Percutaneous coronary intervention is one of the most frequently performed therapeutic procedures in medicine. The latest review in our Drug Therapy series provides an overview of currently available devices, summarizes randomized evidence, and outlines clinical indications for use.
The use of balloon angioplasty, which was limited by abrupt vessel closure owing to dissections and restenosis, prompted the development of stents to maintain lumen integrity. Coronary stents improved procedural safety and efficacy and eliminated the need for surgical standby. However, stent-mediated arterial injury elicited neointimal hyperplasia, leading to restenosis and the need for repeat revascularization in up to one third of patients.
• Which drug-eluting stents are currently available?
Early-generation stents released sirolimus or paclitaxel and had stainless-steel platforms, whereas new-generation stents release everolimus or zotarolimus and feature cobalt-chrome or platinum-chrome platforms with thinner strut thickness and more biocompatible, durable polymer coatings. These new-generation stents have almost completely replaced paclitaxel-eluting stents in clinical practice, and sirolimus-eluting stents are no longer manufactured.
• How have stents that release sirolimus or paclitaxel compared to bare-metal stents?
Stents that release sirolimus or paclitaxel have been associated with an increased risk of very late stent thrombosis, as compared with bare-metal stents. In contrast, the risks of death and myocardial infarction with sirolimus-eluting and paclitaxel-eluting stents were similar to the risks with bare-metal stents, which may be explained by the low incidence of very late stent thrombosis (annual rate, 0.2 to 0.6%) and the compensatory effects of a reduced risk of restenosis, which is manifested as myocardial infarction in 10 to 20% of patients.
Morning Report Questions
Q: What are the recommendations for drug-eluting stents in patients with stable coronary disease and in those with acute myocardial infarction?
A: According to the 2011 guidelines of the American College of Cardiology-American Heart Association for percutaneous coronary interventions, use of drug-eluting stents has a class IA recommendation for patients undergoing elective percutaneous revascularization who are able to adhere to a prolonged regimen of dual antiplatelet therapy. In the Evaluation of Xience-V Stent in Acute Myocardial Infarction (EXAMINATION) trial, everolimus-eluting stents were found not to be superior to bare-metal stents with respect to the composite end point of death, myocardial infarction, or any further revascularization among patients with acute infarction. However, everolimus-eluting stents reduced the risk of target-lesion revascularization as well as stent thrombosis, as compared with bare-metal stents. In patients with acute infarction, the use of drug-eluting stents has a class IA recommendation if patients are able to comply with a prolonged regimen of dual antiplatelet therapy.
Q: What are the recommendations for anti-platelet therapy after the placement of a drug-eluting stent?
A: Dual antiplatelet therapy with aspirin and a P2Y12 inhibitor reduces the risk of ischemic events after stent placement; however, the duration of therapy remains a matter of debate. Clopidogrel in addition to aspirin for at least 12 months has been shown to reduce the composite end point of death, myocardial infarction, or stroke, as compared with aspirin alone, among patients with acute coronary syndromes. The more potent drugs prasugrel and ticagrelor have been shown to be superior to clopidogrel in patients presenting with acute coronary syndromes. However, long-term dual antiplatelet therapy significantly increases the risk of bleeding. Current guidelines support a 12-month regimen of dual antiplatelet therapy in patients treated with drug-eluting stents (class IB) on the basis of observational data pointing to the risk of stent thrombosis after premature discontinuation of clopidogrel.