In cardiology, a<unk>  is a stent (a scaffold) placed into narrowed, diseased coronary arteries that slowly releases a<unk>  to block cell proliferation. This prevents scar-tissue–like growth that, together with clots (thrombus), could otherwise block the stented artery.
Heart attacks, or myocardial infarctions, are major causes of death and disability; they result when a portion of heart muscle dies from inadequate blood flow. This typically occurs at sites where coronary arteries are already narrowed and damaged. Fat and cholesterol deposition as well as inflammation in the arterial wall cause injury; excessive tissue growth and additional cholesterol deposition occur.  Clots can then occur when these plaques rupture releasing their noxious contents in to the passing blood flow.  These noxious chemicals from within the plaques stimulate blood clotting elements to initiate thrombus or clot, formation. These narrowings are prone to being suddenly blocked, or a piece may break off and block a smaller branch downstream (embolism). If blood flow can be restored early enough, permanent damage can be prevented, and pre-emptive manipulation can prevent heart attacks from occurring in the first place.
Coronary artery stents, typically a metal framework, can be placed inside the artery to help keep it open. However, as the stent is a foreign object (not native to the body), it incites an immune response. This may cause scar tissue (cell proliferation) to rapidly grow over the stent. In addition, there is a strong tendency for clots to form at the site where the stent damages the arterial wall. Since platelets are involved in the clotting process, patients must take antiplatelet therapy afterwards, usually clopidogrel for six months and aspirin indefinitely. However, the antiplatelet therapy may be insufficient to fully prevent clots; these and the cell proliferation may cause the standard (“bare-metal”) stents to become blocked.<unk> s were designed to lessen this problem; by releasing an antiproliferative<unk>  <unk> s typically used against cancer or as immunosuppressants), they can help avoid this in-stent restenosis (re-narrowing).<unk> s have been shown to be superior to traditional stents ("bare-metal stents") in reducing short-term complications.  Their long term effectiveness compared to traditional stents or coronary bypass grafting is under scrutiny by the FDA.
Drug eluting stent
Hybrid coronary revascularization
Bare metal stent
Staged PCI
Endovascular surgery
Bioabsorbable stents
Rotational atherectomy
Percutaneous coronary intervention