According to a small case-control study today in Scientific Reports, long COVID can affect heart rate variability (HRV) at rest and during deep breathing, adding to the evidence that persistent symptoms of the virus can be associated with cardiac and dysfunction of the autonomic nervous system (dysautonomia). This system regulates involuntary functions like heartbeat, blood pressure, and sweating.

The study, conducted by Brazilian researchers, included 21 patients with long COVID and 20 controls. Long COVID—defined by the authors as new or persistent symptoms experienced 12 or more weeks after infection—has been associated with heart palpitations, orthostatic intolerance (difficulty staying upright), dizziness, and syncope.