Oral anticoagulation therapy during and after coronary angioplasty.

Coronary Angioplasty To the Editor: We read with great interest the recent article by ten Berg et al1 on oral anticoagulant therapy during and after coronary angioplasty. In previous trials on late restenosis after percutaneous transluminal coronary angioplasty (PTCA), oral anticoagulants were not more effective than aspirin as adjunctive treatment after PTCA. However, in those trials, anticoagulant therapy was only started after PTCA. The study by ten Berg et al1 revealed that coumarin therapy started before PTCA decreased the incidence of late thrombotic events and improved 6-month angiographic outcome. Previously, we investigated changes in blood coagulation and platelet activation in the coronary sinus of patients who underwent PTCA.2 Blood samples were drawn from the coronary sinus immediately before and after, as well as 4 and 24 hours after PTCA. Despite adequate administration of heparin and aspirin, tissue factor levels in the coronary sinus blood showed significant increases 4 and 24 hours after PTCA, and levels of thrombin-antithrombin III complex, a specific and sensitive marker for thrombin generation, also showed a significant increase 24 hours after PTCA. Furthermore, a significant positive correlation was found between changes in tissue factor levels 24 hours after PTCA and the late loss index 6 months after the procedure.3 However, no significant changes in the levels of -thromboglobulin and platelet factor 4, which are markers for platelet disruption and activation, were found after PTCA. These findings suggest that the systemic administration of heparin and aspirin prevents platelet activation but cannot completely inhibit the activation of the hemostatic system in coronary circulation, and this local activation of coagulation plays a critical role in late restenosis after PTCA. Mural thrombosis, which plays a causal role in the development of restenosis, can only be partly prevented by the routine use of a combination of heparin and aspirin. Our observations support the conclusion by ten Berg et al1 that the intensity and duration of anticoagulation are essential to reduce thrombotic complications after PTCA.