| Abstract: | Background: Abnormal autonomic nervous function (ANF), such as an enhanced sympathetic tone and an attenuated parasympathetic tone, have been shown in patients with congestive heart failure (CHF). Methods: We examined the effects of captopril and metoprolol on autonomic nervous function and ventricular arrhythmias in patients with idiopathic dilated cardiomyopathy (DCM), using 24-hour ambulatory electrocardiographic monitoring and power spectral analysis of heart rate variability. Twenty-one patients (pts) with idiopathic DCM (54 ± 15 years [mean ± SDI) were allocated to three groups: a captopril group (8 pts); a metoprolol group (7 pts); and a control group (6 pts). Power spectra were quantified in high (HF) and low frequency power (LF), and natural logarithmic values of HF (In(HF) and LF/HF (In (LF(HF]) were used as indices of parasympathetic and sympathetic nervous activities, respectively. Results: In the captopril and the metoprolol groups, there was a significant increase in In(HF) (P < 0.05), a trend of decrease in ln(LF/HF), and an improvement of ventricular arrhythmia (VA). In contrast, no significant change was found in any of In(HF), In (LF/HF), and VA in the control group. Conclusion: We conclude that both captopril and metoprolol have beneficial effects on ANF and VA, and the restored autonomic balance and the improvement of VA correlate to each other. |
