OBJECTIVES: • Review basic ECG principles like lead placement, wave morphology, and normal variations to accurately interpret ACS-related changes • Recognize ST-segment elevation in specific leads indicating STEMI. • Interpret ST-segment depression and T-wave inversions suggestive of NSTEMI. • Identify reciprocal changes seen in STEMI. • Understand how ECG lead placement relates to coronary artery distribution to localize the area of myocardial ischemia. • Differentiate ECG changes based on the affected coronary artery (e.g., anterior, inferior, lateral). • Integrate ECG findings with patient history and symptoms to make a diagnosis of ACS.