Thrombin formation and fibrinolytic activity in patients with acute myocardial infarction or unstable angina: in-hospital course and relationship with recurrent angina at rest

OBJECTIVES The goal of this study was to investigate possible differences in thrombin generation or fibrinolytic capacity in patients with unstable angina (UA) or acute myocardial infarction (AMI) with or without recurrent angina at rest. BACKGROUND Angina at rest in patients with AMI or UA is generally produced by a reduction in coronary flow, but it is unclear whether patients with or without this event differ in their thrombin generation or in their fibrinolytic capacities, which might influence the course of the culprit lesion. METHODS Thrombin-antithrombin complex (TAT), D-dimer, fibrinogen and plasminogen activator inhibitor (PAI-1) antigen plasma levels were determined in 40 patients with AMI and in 23 with UA on admission, at 10 days and at three months. RESULTS First day values for TAT, fibrinogen and D-dimer were comparable in patients with AMI and in those with UA. At 10 days they increased significantly in each group, and at 3 months they decreased to a similar extent. First day PAI-1 levels, however, were highest in both groups and declined in AMI patients at 10 days and at three months, whereas they also decreased at 10 days in UA patients but not any further at three months. Ten patients with AMI (25%) and 12 with UA (52%) developed in-hospital angina at rest. First day values for TAT, fibrinogen and D-dimer were similar in patients with or without angina, but PAI-1 levels were higher in the former subset (p < 0.008). At 10 days, however, TAT (p < 0.013) and D-dimer (p < 0.013) were higher in patients who developed angina than in those who did not. CONCLUSIONS The higher inhibition of fibrinolytic activity in the first day in patients with AMI or UA who will develop recurrent angina suggests that maintenance of a prothrombotic status may contribute to its mechanisms, perhaps by preventing passivation of the culprit thrombus/plaque. This is consistent with greater thrombin generation and greater levels of fibrynolitic products at 10 days observed in these patients compared with those who attain early stability.