Myocardial injury vs Myocardial infarction
Elevated cardiac troponin levels indicate myocardial injury. But all cases of troponin elevation are not due to myocardial ischemia. If there is clinical evidence of myocardial ischemia or ECG changes consistent with myocardial ischemia, associated with rise in troponin followed by a fall or a fall from initially elevated levels, then a diagnosis of myocardial infarction can be considered.
Ischemic discomfort can be in the chest, upper limbs, mandible or epigastrium. This can occur at rest or with exertion. The discomfort is diffuse and not localised like a pricking pain at one point. Usually there is no change with position or movement of the affected part. Other symptoms (anginal equivalents) like dyspnea or fatigue can occur.
Myocardial injury without infarction can occur with hypotension, kidney disease, anemia, ventricular arrhythmia and heart failure. These conditions might as well be associated with myocardial infarction occasionally.
- Kristian Thygesen , Joseph S. Alpert , Allan S. Jaffe , Bernard R. Chaitman , Jeroen J. Bax , David A. Morrow , Harvey D. White , and the Executive Group on behalf of the Joint European Society of Cardiology (ESC)/American College of Cardiology (ACC)/American Heart Association (AHA)/World Heart Federation (WHF) Task Force for the Universal Definition of Myocardial Infarction. Fourth Universal Definition of Myocardial Infarction (2018). Circulation. 2018 Nov 13;138(20):e618-e651.