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Acute coronary syndrome (ACS) encompasses a spectrum of myocardial ischemia including unstable angina, non-ST-elevation myocardial infarction (NSTEMI), and ST-elevation myocardial infarction (STEMI). It remains a leading cause of morbidity and mortality worldwide and requires time-sensitive diagnosis and management.
ACS typically results from rupture or erosion of an atherosclerotic plaque with subsequent platelet aggregation and thrombus formation. STEMI involves complete coronary occlusion causing transmural ischemia; NSTEMI and unstable angina involve partial occlusion or dynamic obstruction. Myocardial injury is reflected by troponin release, which follows a characteristic rise-and-fall pattern over hours.
The clinical reasoning framework for ACS hinges on risk stratification using history, ECG, and serial troponins. High-risk features include rest pain, dynamic ECG changes, elevated troponin, and hemodynamic instability. STEMI requires immediate reperfusion (primary PCI preferred). NSTEMI management is guided by TIMI or GRACE risk scores. Key differentials include aortic dissection, pulmonary embolism, myocarditis, and esophageal spasm.
Key imaging focus: ST elevation patterns by territory, reciprocal changes, posterior MI