Karacan M et al. – These 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.

• Authors 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.