New global definition of myocardial infarction aims to improve diagnosis, treatment, and patient understanding

For the first time, a universal definition of myocardial infarction has been developed and published by four major cardiac societies: the European Society of Cardiology (ESC), the American College of Cardiology (ACC), the American Heart Association (AHA), and the World Heart Federation (WHF). The Fifth Universal Definition of Myocardial Infarction (MI) was presented at ESC Congress 2026 on 30 August.

MI remains a leading cause of death and is a significant public health concern worldwide.

“People may think of an MI as a heart attack caused by a blocked coronary artery but there are many different causes of MI,” explained ESC Chair, Prof Nicholas Mills from the University of Edinburgh, UK.

“The previous universal definition used a numerical system to categorise the different types of MI, but this was not always easy to apply in clinical practice, leading to inconsistencies in diagnosis and treatment. The ESC, ACC, AHA, and WHF have worked together to devise an updated and simplified classification system for MI, which aims to address these limitations.”

The new system considers the underlying cause of the MI and aligns the diagnosis with established approaches to clinical evaluation. It recognises that MI occurs in three clinical settings: Primary MI, secondary MI, and procedure-related MI. In this updated approach to MI classification, all MIs fit into one of these three clinical categories and the new document outlines the diagnostic tests and investigations that are required for each.

Primary MI is one that arises spontaneously due to an acute problem in a coronary artery. It is most commonly caused by a rupture of an atherosclerotic plaque, but there are other causes such as a tear in the coronary wall (spontaneous coronary artery dissection [SCAD]), spasm or a clot. Secondary MI arises from an imbalance in oxygen supply and demand in the heart caused by another condition, such as very high or very low blood pressure or a very fast heartbeat. The third setting – procedure-related MI – is one that occurs within 30 days of a cardiac procedure (such as coronary stenting) or heart operation (such as coronary artery bypass surgery).

In another first, the new universal definition of MI aligns with International Classification of Diseases (ICD) coding, which captures statistics on the extent, causes and consequences of different diseases. WHF Chair, Associate Prof Sarah Zaman from the University of Sydney, Australia, noted: “Importantly, ICD-11 coding will also standardise data collection on each MI type, enabling further large-scale research in areas of unmet need.”

As an example, the new alignment could facilitate wider study of less common mechanisms of primary MI, such as SCAD, a condition occurring predominantly in women, which is currently under-diagnosed.