Short-Term Changes in Heart Rate Variability Following Kidney Transplantation: A Comparative Analysis with Healthy Donors

Background: Heart rate variability (HRV) is a non-invasive marker of autonomic nervous system function and an established predictor of cardiovascular outcomes in end-stage renal disease (ESRD). While kidney transplantation may restore physiological homeostasis, the short-term impact on HRV remains unclear. Methods: In this observational study, HRV was measured in 32 kidney transplant recipients and 29 healthy living donors. HRV recordings were obtained one day before and between the 5th and 7th days after transplantation using a Polar H10 monitor and Kubios HRV software. Parameters analyzed included time-domain, frequency-domain, nonlinear, and entropy-based indices. Between-group and within-group comparisons were performed using appropriate parametric or non-parametric tests. Results: Preoperatively, transplant recipients demonstrated significantly lower HRV compared to controls across multiple domains: SDNN (29.3 ± 11.8 vs. 47.6 ± 15.1 ms, p