.
• Division of Pulmonary Allergy Sleep and Critical Care, University of Arizona, Tucson, AZ. Electronic address: minsel@arizona.edu.
• Chest. 2024 Sep 3.

BackgroundPost-pulmonary embolism (PE) dyspnea is common. Existing noninvasive studies have demonstrated that post-PE dyspnea is associated with elevations in right ventricular (RV) afterload, dead space ventilation, and deconditioning. We aimed to use invasive cardiopulmonary exercise testing (iCPET) parameters in patients with post-PE dyspnea to identify unique physiologic phenotypes.Research QuestionDo distinct post-PE dyspnea physiologic phenotypes exist that are described with iCPET?Study Design And MethodsPatients were enrolled at the time of acute PE and through our pulmonary hypertension (PH) and dyspnea clinic. iCPET was performed if high suspicion existed for PH or if unexplained dyspnea was present. A hierarchical cluster analysis was performed to identify dyspnea phenotypes. iCPET parameters assessing pulmonary hemodynamics, ventilation, and peripheral oxygen use then were compared within and across each cluster and with iCPET control participants against peak oxygen consumed per minute (VO2).ResultsOne hundred seventy-three patients were enrolled. Sixty-seven patients underwent iCPET. All patients showed reductions in peak VO2 and peak cardiac index relative to control participants. Three clusters were identified. Cluster 1 was defined by having elevated RV afterload and impaired ventilatory efficiency. Cluster 2 was defined by elevated RV afterload with reductions in respiratory mechanics. Cluster 3 was defined by mild derangement in RV afterload with mild reductions in peak cardiac output.InterpretationiCPET revealed significant heterogeneity in post-PE dyspnea. Three phenotypes are characterized by differences in RV afterload: ventilatory efficiency, respiratory mechanics, and peripheral oxygen use.Copyright © 2024 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

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