Heart rate variability changes in mild-symptomatic, physically fit male in 4-6 weeks from the end of SARS-Cov-2 infection

SARS-Cov-2 infection, due to inflammation processes, can affect autonomic nervous system and heart rate variability (HRV) even after disease. Previous studies showed significant changes in HRV parameters in severe (including fatal) infection of SARS-Cov-2. However, HRV analysis for the asymptomatic or mild-symptomatic Covid-19 patients have not been reported. In this study, we suggested that there is an influence of a SARS-Cov-2 infection on the HRV in such patients after weeks form disease.Sixty-five ECG Holter recordings from young (mean age 22.6 ± 3.4 years), physically fit male subjects after 4-6 weeks from the second negative test (considered to be the beginning of recovery) and twenty-six control male subjects (mean age 23.2 ± 2.9 years) were considered in the study. Night-time RR time series were extracted from ECG signals. Selected linear, frequency as well as nonlinear HRV parameters were calculated. We found significant differences in Porta’s symbolic analysis parameters V0 and V2 (p<0.001), α 2 (p<0.001), very low frequency component (VLF; p=0.022), and respiratory peak (from PRSA method; p=0.012). These differences may be caused by the changes of the parasympathetic autonomic nervous system as well as by the coupling of respiratory rhythm with heart rate due to an increase in pulmonary arterial vascular resistance.The results suggest that the changes in the HRV, thus autonomic nervous system, are measurable after a few weeks from the beginning of the recovery even in the post-Covid group of young and physically active population. We indicated HRV sensitive markers which could be used in the long-term monitoring of recovered patients.