Physiologic Associations in Pulmonary Embolism With Exercise-Induced Dyspnea

Patients who received long-term treatment for pulmonary embolism (PE) with exercise-induced dyspnea showed limitations in stroke volume reserve and physiologic dead space proportion (V_D/V_T), according to study results published in CHEST.

The results of cardiopulmonary exercise tests from patients on long-term treatment for PE were retrospectively analyzed to find physiologic associations. V_D/V_T was determined at anaerobic threshold from exhaled carbon dioxide and transcutaneous partial pressure of carbon dioxide, while cardiac stroke volume reserve was estimated at rest and at anaerobic threshold by VO₂/pulse.

Data from 40 patients were analyzed; 65% of patients exhibited either increased V_D/V_T, and/or decreased stroke volume reserve. Increased V_D/V_T (≥0.27) alone was noted in 35% of patients, while decreased stroke volume reserve (≤128% of the resting value) occurred alone in 55% of patients. Both defects were present in 25% of patients. Importantly, increased V_D/V_T at anaerobic threshold significantly correlated with the extent of unmatched perfusion defects on subsequent VQ scans (P =.0085).

“Detailed noninvasive measurements during cardiopulmonary exercise tests after long-term treatment of PE disclosed limitations in V_D/V_T reduction or in stroke volume reserve in the majority of patients with post-PE dyspnea,” the researchers wrote. “Large prospective studies can determine more precisely the prevalence of these defects after PE and validate their clinical utility for the follow-up of patients after acute PE.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Fernandes TM, Alotaibi M, Strozza D, et al. Dyspnea post pulmonary embolism from V_D/V_T and stroke volume defects during exercise [published November 21, 2019]. CHEST. doi:10.1016/j.chest.2019.10.047