Acute myocardial infarction (AMI) refers to ischemic necrosis of the myocardium, which is mainly caused by severe narrowing of the coronary lumen and insufficient myocardial blood supply due to coronary atherosclerosis or coronary embolism, inflammation, spasm, and coronary artery orifice obstruction, while collateral circulation has not been fully established, and is highly likely to lead to serious complications such as sudden death, malignant arrhythmia, cardiogenic shock or heart failure. According to their ECG performance, they are classified into ST-segment elevation myocardial infarction and non-ST-segment elevation myocardial infarction. Acute ST-segment elevation myocardial infarction implies complete occlusion of the coronary vessels; non-ST-segment elevation myocardial infarction is usually considered to be a severe stenosis or occlusion of the coronary vessels with adequate collateral circulation formation. Regardless of the type, achieving “early, complete and durable” patency of the coronary vessels, i.e., reperfusion therapy, is the key to successful treatment of acute myocardial infarction. 1. Acute non-ST-segment elevation myocardial infarction Implementation of “stratified treatment” Acute non-ST-segment elevation myocardial infarction is mostly manifested as non-Q-wave myocardial infarction, and compared with ST-segment elevation myocardial infarction, multiple coronary vascular lesions or Chen-positive myocardial infarction occur again in acute myocardial infarction, and the incidence of complete occlusion of infarct-related vessels is lower. The incidence of complete occlusion of the infarct-related vessels was lower. In terms of clinical history, patients with non-ST-segment elevation AMI tend to have a combination of diabetes mellitus, hypertension, heart failure, and peripheral vascular disease, but there is no significant difference in in-hospital mortality and long-term prognosis compared with acute ST-segment elevation myocardial infarction. The different clinical backgrounds are closely related to their prognosis, so it is important to stratify the risk and “stratify the treatment” of acute non-ST-segment elevation myocardial infarction. The main purpose of risk stratification is to provide a scientific and powerful basis for clinicians to make rapid treatment decisions. The clinical risk stratification is based on the patient’s symptoms, signs, electrocardiogram, laboratory and hemodynamic indices. Specific indicators include advanced age, female, cardiac function classification, history of previous myocardial infarction, atrial fibrillation, ST-T ischemic changes in extensive leads, pulmonary rales, blood pressure <100 mmHg, heart rate >100 beats/min, diabetes mellitus, and significantly elevated troponin or BNP. Patients in the low-risk group tend to have no comorbidities, are hemodynamically stable, and are not associated with recurrent ischemic episodes. Patients in the intermediate risk group tend to have persistent chest pain or recurrent episodes of ischemic chest pain. The high-risk group refers to patients with severe complications such as acute pulmonary edema, cardiogenic shock or persistent hypotension. Current national and international guidelines agree that aggressive revascularization of patients in the intermediate- and high-risk group is beneficial for improving the immediate and long-term prognosis: urgent (<2 hours) intracoronary interventions are usually required for very high-risk patients and early (<72h) intracoronary interventions for intermediate- and high-risk patients. According to the ESC 2010 Revascularization Guidelines, in patients with non-ST-segment elevation myocardial infarction who are stable or medically stabilized, emergency coronary intervention (PCI) may be unnecessary and elective intervention may be safer. Patients who are unstable despite intensive drug therapy should undergo emergency coronary angiography immediately, and depending on the results, emergency coronary intervention or coronary artery bypass grafting (CABG) should be selected. High-risk patients who have not undergone coronary intervention can be closely monitored for changes in their condition on the basis of drug therapy and prepared for emergencies, and emergency coronary angiography and intervention should be performed immediately in case of unsatisfactory drug control or changes in their condition. In patients with clear hemodynamic instability, heart failure, and severe arrhythmias, although there is an indication for emergency coronary angiography, it must be done according to the level of one's interventional team, within one's capabilities, and with the bailout of aortic balloon counterpulsation (IABP), knowing that these patients are at high risk of intraoperative, preoperative, and postoperative death. Mechanically blinded implementation of guidelines will increase the risk of death in patients at high risk for ACS. Therefore, clinical emergency coronary interventions should be performed with minimal risk and patient safety as the primary principle. 