Acute ST-Segment Elevation Myocardial Infarction Secondary to Neoplastic Infiltration of the Left Anterior Descending...

Neoplastic infiltration of the coronary arteries is an exceptionally rare cause of ST-segment elevation myocardial infarction and may closely mimic atherosclerotic acute coronary occlusion on clinical presentation and angiography.

A 69-year-old woman presented with new-onset angina and worsening chest pain. Electrocardiography demonstrated ST-segment elevation in the anterior leads. Coronary angiography revealed long, smooth severe narrowing of the distal left anterior descending coronary artery, raising suspicion for type 2 spontaneous coronary artery dissection. Given hemodynamic stability and distal vessel involvement, a conservative strategy was pursued. Subsequent computed tomography angiography identified an anterior mediastinal mass infiltrating the anterior left ventricular wall, the left anterior descending coronary artery, 2 diagonal branches, and adjacent costal arches. Transthoracic biopsy confirmed squamous cell carcinoma of unknown primary origin. Care was redirected toward symptom-directed (palliative) management.

This case highlights that anterior ST-segment elevation does not invariably reflect acute atherothrombotic coronary occlusion. Alternative mechanisms, including malignant coronary invasion, should be considered, particularly when angiographic findings are atypical.

Even in the presence of classic ST-segment elevation, nonatherosclerotic mechanisms must be considered. Multimodality imaging plays a critical role in identifying uncommon etiologies such as extrinsic compression or infiltrative malignancy.