Cardiopulmonary exercise testing valuable to assess unexplained dyspnea post-COVID-19
In a small study, cardiopulmonary exercise testing identified significant abnormalities, including dysfunctional breathing, resting hypocapnia and chronic fatigue syndrome, associated with post-acute sequelae of severe SARS-CoV-2 infection.
“The current clinical guidelines do not recommend cardiopulmonary exercise testing out of concern that this test could worsen the patients’ [long COVID] symptoms,” Donna M. Mancini, MD, advanced heart failure and transplant specialist at the Icahn School of Medicine at Mount Sinai, told Healio. “However, we found that cardiopulmonary exercise was able to identify reduced exercise capacity in about 46% of patients. This reduced functional capacity was from a circulatory abnormality. This may include changes involving the pulmonary or peripheral vasculature. We also found that nearly 90% of patients had ventilatory abnormalities during exercise.”
Utility of cardiopulmonary exercise testing
Mancini and colleagues aimed to assess the utility of cardiopulmonary exercise test to define unexplained dyspnea in patients with post-acute sequelae of SARS-CoV-2 (PASC) and also assessed patients for criteria to diagnose myalgic encephalomyelitis/chronic fatigue syndrome.
The researchers enrolled 41 patients with long COVID symptoms at a median of 8.9 months after infection. Of those, 18 were men and the mean age was 45 years.
According to Mancini, participants in this study developed COVID-19 before vaccines were widely available.
Mean left ventricular ejection fraction was 59%. In the entire cohort, average peak VO2 was 20.3 mL/kg/min, mean slope of minute ventilation to CO2 production (VE/VCO2) was 30 and average end-tidal pressure of CO2 (PetCO2) at rest was 33.5 mm Hg.
Researchers reported that 58.5% of participants had a peak VO2 of less than 80% of the predicted value, all of whom experienced circulatory limitation to exercise.
Among 17 patients with normal peak VO2, 15 had ventilatory abnormalities, which included a peak respiratory rate greater than 55 or dysfunctional breathing, according to the results.
Eighty-eight percent of participants had ventilatory abnormalities with dysfunctional breathing, elevated VE/VCO2 and/or PetCO2 less than 35 mm Hg.
“Many of the patients had low resting CO2 levels, suggesting chronic hyperventilation. With exercise, many had rapid erratic breathing patterns, which is called dysfunctional breathing,” Mancini told Healio. “Hyperventilation coupled with the dysfunctional breathing may result in shortness of breath along with other vague symptoms these patients commonly report such as mental fogginess, tingling, palpitations, chest pain. Low-level functional testing recommended by the guidelines such as a 6-minute walk test would not be able to detect these abnormalities. Identifying dysfunctional breathing can be difficult, as there is no precise definition and requires careful review of the raw data generated during testing. This finding is important in that dysfunctional breathing can be treated with breathing retraining. Moreover, prognosis related to this as a cause of unexplained dyspnea is good.”
Forty-six percent of patients met the criteria for myalgic encephalomyelitis/chronic fatigue syndrome, according to the results.
“Almost half of these patients meet criteria for chronic fatigue syndrome. This is the first report directly linking long haul COVID to chronic fatigue,” Mancini told Healio.
Further investigation
Mancini said it is important to emphasize that these data apply to a subgroup of patients with long haul COVID with ongoing dyspnea and normal cardiac echocardiography and pulmonary function tests.
Looking forward, Mancini said the researchers are interested in testing the impact of breathing retraining on the patients’ symptoms.
“This is a small cohort of patients, but the findings of dysfunctional breathing and frequent chronic fatigue syndrome are important and deserve further investigation,” Mancini told Healio.
For more information:
Donna M. Mancini, MD, can be reached at donna.mancini@mountsinai.org.
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