Snapshot A 55-year-old man presents to the emergency department due to substernal chest pain. His symptoms began a few hours ago. He describes the pain as "crushing" and it radiates down the left arm. Medical history is significant for type 2 diabetes and hypertension. On physical exam the patient is diaphoretic. An electrocardiogram demonstrates ST-segment elevations and cardiac troponins are significantly elevated. Introduction Clinical definition login to view 2 more bullets Types login to view 10 more bullets Epidemiology login to view 11 more bullets Etiology login to view 8 more bullets Pathophysiology login to view 12 more bullets ECG Changes and STEMI ECG Changes and STEMI Infarction Location Involved ECG Leads Involved Coronary Artery Inferior wall II, III, and aVF RCA Antero-apical V3 and V4 LAD (distal) Antero-septal V1 and V2 LAD Antero-lateral V5 and V6 LAD or LCX Lateral I and aVL LCX Posterior ST depression and tall R waves in V1-3 V7-V9 Posterior descending artery Evolution of MI Morphological Myocardial Changes in an MI Time Gross Features Light Microscopy Complications 0-24 hours Initially no gross findings; however, over the course of the first 24 hours, dark mottling ensues Early coagulation necrosis Wavy fibers Elongated myocytes Neutrophil infiltration Arrhythmia Heart failure 1-3 days Mottling with a yellowish infarct center Extensive coagulation necrosis Brisk neutrophil infiltration Fibrinous pericarditis 3-14 days 3-7 days hyperemic with central yellowing 7-10 days yellow-tan with reddish tan margins 10-14 days reddish gray infarct borders Macrophage infiltration and tissue granulation Myocardial wall rupture may lead to cardiac tamponade Papillary muscle rupture mitral regurgitation posterolateral muscle rupture is more likely than anteromedial muscle rupture Pseudoaneurysm of a ventricular wall may rupture 2 weeks - several months 2-8 weeks gray-white scar > 2 months complete scar Collagenous scar Dressler syndrome Heart failure True ventricular aneurysm a thrombus may form Presentation Symptoms login to view 14 more bullets Physical exam login to view 3 more bullets Imaging Coronary angiography login to view 2 more bullets Studies 12-lead ECG login to view 17 more bullets Biomarkers login to view 7 more bullets Differential Unstable angina login to view 2 more bullets Costochondritis login to view 2 more bullets Treatment Conservative login to view 2 more bullets Medical login to view 32 more bullets Reperfusion therapy login to view 12 more bullets Complications Heart failure Sudden cardiac death Arrhythmia Myocardial stunning