HEART-RATE-VARIABILITY IN PATIENTS WITH FAMILIAL AMYLOID POLYNEUROPATHY

The purpose of this study was to evaluate heart rate variability (HRV) in patients with familial amyloid polyneuropathy (FAP) using the time -and frequency-domain analysis. The study population consisted of 19 p atients with FAP, and 19 age and sex matched normal volunteers. The 24 -hour Holter recordings of all subjects in sinus rhythm and off medica tion were analyzed. Five time-domain indices of HRV were computed. The frequency component of HRV was calculated by fast Fourier transform a nalysis of the RR intervals. The power spectrum of the low frequency ( LF) between 0.04-0.15 Hz and high frequency (HF) between 0.15-0.40 Hz and the LF/HF ratio was calculated. Global measures of HRV including t he standard deviation of the mean of RR intervals (SDNN) and the stand ard deviation of 5-minute mean RR intervals (SDANN) were decreased in patients with FAP. Specific vagal influences on HRV including the prop ortion of RR intervals more than 50 milliseconds different (pNN50) and the HF power on spectral analysis were less in patients with FAP. LF power and LF/HF ratio were more decreased in patients with FAP at the advanced stage than at the early stage. In conclusion, HRV was signifi cantly decreased in patients with FAP at the early stage, and sympathe tic activity was more decreased in patients at the advanced stage. The se findings suggest that the decrease of the HRV is an indicator of th is disease and the power spectral analysis of the HRV is beneficial in assessing the severity of the autonomic dysfunction.