The emerging role of low-molecular-weight heparin and antiplatelet therapies in the cardiac catheterization laboratory.

The advent of new pharmacotherapies and interventional devices has exponentially increased the breadth of coronary procedures in a variety of clinical settings. The low-molecular-weight heparins, a new class of antithrombins, offer several advantages over unfractionated heparin as anticoagulants. New antiplatelet agents have also been developed that block components of the platelet aggregation pathway not inhibited by aspirin. The use of these new therapies has the potential to significantly improve the outcome of percutaneous coronary interventions. One low-molecular-weight heparin, enoxaparin, was shown in the ESSENCE trial to be significantly superior to unfractionated heparin in the medical management of unstable angina. Evidence from ESSENCE suggests that enoxaparin used in conjunction with percutaneous revascularization and stenting does not cause increased bleeding. Trials directly comparing the safety and efficacy of heparin and enoxaparin as adjunctive therapies in percutaneous interventions are in progress. In addition, intramural delivery of enoxaparin to achieve a locally high concentration is being investigated for the prevention of restenosis after coronary stenting. Aspirin together with ticlopidine, which inhibits adenosine diphosphate-induced platelet activation, has been shown to be superior to aspirin plus anticoagulation in trials of patients undergoing percutaneous revascularization with stenting. Clopidogrel has emerged as a possible alternative to ticlopidine. Antiplatelet therapies directed against the glycoprotein IIb/IIIa receptor, which plays a critical role in aggregation, have been tested in several clinical trials in patients undergoing percutaneous intervention. The combination of new antiplatelet and new anticoagulant therapies may offer added benefit not seen with the individual agents alone. The safety and effectiveness of such new regimens is currently being investigated in a number of clinical trials.