Cardiopulmonary Testing and Unexplained Dyspnea Post–COVID-19

Quick Takes

  • This is a small study using cardiopulmonary testing to evaluate unexplained shortness of breath in patients with suspected post-acute sequelae of COVID-19.
  • The majority of participants had evidence of ventilatory abnormalities. Symptoms of chronic fatigue syndrome were common.

Study Questions:

Do individuals with a history of coronavirus disease 2019 (COVID-19) and persistent unexplained dyspnea have abnormalities on cardiopulmonary testing?


The authors performed cardiopulmonary exercise testing (CPET) and symptom assessment in 41 patients who were positive for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection (PASC) with new and unexplained shortness of breath >3 months after diagnosis. All patients had normal pulmonary function tests, chest X-ray, and chest computed tomography scans. Seven patients underwent hemodynamic assessment with Swan-Ganz catheter during exercise. All participants responded to interview questions assessing for the diagnosis of chronic fatigue syndrome.


A total of 18 men and 23 women (average age, 45 ± 13 years) participated, with an average of 9 ± 3 months from the time of acute COVID-19; 8 of the 41 patients had been hospitalized for acute COVID-19. Twenty-four patients (58.5%) had a peak oxygen consumption (peak VO2) <80% predicted. All patients with peak VO2 <80% had a circulatory limitation to exercise. Fifteen of 17 patients with normal peak VO2 had ventilatory abnormalities including peak respiratory rate >55 (n = 3) or dysfunctional breathing (n = 12). A total of 36 (88%) patients had ventilatory abnormalities with dysfunctional breathing (n = 26), increased slope of minute ventilation to carbon dioxide production (VE/VCO2) (n = 17), and/or hypocapnia patient end tidal pressure of carbon dioxide (PetCO2) <35 (n = 25). On hemodynamic assessment, five of seven patients had preload failure and borderline oxygen extraction ratios. These five also had symptoms consistent with chronic fatigue syndrome. Overall, 32 patients met criteria for chronic fatigue syndrome.


Circulatory impairment, abnormal ventilatory pattern, and chronic fatigue syndrome may be common in patients with post-acute sequelae of PASC.


PASC is a public health concern given the large number of patients with COVID-19 and the impact of symptoms on quality of life and ability to work. The major symptoms in PASC include severe fatigue, cognitive difficulty, unrefreshing sleep, myalgias, and neuropathy. These symptoms are also seen in other viral infections and their severity correlate with the severity of the acute illness. Mechanisms underlying PASC are unclear. This study evaluated a small group of patients with suspected PASC using CPET and found unsurprising abnormalities such as excessive ventilator response, circulatory impairment, and a high prevalence of symptoms consistent with chronic fatigue syndrome. The study is small in sample size (<50 patients), mainly descriptive, with significant heterogeneity between patients, with a constellation of abnormalities that varied between patients. It highlights that cardiopulmonary abnormalities exist in this patient population, and allows for postulation on potential mechanisms for PASC symptoms. However, the study falls short of justifying CPET as a clinical tool to evaluate PASC.

Clinical Topics: Heart Failure and Cardiomyopathies, Noninvasive Imaging, Prevention, Acute Heart Failure, Computed Tomography, Nuclear Imaging

Keywords: Acute Disease, Catheters, Coronavirus, COVID-19, Dyspnea, Exercise Test, Fatigue Syndrome, Chronic, Heart Failure, Hypocapnia, Myalgia, Primary Prevention, Quality of Life, Respiratory Rate, SARS-CoV-2, Tomography, X-Ray Computed, Ventilators, Mechanical

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