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Domain

Coronary Artery Disease

Modules

STEMI: Recognition and Reperfusion

Door-to-balloon under 90 minutes. Every minute of delay costs myocardium.

Pathophysiology

Acute plaque rupture or erosion exposes a lipid-rich, thin-cap fibroatheroma, triggering platelet aggregation and thrombus formation that abruptly occludes the vessel. Ischemia progresses from subendocardium toward full-thickness (transmural) infarction over hours without reperfusion — the biological basis for “time is muscle” and the door-to-balloon target below.

Diagnostic Criteria

ECG showing ST-elevation myocardial infarction (Wikimedia Commons, CC BY 4.0)New ST elevation at the J-point in ≥2 contiguous leads: ≥1 mm all leads except V2–V3 (≥2 mm men ≥40, ≥2.5 men <40, ≥1.5 women). New LBBB is no longer STEMI-equivalent — use Sgarbossa.

Right-Sided & Posterior Involvement

Inferior STEMI — ST elevation in II, III, aVF

Inferior STEMI — from the ECG case library. Try this case.

Roughly one-third of inferior STEMIs involve the right ventricle (proximal RCA occlusion). Check right-sided leads (V4R): ST elevation >1 mm identifies RV involvement. RV infarction is preload-dependent — avoid nitrates and diuretics, and support with IV fluids if hypotensive. Posterior extension (ST depression V1–V3 with a tall R wave) warrants posterior leads V7–V9.

Reperfusion Strategy

Primary PCI within 90 min of first medical contact (120 min if transfer). Fibrinolysis if timely PCI unavailable and no contraindications, with rescue PCI if reperfusion fails.

Adjunctive Therapy

DAPT (ASA + ticagrelor or prasugrel preferred), UFH or bivalirudin during PCI, high-intensity statin, beta-blocker once stable.

Complete Revascularization

2025 ACS: complete revascularization of significant non-culprit lesions is reasonable in STEMI without shock (COMPLETE, FULL REVASC), staged during index hospitalization or within 45 days.

Mechanical Complications

Free wall rupture, ventricular septal rupture, and acute papillary muscle rupture each classically present days after a delayed or missed STEMI, with new hemodynamic collapse or a new murmur. Bedside echocardiography should be obtained immediately whenever a post-MI patient develops sudden shock or pulmonary edema.
Clinical pearls
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Isolated ST elevation in aVR with diffuse ST depression suggests left main or triple-vessel disease.
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Right-sided leads (V4R) in inferior STEMI: ST elevation >1 mm identifies RV involvement — preload-dependent, avoid nitrates.
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Sgarbossa: concordant ST elevation ≥1 mm (5 pts), concordant ST depression V1–V3 (3 pts), discordant ST elevation ≥5 mm (2 pts).
Related guidelines