For example, humanplaques without fissures or ulceration contain large amounts of fibrin that is localizedthroughout,5 while earlyplaques contain clotting factors and thrombin:antithrombin (TAT) complexes.6 Indeed, levels of TAT complexes predictthe severity of coronary atherosclerosis.7 Furthermore, inducing a hypercoagulable state in ApoE mice by knockingout Heparin Cofactor II8 or tissuefactor pathway inhibitor9 increasesplaque size. Here, TAT is linked to coronary atherosclerosis.