Electrocardiographic changes in spontaneous left pneumothorax.

A 25-year-old man was admitted with severe chest pain and an electrocardiogram suggestive of anterior myocardial infarction. Echocardiogram was normal, but chest X-ray showed left-sided pneumothorax. The electrocardiogram showed increasing R-wave amplitude in the days after correction of pneumothorax. Taken in the supine position the electrocardiogram can be misleading in case of pneumothorax or mediastinal emphysema, but the electrocardiogram should be normal if taken in the erect position.