Heart rate variability and cardiac arrhythmias in patients with chronic renal failure.

Heart rate variability was measured from 24-h electrocardiograms in 61 patients with end stage chronic renal failure. The method used counts the number of times successive RR intervals differ by more than 50 ms over the 24-h period, and is a reliable indicator of cardiac parasympathetic activity. Also analysed were the frequency and type of ectopic beats and other arrhythmias. Twenty-one subjects (34%) had varying numbers of ventricular ectopic beats, and twelve (20%) had frequent supraventricular ectopics. Total 24-h count values were abnormal in 30 (76%) of the 41 subjects whose tapes were technically suitable for this analysis. There were no sex differences, but those patients maintained on haemodialysis had significantly lower counts than those on continuous ambulatory peritoneal dialysis. We conclude that about three-quarters of patients with chronic renal failure have abnormal cardiac parasympathetic activity. This may increase susceptibility to cardiac arrhythmias and sudden death and contribute to the high mortality of patients with chronic renal failure.