Cardiology
Acute Myocardial Infarction (STEMI)
급성심근경색
Myocardial necrosis from complete coronary occlusion with ST elevation
- How common
- ~70-100K/yr (Korea)
- Typical age
- Ages 50+
What is it?
Plaque rupture → thrombus → complete coronary occlusion → myocardial O2 supply stops → irreversible necrosis after >20 min.
Commonly affected: Myocardium supplied by occluded artery (LAD: anterior, RCA: inferior, LCx: lateral)
How it develops
- Plaque ruptureFibrous cap of vulnerable plaque ruptures
- Platelet activation/thrombosisTissue factor exposure, clot formation
- Complete occlusion100% coronary occlusion
- Myocardial necrosisBegins after 20 min, complete by 6 hrs
Symptoms
- Severe chest painCrushing >20 min, "elephant on chest"
- Syncope/cardiac arrestLethal arrhythmias, cardiogenic shock
- Radiating painL arm, jaw, back, epigastrium
- Diaphoresis/nausea/vomitingSympathetic activation
- DyspneaWith pulmonary edema
How it is examined
- 12-lead ECG (within 10 min)ST elevation, Q waves, reciprocal changes
- Serial cardiac enzymesTroponin I/T at 3 and 6 hrs
- Cardiac auscultationS4 gallop, new murmur (MR/VSD)
Imaging
CXR assesses pulmonary edema/cardiomegaly.
- Pulmonary edema
- Cardiomegaly
Emergent coronary angiography → PCI (door-to-balloon <90 min).
- 100% LAD/RCA occlusion
- Stent placement
Non-surgical care
- Initial MONAMorphine, O2 (if hypoxic), nitroglycerin, aspirin 325mg
- Dual antiplateletAspirin + clopidogrel (or ticagrelor)
- AnticoagulationHeparin or bivalirudin
- BB/ACEi/statinStart within 24-48 hrs of admission
- FibrinolyticsAlteplase within 30 min if no PCI
Conservative options are generally tried first. Medications listed here can have side effects — discuss them with your prescriber.
When surgery is considered
All STEMI patients within 12 hrs
Procedures that may be discussed
- Primary PCI (standard of care)
- Emergent CABG (if PCI fails)
- Mechanical support (IABP, ECMO for cardiogenic shock)
Outlook
In-hospital mortality 5-10%; primary PCI reduces 30-day mortality to <5%.