ST-Segment Elevation Caused by Lung Cancer Mimicking STEMI

ST-segment elevation on an electrocardiogram (ECG) is a hallmark of acute ST-segment elevation myocardial infarction (STEMI). However, thoracic malignancies can produce electrocardiographic patterns identical to acute ischemia through direct myocardial invasion or extrinsic compression, creating a significant diagnostic dilemma.

We present 2 patients with primary lung cancer who exhibited ECG findings strongly mimicking acute STEMI. Case 1 involves a 70-year-old man presenting with acute chest pain. His ECG demonstrated anterolateral ST-segment elevation with diffuse PR depression. Coronary angiography revealed nonobstructive disease with mildly elevated troponin. Multimodality imaging identified a hypermetabolic mass externally compressing the anterolateral myocardium. Case 2 describes an 80-year-old man presenting with dizziness and ST-segment elevation in leads V₁ to V₃. Imaging revealed a large thoracic mass compressing the right ventricular outflow tract and left pulmonary artery without coronary occlusion. After appropriate oncological treatment, the patient demonstrated partial tumor regression on follow-up positron emission tomography-computed tomography, which correlated with the complete resolution of the initial ECG abnormalities.

These cases demonstrate that ST-segment elevation in patients with advanced malignancy may arise from myocardial tumor invasion or extrinsic compression rather than acute coronary thrombosis, underscoring the importance of careful correlation between clinical findings and multimodality cardiac imaging.