Comparison of activated partial thromboplastin time to activated clotting time for adequacy of heparin anticoagulation just before percutaneous transluminal coronary angioplasty

Abstract

Patients must undergo systemic anticoagulation with heparin before undergoing percutaneous transluminal coronary angioplasty (PTCA) to minimize the risk of intracoronary thrombus formation and acute vessel occlusion. Although most patients undergo anticoagulation just before PTCA, a subset consisting of those who have received thrombolytic therapy and those with unstable angina are frequently brought to the interventional laboratory already being treated with a continuous heparin infusion. Such anticoagulation is thought to reduce the risk of spontaneous coronary thrombosis. Heparin anticoagulation is typically monitored using activated partial thromboplastin time (aPTT). There are several other laboratory methods, however, available for evaluating the anticoagulant effect of heparin. The activated clotting time (ACT) is another frequently used parameter 1 that is rapidly obtainable in an on-line fashion. Bedside kits have also become available for the rapid determination of aPTT. This study determines if therapeutic aPTT in patients maintained on a continuous heparin infusion for > 24 hours before PTCA is indicative of an adequate level of preprocedural anticoagulation as assessed by ACT.