This is a prospective observational cohort study, and patients meeting the following criteria and admitted in the department of cardiology of our hospital were enrolled in this study. Entry criteria were listed as follows: 1. The patient must be adult; 2. The patient must be examined with DSA and diagnosed with STEMI; 3. The patient must receive revascularization treatment; 4. The patient must not die in the hospital due to STEMI; 5. The patient and family must be aware of the study and willing to participate. Exclusion criteria: 1. Patients diagnosed with NSTEMI or unstable angina; 2. Patients in coma or unconsciousness condition; 3. Patients and family cannot cooperate or do not want to cooperate with the follow-up. According to the 2017 ESC Guidelines for the Management of STEMI, STEMI was defined as electrocardiographic ST-segment elevation ≥2 mm in 2 or more contiguous chest leads or ≥1 mm in 2 or more limb leads or new onset of left bundle-branch block, together with chest pain or other typical symptoms and elevated troponin levels >99th percentile(13).
From Jan 2014 to Jan 2016, a total of 426 STEMI patients were enrolled into the prospective observational cohort study and their blood sample was acquired. All patients and their family had learned about this study and signed informed consent. This study was also approved by the Medical Ethics Committee (the First Affiliated Hospital of Chongqing Medical University). Clinical data were collected from the electric database of the hospital. Routine myocardial injury markers including cTnT as well as CK-MB, and other laboratory indicators including Creatinine, NT-proBNP, hsCRP were also tested.
Sample collection and Cyr61 test
Venous blood sample was acquired at a median of 24 hours after symptom onset and 18 hours after the PCI procedure between 8:00 and 10:00 AM the following morning, which was centrifuged for 10 mins at 2000rpm. Serum sample was stored at -20℃ refrigerator for future study. Human Cyr61/CCN1 Quantikine ELISA Kit (Catalog # DCYR10, R&D Systems, Inc, MN, USA) was used to quantify the serum Cyr61 level according to the manufacturer’s protocol. The absorbance value was measured on a microplate reader set at a wavelength of 540nm. Standard curve was plotted to get the absolute value of Cyr61 by comparing to the standard sample(9).
Primary endpoint was defined as all-cause mortality during the follow-up, while secondary endpoint was defined as a composite if adverse events including myocardial infarction, stroke, unscheduled revascularization, or rehospitalization for heart failure.
All enrolled patients were given follow-up by telephone or clinics every year and for a total of 5 years. Follow-up content included survival condition, recent readmission and other complications. Self-dropout or miss contact was considered as censored data.
IBM SPSS Statistics, version 19.0 (SPSS, Inc, Armonk, NY) was chosen for statistical analysis in this study. Normality distribution test of the variables was conducted to check the variables distribution condition. Continuous variables meeting the normal distribution were presented as mean ± standard deviations and categorical variables were presented as proportions, while continuous variables unfitting the normal distribution were described as median and interquartile range (IQR). Comparison of continuous variable of different groups was conducted with One-way ANOVA and Tukey's multiple comparisons test of independent samples. Kruskal-Wallis test and Dunn's multiple comparisons test was adopted for the comparison of different groups in non-normal variables of independent samples. Chi-square test were performed in different evaluations of categorical variables.
According to the serum level of Cyr61, patients were divided into four quartiles of Q1, Q2, Q3, Q4 group respectively. Cox hazard ratios (HR) model was adopted as the regression method to compare the relative hazard between patients with Q4 Cyr61and patients with Q1-Q3 Cyr61. Univariate analysis between covariates and endpoints was conducted, when covariates with P value <0.10 was entered into the multivariate analysis. Kaplan-meier survival curves and log rank tests were used to compare the survival status of patients in Q4 and Q1 to Q3. A p-value less than 0.05 was considered statistically significant.