Could decreased vitamin D levels be related with impaired cardiac autonomic functions in patients with chronic heart failure: an observational study

Objective: Vitamin D status has been implicated in the pathophysiology of heart failure (HF). The aim of this study was to investigate the association between vitamin D levels with heart rate variability and heart rate turbulence in patients with heart failure whom had ischemic and non-ischemic dilated cardiomyopathy. Methods: Study designed as an observational cross-sectional study. Seventy-one patients [36 non-ischemic dilated cardiomyopathy (NIDCM), 35 ischemic dilated cardiomyopathy (IDCM)] with chronic heart failure and 25 control subject were included It was evaluated the association between 25 hydroxyvitamin D [25(OH)D] and calcitriol levels with heart rate variability time domain (SDNN, SDANN, RMSSD) and heart rate turbulence [turbulence onset (TO), turbulence slope (TS)] parameters. Statistical analysis was performed using Kruskal-Wallis test and ANOVA. Results: Calcitriol levels in NIDCM patients with abnormal TO and TS were significantly lower than NIDCM patients with normal TO (17.1±11.3 vs 27.6±15.5 pg/mL, p=0.05) and TS (16.6±9.1 vs 29.4±16.9 pg/mL, p=.018). There was a positive correlation between 25 (OH) D with heart rate variability parameters SDNN (r=0.368, p=0.027) and SDANN (r=0.360, p=0.031). It was not found any association between vitamin D and parameters of heart rate variability and heart rate turbulence in IDCM patients. Conclusion: Insufficiency of vitamin D may have deleterious effects on cardiac autonomic functions which were showed with heart rate turbulence and heart rate variability in patients with NIDCM. Vitamin D levels might be a predictor to determine the sudden cardiac death in patients with non-ischemic etiology.