OBJECTIVE: To investigate the effects of bisoprolol on the QRS-T angle in ACS patients after emergency PCI. METHODS: 100 ACS patients who took PCI were randomly divided into conventional group (50 cases) and bisoprolol group (50 cases), and other 50 coronary stenosis<50% were selected as control group. Patients in conventional group received Aspirin enteric-coated tablet 300 mg 30 min before PCI, orally, once a day+Clopidogrel bisulfate tablet 600 mg, orally, once a day, 100 mg aspirin was given in the night after PCI, orally, once a day+clopidogrel 75 mg, orally, once a day+Atorvastatin calcium tablet 20 mg, orally, once a day, and other conventional treatment. Bisoprolol group was additionally given Bisoprolol fumarate tablet 5 mg, orally, once a day. Control group received Aspirin enteric-coated tablet+Clopidogrel bisulfate tablet+Atorvastatin calcium tablet (the same dosage and usage as conventional group). All patients were treated for 12 months. The frontal QRS-T angle before and after operation, Gensini score in all groups the incidence of MACE in 1-year was followed-up. RESULTS: After operation, QRS-T angle in bisoprolol group was significantly lower than before and conventional group, but higher than control group, with statistical significances (P<0.05), there was no significant difference in conventional group before and after operation (P>0.05), so as the Gensini score in 2 groups (P>0.05). The incidence of MACE in bisoprolol group was significantly lower than conventional group, with statistical significance (P<0.05). The QRS-T angle in bisoprolol group(preoperative-postoperative) negatively correlated with the incidence of MACE (r=-0.339,P=0.057). MACE risk decreased 8% if frontal QRS-T angle increased 1° in bisoprolol group (P=0.041), MACE risk increased 32% if Gensini increased 1 score(P=0.035). CONCLUSIONS: Based on conventional treatment, early use of bisoprolol can reduce the QRS-T angle and the MACE risk, and the decrease degree of frontal QRS-T angle is correlated with the incidence of MACE.