ACS

Pathophysiology: rupture or erosion of a vulnerable atherosclerotic plaque exposes thrombogenic content, platelets aggregate, and a fibrin-rich thrombus partially or fully occludes a coronary artery. Classification: STEMI (ST-elevation ≥1 mm in 2 contiguous leads or new LBBB, full-thickness ischemia, elevated troponin) — emergent reperfusion with PCI within 90 min door-to-balloon or fibrinolytics within 30 min if PCI unavailable; NSTEMI (ST depression or T-wave inversion, elevated troponin) — risk-stratify (TIMI/GRACE), antiplatelet + anticoagulation, early invasive strategy in high-risk patients; unstable angina (ischemic chest pain at rest or with minimal exertion, normal troponin). Universal acute treatment mnemonic 'MONA-BASH' (or more accurately: aspirin, P2Y12 inhibitor, anticoagulation, beta-blocker, statin, nitrates, oxygen if hypoxic, morphine selectively). Long-term: dual antiplatelet therapy, high-intensity statin, beta-blocker, ACE inhibitor (especially if EF reduced or diabetic), cardiac rehab.