Which ACS involves complete blockage of coronary blood flow?

Which ACS involves complete blockage of coronary blood flow?

• A. STEMI
• B. NSTEMI
• C. Unstable Angina
• D. Stable Angina

Answer: (A)

Complete blockage of a coronary artery causes transmural, full-thickness myocardial ischemia, which is the hallmark of a STEMI. This full occlusion leads to ST-segment elevation on the ECG and rapid, extensive heart muscle damage if not treated promptly with reperfusion. The other conditions describe different levels of ischemia: NSTEMI involves myocardial injury from a partial or transient blockage and typically does not show ST elevation on the ECG (troponin may be elevated). Unstable angina is ischemia without any detectable myocardial injury, so troponin is not elevated. Stable angina reflects predictable chest pain from fixed narrowing, not an acute occlusive event.

Complete blockage of a coronary artery causes transmural, full-thickness myocardial ischemia, which is the hallmark of a STEMI. This full occlusion leads to ST-segment elevation on the ECG and rapid, extensive heart muscle damage if not treated promptly with reperfusion. The other conditions describe different levels of ischemia: NSTEMI involves myocardial injury from a partial or transient blockage and typically does not show ST elevation on the ECG (troponin may be elevated). Unstable angina is ischemia without any detectable myocardial injury, so troponin is not elevated. Stable angina reflects predictable chest pain from fixed narrowing, not an acute occlusive event.