Deferred Optical Coherence Tomography-guided Stenting of a Left Main-left Anterior Descending Artery Bifurcation Lesion in a 25-Year-old Woman With ST-segment Elevation Myocardial Infarction Initially Mimicking Myocarditis: A Case Report

Background & Aims: ST-segment elevation myocardial infarction (STEMI) is uncommon in young women and may present with features that initially suggest an alternative diagnosis. To report a deferred, optical coherence tomography-guided revascularization strategy for a high-thrombus-burden left main-left anterior descending artery bifurcation lesion in a young woman with ST-segment elevation myocardial infarction and a concomitant left ventricular thrombus. Presentation of Case: This case describes a 25-year-old active smoker with no known cardiovascular history presented with prolonged chest pain and diffuse ST-segment elevation with biphasic T waves, initially raising suspicion of acute myocarditis. Echocardiography demonstrated apical akinesia with preserved ejection fraction and a mobile apical thrombus. Coronary angiography with optical coherence tomography (OCT) revealed a severe thrombotic stenosis of the ostial-proximal left anterior descending artery (LAD) extending into the left main (LM) coronary artery, with a distal LAD embolic occlusion. A staged strategy was adopted: therapeutic anticoagulation for one week followed by OCT-guided LM-LAD bifurcation angioplasty, with complete technical and angiographic success (TIMI 3 flow). Aetiological work-up revealed marked hyperhomocysteinaemia; despite a family history suggestive of autoimmune disease, the patient's own thrombophilia and antiphospholipid work-up did not confirm a defined heritable or acquired prothrombotic disorder; only isolated low-titre antinuclear antibodies were detected.