Persistent autonomic dysfunction following mild COVID-19: evidence from the orthostatic heart rate variability response

Introduction: Autonomic alterations following COVID-19 have been reported in individuals with mild disease. Objective: To investigate long-term effects of non-hospitalized COVID-19 on cardiovascular autonomic regulation, focusing on heart rate variability (HRV), blood pressure variability (BPV), and baroreflex sensitivity (BRS). Methodology: Eighty-five sedentary men aged 35–55 were allocated to CONTROL group (n = 43), assessed before the COVID-19 pandemic, and COVID-19 group (n = 42), evaluated at least six months after SARS-CoV-2 infection. Continuous recordings of heart rate and blood pressure were obtained in the supine position and during active standing. HRV, BPV, and BRS were analyzed using linear, nonlinear methods. Results: Anthropometric and baseline hemodynamic variables did not differ between groups. In the supine position, HRV indices were comparable, except for approximate entropy in the COVID-19 group (1.46 ± 0.14 vs. 1.35 ± 0.13; p = 0.020). During orthostasis, the COVID-19 group showed reduced low-frequency (LF) oscillations of HRV (70 ± 17 vs. 81 ± 10%; p < 0.001), a lower LF/high-frequency ratio (4.12 ± 3.70 vs. 6.7 ± 4.4; p < 0.001), and decreased SD2 (standard deviation of long-term variability) from the Poincaré plot (45 ± 14 vs. 51 ± 19 ms; p = 0.048). BPV, BRS responses to postural stress were similar between groups. Discussion: These findings indicate that individuals recovered from mild COVID-19 present subtle, persistent alterations in heart rate dynamics during postural challenge, suggesting incomplete autonomic adjustment to physiological stress. Conclusion: Mild COVID-19 may be associated with persistent autonomic alterations during physiological stress.