An 80-year-old male patient underwent a coronary angioplasty without signs of complications. The day after the procedure, the patient complained of chest pain. The electrocardiogram showed a widespread ST segment elevation. A chest X-ray revealed pulmonary congestion with pleural effusion. There was no significant pericardial effusion detected with an echocardiogram. An administration of diuretics was initiated. After he showed an improvement of symptoms, the administration of diuretics was tapered. However, a deterioration of the oxygenation level was re-observed. The echocardiogram confirmed a cardiac tamponade at this time. The oxygenation level recovered after pericardiocentesis and pleurocentesis. Post-cardiac injury syndrome was suspected to be the cause of this clinical course, and the patient was given an intravenous administration of hydrocortisone followed by an oral administration of prednisone. All clinical parameters started to improve drastically.