Heart rate and heart rate variability in patients with frequent ventricular arrhythmias

The authors studied associations between heart rate and heart rate variability in 31 patients with frequent ventricular arrhythmias. For each patient, a 24-h Holter tape was analyzed. Tapes were divided into 5-min episodes. Per episode, they computed heart rate (HR), the fraction low-frequency power (LF), and the coefficient of variance (CV). For each patient, scatterplots were made of LF=f(HR), CV=f(HR), and CV=f(LF). Also, linear least square fits of LF on HR, of CV on HR, and of CV on LF were done. The parameters HR, LF, and CV contribute in a different manner to the generation of arrhythmias. The cardiac rhythm, and hence HR, CV, and LF, are all governed by the automatic nervous system. A certain interdependence is therefore likely. However, at visual inspection of scatterplots of HR, CV, and LF, no obvious relations could be detected. The correlation coefficients were low. The study demonstrates that, in a group of patients with frequency ventricular arrhythmias of mixed etiology, where necessary treated with antiarrhythmic or other drugs, HR, LF, and CV are so weakly associated that all three can potentially contribute to the spontaneous variability of ventricular arrhythmias