- Common electrocardiogram (ECG) changes associated with left-sided pneumothorax include right axis deviation, reduced R-wave amplitude in precordial leads, QRS alterations (amplitude changes), and T-wave inversions. Few reports exist of ST-segment elevations or changes suggestive of acute myocardial infarction (AMI), and these involve older patients with tension pneumothorax and previous coronary heart disease. We report on a young man with no significant medical history, presenting with left-sided spontaneous pneumothorax and ECG changes that included ST-segment elevations and T-wave inversions in the precordial leads, reminiscent of AMI. All changes resolved after decompression of the pneumothorax. On the basis of the patient’s presenting symptoms, response to therapy, and our review of the literature, we propose a number of possible mechanisms explaining his electrocardiographic findings.