When does a raised troponin become a myocardial infarction? What has happened to “type 2 MI”? And how certain can we be about the diagnosis without imaging?

Iain Beardsell introduces Professor Rick Body for a practical guide to the Fifth Universal Definition of Myocardial Infarction. Rick explains the changes in terminology, troponin interpretation and diagnostic criteria, focusing on what they mean for clinicians assessing patients in the emergency department.

What Rick covers

Primary, secondary and procedure-related MI. The new classification replaces the previous numbered types. Rick explains why primary MI now includes coronary dissection, vasospasm and embolism, alongside atherothrombosis. He also describes how the 30-day window after coronary intervention or bypass surgery defines procedure-related MI.
Sex-specific troponin thresholds. The definition explicitly recommends sex-specific upper reference limits. Rick discusses why this matters and encourages clinicians to understand the thresholds used by their own laboratory, rather than assuming every troponin assay works in the same way.
A likely diagnosis versus a confirmed diagnosis. Cardiac and coronary imaging take a more prominent role in confirming MI and identifying its cause. This is particularly relevant when considering secondary MI in patients with sepsis, tachyarrhythmia or gastrointestinal haemorrhage. A troponin rise alone does not establish myocardial infarction.
Acute and chronic myocardial injury. Rick explores the causes of myocardial injury beyond infarction, including inflammation, haemodynamic stress, catecholamine effects, toxicity and trauma. He also challenges the habit of diagnosing chronic myocardial injury from two similar troponin results during an acute ED attendance, without establishing the patient’s stable baseline or investigating the underlying cause.
Making sense of the troponin delta. Absolute changes, percentage changes, the starting concentration, time from symptom onset and the interval between samples all influence interpretation. Rick explains why there is no single delta that works for every patient, and why sampling intervals must match the evidence supporting the thresholds being used.
STEMI, NSTEMI and occlusive MI. The traditional terminology remains, but the definition recognises important ECG patterns beyond conventional ST elevation. Rick discusses the place of posterior MI, de Winter T waves, Wellens syndrome, the Aslanger pattern and Sgarbossa criteria within this evolving approach.

The episode also considers the practical consequences of these changes. More investigation brings additional resource demands, and Rick highlights the uncertainty about whether a more extensive assessment of chronic myocardial injury will improve patient outcomes.

More from the accompanying blog

Professor Nick Mills, first author of the new definition, adds an important clarification: a working clinical diagnosis can guide initial treatment. Imaging helps identify the cause and improve diagnostic certainty, but unavailable or inappropriate angiography does not prevent a clinical diagnosis. In secondary MI, managing the presenting illness remains the immediate priority.

Rick also notes that HEART, T-MACS, EDACS and MI-3 are not addressed in the document. He interprets this as being outside its scope, rather than a change to their use.

The post includes Rick’s video presentation and details of ADOPT-UDMI, an education, evaluation and research programme inviting clinicians from all specialties to help put the new classification into practice.

Read the full post: The Fifth Universal Definition of Myocardial Infarction: What Emergency Clinicians Need to Know

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Ep 297 - The 5th Universal Definition of MI - what emergency clinicians need to know

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Ep 297 - The 5th Universal Definition of MI - what emergency clinicians need to know