Aims and objectives: This study was carried out to determine the prevalence of ventricular arrhythmias and heart rate variability pattern in patients on treatment for chronic heart failure.
Patients and methods: Twenty four hour ambulatory electrocardiograms were recorded in 60 patients with chronic heart failure and echocardiography left ventricular ejection fraction of less than 45%.Sixty age and sex- matched individuals with no obvious evidence of underlying cardiac disease were also evaluated for comparison.
Results: Premature ventricular complexes (PVCs) were evident in all subjects being infrequent [ < 30 PVCs per hour], in 21 (35%) and frequent [ > 30 PVCs per hour] in 39 (65%).Multiform extra systoles were recorded in 44 (73.3%) subjects, ventricular couplets in 50 (83.4%), and non-sustained ventricular tachycardia (NSVT) in 28 (46.7%) of the 60 subjects. Among the controls, PVCs were seen in 27(45%) and were all infrequent. None of the controls had multiform extra systole, ventricular couplets or NSVT. Significant inverse relationships were found between ejection fraction and PVC per h ( P-value < 0.001), ventricular couplet per 24h (P-value < 0.001) and NSVT per hour (P-value 0.002).Time domain heart rate variability measures i.eMean Standard Deviation of Normal to Normal RR Interval (SDNN), mean Percentage of Adjacent NN Intervals in a 24 hour recording which differ by at least 50ms (pNN550) , mean Root Mean Square Successive Difference in RR Interval (rMSSD) were significantly lower in the subjects compared to the controls. The corresponding P-values were < 0.001, < 0.001, < 0.001 respectively. A significant positive correlation was found between EF and SDNN ( P-value < 0.001), pNN50 (P-value 0.044) and rMSSD (P-value < 0.001).
Conclusion: This study showed that ambulant out patients with chronic heart failure, have significantly higher prevalence of ventricular arrhythmias and narrow heart rate variability compared to healthy individuals of comparable age and gender.