We continuously enrolled 107 patients who were admitted to the Xuzhou Center Hospital (Jiangsu, China) between December 2013 and January 2015 for acute STEMI, accepted the procedure of PCI and met the inclusion criteria. There were 62 males and 45 females aged 30–70 years. After obtaining written informed consent, we randomly divided these patients into two groups according to the administration of ticagrelor or clopidogrel during the therapy, 54 patients in the ticagrelor group (treatment group: Load dosage of 180 mg, maintenance dosage of 90 mg/time, twice a day) and 53 patients in the clopidogrel group (control group: Load dosage of 300 mg, maintenance dosage of 75 mg/time, once a day), and performed follow-up by telephone for 30 days after the discharge of the enrolled patients. All the cases corresponded with the definition of acute myocardial infarction of the Third Global Seminar of ESC/ACCF/AHA/WHF and the Diagnostic Criteria of Acute Myocardial Infarction stipulated by the Chinese Society of Cardiology (2010) (3,4). Exclusion criteria were: i) Patients who would have severe adverse reaction to ticagrelor or were resistant to clopidogrel; ii) patients with a history of myocardial infarction or with other heart diseases and/or severe heart failure (NYHA III or IV); iii) patients who had severe hepatic or renal dysfunction; iv) patients who had history of PCI or coronary artery bypass grafting (CABG) or had accepted other types of surgeries or been injured recently; v) patients with endocrine diseases such as diabetes, and immune system diseases such as acute or chronic infections, digestive tract infections, hematological diseases, malignant tumors, rheumatic disease of connective tissues; vi) patients with severe hypertension without any drug controls, cerebrovascular diseases or peripheral vascular disease; and vii) patients who had any conditions deemed inappropriate by researchers for inclusion in the study.

The baseline material of patients included the gender, age, body mass index (BMI), risk factors of cardiology [smoking, intake of alcohol, hypertension, family medical history of coronary heart disease, the level of total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglyceride], the drugs utilized during the study (administration of low-molecular-weight heparin, IIb/IIIa glycoprotein inhibitors, β-receptor inhibitor, ACEI, statins, CCB, nitrates, PPIs, H2RA), count of platelet, levels of glutamic oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), creatinine, urea nitrogen, blood glucose under stress and ejection fraction (EF).

Venous blood (5 ml) was drawn from the elbow of each subject at the time of admission, 24 h after administration of drugs and 5 ml of fasting venous blood was drawn from the same site of patients in the morning of the 4th and 7th day after administration. The supernatant of samples was collected for analysis by BN II Automatic Analyzer of Protein (Siemens AG, Munich, Germany) and measurement of hs-CRP by chemiluminescence with the measurement agent of hs-CRP.

Venous blood (5 ml) was drawn from the elbow of each subject at the time of admission, 24 h after administration of drugs and 5 ml of fasting venous blood was drawn from the same site of patients in the morning of the 4th and 7th day after administration. Samples were required to be in a supine position for ≥20 min without any procedures for anti-coagulation and then immediately placed at 4°C to coagulate for 1 h. Samples were centrifuged at 1,760 × g for 15 min under 4°C, and the serum were drawn into EP tubes and stored at −80°C for measurement. The expression level of EMS-1 was measured by ELISA, and the ELISA kits were provided by Shanghai Enzyme-linked Biotechnology Co., Ltd. (Shanghai, China).

A 30-day follow-up was performed for the patients in the two groups and the items for statistical analysis included the following: i) The occurrence rate of ischemic endpoint events, including cardiac death, acute myocardial infarction, symptoms with the urgent need of performing coronary revascularization, or stroke; and ii) occurrence rate of bleeding events, i.e., identifying the occurrence rate of major safety endpoint events (bleeding) during hospitalization and in 30 days after surgery according to PLATO, including major bleeding events (life-threatening or lethal events), other major bleeding events, secondary bleeding events and slight bleeding events, i.e., other bleeding events that did not need any medical intervention, such as bruise, gingival bleeding, bleeding at the injection site (5).

Data analysis was performed using SPSS 22.0 (SPSS, Inc., Chicago, IL, USA). Quantitative data were presented as mean ± standard deviation (SD). A normality test was conducted for quantitative data. If the data were correspondent with the normal distribution, an independent t-test was applied in difference analysis of quantitative data of two groups; if not correspondent with normal distribution, the Mann-Whitney rank sum test was utilized for the difference analysis of quantitative data of two groups. Quantitative data were presented as cases or percentage (n/%), tested by χ² test or Fisher's exact test. Difference with P<0.05 was considered statistically significant. For correlation analysis among variables, if the distribution of variables were correspondent with bivariate normal distribution, Pearson's product-moment correlation analysis was performed and if not correspondent with bivariate normal distribution or ranked data, Spearman's rank correlation analysis was applied. P<0.05 was considered to indicate a statistically significant difference.

In the two groups, no statistically significant differences (P>0.05) were found following a comparison of gender, age, BMI, risk factors of cardiology (smoking, intake of alcohol, hypertension, family medical history of coronary heart disease, the level of total cholesterol, LDL, HDL and triglyceride). The results obtained from different treatments during the study (administration of low-molecular-weight heparin, IIb/IIIa glycoprotein inhibitors, β-receptor inhibitor, ACEI, statins, CCB, nitrates, PPIs, H2RA), count of platelet, levels of GOT, GPT, creatinine, urea nitrogen, blood glucose under stress and EF are presented in Table I.

No statistically significant differences were found in the comparison of serum levels of hs-CRP and ESM-1 between the two groups at the time of admission, but significant increases of serum levels of hs-CRP and ESM-1 were seen in patients of the two groups 24 h after administration of drugs with statistically significant differences between the groups (P<0.05), and in the 4th and 7th day we found a downward trend with statistically significant differences (P<0.05) (Table II and Figs. 1 and 2).

To investigate the correlation between serum levels of ESM-1 and hs-CRP, we performed Spearman's bivariate analysis. The level of ESM-1 was enhanced with the increase of inflammatory factors, indicating there was a positive correlation between ESM-1 and hs-CRP (r=0.535, P<0.001) (Table III and Fig. 3).

In comparison of the occurrence rates of ischemic outcome events, bleeding and overall adverse events between the groups, we found no statistically significant difference (P>0.05) (Table IV).