The new categorization for myocardial infarction (heart attack) could have an impact on diagnosis and treatment, and improved standardization of the diagnosis of myocardial infarction clinically and for research purposes. But while definitions are important clinically, underwriting risk assessment has always depended upon pathophysiology.
The new 2026 Fifth Universal Definition of Myocardial Infarction modifies the previous four categories of MI (Type 1, Type 2, Type 3, Type 4/5) by reassigning them into a clinically intuitive three-category classification based on pathophysiology.
These are synced with the International Classification of Diseases, 11th Revision (ICD-11), which is not currently adopted for clinical billing and claims coding in the U.S. However, since the new Fifth Universal Definition is available, we may start to see this in clinical documentation.
The definition was published at the European Society of Cardiology (ESC) Congress 2026 and developed jointly by the ESC, World Heart Federation (WHF), American College of Cardiology (ACC), and American Heart Association (AHA).
This category includes all acute coronary pathologies:
Defined by a myocardial oxygen supply-demand imbalance due to an alternative acute condition, as well as one or both of the following:
Coronary complications occur within 30 days of a cardiac procedure, resulting in an acute myocardial injury with one or more features:
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While definitions are important for clinical purposes, underwriting risk assessment has always considered pathophysiology. As long as we continue to receive this information, such as primary myocardial infarction due to SCAD, not much will change. The labels of the Fifth Universal Definition of Myocardial Infarction will be less important than the actual pathophysiology, such as coronary artery disease, SCAD, or vasospastic disease. Additionally, since U.S. coding still uses ICD-10, insurers may need clinical context for accurate risk assessment.
That said, improved specificity for MI means insurers can avoid overestimating risk for false positives (troponin bump due to injury such as sepsis, and not true infarction). From a claims standpoint, insurers may need to review current policy definitions against evolving terminology to ensure claims are assessed consistently and accurately. Holistically, the ability to better capture the data at a clinical level has the potential to improve granularity and mortality studies.
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