No evidence of cardiac autonomic involvement in ankylosing spondylitis, asassessed by heart rate variability

The aim of this study was to investigate the involvement of autonomic nervo us system (ANS) function by using power spectral analysis of heart rate var iability (HRV) method in patients with ankylosing spondylitis (AS). The stu dy included 94 AS patients all fulfilling the New York criteria for AS, and 49 healthy volunteers. Recordings for HRV were obtained with a PC-based hi gh-resolution electrocardiographic system and analysed using power spectral analysis. The peak around 0.04-0. 15 Hz was defined as low-frequency peak (LF) and the other, around 0. 15-0.40 Hz, was defined as high-frequency pea k (HF), representing mostly the sympathetic and the parasympathetic compone nts of the ANS, respectively. The following variables were calculated and c ompared between groups: the LF in absolute and normalised units (LF nU), th e HF in absolute and normalised units (HF nU); and LF/HF ratio. The AS grou p included 47 male and 47 female subjects with a mean age of 33 +/- ii year s (range 16-64). In the control group there were 23 male and 26 female heal thy subjects (mean age 33 +/- X: range 19-60). None of the patients or cont rol subjects had any cardiac or neurological symptoms. Both groups were sim ilar with respect to age and sex characteristics (p >0.05). The HRV analysi s indicated that the peaks of LF, LF nU? HF, HF nU and LF:HF ratio were sim ilar in both groups. Groups also did not differ with respect to heart rate at the time of examination. Our data demonstrated no evidence of ANS involv ement as assessed by HRV analysis in AS patients.