Symptom cluster
Cardiopulmonary symptoms
Breathlessness, chest tightness, and exercise limits, often when standard heart and lung tests read normal. This page covers: Dyspnea / breathlessness, Chest pain / palpitations, Incident cardiovascular events (1-year elevated risk), Exercise intolerance / reduced VO2.
What this is
Cardiopulmonary simply means heart-and-lung. Many people with long COVID feel breathless, tight-chested, or unable to exert themselves the way they used to — yet standard heart and lung tests come back normal.
That mismatch is the point. The problem often is not in the heart muscle or the large airways, but in how oxygen is delivered and used: blood flow, the smallest blood vessels, breathing pattern, and the body’s response to effort. Specialized tests, like an invasive cardiopulmonary exercise test, can reveal limits that resting scans miss.
Breathlessness here is real and has measurable causes, even when the obvious tests are reassuring.
How to read this page
Each row under What causes it and What has been tried represents one proposed explanation or treatment. The tags help you judge the claim quickly, without treating every row as equally proven.
gradeHow strong the underlying evidence is.
Example: a treatment tested in multiple randomized controlled trials would receive a stronger grade than one supported only by case reports, expert opinion, or animal studies.
auditHow reliable the claim remains after tracing its sources.
Example: a claim may appear in many reviews, but if those reviews all cite the same small, uncontrolled study, the audit may be weak because the claim is being repeated more than it is being independently confirmed.
A claim can have a strong grade but a weak audit, or the reverse. That is why both are shown.
endpointWhat was actually measured.
Example: a study showing that patients “felt better” measured a patient-reported outcome. A study showing improved oxygen levels, reduced inflammation markers, better walking distance, or abnormal MRI findings measured something different. The endpoint tells you what kind of evidence the claim rests on.
safety / conflictImportant cautions about harm, bias, or financial interests.
Example: a supplement may look low-risk but still interact with medications. A device or drug study may look promising, but if the evidence comes mainly from the manufacturer, that conflict should be visible before the claim is weighed.
What causes it
The leading explanations, each with its evidence grade and audit status.
caused byDyspnea / breathlessness
Dysautonomia / autonomic dysfunction produces Dyspnea / breathlessness. full page →
fibrinaloid microclots">fibrinaloid microclots">Fibrinaloid microclots / coagulopathy produces Dyspnea / breathlessness. full page →
caused byIncident cardiovascular events (1-year elevated risk)
Endothelial dysfunction produces Incident cardiovascular events (1-year elevated risk). full page →
caused byExercise intolerance / reduced VO2
Mitochondrial / metabolic dysfunction produces Exercise intolerance / reduced VO2.
Deconditioning (as cause) contested-cause Exercise intolerance / reduced VO2.
Dysautonomia / autonomic dysfunction produces Exercise intolerance / reduced VO2.
What has been tried
No treatment is approved. Each row shows how strong the evidence is, what it was measured on, and any safety or conflict flag.
tried forDyspnea / breathlessness
Breathing retraining / physiotherapy (breathing pattern disorder) relieves Dyspnea / breathlessness.
tried forChest pain / palpitations
Treat the substrate (POTS, dysautonomia) + cardiac surveillance manages Chest pain / palpitations. full page →
tried forExercise intolerance / reduced VO2
Pyridostigmine improves Exercise intolerance / reduced VO2.
Recumbent / supine-biased rehabilitation (PEM-bounded) manages Exercise intolerance / reduced VO2.
How it is measured
tests forExercise intolerance / reduced VO2
Invasive CPET (iCPET) diagnoses Exercise intolerance / reduced VO2.
Cardiovascular event risk carries paired relative and absolute framing, and a VA-cohort generalizability note, so the numbers are not read out of context.