Heart rate variability in familial Mediterranean fever

Familial Mediterranean fever (FMF) is a hereditary disease, characterized by recurrent episodes of fever and polyserositis. Heart rate variability (HRV) is a powerful, simple and reliable technique to evaluate autonomic nervous system function. Previous studies of physiologic parameters during tilt-test have suggested that patients with FMF have abnormal cardiovascular reactivity and occult dysautonomia. Prompted by these findings, the present study sought to evaluate HRV in patients with FMF, at rest and in the standing position. The study sample included 34 patients with FMF and 34 sex- and age-matched control subjects. All underwent electrocardiography according to strict criteria. HRV parameters were computed with custom-made software. There was no significant difference in HRV parameters, in either the supine or standing position, between the FMF and control groups. In both groups, the upright position was associated with a significant decrease, when compared with the supine position, in maximal RR interval, minimal RR, average RR, root square of successive differences in RR interval, number of intervals differing by >50 ms from preceding interval (NN50), NN50 divided by total number of intervals (pNN50) and high-frequency components as well as a significant increase in average heart rate, very low frequency or low-frequency components, low-frequency/high-frequency components ratio and total power. In conclusion, patients with FMF who are continuously treated with low-dose colchicine have not developed amyloidosis and have normal HRV parameters in the supine and upright position. Further investigation of occult dysautonomia in FMF is needed.