To investigate the effect of early application of β-blocker on cardiac and autonomic nervous functions of the acute myocardial infarction (AMI) patients with interventional treatment.

According to the β-blocker (metoprolol) usage, 122 AMI patients with interventional treatment were divided into the control group (62 cases) and β-blocker treatment group (60 cases).

Compared with the control group, the adverse event and case fatality rates in the β-blocker treatment group were both lower, but had no significant differences (33.3% vs. 37.1%, 6.7% vs. 8.1%; χ² = 0.189, 0.087, all P > 0.05). After a 28-d treatment, the left ventricular ejection fraction (LVEF) and standard diviation of NN intervals (SDNN) in the β-blocker treatment group were much higher than that in the control group, while the low frequency (LF)/high frequency (HF) was much lower than control group [(53 ± 7)% vs. (49 ± 7)%, (186 ± 49) ms vs. (156 ± 53) ms, (1.2 ± 0.5) vs. (2.1 ± 1.0); t = 3.440, 3.103, 5.769, all P < 0.05].

For the AMI patients with interventional treatment, early application of β-blocker (metoprolol) and adjustment of its usage based on the concentration of plasma B-type natriuretic peptide (BNP) and state of the illness changes could effectively promote the cardiac function recovery of AMI patients, also prompt the sympathetic nervous activity/vagus nerve activity ratio returns to the normal level, thus it may help to improve the prognosis of AMI patients.