Pulse ·
New MI definition finally makes room for how women's hearts fail
The Fifth Universal Definition of Myocardial Infarction, published in the Global Heart Journal, reorganises heart attacks into three categories — primary, secondary, and procedure-related — and formally recognises SCAD (spontaneous coronary artery dissection) as a primary form of myocardial infarction alongside atherosclerotic disease.
For Australian women, the key change is sex-specific high-sensitivity cardiac troponin thresholds. Women have lower normal troponin levels, meaning they were more likely to be misclassified under male-derived criteria. Australian research suggests SCAD causes up to one in four acute coronary events in women under 60.
Natalie Raffoul from the Heart Foundation said the new definition does “a better job at picking up heart attacks in women when they’re presenting with symptoms.”
A better job. In 2026.
The Fifth Universal Definition of Myocardial Infarction, published this week in the Global Heart Journal by the World Heart Federation and European Society of Cardiology, is being welcomed by Australian cardiac specialists — and for good reason. It is a genuine improvement. It is also a reminder that the standard being improved was, for many women, never quite adequate.
What changed
The previous universal definition of myocardial infarction had one central category: a heart attack caused by reduced blood supply to the heart muscle, measured by troponin levels derived predominantly from male populations, attributed predominantly to atherosclerosis.
The fifth universal definition reorganises this into three clinical categories: primary myocardial infarction (caused by the heart’s own blood supply being interrupted), secondary myocardial infarction (caused by another acute medical condition — sepsis, arrhythmia, severe anaemia — increasing cardiac demand), and procedure-related myocardial infarction (following cardiac surgery or intervention).
The category change is not cosmetic. Under the new framework, conditions that mainly affect women — spontaneous coronary artery dissection (SCAD), coronary artery spasm, and coronary embolism — are formally classified as causes of primary myocardial infarction. Associate Professor Sarah Zaman, a WHF taskforce member, has noted that this formalisation matters precisely because clinicians need to be actively looking for these entities, not reaching for “normal coronaries, no cause found” as a default when atherosclerosis is absent.
The second key change is the incorporation of sex-specific high-sensitivity cardiac troponin thresholds. Women have lower baseline cardiac troponin levels than men. When diagnostic criteria use male-derived normal ranges — which most previous testing protocols did — a troponin that is genuinely elevated for a woman may register as “normal” and the diagnosis is missed or delayed. Australian data suggest that women having heart attacks were less likely to be promptly diagnosed and treated compared to men — a gap attributable in part to troponin thresholds that were not calibrated to female physiology.
Both sides of this
The new definition is a real step. Associate Professor Ralph Audehm, a Melbourne GP on the RACGP taskforce, is direct about why it matters: “women aren’t men shaped a little bit differently. They are different.” Sex-specific troponin thresholds were not a controversial scientific proposal — the data had been there for years. The definition making them official changes what a test result means when a woman presents with chest pain.
And SCAD recognition matters for real patients. Australian research suggests nearly one in four acute coronary syndrome events in women under 60 are caused by SCAD — a condition typically missed when clinicians find no atherosclerosis on angiography and conclude nothing cardiac is happening. SCAD is caused by a tear in the coronary artery wall. It has different risk factors, different management, and a different recurrence picture than atherosclerotic disease. Naming it correctly in a universal definition is not a technicality.
What must be held alongside this: Julie Redfern, Bond University professor of public health, notes that women are still “falling through the cracks” and that what is still needed is “better adherence” to guidelines, not just better guidelines. A definition is not a guarantee of changed practice. Nurses, paramedics, emergency department clinicians, rural GPs — the full chain of care needs to be calibrated to these standards for them to alter outcomes. The “significant treatment gap for women” Raffoul describes is not just diagnostic. It includes delayed thrombolysis, underuse of guideline-recommended therapies post-infarct, and inadequate cardiac rehabilitation referral. The new definition addresses the front door. The rest of the house still needs attention.
What this means for general practice this week
The immediate clinical implication is troponin interpretation. If your laboratory has not yet updated to sex-specific high-sensitivity troponin reference ranges, it is worth confirming with your pathology provider when that transition will occur. The evidence base for female-specific thresholds has been strong for several years; this definition simply confirms that standard practice should reflect it.
The SCAD implication is primarily about pattern recognition. A woman — particularly in her 30s to 50s, without significant cardiovascular risk factors, who presents with acute chest pain, dyspnoea or neck and jaw discomfort — warrants urgent consideration of SCAD even if you do not find a classic atherosclerotic risk profile. The national cardiac guidelines now have formal support for naming this entity and expediting investigation.
Audehm’s point about discharge summaries is practically important: when a patient is discharged after a myocardial infarction, the cause should be specified — atherosclerosis, SCAD, stent-related, secondary. Category alone is not enough for the receiving GP to understand what happened and what follow-up management is appropriate.
For women who have been told their symptoms were anxiety, musculoskeletal, or non-cardiac: this definition will not instantly change their experience in emergency departments. But it shifts the evidentiary floor. The standard, now formally, is to consider female-pattern presentations as cardiac until they are not.
Verdict: yes — this changes the standard you’re holding labs and colleagues to when a woman presents with chest pain.
The definition update doesn’t fix the gap between what guidelines say and what gets done. That fix is still a clinical culture question. But it removes one more layer of cover for the status quo.
Sources cited
Frequently asked questions
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What is SCAD and who does it affect?
Spontaneous coronary artery dissection (SCAD) is a tear in a coronary artery wall that causes reduced blood flow to the heart. It mainly affects women under 60 who lack the traditional heart attack risk factors — smoking, diabetes, high blood pressure, elevated cholesterol. It can be missed when clinicians are looking for atherosclerosis and not finding it. Australian data suggests it may cause up to one in four acute coronary syndrome events in women under 60.
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What does sex-specific troponin mean for a woman presenting with chest pain?
High-sensitivity troponin blood tests are now calibrated to sex-specific normal ranges. Women naturally have lower cardiac troponin levels at baseline, so a troponin that falls within the 'normal' male-derived range may actually represent significant cardiac injury for a woman. The new definition makes female-specific reference ranges part of the diagnostic standard, which should reduce missed diagnoses.