Cardiac Autonomic Dysfunction Measured as Reduced Heart Rate Variability, in the Intermediate Post-Covid State in Men

Background: A critical illness such as severe coronavirus disease 2019 (COVID-19) activates autonomic, endocrine, and emotional stress responses. Whether the manifestations of excessive stress experience persist beyond full recovery into the intermediate post-COVID period (3–6 months after recovery) is not known and was the question we addressed in the current study. Methods: An analytical observational cross-sectional study compared the heart rate variability (HRV), 8 AM serum cortisol concentration, and the Depression, Anxiety, and Stress Scale–21 (DASS-21) scores between COVID-19 recovered participants and their age-matched control subjects (21 male participants, 30–70 years of age, in each group). Results: The median (Q1–Q3) of low frequency (LF), high frequency (HF), and total powers of HRV was significantly reduced in those who recovered from severe COVID-19, compared to control subjects (respectively LF power: 410.871 [245.10–861.94], 947.57 [536.11–1778.55], P = 0.011; HF power: 192.916 [87.66–564.43], 705.18 [248.67–1192.19] P = 0.013; Total power: 646.33 [308.72–1518.28], 1613.33 [956.14–4022.55] P = 0.015, Mann–Whitney U -test). Serum cortisol and DASS-21 scores were not different from the control group. Conclusions: Impaired cardiac autonomic function, evidenced by reduced HRV, was observed in the intermediate period following recovery from severe COVID-19. However, psychological stress and elevated serum cortisol were not noted. Our result that exposes the effect of COVID-19 on cardiac autonomic responsiveness is important as diminished HRV increases the vulnerability of COVID-19 survivors to diseases. These findings may also suggest a focus of therapy in them, as specific interventions are known to improve HRV and cardiac autonomic functioning.