This is a prospective, randomized, parallel design study to investigate that ticagrelor could attenuate inflammatory cell infiltration in thrombus aspirated from ST elevation myocardial infarction (STEMI) patients. The anticipated duration of the study is approximately 9 months, including an anticipated enrolment period of 8 months and follow-up period of 1 month. Patients within 12 hours of symptom onset were randomly assigned in a one-to-one ratio to receive ticagrelor or clopidogrel at time of STEMI diagnosis. The primary endpoint was the extent of inflammatory cell infiltration in thrombus aspirated from STEMI patients, expressed as number of total inflammatory cells per mm2 thrombus area.

This is a prospective, randomized, parallel design study to investigate that ticagrelor could attenuate inflammatory cell infiltration in thrombus aspirated from STEMI patients. The anticipated duration of the study is approximately 9 months, including an anticipated enrolment period of 8 months and follow-up period of 1 month. Patients within 12 hours of symptom onset were randomly assigned in a one-to-one ratio to receive ticagrelor or clopidogrel at time of STEMI diagnosis. The primary endpoint was the extent of inflammatory cell infiltration in thrombus aspirated from STEMI patients, expressed as number of total inflammatory cells per mm2 thrombus area.

Screening will be made to select eligible participants before intervention. Patients with documented STEMI and within 12 hours of symptom onset will be enrolled from the study site. For patients post percutaneous coronary intervention (PCI), they must be on dual-antiplatelet therapy for at least 12 months to be eligible for the study.

After the enrollment period, patients were randomly assigned in a one-to-one ratio to receive ticagrelor (180 mg loading dose) or clopidogrel (600 mg loading dose) at time of STEMI diagnosis. In addition to randomized study medication all patients should receive concomitant Ace Salicylic Acid (ASA) 100 mg daily during the treatment period according to local practice, unless they are allergic or intolerant. For those not previously given aspirin, a loading dose of 300 mg was preferred. At the end of the study, data will be collected and analyzed.

Inclusion Criteria:

• Provision of informed consent prior to any study specific procedures
• Males and non-pregnant females > 18 and < 79 years of age.
• Symptoms consistent with STEMI lasting > 30 min.
• Arrival at the hospital within 12 h of the onset of chest pain.
• Intention to perform PCI

Exclusion Criteria:

• On treatment with a P2Y12 receptor antagonist (ticlopidine, clopidogrel, prasugrel, ticagrelor) in past 30 days.
• Known allergies to aspirin or ticagrelor or clopidogrel.
• On treatment with oral anticoagulant (Vitamin K antagonists, dabigatran, rivaroxaban).
• Treatment with IIb/IIIa glycoprotein inhibitors in the last 7 days.
• Known pregnancy, breast-feeding, or intend to become pregnant during the study period.
• Active pathological bleeding
• History of prior intracranial bleeding.
• Renal dysfunction (serum creatinine levels ≥ 2.0 mg/dL).
• Severe, non-catheter-related coronary artery spasm.
• New York Heart Association (NYHA) class III or IV heart failure or known left ventricular ejection fraction < 30%.
• Known severe hepatic dysfunction.
• Hemodynamic or electrical instability (including shock).
• Concomitant inflammatory diseases, malignant tumours, anaemia or thrombocytopenia.