Heart rate variability modulation through slow paced breathing in Healthcare workers with Long-COVID: a case-control study

Background: Long-COVID is a syndrome persisting 12+ weeks after COVID-19 infection, impacting life and work ability. Autonomic nervous system imbalance has been hypothesised as the cause. This study aims to investigate cardiovascular autonomic function in health care workers (HCWs) with Long-COVID and the effectiveness of slow paced breathing SPB on autonomic modulation. Methods: From 1st December 2022 to 31th March 2023, 6655 HCWs of the University Hospitals of Trieste (Northeast Italy) were asked to participate the study by company-email. Inclusion/exclusion criteria were assessed. Global health status and psychosomatic disorders were evaluated through validated questionnaires. Heart rate variability was assessed by finger-photoplethysmography during spontaneous breathing (SB) and SPB, which stimulate vagal response. Long-COVID-HCWs (G1) were contrasted with never infected (G2) and fully recovered COVID-19 workers (G3). Results: 126 HCWs were evaluated. The. 58 Long-COVID were assessed at a median time since COVID-19 of 419.5 days (IQR 269-730) and had significantly more psychosomatic symptoms and lower detectability of spontaneous systolic pressure oscillation at 0.1 Hz (Mayer wave - baroreflex arc) during SB compared to 53 never-infected and 14 fully-recovered HCWs (19%, 42% and 40%, respectively, p=0.027). During SPB, the increase in this parameter was close to controls (91.2%, 100% and 100%, respectively, p=0.09). No other differences in HRV parameters were found among groups. Conclusions: Resting vascular modulation was reduced in Long-COVID, while during SPB baroreflex sensitivity effectively improved. Long-term studies are needed to evaluate whether multiple sessions of breathing exercises can restore basal vascular reactivity and reduce cardiovascular risk in these patients.