Fourth Universal Definition of Myocardial Infarction (2018)

• myocardial cell death due to prolonged ischemia
• Increases in cTnI values have not been reported to occur following injury to noncardiac tissues.
• high-sensitivity (hs)–cTn assays are recommended for routine clinical use.
• Myocardial injury is defined as being present when blood levels of cTn are increased above the 99th percentile upper reference limit (URL).

→ 這張美說：會造成心臟受傷的原因有六個： 缺氧、沒血、休克、腎虧、心衰、vt 嚴重度，只要cTn上升：叫myocardial injury 但如果已經進展到acute ischemic myocardial injury 就叫myocardial infarction

• The criteria for type 1 MI 直接塞住
• The criteria for type 2 MI 收支不平衝
• type 3 myocardial infarction 死了才診斷

1. Cardiac procedural myocardial injury is arbitrarily defined by increases of cTn values (>99th percentile URL) in patients with normal baseline values (≤99th percentile URL) or a rise of cTn values >20% of the baseline value when it is above the 99th percentile, but it is stable or falling.

2. Coronary intervention-related MI is arbitrarily defined by elevation of cTn values >5 times the 99th percentile URL in patients with normal baseline values. In patients with elevated pre-procedure cTn in whom the cTn levels are stable (≤20% variation) or falling, the post-procedure cTn must rise by >20%. However, the absolute post-procedural value must still be at least five times the 99th percentile URL. In addition, one of the following elements is required:

3. New ischemic ECG changes;

4. Development of new pathological Q waves;

5. Angiographic findings consistent with a procedural flow-limiting complication such as coronary dissection, occlusion of a major epicardial artery or a side branch occlusion/thrombus, disruption of collateral flow or distal embolization.

6. Coronary artery bypass grafting (CABG)-related MI

7. Development of new pathological Q waves;

8. Angiographic documented new graft occlusion or new native coronary artery occlusion;

9. Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality in a pattern consistent with an ischemic etiology.

10. It is increasingly recognized that there is a group of MI patients with no angiographic obstructive coronary artery disease (≥50% diameter stenosis in a major epicardial vessel), and the term “myocardial infarction with non-obstructive coronary arteries (MINOCA)” has been coined for this entity.

11. Patients may have elevated cTn values and marked decreases in ejection fraction due to sepsis caused by endotoxin, with myocardial function recovering completely with normal ejection fraction once the sepsis is treated.

12. Arriving at a diagnosis of MI using the criteria set forth in this document requires integration of clinical findings, patterns on the ECG, laboratory data, observations from imaging procedures, and on occasion pathological findings, all viewed in the context of the time horizon over which the suspected event unfolds.