The 'bystander' stenosis dilemma: a case against revascularization in a territory of extensive myocardial scar-a case report.

Background: Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a working diagnosis that requires careful exclusion of alternative ischaemic mechanisms. This case highlights a MINOCA mimic: a silently evolved, spontaneously reperfused transmural infarction, where cardiac magnetic resonance (CMR) was decisive for clarifying the mechanism and guiding management. Case summary: A 38-year-old man with heavy smoking as his sole cardiovascular risk factor underwent a routine evaluation. ECG demonstrated features of a large anterior infarction, while cardiac biomarkers were negative. Echocardiography showed severe left ventricular dysfunction and a large apical thrombus. Angiography revealed a partially recanalized mid-left anterior descending (LAD) and a severe diagonal stenosis without an obvious culprit lesion. CMR demonstrated a large transmural, non-viable LAD territory infarction with microvascular obstruction. A genetic panel revealed polymorphisms potentially contributing to a prothrombotic condition. Given the absence of viability, revascularization was deferred. At 6-month follow-up, the patient remained asymptomatic, with persistent apical thrombus despite anticoagulation. Discussion: Silent, spontaneously reperfused infarction may mimic MINOCA when angiography reveals only mild or intermediate lesions. CMR is essential for identifying non-viable myocardium, avoiding misclassification, and guiding management. Young patients with extensive infarction may benefit from targeted thrombophilia evaluation.