The third edition of the updated global uniform definition of myocardial infarction was announced at the ESC Congress held in Munich, Germany from August 45-29, 2012. 1. Update on the definition of myocardial infarction The unified definition of global myocardial infarction by the European Society of Cardiology (ESC), American College of Cardiology (ACC), American Heart Association (AHA) and World Heart Federation (WHF) in October 2007 defines acute myocardial infarction as the death of myocardial cells due to myocardial ischemia, and this definition remains unchanged in the new edition. The criteria for myocardial infarction defined in the new version are: elevated serum myocardial markers (mainly troponin) (at least above the upper 99% reference value) with at least one of the following clinical indicators: (1) ischemic symptoms; (2) new ischemic ECG changes [new ST-T changes or left bundle branch block (LBBB)]. (3) pathological ECG Q-wave formation; (4) imaging evidence of new loss of myocardial activity or new localized ventricular wall motion abnormalities; (5) coronary angiography or autopsy confirmation of intracoronary thrombus. Article 5 of the new definition is a new addition, the significance of which is to emphasize that once a myocardial infarction has occurred, coronary angiography should be actively performed to verify the cause of the myocardial infarction during the inauguration process and to start treatment of coronary artery in the early stage. It is also clear from the definitions in the 07 and 12 editions that alterations in serum troponin levels are of absolute importance in the diagnosis of myocardial infarction. Elevated serum troponin levels are seen in both type I and type II myocardial infarction, but there is little change in serum troponin levels when there is only myocardial ischemia without necrosis. In the new version, it is emphasized that a diagnosis of myocardial infarction is confirmed if a patient has typical clinical symptoms of acute myocardial ischemia with an elevated serum troponin level, because an elevated serum troponin level marks the beginning of death of the ischemic myocardium. By analyzing the changes in serum myocardial markers (mainly troponin) levels in patients with acute coronary syndrome, it is helpful to guide us on what therapeutic measures to use. 2. Clinical staging of myocardial infarction The clinical staging of myocardial infarction in the new version is roughly the same as the 2007 definition. Type 1: spontaneous myocardial infarction due to intracoronary thrombosis caused by coronary plaque rupture, fissure or entrapment; Type 2: myocardial infarction secondary to an imbalance in myocardial oxygen supply and demand (e.g., coronary spasm, arrhythmia, anemia, respiratory failure, hypertension or hypotension) leading to ischemia; Type 3: sudden cardiac death suspected to be myocardial ischemia or suspected to be newly occurring ECG ischemic changes or new LBBB of cardiac death. Because death has already occurred, the patient is too late to collect a blood sample for myocardial marker measurements. Type 4 (4a and 4b): myocardial infarction associated with PCI, where type 4 myocardial infarction is divided into type 4a and type 4b; type 5: myocardial infarction associated with CABG. The difference between type 1 and type 2 myocardial infarction is that the coronary intima in patients with type 1 infarction is unstable, and thrombosis is the main cause of infarction, requiring aggressive treatment such as thrombolysis, antithrombosis and antiplatelet; type 2 infarction has no thrombosis, and dilatation of coronary arteries and improvement of myocardial oxygenation are the main measures of treatment. Type 4 myocardial infarction is associated with PCI and is now classified as type 4a and type 4b. type 4a infarction is defined as myocardial infarction due to the PCI process, including the balloon dilation and stent implantation process, and the criteria are: post-procedure patient with elevated serum troponin levels more than 5 times the upper limit of the 99% reference value and one of the following: symptoms of myocardial ischemia, new ECG ischemic changes, angiographically seen vessel absence, new loss of myocardial viability, or new imaging evidence of ventricular wall motion abnormalities. Type 4b infarction was defined as myocardial infarction with stent thrombosis, with criteria such as thrombosis in an ischemia-related vessel seen on coronary angiography or autopsy and elevation of serum myocardial markers above at least 99% of the upper reference value. Type 5 myocardial infarction is defined as a myocardial infarction associated with CABG in which the patient’s troponin exceeds the upper 99% reference value by a factor of 10 and is associated with one of the following: new pathological Q waves or LBBB on ECG, new intra-bridge (venous or arterial) occlusion confirmed by imaging, new loss of myocardial activity or new local ventricular wall motion abnormalities. 3. Diagnostic Definition and Technical Indicators The technical indicators and criteria for the diagnosis of myocardial infarction in the new version are roughly the same as the 2007 definition. The electrocardiographic criteria and echocardiographic criteria are unchanged. The following definitions are used: Reinfarction: acute myocardial infarction that occurs again within 28 days after an infarction; Recurrent MI: myocardial infarction that occurs again 28 days after an acute infarction; Silent MI: the patient’s ECG shows a pathological Q wave consistent with the diagnosis of infarction or imaging confirms an infarction, but there are no clinical symptoms. However, the following definitions have been added in the new edition: infarction associated with surgical operations, such as infarction due to TAVI (percutaneous transluminal valvuloplasty) surgery, infarction due to mitral valve capture (Mitralclip), infarction due to radiofrequency treatment of arrhythmias; infarction due to non-cardiac surgery; infarction occurring in the ICU; and myocardial ischemia or infarction associated with heart failure. These heart attacks are crowned with the names of the causes that lead to the occurrence of heart attacks, reminding us that heart attacks can occur in many cases and that it is important to clarify the causes that trigger heart attacks when diagnosing and managing heart attacks in order to achieve the correct treatment.