Which ECG finding indicates ischemia or infarction?

• A. QRS widening
• B. ST elevation
• C. Peaked T waves
• D. Normal sinus rhythm

Answer: (B)

ST segment elevation signals acute myocardial injury due to ischemia or infarction. When a region of heart muscle is deprived of oxygen, the injured cells create a current of injury that elevates the ST segment on the ECG, especially in the leads over the affected area. This pattern is the classic sign of a transmural ischemic event, often labeled as a STEMI when clinical symptoms align. Other changes aren’t as specific: widening of the QRS complex points to conduction problems or ventricular conditions, not necessarily ischemia; peaked T waves can occur with hyperkalemia and sometimes early ischemia but do not alone prove infarction; a normal sinus rhythm simply shows a regular rhythm without evident acute ischemic changes.