Differential Cardiopulmonary Hemodynamic Phenotypes in PASC Related Exercise Intolerance
The study titled “Differential Cardiopulmonary Hemodynamic Phenotypes in PASC Related Exercise Intolerance” conducted by Kahn, Joseph, Heerdt, and Singh, focuses on the cardiopulmonary effects in patients with Post-Acute Sequelae of COVID-19 (PASC) who exhibit exercise intolerance. It uses data from invasive cardiopulmonary exercise testing (iCPET) to explore these effects.
Key findings include:
- Peripheral Limitation in Majority of PASC Patients: Around 75% of the PASC patients in the study exhibited impaired peak systemic oxygen extraction (pEO2) during iCPET, along with abnormally high cardiac output. This group, on average, showed normal peak exercise capacity (VO2), indicating a primary peripheral limitation to exercise.
- High Output Heart Failure Phenotype in a Subset: Approximately 25% of the patients had evidence of central cardiopulmonary pathology, including heart failure with preserved ejection fraction (HFpEF) and exercise pulmonary hypertension (PH). The HFpEF group in particular exhibited a distinct high-output heart failure phenotype.
- Implications for Treatment and Diagnosis: The study emphasizes the importance of considering impaired pEO2 in PASC patients with persistent exertional intolerance that is unexplained by standard testing. It suggests that identifying subgroups like HFpEF and exercise PH is crucial as it can lead to the initiation of effective pharmacotherapies.
- Study Methodology: The study involved 55 patients referred for iCPET evaluation due to exertional intolerance. Various measurements were taken, including right heart catheterization, arterial and mixed venous blood gases, systemic oxygen extraction, cardiac output, and pulmonary vascular resistance.
- Study Limitations and Further Research: The study acknowledges limitations such as the specific patient phenotype and varying degrees of initial illness and recovery time. The findings highlight the need for larger studies at different recovery stages to further understand PASC and develop targeted treatments.
This research contributes significantly to understanding the complex cardiopulmonary dynamics in PASC, especially in the context of exercise intolerance. It provides a foundation for further investigation and potential therapeutic avenues for managing PASC symptoms.