Optical coherence tomography (OCT) offers a high-resolution intravascular imaging modality to accurately assess vessel and lumen geometry and identify the hallmark of a culprit lesion including plaque disruption and thrombus. In addition, the incorporation of the MLD MAX algorithm into daily practice guides an efficient and easily-memorable workflow for optimized OCT-guided percutaneous coronary intervention (PCI) with drug-eluting stents (DES). Regarding the antithrombotic therapy after revascularization, the 2023 ESC guidelines recommend the P2Y12 receptor inhibitor de-escalation (i.e. switching from ticagrelor to clopidogrel) in ACS patients may be considered as an alternative strategy to the default treatment regimen in order to reduce the risk of bleeding events.

Based on the above conclusions, we designed a single-center, prospective, randomized controlled, exploratory study trial to evaluate whether the utility of OCT for guiding PCI with DES followed by antiplatelet de-escalation therapy could further reduce the stent-induced intimal hyperplasia of STEMI patients after stent implantation.

Inclusion Criteria:

1. 18 ~ 85 years old adult patients;
2. Patients diagnosed with STEMI and undergoing PCI.
3. Patients able and willing to give written informed consent and to comply with the requirements of this study protocol.

Exclusion Criteria:

1. Prior history of intracranial hemorrhage or ischemic stroke during the past 6 months；
2. Allergy to aspirin or clopidogrel or ticagrelor;
3. Occurrence of major adverse cardiovascular event (MACE) within 30 days after undergoing PCI;
4. Platelet count < 50 × 109/L;
5. Major bleeding during the past 12 months;
6. Any form of oral, long-term anticoagulation therapy;
7. Pregnancy or lactation;
8. Suspected aortic dissection;
9. Coronary CT-negative patients;
10. Life expectancy <1 year;
11. Uncontrolled hypertension, systolic blood pressure (SBP) ≥180 mmHg, and/or diastolic blood pressure (DBP) ≥110 mmHg;
12. Comorbid conditions included the presence of any of the following: cardiogenic shock, chronic congestive heart failure with NYHA classes III or IV, left ventricular ejection fraction (LVEF) < 35% at transthoracic echocardiography, hypotension with SBP < 90mmHg and/or DBP < 60mmHg, severe arrhythmia (including high-degree AV block, sick sinus syndrome, sustained ventricular tachycardia), severe pulmonary insufficiency, pulmonary embolism, hepatic insufficiency due to non-cardiac causes (ALT or AST more than three times the upper limit of the institution's normal reference ranges), cirrhosis, severe renal failure (eGFR < 30ml/min/1.73m2);
13. Surgery plan within 30 days;
14. Psychiatric abnormalities or alcohol dependence;
15. Patients who are participating in other clinical trials;
16. Unable to tolerate 1 month of DAPT;
17. Angiographic triple vessel disease coronary disease;
18. Other situations judged by the investigators not to be suitable for the clinical trial.