To identify pulmonary vascular disease in post/long-COVID-19 patients as a cause of dyspnea/exercise limitation and to differentiate it from other causes of dyspnea

The aim is to identify pulmonary vascular disease in post/long-COVID-19 patients as a cause of dyspnea/exercise limitation and to differentiate it from other causes of dyspnea (muscular, left cardiac, psychological, deconditioning-related causes) by investigating ventilation-perfusion (V/Q) mismatch and (exercise-induced) pulmonary hypertension (PH) or right heart dysfunction.

Inclusion Criteria:

• Age ≥ 18 years, patients with a suspected diagnosis of post/long-COVID-19 syndrome who present to our pneumology or infectious disease outpatient clinic or corresponding ward from the start of the study and whose SARS-CoV-2 infection was diagnosed at least 3 and not longer than 18 months prior to presentation
• Patients at least 3 and not longer than 18 months after a SARS-CoV-2 infection without post/long-COVID-19 syndrome who present to our post-infection outpatient clinic for follow-up

Exclusion Criteria:

• Patients who refuse to participate in the study
• Severe underlying chronic pulmonary, cardiac, or systemic disease (e.g., Chronic obstructive pulmonary disease (COPD), severe heart failure, neuromuscular disease) that was diagnosed prior to acute COVID-19 disease and whose progression appears likely as the cause of dyspnea
• Other non pneumologic causes of dyspnea (e.g., hemoglobin < 100 g/L)
• Unstable or acute disease (e.g., acute infection, acute renal failure, acute coronary syndrome)
• Inability to perform spiroergometry, including transient orthopedic problems, contraindications to central venous and arterial catheter placement (e.g., severe bleeding tendency).

Patients with a post-COVID-19 syndrome or a long-COVID-19 syndrome at least 3 months after SARS-CoV-2 infection (symptomatic or asymptomatic); Patients at least 3 months after a SARS-CoV-2 infection (symptomatic or asymptomatic) without post/long-COVID-19.