The updated MI definition helps healthcare professionals identify the cause of an MI and determine the most appropriate tests and treatment.
A better way to classify heart attacksMyocardial infarction is a major cardiovascular health problem worldwide and remains one of the leading causes of death.
Every myocardial infarction is now placed into one of three broad categories: primary MI, secondary MI or procedure-related MI.
A clearer explanation of the underlying cause could also help patients better understand their future cardiovascular health and the importance of ongoing treatment.
More consistent classification and data collection could help researchers better understand the condition and improve its diagnosis and management.
A new global definition of myocardial infarction (MI), commonly known as a heart attack, has been introduced to make diagnosis and treatment more consistent and easier for patients to understand
Four major international heart organisations developed the new definition, including the European Society of Cardiology (ESC), American College of Cardiology (ACC), American Heart Association (AHA), and World Heart Federation (WHF). The Fifth Universal Definition of Myocardial Infarction replaces the previous numerical classification system with three simpler clinical categories.
The updated MI definition helps healthcare professionals identify the cause of an MI and determine the most appropriate tests and treatment.
A better way to classify heart attacks
Myocardial infarction is a major cardiovascular health problem worldwide and remains one of the leading causes of death.
Under the previous system, clinicians identified different types of MI using numerical labels. These classifications were difficult to apply consistently in everyday clinical practice and were often hard for patients to understand.
The new system instead focuses on the circumstances and underlying cause of the MI. Every myocardial infarction is now placed into one of three broad categories: primary MI, secondary MI or procedure-related MI.
Three categories explaining the cause
Primary MI occurs when an acute problem develops within a coronary artery. The most common cause is the rupture of an atherosclerotic plaque, which can trigger a blood clot and restrict blood flow to the heart. Other causes include coronary artery spasm, blood clots and spontaneous coronary artery dissection (SCAD), where a tear develops in the wall of a coronary artery.
Secondary MI happens when another medical condition causes an imbalance between the heart’s oxygen supply and demand. This can occur with conditions such as extremely high or low blood pressure or a very rapid heartbeat.
The third category is procedure-related MI, which occurs within 30 days of a cardiac procedure or heart operation. Examples include coronary stenting and coronary artery bypass surgery.
The new definition also sets out the diagnostic tests and investigations needed for each category, helping clinicians take a more consistent approach to diagnosis.
Making the diagnosis easier to understand
The changes could also make conversations between doctors and patients clearer.
Rather than relying on complex numerical terms, healthcare professionals can explain the cause of an individual’s MI in more straightforward language. This may help patients understand why additional tests, treatments or follow-up care are recommended.
A clearer explanation of the underlying cause could also help patients better understand their future cardiovascular health and the importance of ongoing treatment.
Better data could support future research
The new definition also works better with the International Classification of Diseases (ICD).
The organisations involved have worked with the World Health Organization on proposed ICD-11 codes that correspond with the new categories. Once implemented, these codes could improve health data collection and help healthcare systems monitor the number and causes of different types of MI more accurately.
Better data could also support research into less common and potentially underdiagnosed causes of MI.
One example is SCAD, which predominantly affects women and can be difficult to recognise. More consistent classification and data collection could help researchers better understand the condition and improve its diagnosis and management.
A step towards more consistent care
The Fifth Universal Definition of Myocardial Infarction represents an effort to make MI classification simpler, more clinically meaningful and easier to communicate.
By focusing on the cause of an MI rather than complex numerical labels, the new approach aims to improve consistency in diagnosis and treatment, strengthen patient understanding and create better opportunities for research and public health monitoring.
