Dolphin
Senior Member (Voting Rights)
18 December 2025
Long COVID Patients with Orthostatic Intolerance Have Reduced Heart Rate Variability and Preserved Physiological Response to Active Standing
J. Antonio González-Hermosillo González1,Claudia Lerma2,
Dulce Andrea Celestino Montelongo1,
María del Carmen Alba Lorenzo1,
Emiliano Salas Santos1,
Atziri Gun Cuninghame Ballesteros1,
Esteban Jorge-Galarza3 and
María del Rocío Martínez-Alvarado1,*
1
Department of Cardiovascular Dysautonomia, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City 14080, Mexico
2
Laboratory of Cardiovascular Dynamics, Department of Molecular Biology, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City 14080, Mexico
3
Department of Outpatients Care, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City 14080, Mexico
*
Author to whom correspondence should be addressed.
Biology2026, 15(1), 1;https://doi.org/10.3390/biology15010001
Simple Summary
A substantial number of patients recovering from COVID-19 develop symptoms three months after infection, lasting at least two months and not explained by other diagnoses, a condition known as long COVID.They include symptoms of autonomic nervous system dysfunction: orthostatic intolerance (dizziness, fainting), fatigue, brain fog, headache, sleep problems, and palpitations.
The present study assessed the autonomic nervous system modulation of the heart by performing an analysis of heart rate variability at rest and during standing in patients with long COVID and orthostatic intolerance compared to asymptomatic healthy people.
The time from SARS-CoV-2 infection to testing in the COVID-19 group was 573 ± 289 days.
Long COVID patients had lower heart variability at rest compared to healthy participants.
In response to standing, both groups had similar physiological changes in heart rate variability.
This indicates that patients with long COVID and orthostatic intolerance, despite having reduced heart rate variability at rest, do not show immediate autonomic dysregulation upon standing.
These results warrant further studies to prove if the cardiac autonomic modulation may recover after the long elapsing time post-infection.
Abstract
The aim of this study was to assess the heart rate variability (HRV) at rest and during active orthostatic challenge in long COVID patients with orthostatic intolerance symptoms (dizziness, pre-syncope, and syncope).We performed a cross-sectional, observational, comparative study of 60 subjects of both sexes, aged 18 to 60 years (31 met the criteria of long COVID, 15 were infected individuals without symptoms, and 14 who had neither infection nor symptoms formed the age-matched control group).
HRV was obtained from continuous electrocardiograms in a supine position and active standing with spontaneous breathing.
The time from SARS-CoV-2 infection to testing in the COVID-19 group was 573 ± 289 days.
The resting (supine position) values of SDNN, RMSSD, SD1, and SD2 were lower in long COVID patients than in control participants, while all other HRV indexes were similar between groups.
In response to active standing, both groups had similar changes in all HRV indices.
In conclusion, an active orthostatic test was not able to exhibit an autonomic dysregulation in these patients with long COVID, suggesting that cardiac autonomic modulation may have recovered due to the long time that elapsed after SARS-CoV-2 infection.
Keywords:
long COVID; heart rate variability; autonomic nervous system