Localization of myocardial infarction on ECG

What it is

The leads that carry the ST change name the area of infarction, and the area names the artery. First the ECG has to be a STEMI: clinical symptoms consistent with ACS plus any of persistent ST-segment elevation of ≥1 mm in two contiguous limb leads, ST-segment elevation of ≥2 mm in two contiguous chest leads, or a new LBBB pattern. The most occluded coronary arteries, in descending order, are the left anterior descending artery, the right coronary artery, then the circumflex artery. ACS is the umbrella term for unstable angina, NSTEMI and STEMI, due to acute plaque rupture and thrombosis: atherosclerotic plaque rupture, then platelet aggregation, then thrombus, then partial or complete coronary occlusion. The three are separated by the ECG, the troponins and the extent of occlusion. Unstable angina has a normal ECG or ST depression and T-wave inversion, normal troponins, and partial or subtotal occlusion. NSTEMI has ST depression and T-wave inversion, elevated troponins, and partial or subtotal occlusion. STEMI has ST elevation of 1 mm or more in 2 or more leads, or a new LBBB, with elevated troponins and complete occlusion.