Spontaneous Heart Rate Variability and Arrhythmias in Congestive Heart Failure

Abstract

Recent studies indicated that congestive heart failure is characterized by decreased parasympathetic and increased sympathetic nervous system activity, and that heart rate variability represents a non-invasive parameter for studying this autonomic imbalance to the heart. Also, various studies were designed to detect the frequency of different types of cardiac arrhythmias in congestive heart failure and their prognostic value. The present study was designed to investigate the 24-hour heart rate variability and the pattern of cardiac arrhythmias in 20 patients with congestive heart failure due to ischaemic cardiomyopathy and 20 healthy control subjects. Heart rate variability was assessed by measuring the overall 24-hours mean maximum and minimum heart rates, the mean heart rate during awakening and sleep, and the mean hourly maximum and minimum heart rate. Analysis also included the mean 24 hours number of episodes of different cardiac arrhythmias. The ischaemic cardiomyopathy patients had a lower mean maximum overall

24-hours heart rate than that of healthy control subjects (p<O.OOl). At the same time, they showed a higher mean minimum heart rate than that of healthy control subjects (p<O.Ol). On the other hand, ischaemic cardiomyopathy patients had a slightly higher (but not statistically significant) mean awakening heart rate than healthy control subjects and had a significantly higher (p < 0.001) mean sleep heart