The world's four leading cardiology societies published on Friday (28) the Fifth Universal Definition of Myocardial Infarction, a document that retires the numbered classification of heart attacks (types 1 through 5) and instead groups cases by the mechanism that injured the heart. The text appeared in the European Heart Journal and was presented at the European Society of Cardiology (ESC) 2026 congress in Munich, Germany. One of its central messages is blunt: an abnormal blood test for troponin, the protein released when heart muscle is damaged, does not by itself confirm a heart attack.
The document was drawn up jointly by the ESC, the American College of Cardiology (ACC), the American Heart Association (AHA) and the World Heart Federation (WHF), with specialists from 12 countries and five continents, according to Brazilian news portal G1. Citing figures from the document itself, magazine Veja reports that the estimated prevalence of myocardial infarction is 3.8% among people under 60 and 9.5% in older adults, and the disease remains one of the leading causes of death worldwide.
From five types to three groups
Under the new structure, a primary heart attack begins with an acute problem in the coronary artery itself. The most common cause is still the rupture or erosion of an atherosclerotic plaque followed by a clot, but the group also includes spontaneous artery dissection, embolism and vasospasm. A secondary heart attack occurs when another illness breaks the balance between the oxygen reaching the heart and what the organ needs, as in severe anemia, a sharp drop in blood pressure or certain tachycardias. A procedure-related heart attack arises as a complication of a cardiac intervention, such as a catheterization or bypass surgery, within a window of up to 30 days.
It is in the secondary group that the definition tightens its criteria. According to G1, having an illness capable of causing the imbalance plus elevated troponin is no longer enough: doctors must gather evidence of ischemia and heart muscle injury consistent with a heart attack, separating patients who truly had one from those whose heart was injured by another process. The revision also abolished the old type 3 and dropped the troponin multiples (five or ten times the reference limit) once used to classify procedure-related cases, which now rely on objective imaging criteria. Cardiovascular surgeon Ricardo Kazunori, of the BP hospital in São Paulo, told G1 that tying the classification to the origin of the event is the most direct advance of the revision. Elzo Mattar, of the Brazilian Society of Cardiology (SBC) and a professor at the Famerp medical school, pointed to severe conditions such as septic shock, in which a heart attack appears as a complication of another disease. Veja also noted that spontaneous coronary artery dissection, now listed among primary infarctions, affects predominantly women and is still considered underdiagnosed.
What is confirmed and what remains expectation
What is confirmed is the publication of the new consensus and the retirement of the numbered classification. The practical impact, however, remains an expectation of the authors: the stated hope is for more consistent diagnoses across hospitals and countries, something that can only be measured as the document is adopted. In Brazil, the revision lands amid a worrying figure: hospital admissions for heart attack among patients up to 39 years old more than doubled over the past 15 years, according to data presented by G1. The new definition does not change that trend, but it should make the count of true cases more precise.
For patients, the response to symptoms does not change. Chest pain or pressure, shortness of breath, cold sweat or sudden malaise call for immediate evaluation at an emergency service. What the revision makes clear, according to the specialists interviewed, is that diagnosing a heart attack is a clinical task: the blood test is an important piece, but it must come together with symptoms, an electrocardiogram and, when needed, imaging of the coronary arteries.