Pneumomediastinum mimicking acute ST-segment elevation myocardial infarction.

Pneumomediastinum is characterized by dissecting air within the connective tissues supporting the mediastinum. This condition has been associated with multiple electrocardiographic abnormalities including T-wave inversion, electrical alternans, loss of R wave progression, and low voltage QRS. We describe a case of pneumomediastinum with electrocardiographic changes mimicking acute ST-segment elevation myocardial infarction. Laboratory studies and echocardiography demonstrated no evidence of myocardial injury, and the electrocardiographic abnormality promptly resolved with resolution of the pneumomediastinum. The apparent ST-segment elevation appeared to be the result of electrocardiographic artifact, possibly related to epidermal stretch synchronous with the cardiac cycles.