ABSTRACT
Introduction Post-covid-19 syndrome, or Long covid (LC) refers to symptoms persisting 12 weeks after Covid-19 infection. LC comprises a wide range of dysautonomia symptoms, including fatigue, breathlessness, palpitations, dizziness, pain and brain fog. This study tested the feasibility and estimated the efficacy, of a Heart Rate Variability Biofeedback (HRV-B) technique via a standardised slow diaphragmatic breathing programme in individuals with LC. Methods and Analysis LC patients underwent a 4-week HRV-B intervention for 10 minutes twice daily for a total of 4 weeks using the Polar H10 ECG (Electrocardiogram) chest strap and Elite HRV phone application. Outcome measures C19-YRSm (Yorkshire Rehabilitation Scale modified), EQ5D- 5L (EuroQol 5 Dimensions), Composite Autonomic Symptom Score (COMPASS-31), WHO Disability Assessment Schedule (WHODAS), and Root Mean Square of Successive Differences between heartbeats (RMSSD) using a Fitbit device were completed before and after the intervention. The study was pre-registered at clinicaltrials.gov NCT05228665. Results 13 participants (54% female, 46% male) completed the study with high levels of data completeness and adherence. There was a statistically significant improvement in C19YRS-m (p=0.001), EQ5D Global Health Score (p=0.009), COMPASS-31 (p=0.007), RMSSD (p=0.047) and EHODAS (p=0.02). Qualitative feedback suggested participants were able to use it independently, were satisfied with the intervention, and reported beneficial effects from the intervention. Conclusion This is the first study in the literature to report that HRV-B is a feasible intervention for LC and seems to be potentially improving symptoms of LC and dysautonomia.