RÉSUMÉ
BACKGROUND: Vitamin D (VitD) has important prohormone functions in a wide range of clinical processes. Although it is known that individuals with VitD deficiency have cardiac autonomic dysfunction, there are no convincing data regarding the effect of VitD replacement. We aimed to evaluate the impact of VitD replacement on cardiac autonomic dysfunction. METHODS: Fifty-two apparently healthy subjects with VitD deficiency and 50 healthy control subjects were enrolled. Prior to VitD replacement, 24-hr Holter recordings were obtained, and HRV parameters were recorded. VitD levels were measured 2 months later after replacement, and control 24-hr Holter recordings were analyzed. RESULTS: The mean age of the patients was 36.04 ± 7.6 years, and 53.9% were female. SDNN (68.58 ± 13.53 vs. 121.02 ± 27.45 ms, p = .001), SDANN (95.96 ± 22.26 vs. 166.48 ± 32.97 ms, p = .001), RMSSD (23 vs. 59 ms, p < .001), and PNN50 (6.5% vs. 36%, p < .001) were significantly lower in patients with VitD deficiency compared with the control group. HRV parameters were improved after VitD replacement [SDNN (68.58 ± 13.53 to 119.87 ± 28.28 ms, p < .001), SDANN (95.96 ± 22.26 to 164.44 ± 33.90 ms, p < .001), RMSSD (23 to 58 ms, p < .001), and PNN50 (6.5 to 33%, p < .001)]. CONCLUSION: The present study suggested that VitD deficiency was significantly correlated with impaired cardiac autonomic functions assessed by parameters of HRV, and cardiac autonomic dysfunction improved after VitD replacement in otherwise apparently healthy individuals.