Coronary artery perforation is a rare complication of percutaneous coronary intervention, but can result in cardiac tamponade and is thus potentially life-threatening. It is well recognized that the use of hydrophilic wires during interventional procedures increases the risk of coronary perforation. We report two cases in which a particular looping configuration was suspected of causing vessel laceration with subsequent development of pericardial effusion and tamponade. In one case, tamponade occurred several days after the index procedure, mimicking acute myocardial infarction. In the second case, tamponade was successfully treated with immediate pericardial drainage, but tamponade recurred several days later.