Heart Rate Variability in Patients With Multiple Sclerosis

Abstract

Objective: The aims of the present study were to compare heart rate variability (HRV) parameters of patients with multiple sclerosis (MS) and healthy controls and to investigate the correlations between HRV parameters and disease duration, subtype and severity. Methods: Thirty-two patients with MS [18 with relapsing-remitting MS (RRMS), 4 with primary progressive MS (PPMS) and 10 with secondary progressive MS (SPMS)] and 32 healthy, age-and sex-matched volunteers were included. HRV was evaluated by frequency-domain spectral analysis method; total power (TP), low frequency (LF) power, high frequency (HF) power, very low frequency (VLF) power in absolute values and in normalized units (n.u.) and the ratio of LF to HF was used. Results: The patients had lower TP, VLF, LF, HF and HF n.u. and higher LF n.u. and the ratio of LF to HF reflecting overall decreased HRV accompanied by sympathetic overactivity and parasympathetic hypoactivity. There was no association between EDSS score and HRV parameters; however, we found a positive correlation between disease duration and LF n.u. We did not find significant differences between the patients with RRMS and the patients with SPMS regarding cardiac autonomic activity. Although TP, LF power, HF power and VLF power of the patients with PPMS were lower than of the patients with RRMS and the patients with SPMS, no statistical analysis could be made for this group due to inadequate number of the patients in this group. Interpretation: Patients with MS have higher sympathetic and lower parasympathetic regulation activity of heart rate. Disease duration, rather than severity seems to be associated with increased sympathetic activity.