Autonomic Imbalance and Elevated Inflammatory Cytokines in Long COVID: A Cross-Sectional Study

Abstract

Introduction: Following an infection with SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), many individuals fully recover. On the other hand, a few have symptoms that last for weeks, months, or even years after their initial diagnosis. Symptoms of COVID-19 persisting for four weeks and more are termed long COVID.

Aim: To assess the long-term cardiovascular morbidity by battery of cardiac autonomic function tests as well as the persistence of inflammation in COVID-recovered patients three months after initial infection. Methodology: 150 patients were selected who had recovered from COVID-19 at least three months prior to the study. After obtaining informed written consent, a throat swab was tested for COVID-19, and those with negative reverse transcription polymerase chain reaction (RT-PCR) results were subjected to autonomic function testing. Serum interleukin-6 and C-reactive protein levels were determined by enzyme-linked immunosorbent assay (ELISA) test.

Results: Out of 150 subjects 36 were found to have autonomic dysfunction graded according to Ewing's criteria. Individuals with autonomic dysfunction also had significantly increased inflammatory biomarker levels. There was also significant correlation between inflammatory markers and autonomic function test and heart rate variability parameters.

Conclusion: Even years after the COVID-19 pandemic was declared, new symptom patterns and syndromes such as 'long COVID' are appearing. A better understanding of the pathophysiological mechanisms of post-COVID manifestations that affect the autonomic nervous system, as well as customized therapeutic care, should help reduce COVID-19 sequelae, particularly if we act early in the disease.

Keywords: autonomic imbalance; chronic covid; interleukin – 6; long covid; long haul covid; post covid syndrome.