2. Acute ST-segment elevation myocardial infarction "recanalization therapy" is the key The basic methods of coronary artery recanalization therapy include intravenous thrombolysis, percutaneous coronary intervention and coronary artery bypass grafting. Due to the rapid development and great advantages of PCI technology and the shortcomings of CABG technology, such as invasiveness, risk and difficulty in generalization, the number of emergency CABG cases in the real world is decreasing. Intravenous thrombolysis, coronary intervention, and a reasonable combination of both remain the most mainstream recanalization therapies today. Intravenous thrombolytic therapy has obvious advantages: easy to perform, easy to apply, inexpensive, precise efficacy, reduced mortality, and protection of left ventricular function, and has become the standard strategy for AMI recanalization therapy. However, there are still many shortcomings of thrombolytic therapy: (1) "incomplete recanalization": the recanalization rate of intravenous thrombolysis is only 60% to 80%, and because it can only solve the problem of thrombus, it cannot effectively solve the residual stenosis caused by plaque after recanalization. (2) "Inadequate recanalization": Only 30% to 55% of patients can achieve TIMI3 level of coronary blood flow after thrombolysis. In contrast, although those with TIMI grade 2 flow meet the criteria for recanalization, the mortality rate does not decrease significantly and the reinfarction rate is high. (3) " Recanalization is not durable": the recurrence of myocardial ischemia or coronary artery re-occlusion rate after thrombolysis is 15%-20%. (4) " Many bleeding complications": there are 1% to 2% bleeding complications, often fatal and serious bleeding complications, and a considerable number of patients cannot receive thrombolytic therapy because of contraindications to thrombolysis. (5) "Time-sensitive": It is usually considered the "golden time" for thrombolysis within 2 hours, and the effect of thrombolysis beyond 2 hours is "greatly reduced". Coronary intervention is not as restricted by time as thrombolytic therapy, and it can basically meet the requirement of "early, complete and lasting" coronary vascular patency at different time points, which is the "gold standard" of AMI treatment. In particular, in patients undergoing direct PCI, serious bleeding, including intracranial hemorrhage and fatal gastrointestinal bleeding, is less common than in those undergoing intravenous thrombolysis, and major clinical events such as re-occlusion of infarct-related vessels and recurrent ischemia, reinfarction, death, and intracranial hemorrhage are significantly reduced. The benefit is greater in higher-risk subgroups of patients, such as those with cardiogenic shock, heart failure, massive myocardial infarction, advanced age, late presentation, diabetes, history of prior myocardial infarction or intervention, and prior history of CABG. The many advantages make direct PCI the first-line treatment for myocardial infarction. Unfortunately, not all hospitals are equipped to perform direct PCI, and how should providers who do not have direct PCI make decisions regarding AMI patients they see? Should the patient be kept for local thrombolysis or immediately transferred for coronary intervention? Numerous clinical trials and their subgroup analyses have shown that the mortality rate in the thrombolysis group is significantly higher than that in the direct PCI group when treated more than 3 h after onset, while within the 3-h time window, especially within 2 h, the near-term and long-term outcomes of the two strategies are basically the same. Therefore, for patients with AMI within 3h of onset, if there is no contraindication, the choice between emergency PCI or intravenous thrombolysis depends on which is easier and faster, and in situ thrombolysis is a good choice. However, if the patient is more than 3 h from onset or has a contraindication to thrombolysis, transfer to PCI is preferable to in situ thrombolysis, with significantly lower rates of death, reinfarction, and stroke in the former. Patients with acute ST-segment elevation myocardial infarction who have lost the opportunity for emergency PCI should not be revascularized prematurely, but later (at least >7 days) is safer, with no recurrent flow or less occurrence of slow flow and good recovery of cardiac function. Patients with ST-segment elevation myocardial infarction who come to the clinic >12 h after onset, especially 24 to 48 h, and patients who are revascularized prematurely electively within <7 days should be alerted to the risk of cardiac rupture after revascularization. Emergency coronary interventions are usually performed only on the offender vessel, the vessel responsible for this coronary event, and interventions on non-offender vessels are not advocated. Numerous studies have shown that emergency PCI stenting of noninfarcted vessels not only significantly increases the incidence of cardiovascular events in the acute phase due to further extensive activation of the coagulation system, but also significantly increases the incidence of in-stent restenosis in the distant phase due to overexpression of platelet growth factors and other factors. There is a third reperfusion treatment modality at the strategic level, which is the combination of thrombolysis and intervention, i.e., thrombolysis followed by selective coronary intervention based on the clinical outcome of thrombolysis. This treatment strategy, which was once "rejected", has made a comeback in recent years because of the evidence-based evidence of its potential advantages, and some scholars call it "optimized reperfusion therapy ". In any case, recanalization therapies such as coronary interventions and intravenous thrombolysis, as well as their combination, have their own advantages and disadvantages and are not incompatible with each other. Cardiologists need to make individualized decisions based on the actual conditions of the patient and the medical unit to provide optimal treatment options for the patient.