Effects of metoprolol and captopril on heart rate variability in patients with acute coronary syndrome

Objective To observe the effects of metoprolol and captopril on heart rate variability (HRV) in patients with acute coronary syndrome (ACS). Methods The patients with ACS were randomly divided into 3 groups: metoprolol group (n=19), captopril group (n=15) and control group (n=18). Twenty-four hour heart rate variability was examined before medication and 30 days after medication. Results ①There were no significant differences before treatments in HRV time-domain indexes between 3 groups (P0.05). ②In metoprolol group and captopril group, the HRV time-domain indexes were improved significantly after treatment with metoprolol or captopril (P0.05). ③There were significant differences of the standard deviation of all normal-to-normal RR intervals (SDNN) in 3 groups after therapy (P0.01), and SDNN metoprolol group(132.5±21.2ms)SDNN captopril group (112.9±22.4ms)SDNN control group (86.9±22.6ms). Conclusion Metoprolol and captopril can significantly improve the HRV of patients with uncomplicated acute coronary syndrome, and improve imbalance of the autonomic nervous system of patients. The effect of metoprolol is superior to captopril.