Use of Cardiopulmonary Stress Testing for Patients With Unexplained Dyspnea Post-Coronavirus Disease

OBJECTIVES The authors used cardiopulmonary exercise testing (CPET) to define unexplained dyspnea in patients with post-acute sequelae of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection (PASC). We assessed participants for criteria to diagnose myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). BACKGROUND Approximately 20% of patients who recover from coronavirus disease (COVID) remain symptomatic. This syndrome is named PASC. Its etiology is unclear. Dyspnea is a frequent symptom. METHODS The authors performed CPET and symptom assessment for ME/CFS in 41 patients with PASC 8.9 +/- 3.3 months after COVID. All patients had normal pulmonary function tests, chest X-ray, and chest computed tomography scans. Peak oxygen consumption (peak VO2), slope of minute ventilation to CO2 production (VE/VCO2 slope), and end tidal pressure of CO2 (PetCO(2)) were measured. Ventilatory patterns were reviewed with dysfunctional breathing defined as rapid erratic breathing. RESULTS Eighteen men and 23 women (average age: 45 +/- 13 years) were studied. Left ventricular ejection fraction was 59% +/- 9%. Peak VO2 averaged 20.3 +/- 7 mL/kg/min (77% +/- 21% predicted VO2). VE/VCO2 slope was 30 +/- 7. PetCO(2) at rest was 33.5 +/- 4.5 mm Hg. Twenty-four patients (58.5%) had a 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). For the whole cohort, 88% of patients (n = 36) had ventilatory abnormalities with dysfunctional breathing (n = 26), increased VE/VCO2 (n = 17), and/or hypocapnia PetCO(2) <35 (n = 25). Nineteen patients (46%) met criteria for ME/CFS. CONCLUSIONS Circulatory impairment, abnormal ventilatory pattern, and ME/CFS are common in patients with PASC. The dysfunctional breathing, resting hypocapnia, and ME/CFS may contribute to symptoms. CPET is a valuable tool to assess these patients. (C) 2021 by the American College of Cardiology Foundation.