Occlusion of which artery is most likely to cause ST-segment elevation in leads II, III, and aVF in a patient with acute chest pain?

• A. Anterior interventricular (left anterior descending)
• B. Circumflex
• C. Left coronary
• D. Right coronary

Answer: (D)

The presentation of ST-segment elevation in leads II, III, and aVF is indicative of inferior wall myocardial infarction, which is often associated with occlusion of the right coronary artery. In a right-dominant coronary circulation, which is typical in a majority of individuals, the right coronary artery supplies the inferior wall of the heart, including the inferior portion of the left ventricle.

When the right coronary artery is occluded, the blood supply to this area is compromised, leading to ischemia and resultant ST-segment elevation in the inferior leads (II, III, and aVF). This clinical pattern is specifically associated with inferior myocardial infarctions.

The other arteries listed are less likely to cause this specific pattern of ST-segment elevation. The left anterior descending artery is primarily responsible for supplying the anterior wall of the heart and would typically lead to ST-segment elevation in leads V1-V4. The circumflex artery generally affects the lateral wall, which is reflected in leads I and aVL rather than the inferior leads. The left coronary artery encompasses both the anterior descending and circumflex branches and does not directly correlate with the lead findings specified in the question.

Understanding coronary circulation is crucial here, as it helps in localizing the