Reversible, regional ST-segment elevation due to chylothorax

Chylothorax is an uncommon complication of thoracic surgery and, to our knowledge, has never been documented as a cause of dynamic ST-segment elevation (STE). A 63-year-old woman with history of right pneumonectomy presented with chest pain and regional STE on 12-lead electrocardiogram (ECG). Normal troponin-I and a computed tomography (CT) scan showing a large right hemithoracic fluid collection indicated the unique cause of STE, which resolved after thoracentesis, was pericardial inflammation and cardiac compression from chylothorax. This case emphasizes nuances of ECG interpretation in the context of regional STE and explores the pathophysiology that links chylothorax with acute pericarditis.