Prolonged procoagulant activity on overstretch-injured coronary arteries in pigs

This study was designed to assess the time course and nature of the vascular procoagulant response after 1.5-fold balloon overstretch injury of the coronary arteries in pigs. Arteries were excised for chromogenic assay of bound factor (F)Xa and thrombin at 24 h, 3 days, I week, or 2 weeks after injury. FXa at the site of injury remained elevated for I week (4.9+/-5.9 mug cm(-2), n=10), compared with non-injured control arteries (0.4+/-0.2 mug cm(-2), n=18 P=0.00025), while thrombin was increased only at 24 h. Tissue factor protein was abundant in non-injured coronaries (10+/-6 ng mug(-1) total protein, n=9) and levels were unchanged by injury (13+/-11 ng mug(-1), n=6) or 24-h administration of tissue factor pathway inhibitor (16+/-6 ng mug(-1), n=6). Persistent tissue factor-mediated procoagulant activity may explain the need for prolonged anticoagulation to attenuate neointimal formation after balloon-induced coronary injury.