A 58-year-old male presents with crushing chest pain radiating to the jaw. His ECG reveals ST- segment elevation in leads II, III, and aVF. Which coronary artery is most likely occluded?

1. A

   A. Right coronary artery

2. B

   B. Posterior descending artery

3. C

   C. Left circumflex artery

4. D

   D. Anterior interventricular artery

Appeared in: INI-CET EXAM -2026

Explanation

• The patient's ECG shows ST-segment elevation in leads II, III, and aVF, which are known as the inferior leads.
• This pattern is the hallmark of an acute inferior wall myocardial infarction (MI), indicating injury to the bottom portion of the heart.
• The Right Coronary Artery (RCA) is the vessel that supplies blood to the inferior wall of the left ventricle in approximately 85% of the population (a right-dominant circulation).
• Therefore, an occlusion in the RCA is the most common and likely cause of an inferior wall MI.

Why Other Options Were Wrong

• Option B: The Posterior Descending Artery (PDA) is typically a branch of the Right Coronary Artery (RCA). While an occlusion of the PDA is involved in an inferior MI, the RCA is the main parent vessel that is occluded.
• Option C: The Left Circumflex Artery (LCx) primarily supplies the lateral wall of the heart. An occlusion would cause ST elevation in the lateral leads (I, aVL, V5, V6).
• Option D: The Anterior Interventricular Artery, also known as the Left Anterior Descending (LAD) artery, supplies the anterior wall of the heart. An occlusion here causes ST elevation in the anterior/septal leads (V1-V4).

Related Visual

Clinical Relevance

• Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain ECG Interpretation for Myocardial Infarction Localization as background academic context rather than a clinical decision trigger.
• Rapidly identifying the location of an MI is critical for anticipating complications. Inferior MIs due to RCA occlusion can lead to bradycardia and various forms of heart block, as the RCA also supplies the SA and AV nodes.
• Nurses caring for a patient with an inferior MI must monitor for hypotension and be prepared for potential right ventricular (RV) infarction. A right-sided ECG should be performed to check for RV involvement.
• In cases of RV infarction, nitrates and diuretics are used with extreme caution or avoided, as they can drastically reduce preload and cause severe hypotension.

How to Approach the Question

• First, identify the key clinical information from the stem: a patient with symptoms of a heart attack (crushing chest pain).
• Next, focus on the primary diagnostic finding: ST-segment elevation on the ECG, which signifies acute myocardial injury.
• Localize the area of injury by identifying the specific leads with ST elevation. In this case, leads II, III, and aVF are affected.
• Recall or determine the anatomical region of the heart that corresponds to these leads. Leads II, III, and aVF are the 'inferior leads,' monitoring the inferior wall of the left ventricle.
• Finally, match the affected heart wall to the coronary artery that most commonly supplies it. The Right Coronary Artery (RCA) is the primary blood supply to the inferior wall.
• Select the option that correctly links the ECG findings to the occluded artery.

Concept Tested & Keywords

• Concept Tested: ECG Interpretation for Myocardial Infarction Localization
• Stem keywords: crushing chest pain, ST-segment elevation, leads II, III, and aVF, coronary artery, occluded
• Lead-in keywords: most likely
• Clinical cues: ST-segment elevation in leads II, III, and aVF is the classic sign of an inferior wall MI.

Question ID

QsIuiZrcSUJ4sW0QEVxEAb

Copy ID

Reference Book

E6 Medicine Harrison 22e Part 1 p. 1913-1915

E6 Pathology-Textbook of PATHOLOGYHarsh Mohan Part 2 (215-514) p. 5-7