Heart rate variability in children with acute rheumatic fever

Acute rheumatic fever is a systemic inflammatory disease occurring after acute streptococcal tonsillopharyngitis. The PR prolongation in these patients is thought to be due to increased vagal activity. There has been no previous study investigating the autonomic balance in patients with acute rheumatic fever. In this study, we aimed to investigate the balance of the autonomic nervous system in children with acute rheumatic fever by analysis of heart rate variability. We evaluated the heart rate variability parameters in 50 patients with acute rheumatic fever and 37 comparable control subjects. Both groups underwent 24-hour electrocardiography monitoring, and time- and frequency-domain heart rate variability parameters were calculated. A total of 39 patients (78%), with (n = 28) or without (n = 11) other major findings, had carditis, and the remaining 11 (22%) did not. The PR interval was found to be prolonged in 10 (20%) of the patients at the beginning. In the study group, the time- and frequency-domain heart rate variability parameters showed a sympathetic dominance compared with the control group, with a p-value less than 0.05. When compared with the control group, the time- and frequency-domain heart rate variability parameters showed a significant sympathetic dominance in patients with both prolonged PR and normal PR intervals in the acute period, with a p-value less than 0.05. When compared with patients with normal PR interval, mean normalised low frequency and normalised high frequency parameters suggested a relatively lower sympathetic dominance in patients with prolonged PR interval, with a p-value less than 0.05. Our results indicated that in the acute period of rheumatic fever, sympathetic dominance is apparent; in patients with prolonged PR interval, sympathetic dominance is relatively lower when compared with the patients with normal PR interval.