Background: Heart rate variability (HRV) is an effective way to estimate heart rate (HR) autonomic regulation. In some cardiovascular diseases increased sympathetic activity (low frequency spectral power of HRV) was shown to be an unfavorable risk factor which could be downregulated by beta-blockers. There are only few data on If-blocker ivabradine impact on HRV parameters and direct comparison between betablockers and ivabradine in relation to HRV was not conducted. The purpose of the study was to compare the impact of If-blocker ivabradine and metoprolol tartrate on autonomic control of nervous system HR control in patients with stable angina pectoris.
Methods: Effects of ivabradine 7.5 mg and 50 mg metoprolol tartrate HRV were estimated in 33 patients with angina pectoris in the open-labeled randomized, controlled, crossover design and acute pharmacological test study. HRV was determined for 10 minutes in supine position before and after 4h the each test drug according to randomization.
Results: Equal negative chronotropic impact for ivabradine and metoprolol was shown, the effect increased with HR upraise and was positively correlated with baseline HR. Both ivabradine and metoprolol produced downregulating effect of sympathetic tone, but the effect of ivabradine was more significant. However, metoprolol decreased the total power parameter and the value of adaptation.
Conclusions: In patients with angina pectoris If-blocker ivabradine downregulation of sympathetic status in comparison with beta-blocker metoprolol tartrate effect was firstly shown.
Keywords: Heart rate variability, ivabradine, metoprolol, CHD