Coronary artery stents, particularly drug-eluting stents (DES), are used in the majority of patients who undergo percutaneous coronary intervention (PCI) to improve symptoms in patients with obstructive coronary artery disease. They function both to prevent abrupt closure of the stented artery soon after the procedure as well as to lower the need for repeat revascularization compared to balloon angioplasty alone (formerly referred to as percutaneous transluminal coronary angioplasty).
Stent restenosis and stent thrombosis are potential complications of coronary artery stenting; their incidence is highest in the first year after PCI. Stent restenosis, which occurs more frequently with bare metal stents (BMS) than DES, may occasionally present as an acute myocardial infarction (MI).
Stent thrombosis is an uncommon but serious complication that often presents as death and is almost always accompanied by MI, usually with ST-segment elevation. The cumulative incidence of stent thrombosis appears to occur with similar frequency in patients with BMS or DES, as long as patients are treated with dual antiplatelet therapy (DAPT) for the recommended duration for the particular stent. DAPT (aspirin plus platelet P2Y12 receptor blocker) significantly lowers the risk of stent thrombosis. In the absence of DAPT, the period of high risk for stent thrombosis is longer with DES than BMS due to a delay in neointimal coverage. (See "Coronary artery stent thrombosis: Incidence and risk factors", section on 'Comparison of DES and BMS' and "Coronary artery stent thrombosis: Incidence and risk factors", section on 'Very late stent thrombosis'.)
This topic will discuss the use of antiplatelet therapy to reduce the risk of adverse outcomes such as MI or death after stenting. Issues related to the incidence and timing of stent thrombosis and the use of antiplatelet drugs in the periprocedural period are discussed separately. (See "Coronary artery stent thrombosis: Incidence and risk factors" and "Antithrombotic therapy for percutaneous coronary intervention: General use", section on 'Aspirin' and "Antithrombotic therapy for percutaneous coronary intervention: General use", section on 'P2Y12 receptor blockers'.)
DEFINITIONS OF STENT THROMBOSIS AND RESTENOSIS
After a successful procedure, coronary stents can fail to maintain vessel patency due to stent thrombosis or stent restenosis. Stent thrombosis is an abrupt thrombotic occlusion of a previously patent stent. It is a serious complication that presents as sudden death or myocardial infarction (MI) in most patients. Despite successful repeat revascularization, the six-month mortality is high. Earlier randomized clinical trials that evaluated the frequency of stent thrombosis did not use a uniform definition in their protocols, leading to difficulty in comparing the different studies. The following definitions were used in most studies and will be referred to as the historical definition :