On 28 August 2026, four of the world’s leading cardiovascular organisations agreed on a new framework for heart attack diagnosis for women, correcting what one researcher called ‘unintended systematic bias’ built into clinical tools used for decades. The announcement came at the European Society of Cardiology congress in Munich.
What the new definition changes for heart attack diagnosis in women
The document, formally titled the Fifth Universal Definition of Myocardial Infarction, is the first universal heart attack definition agreed upon globally. It was developed by a multidisciplinary panel representing 12 countries across five continents, according to the American College of Cardiology. The European Society of Cardiology, the American College of Cardiology, the American Heart Association, and the World Heart Federation are all party to it.
The definition introduces two changes that bear directly on how women are diagnosed. First, three heart attack types that are up to ten times more common in women have been reclassified into the same tier as the clot-caused attacks that have historically set the terms for cardiac care. Second, the blood test used to detect heart attacks worldwide will now use sex-specific thresholds rather than a single cutoff that had been missing attacks in female patients.
Under the updated framework, myocardial infarction is now classified into one of three clinical types: primary, secondary, or procedure-related. That restructuring creates the space within which coronary artery spasm, coronary embolism, and spontaneous coronary artery dissection, known as SCAD, now sit alongside the arterial-clot attacks that have long dominated clinical attention.
Each of these three types carries specific patterns. Coronary artery spasm is a tightening of the artery that cuts off blood and oxygen; it can be triggered by emotional stress, exercise, or extreme cold. Coronary embolism occurs when a clot or fatty deposit travels to a coronary artery and blocks it. SCAD is a tear in the artery wall, with about 80 percent of cases occurring in women, often during or shortly after pregnancy.
Because these types previously ranked lower in clinical priority, women who experienced them often received care that did not match the actual cause. In some cases, treatment made them more unwell.
The troponin problem and why the threshold matters
The other correction targets the troponin test, the main diagnostic tool for heart attacks worldwide. Troponin is a protein the heart releases when it is injured, and laboratories measure it to confirm or rule out a heart attack. Until now, a single threshold applied to all patients regardless of sex, one calibrated to catch all men having a heart attack but not consistently catching attacks in women.
Prof. Nicholas Mills of the University of Edinburgh, who led the international task force, called that disparity ‘unintended systematic bias against women.’ Emergency departments will now apply sex-specific troponin thresholds, removing the gap that had allowed attacks in female patients to go undetected at the first point of clinical decision-making.
‘For decades, women have missed out on accurate diagnoses and treatment,’ said Prof. Bryan Williams, chief scientific and medical officer of the British Heart Foundation. ‘This focus on finding less common causes of heart attacks, which predominantly affect women, should help to change that. It could be life-changing for huge numbers of women in the UK and worldwide.’
Mills described the document as ‘the first time that we’ve had a truly global approach to aligning how we diagnose what is probably the most important diagnosis there is.’ Achieving alignment across the ESC, the American College of Cardiology, the American Heart Association, and the World Heart Federation was, by itself, a significant logistical undertaking. The guidelines have been published in the European Heart Journal.
Getting four major organisations onto a single shared definition required reconciling different national research traditions, clinical cultures, and regulatory contexts across those 12 countries and five continents. The resulting document is a statement that the field acknowledges the diagnostic shortfall and has a concrete mechanism for addressing it.
The sex-specific troponin thresholds and the reclassification of SCAD, coronary embolism, and coronary artery spasm will apply in emergency departments going forward, with the guidelines published and available for immediate clinical adoption.
