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A new universal definition of myocardial infarction (MI) was unveiled at the European Society of Cardiology meeting in Munich. The document was developed jointly by the European Society of Cardiology (ESC), the American College of Cardiology Foundation (ACCF), the American Heart Association (AHA), and the World Heart Federation (WHF).
The definition establishes the troponin levels required to make a diagnosis of MI in various situations. Here is a summary from a fact sheet published by the AHA:
The preferred biomarker overall and for each specific category of MI is cardiac troponin (cTn) (I or T), which has high myocardial tissue specificity as well as high clinical sensitivity. An increased cTn concentration is defined as a value exceeding the 99th percentile of a normal reference population (upper reference limit, URL).
Myocardial infarction is determined by the specified cTn value, and at least one of the five following diagnostic criteria:
1. Symptoms of ischemia
2. New (or presumably new) significant ST-T wave changes or left bundle branch block
3. Development of pathological Q waves on electrocardiogram (ECG)
4. Imaging evidence of new loss of viable myocardium or regional wall-motion abnormality
5. Identification of intracoronary thrombus by angiography or autopsy
Several types of MI are defined:
Reference : Thygesen K et al. on behalf of the Joint ESC/ACCF/AHA/WHF Task Force for the Universal Definition of Myocardial Infarction. Third universal definition of myocardial infarction. Circulation 2012 Aug 24; [e-pub ahead of print]. (http://dx.doi.org/10.1161/CIR.0b013e31826e1058)