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New heart attack definition: three categories, sex-specific thresholds
A revised global heart attack definition introduces three categories — primary (plaque rupture or SCAD), secondary (demand-supply mismatch from another acute illness), and procedure-related — and mandates sex-specific troponin reference intervals. The previous single threshold was calibrated on men; many women had a 'normal' result during an active cardiac event.
The most significant change for Australian GPs is formal inclusion of spontaneous coronary artery dissection (SCAD). An Australian study estimates 1 in 4 acute coronary events in women under 60 results from SCAD — frequently unclassified under the old framework and more common in younger women without traditional risk factors.
There is a quiet failure at the heart of cardiac care for women in Australia — and a new global definition of heart attack attempts to name it.
Published in the European Heart Journal, the updated Universal Definition of Myocardial Infarction introduces three clinical categories and, critically, mandates sex-specific troponin reference intervals. The change formalises what many Australian cardiologists have been advocating for years: that the diagnostic threshold built largely from male physiology has been leaving women with active cardiac events in the “normal” range.
Tom Marwick from the Baker Heart and Diabetes Institute described the update as a “good” revision that also makes it easier to explain to patients what type of event they have had. Natalie Raffoul from the Heart Foundation was more direct: sex-specific thresholds would help doctors “do a better job at picking up heart attacks in women.”
Those are measured words for a longstanding and well-documented problem.
What changed — and why it matters for your consulting room
The three-category framework is not entirely new, but the new definition sharpens the language and gives it formal clinical weight.
Category 1 — primary: Spontaneous plaque rupture or spontaneous coronary artery dissection (SCAD) causing reduced blood flow to the heart. This is what most patients picture when they hear the words “heart attack.”
Category 2 — secondary: A demand-supply mismatch from another acute cause — severe anaemia, sepsis, a rapid arrhythmia, or acute respiratory failure. These events are common in hospitalised patients and are frequently missed or misclassified.
Category 3 — procedure-related: Events following percutaneous coronary intervention or bypass surgery.
The most significant addition for women is SCAD sitting formally inside the primary category with its own diagnostic pathway. An Australian study estimates nearly one in four acute coronary events in women under 60 result from SCAD — a coronary artery wall tear that causes blood flow restriction without the atherosclerotic plaque seen in classic MI. SCAD occurs disproportionately in younger women, often in the peripartum period, and can be missed on standard angiography. Under the old framework it existed in a diagnostic grey zone. Under the new one, it has a named place.
Both sides of this story
The update reflects a genuine improvement in clinical thinking. Sex differences in troponin kinetics, symptom presentation, and underlying pathophysiology are well established. Women with acute coronary events more commonly report nausea, vomiting, jaw or shoulder pain, and breathlessness rather than the textbook crushing central chest pain — and a 2025 Australian study found women with heart attacks receive less timely diagnosis and treatment than men. A guideline that makes sex-specific diagnostics the default rather than the optional is a step forward.
The honest complication is implementation. A guideline update in a European journal does not automatically change what happens in Australian emergency departments or general practice rooms at 11pm on a Tuesday. Bond University’s Julie Redfern put it plainly: some women are still “falling through the cracks,” and the need is for “better adherence” to guidelines, not just new ones. The new definition is a better tool. Whether it changes the way the tool is used depends on clinical culture, pathology reporting practices, and the willingness to interrogate a normal result when the clinical picture is suspicious.
The other tension worth naming is equity. The diagnostic improvements in this guideline are written for a healthcare system that can perform high-sensitivity troponin assays with sex-specific reference intervals. Not every emergency setting in regional or remote Australia has that infrastructure reliably in place. The guideline’s value in practice is contingent on what labs can actually deliver.
2 cents this week
Confirm your lab’s reporting standard. If your practice orders troponin on suspected ACS presentations, check whether your pathology provider is applying sex-specific high-sensitivity troponin reference intervals on reports. If not, raise it with your pathology liaison. You cannot apply a better threshold you cannot see on the result.
Keep SCAD in your differential for younger women. A woman under 55 presenting with chest discomfort, back pain, or jaw tightness — even without traditional cardiovascular risk factors — warrants a low threshold for referral. SCAD can follow physical exertion or intense emotional distress. A “normal” ECG and even a negative troponin on a single-threshold assay does not rule it out.
Use the three-category language with patients. “The type of heart attack you had was caused by…” is a far more useful sentence than the previous confusion about whether SCAD “counts” as a real heart attack. For many women who have been dismissed or minimised, having language that validates the event’s medical category matters clinically and for ongoing engagement with follow-up care.
The definition catching up to women’s cardiac biology is overdue. General practice is where most of the missed presentations first encounter the system — and where a higher index of suspicion can make the difference between a timely diagnosis and a delayed one.
Verdict: yes — review your troponin reporting and keep SCAD in mind for younger women presenting with atypical symptoms.
Sources cited
Frequently asked questions
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What are the three categories in the new heart attack definition?
The revised European Heart Journal framework classifies myocardial infarction as type 1 (primary — spontaneous plaque rupture or SCAD reducing coronary blood flow), type 2 (secondary — reduced oxygen delivery from another acute cause, such as severe anaemia, sepsis, or tachyarrhythmia), and type 5 (procedure-related — following percutaneous coronary intervention or bypass surgery). The categories were previously described but the new definition sharpens the language and places them alongside explicit sex-specific troponin criteria.
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How do sex-specific troponin thresholds change my practice?
The change is largely one of formalisation — many Australian pathology labs already report sex-specific high-sensitivity troponin reference intervals, which have a lower upper limit of normal for women. The key practical step is confirming your lab applies sex-specific cut-points and documenting your clinical reasoning accordingly. If a woman presents with chest tightness, jaw pain, or unexplained nausea and her troponin is in the 'normal' range on an older single-threshold report, review whether the lab's female-specific interval was applied.