A coronary stent is a small tube (typically of metal framework) placed in the coronary arteries that supply the heart, to keep the arteries open in the treatment of coronary heart disease. It is used in a procedure called percutaneous coronary intervention (PCI). Stents reduce chest pain and have been shown to improve survivability in the event of an acute myocardial infarction. Similar stents and procedures are used in non-coronary vessels e.g. in the legs in peripheral artery disease.