Universal definition of myocardial infarction

Universal definition of myocardial infarction

Universal definition of myocardial infarction has been under the joint auspices of the European Society of Cardiology, American College of Cardiology Foundation, American Heart Association and World Heart Federation [1]. Myocardial infarction has been classified into types 1 to 5 of which type 4 has subtypes a and b.

• Type 1 is spontaneous myocardial infarction due to a primary coronary event like plaque rupture.
• Type 2 is secondary to a supply demand mismatch as in coronary vasospasm, anemia or hypotension.
• Type 3 denotes sudden cardiac death with symptoms of myocardial ischemia which has been documented by ECG (ST segment elevation or left bundle branch block), coronary thrombus by angiography or pathological studies, but death has occurred before blood samples could be collected.
• Type 4a is myocardial infarction associated with percutaneous coronary intervention (PCI) while type 4b is associated with a verified stent thrombosis.
• Myocardial infarction associated with coronary artery bypass grafting (CABG) is termed type 5.

For diagnosing type 1 and 2, a rise and/or fall of cardiac biomarkers with at least one value above the ninety ninth percentile of the upper reference limit is needed along with at least one of the other diagnostic features like symptoms of myocardial ischemia, new ST-T changes on ECG, new pathological Q waves or evidence of new loss of viable myocardium or new regional wall motion abnormality. The preferred cardiac biomarker is troponin.

In case of myocardial infarction associated with percutaneous coronary intervention (type 4a), a rise in cardiac biomarkers more than three times the ninety ninth percentile of the upper reference limit is needed for diagnosis. This is presuming a normal baseline value in case of troponin. In case of type 4b (stent thrombosis), documentation of stent thrombosis by angiography or pathological studies in addition to meeting the criteria for spontaneous myocardial infarction are needed. More than five times the ninety ninth percentile of upper reference limit elevation of cardiac biomarkers is needed for the diagnosis of myocardial infarction after coronary artery bypass grafting (type 5). In addition there should be either new Q waves, new left bundle branch block (LBBB) or new occlusion of graft or native coronary artery by angiography or new loss of viable myocardium by imaging studies.

Diagnosis of re-infarction can be considered in the presence of recurrent ischemic symptoms or electrocardiographic changes along with twenty percent or more increase in the cardiac markers with at least one value above the ninety ninth percentile of the reference range.

This is the first universal definition of myocardial infarction. The fourth universal definition of myocardial infarction was published in 2018 [2].

References

1. Kristian Thygesen, Joseph S Alpert, Harvey D White, Joint ESC/ACCF/AHA/WHF Task Force for the Redefinition of Myocardial Infarction. Universal definition of myocardial infarction. Eur Heart J 2007;28:2525-2538.
2. Kristian Thygesen, Joseph S Alpert, Allan S Jaffe, Bernard R Chaitman, Jeroen J Bax, David A Morrow, Harvey D White, 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). J Am Coll Cardiol. 2018 Oct 30;72(18):2231-2264.