Relationship between elevated plasma levels of crosslinked fibrin degradation products (XL-FDP) and the clinical presentation of patients with myocardial infarction

To assess whether the intense thrombosic state known to occur early after the onset of acute myocardial infarction is further exacerbated by impaired intrinsic fibrinolysis, we compared the intensity of fibrinolysis as measured by the level of crosslinked fibrin degradation products (XL-FDP) in plasma with the intensity of thrombosis as assessed by fibrinopeptide A (FPA) in 98 patients with transmural and 14 patients with non-Q wave infarction. Patients without complications of infarction such as shock, mural thrombi, or malignant arrhythmias requiring countershock generally had normal plasma levels of XL-FDP, ≤ 300 nq/ml (81% of those presenting < 8 hours after onset and 66% of those presenting > 8 hours after onset) on admission despite elevated FPA indicative of ongoing thrombosis. In contrast, patients with complications generally had elevated levels of XL-FDP > 300 nq/mi (80% of those presenting early and 62.5% of those presenting late) and 50% of these patients had marked elevations to > 1000 nq/ml. FPA was markedly elevated in patients with complications whether they presented early or late after onset of infarction. Our direct measurements at the time of infarction support previous data indicating that intrinsic fibrinolysis is impaired in patients with acute infarction, despite marked thrombin activity, when complications are not present. However, when complications are present initially, a more exuberant fibrinolytic response is observed perhaps due to thrombosis associated with the complications themselves.