Long COVID can have a significant impact on the heart rate variability (HRV) at rest and during deep breathing, according to a small study.

While the majority of individuals with COVID-19 recover completely, a significant percentage experience persistent symptoms, characterised as long-term COVID-19-- particularly causing cardiac problems and dysfunction of the autonomic nervous system (dysautonomia), which regulates involuntary functions like heartbeat, blood pressure, and sweating.

"Dysautonomia, characterised by dysregulation of HRV, may explain the persistent symptoms observed in Long COVID patients," said the researchers from the University of Santa Cruz do Sul, in a paper published in the journal Scientific Reports.

"There is currently a lack of evidence demonstrating how long these autonomic symptoms persist post-infection." For the study, the researchers included 21 patients with long COVID and 20 controls.

Long COVID patients showed reduced HRV at rest and during deep breathing, but the mean heart rate was significantly higher in the long COVID group than in controls.

The team observed these differences during a series of tests that measured heart rate during supine positioning and breathing exercises.

"Patients with Long COVID may present with dysautonomia characterised by an imbalance of HRV, and highlights that this dysautonomia could explain the persistent symptoms observed in patients with Long COVID," they said.

The researchers said their findings should guide treatments for long COVID fatigue and dysautonomia, CIDRAP reported.

"Our findings provide a rationale for improving fatigability with interventions aimed at improving cardiac and respiratory system autonomic control, through pharmacological and non-pharmacological measures aimed at reducing the cardiovascular risk in these patients," the team said.

"For example, cardiorespiratory rehabilitation can reduce muscle fatigue and improve cardiac autonomic function in other chronic conditions and has been the focus of numerous studies in patients with Long COVID."