Intraoperative MI — FRCA Final MCQ

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ModerateGeneral AnaesthesiaIntraoperative MIFRCA Final

A 62-year-old man (ASA III) develops acute ST-segment elevation in leads II, III and aVF during a laparoscopic colectomy. The ST-segment elevation is greater in lead III than in lead II. He develops new complete atrioventricular block, with a heart rate of 35 beats min−1 and arterial pressure of 70/40 mmHg. Which coronary artery is most likely occluded?

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Correct answer: E — Right coronary artery

The most likely culprit is the right coronary artery (RCA). ST elevation in II, III and aVF identifies an inferior STEMI, which may arise from RCA or left circumflex occlusion. Elevation in III greater than II favours the RCA. Complete atrioventricular block provides further discrimination because the atrioventricular nodal artery arises from the RCA in approximately 82% of hearts. Left circumflex occlusion remains an alternative cause of inferior STEMI but is less consistent with this combined ECG pattern. LAD occlusion usually produces anterior or anteroseptal changes, while left main stem occlusion more often causes extensive anterior-lateral ischaemia with inferior reciprocal depression. An isolated posterior descending artery lesion is usually too distal to interrupt the atrioventricular nodal blood supply.

Reference: Zhou P et al. Identifying the culprit artery via 12-lead electrocardiogram in inferior wall ST-segment elevation myocardial infarction: a meta-analysis. Ann Noninvasive Electrocardiol. 2023;28:e13016. https://pubmed.ncbi.nlm.nih.gov/36317727/