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Type 4a MI (PCI-related) — EECC MCQ

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ModerateCoronary Artery DiseaseType 4a MI (PCI-related)EECC

A 56-year-old woman undergoes elective PCI with DES implantation. During the procedure, she develops chest pain with new ST elevation. Immediate angiography shows the LAD is patent but there is slow flow (TIMI 2) in a large diagonal branch that was jailed by the stent. Troponin rises to 15x the upper limit of normal post-procedure. How is this classified?

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Correct answer: B — Type 4a myocardial infarction (PCI-related MI)

The Fourth Universal Definition of MI classifies MI types: Type 4a is PCI-related MI, defined as troponin elevation >5x the 99th percentile URL within 48 hours of PCI, combined with evidence of new ischaemia (symptoms, new ECG changes, angiographic loss of flow, or imaging evidence of new loss of viable myocardium). This patient has troponin >5x URL with new ST changes and compromised flow in a side branch, meeting Type 4a criteria. Type 4b is specifically stent thrombosis-related MI. Periprocedural myocardial injury (troponin rise without ischaemic features) is distinct from Type 4a MI.

Reference: ESC (2023): Fourth Universal Definition of Myocardial Infarction