BACKGROUND
Blunt thoracic trauma can produce chest wall pain that obscures concurrent acute coronary syndrome. This report describes delayed recognition of inferior ST-segment elevation myocardial infarction (STEMI) after blunt chest trauma with rib fractures and emphasizes the limitations of attributing the event to a trauma-specific coronary mechanism.
CASE REPORT
A 56-year-old man developed persistent chest pain immediately after an anterior chest impact. At a local hospital, computed tomography showed fractures of the left seventh to ninth ribs, and no electrocardiogram (ECG) was initially obtained. Approximately 11 hours after injury, the first ECG showed inferior STEMI. He was transferred 13 hours after symptom onset; his pain had improved, he was hemodynamically stable, and repeat ECG showed ST-segment resolution with Q-wave formation. The cardiac troponin I level was 8.05 ng/mL on arrival and later peaked at 48 ng/mL. Coronary angiography on hospital day 10 showed approximately 90% stenosis of the proximal-to-mid right coronary artery. After balloon predilatation, optical coherence tomography showed a complex lipid-rich lesion with thrombotic features and localized dissection. Because imaging was performed after predilatation, the original mechanism could not be established. Percutaneous coronary intervention restored Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow. Cardiac magnetic resonance imaging 5 days later confirmed an ischemic-pattern infarction in the right coronary artery territory with microvascular obstruction.
CONCLUSIONS
Persistent or unexplained chest pain after blunt thoracic trauma warrants early ECG and troponin testing, even when rib fractures are present. Post-predilatation intracoronary imaging can characterize a culprit lesion but cannot, by itself, establish that trauma caused plaque disruption or coronary dissection.

Keywords: Wounds, Nonpenetrating; Myocardial Infarction; ST Elevation Myocardial Infarction; Coronary Vessels; Tomography, Optical Coherence; Magnetic Resonance Imaging