MYOCARDIAL infarction classification has been simplified through a new universal definition that replaced numerical categories with three clinically meaningful groups, as per the newly release Fifth Universal Definition of Myocardial Infarction during the ESC Congress 2026.1
The new definition was jointly released by the European Society of Cardiology (ESC), American College of Cardiology, American Heart Association and the World Heart Federation Task Force for the Universal Definition of Myocardial Infarction
The updated framework recognises myocardial infarction as occurring in one of three clinical settings: primary myocardial infarction, secondary myocardial infarction, or procedure related myocardial infarction.
The previous myocardial infarction classification system used numerical labels to categorise different forms of myocardial infarction.
According to the task force behind the updated definition, this approach was not always straightforward to apply in routine clinical practice, contributing to inconsistencies in diagnosis and management.
The revised system instead classifies myocardial infarction according to its underlying cause.
Primary myocardial infarction occurs spontaneously because of an acute coronary artery problem. While rupture of an atherosclerotic plaque remains the most common cause, other mechanisms include spontaneous coronary artery dissection, coronary artery spasm, and coronary thrombosis.
Secondary myocardial infarction results from an imbalance between myocardial oxygen supply and demand caused by another condition, such as markedly abnormal blood pressure or a rapid heart rate.
Procedure related myocardial infarction occurs within 30 days of a cardiac intervention or cardiac surgery.
The document also outlines the diagnostic tests and investigations required for each category, providing a framework designed to align diagnosis with established clinical assessment pathways.
The framework authors noted that numerical terminology was often not used in discussions with patients because of its complexity.
By focusing on the cause of myocardial infarction rather than a numbered classification, the authors suggest that clinicians may find it easier to explain diagnoses, investigations, and treatment plans to patients with myocardial infarction.
This approach is intended to make the diagnosis more meaningful, while supporting greater consistency across healthcare settings.
Improved communication may also help patients better understand their condition and the rationale for subsequent care.
A further development in the new definition is alignment with International Classification of Disease (ICD) coding developed by the World Health Organization.2
The updated classification has been designed to correspond with proposed ICD 11th edition codes, which could support more consistent data collection, disease monitoring, and healthcare planning.
The framework authors also highlighted potential research benefits. Standardised coding may facilitate larger studies of less common causes of primary myocardial infarction, including spontaneous coronary artery dissection, which predominantly affects women and is currently underdiagnosed.
Ultimately, the task force stated that the simplified classification aims to improve treatment decisions, enhance patient understanding, and strengthen opportunities for future research and surveillance.
1. Fifth Universal Definition of Myocardial Infarction (2026). Eur Heart J. 2026;DOI:10.1093/eurheartj/ehag101.
2. World Health Organization. ICD-11: International Classification of Diseases (11th Revision). World Health Organization. Available at: https://icd.who.int/. Last accessed: 29 August 2026.
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