Rationale for low-molecular weight heparin in coronary stenting

Stents have been as revolutionary for the practice of coronary revascularization in recent years as was the coronary angioplasty balloon 15 years ago, but they have also been associated with a high rate of stent thrombosis. The Enoxaparin and Ticlopidine After Elective Stenting (ENTICES) trial is designed to determine the impact of a reduced anticoagulation regimen on clinical outcomes after stent deployment. Patients are randomly assigned 2:1 to enoxaparin-ticlopidine-aspirin versus the conventional warfarin regimen, and surrogate markers of platelet activation and thrombin activity are measured after 3 days. Three factors underpin ENTICES: (1) a desire to eliminate stent thrombosis, (2) a desire to reduce length of stay after stent placement by avoiding the prolonged hospitalization required with the five-drug regimen of heparin, aspirin, dipyridamole, dextran, and warfarin, and (3) a desire to reduce the bleeding complications associated with the intense anticoagulation typically used in patients receiving stents. Patients are enrolled at seven sites in the United States and include patients with recent infarctions, restenotic lesions, and lesions as large as 30 mm in length. Other trials have also addressed issues concerning anticoagulation in patients undergoing stenting. The Stent Antithrombotic Regimen Study (STARS) trial compared aspirin, aspirin plus ticlopidine, and aspirin plus warfarin in 1650 patients receiving stents. The Aspirin/Ticlopidine vs Low-Molecular Weight Heparin/Aspirin/Ticlopidine High-Risk Stent Trial (ATLAST) is comparing aspirin plus ticlopidine with enoxaparin, aspirin, and ticlopidine in a group of patients at high risk undergoing stenting. The Intracoronary Stenting and Antithrombotic Regimen (ISAR) trial, a trial of ticlopidine, aspirin, and 12 hours of postprocedural heparin versus phenocoumaron on and aspirin after stenting in 517 patients, found a significantly lower incidence of the combined end point of death, myocardial infarction, bypass surgery, or repeated percutaneous transluminal angioplasty in the patients who received antiplatelet therapy, but the patients enrolled were not representative of the usual population undergoing stenting. New trials of stents and their sequelae should include low-molecular weight heparins and should gather cost and outcome data to satisfy capitated systems and managed care. Innovative stent designs may also permit changes in antithrombotic regimens.