In an inferior STEMI suspected to involve the right coronary artery, which condition must be ruled out before giving nitrates?

• A. Left main coronary artery disease
• B. Left ventricular infarction
• C. Right ventricular infarction
• D. Aortic dissection

Answer: (C)

In an inferior STEMI with suspected RCA involvement, the right ventricle may also be infarcted. The key idea is that nitrates lower preload by venodilation. If the right ventricle is damaged, the heart relies on adequate preload to drive output to the left ventricle. Reducing that preload can cause a dangerous drop in cardiac output and profound hypotension or shock. So before giving nitrates, you must determine whether there is right ventricular infarction.

Look for signs of RV involvement such as hypotension with clear lungs and elevated JVP, and obtain right‑sided ECG leads (like V4R) to detect right‑sided ST elevations. If RV infarction is present, the appropriate approach is to avoid nitrates and provide measures to support RV preload, typically with cautious IV fluid boluses and careful hemodynamic monitoring. Only after RV involvement is ruled out or adequately managed can nitrates be considered based on the patient’s overall stability.