Increased plasma concentration of cross-linked fibrin polymers in acute myocardial infarction.

Thrombin cleaves fibrinopeptides from fibrinogen, converting it to fibrin monomer, and activates factor XIII, which catalyzes the formation of intermolecular epsilon-(gamma-glutamyl)-lysine bonds to stabilize the fibrin polymer. The formation of factor XIIIa-catalyzed fibrin polymers during clotting of plasma and purified fibrinogen in vivo was followed by a sodium dodecyl sulfate agarose gel technique, and an increase in both amount and size of gamma-chain cross-linked polymers was demonstrated before visible clot formation. Plasma from patients presenting with acute myocardial infarction showed increases in the plasma concentration of fibrin polymer and in the proportion of total fibrinogen present as polymer, as determined by a quantitative adaptation of the electrophoretic technique. The plasma concentration in patients with subendocardial or transmural myocardial infarction showed significant (p less than .005) increases to 4.0 +/- 1.0% and 3.6 +/- .8%, respectively, as compared with the concentration in normal plasma (0.8 +/- 0.1%). There was no difference in plasma concentration in samples from patients with transmural compared with those with subendocardial myocardial infarction. This study provides the first demonstration of factor XIIIa cross-linked fibrin polymers in thrombotic disease and indicates the presence of increased activity of both thrombin and factor XIIIa in patients with acute myocardial infarction.