1, aspirin: smaller doses are more beneficial The benefits of aspirin in STEMI patients have been demonstrated in numerous clinical trials, so guidelines recommend that STEMI patients take it for life. Previous guidelines have recommended aspirin doses of 300-325 mg/day. However, according to the results of the recent large randomized controlled clinical trial CURRENT/OASIS7 study, high-dose aspirin (300-325 mg/day) did not additionally reduce the incidence of ischemic endpoints compared to low-dose aspirin (75-100 mg/day), but rather increased the risk of GI bleeding. Therefore, for the general STEMI population, small doses of aspirin (70-100 mg) are recommended in the new guidelines for long-term use. For patients with STEMI with diabetes, some studies suggest that higher doses and more frequent dosing are needed to achieve adequate platelet inhibition, but the evidence for this is currently insufficient. Patients who are intolerant to aspirin are recommended to take clopidogrel (75 mg/day) for long-term use. 2. Dual antiplatelet therapy: not the longer the better Dual antiplatelet therapy with aspirin combined with ADP receptor blockers (including clopidogrel, prasugrel, or ticagrelor) is the cornerstone of antithrombotic therapy for all patients with STEMI, whether they receive emergency PCI, thrombolytic therapy, or no reperfusion therapy. In previous guidelines, duplex antiplatelet therapy was recommended for 12 months in patients with stenting and 9-12 months in patients without PCI. There is still a lack of conclusive recommendations as to whether dual antiplatelet therapy should be continued for longer. Given that histologic and angiographic data suggest that endothelial repair may be delayed beyond 12 months in some patients, it has been suggested that dual antiplatelet therapy should be extended to 2 years or even longer; however, there is currently insufficient evidence to support this recommendation. Several recent studies have shown that extending dual antiplatelet therapy beyond 6 or 12 months does not further reduce the risk of ischemic events and stent thrombosis compared with relatively short-term therapy. However, the sample sizes of these studies were too small to draw definitive conclusions. Several ongoing clinical trials with large samples, including the DAPT (Dual Antiplatelet Therapy) study, will answer this topical question. Given the current lack of evidence, the new guidelines continue to recommend that dual antiplatelet therapy in STEMI patients should be maintained for 9-12 months, with dual therapy for at least 1 month in patients with BMS placement and at least 6 months in patients with DES placement. All patients should be fully aware of the importance of duplex antiplatelet therapy to avoid early discontinuation. 3, STEMI with atrial fibrillation: antithrombotic regimen remains to be defined The guidelines recommend that for patients with STEMI with atrial fibrillation, the antithrombotic regimen should be selected in conjunction with the CHADS2-VASc scoring system. the CHADS2-VASc scoring system is based on whether the patient has concomitant heart failure (C), hypertensive disease (H), age >75 years (A, 2 points), diabetes mellitus (D) Stroke (S, 2 points), vascular disease (V), age 65-74 years (A), and female (Sc). If the score is ≥2, then the recommendation is to add Warfarin “triple antithrombotic therapy” to the dual antiplatelet therapy. However, there is no conclusive evidence for this recommendation. Most of the current studies are observational studies with small samples. A recent meta-analysis showed that triple antiplatelet therapy in patients with coronary artery disease with atrial fibrillation may reduce ischemic events but increase the risk of bleeding. Although various calculations for antithrombotic regimens in such patients have been proposed in a number of expert consensus studies, all lack sufficient evidence to support them. The guidelines suggest that BMS may be considered for STEMI patients with indications for anticoagulation to reduce the duration of triple antithrombotic therapy, but should be evaluated in combination with the patient’s risk of restenosis. 4. Interaction of PPI with clopidogrel: insufficient evidence Gastrointestinal bleeding is one of the major complications of dual antiplatelet therapy. In patients at high risk of bleeding, such as a history of gastrointestinal bleeding or gastric ulcer, advanced age, and concomitant application of anticoagulants, steroidal and nonsteroidal anti-inflammatory drugs, proton pump inhibitors (PPIs) are an important treatment option to protect the gastric mucosa against gastrointestinal bleeding. However, clopidogrel, a drug precursor, does not have antiplatelet activity per se and must be metabolized in vivo to the active ingredient by the cytochrome P450 (CYP) system. Several laboratory and retrospective studies have shown that some of the PPIs that also pass through the P450 metabolic pathway may interact with clopidogrel, thereby affecting the efficacy of clopidogrel. The US FDA has repeatedly issued a boxed warning in 2009 regarding the combination of clopidogrel and PPIs recommending avoiding the use of clopidogrel in combination with the PPIs omeprazole and esomeprazole because both drugs are metabolized through the P450 pathway and therefore have an impact on the metabolism of clopidogrel, thus affecting the efficacy of clopidogrel. The efficacy of clopidogrel. However, due to insufficient evidence, the FDA has not made a definitive recommendation for PPIs other than omeprazole and emeprazole. However, the interaction of PPIs with clopidogrel has not been confirmed by prospective randomized controlled clinical trials (including the COGENT study). In light of this, the new guideline concludes that the evidence for this interaction is insufficient and that no interaction has been found between PPIs and ADP receptor blockers other than clopidogrel, including prasugrel and ticagrelor. Therefore, concerns about GI bleeding far outweigh concerns about drug interactions. 5. Factor Xa antagonists: first signs of success Recent results from the ATLAS ACS 2CTIMI51 trial showed that the addition of low-dose rivaroxaban (rivaroxaban. 2.5 mg twice daily) to aspirin and clopidogrel significantly reduced the incidence of cardiac death, all-cause death, myocardial infarction, and stroke in patients with acute coronary syndrome (ACS) At the same time, rivaroxaban increased the risk of non-CABG-related bleeding and intracranial hemorrhage by a factor of 3. High-dose rivaroxaban (5 mg twice daily) did not provide the same benefit as low-dose, and further increased the risk of bleeding. The trial did not validate the combination of rivaroxaban with prasugrel or ticagrelor, but it can be assumed that the risk of bleeding would be higher. The study suggests that low-dose rivaroxaban may be considered for home use in combination with clopidogrel and aspirin in ACS patients with a low risk of bleeding. However, other factor Xa antagonists, including apixaban, dabigatran, and darexaban, have not shown the same benefit in clinical trials. Therefore, the benefit of adding factor Xa antagonists to dual antiplatelet agents in the secondary prevention of STEMI remains to be further investigated.