Fibrin formation and platelet aggregation in patients with acute myocardial infarction: effects of intravenous and subcutaneous low-dose heparin.
Fibrinopeptide A (FPA) and beta thromboglobulin (BTG) were measured in 42 patients with acute myocardial infarction (AMI) allocated on admission to one of three groups: 14 patients received a heparin bolus injection of 5000 IU intravenously followed by a 2-hour intravenous infusion (830 IU/hr) (group 1), 14 patients received a heparin bolus of 5000 IU subcutaneously (group 2), and the remaining 14 patients received no anticoagulant treatment (group 3). In group 1 the initially elevated FPA level of 5.8 +/- 1.8 ng/ml dropped to 2.0 +/- 1.5 ng/ml 30 minutes after the intravenous heparin bolus injection of 5000 IU (p less than 0.001) and returned to normal (1.9 +/- 0.8 ng/ml) in 8 of 14 patients. The initially elevated BTG level of 64 +/- 21 ng/ml did not change significantly during intravenous heparin treatment, whereas there was a rapid but only transitory increase in platelet factor 4, (PF4) from 25 +/- 9 to 74 +/- 16 ng/ml (p less than 0.01) after the intravenous heparin bolus. In group 2 the initial FPA of 5.0 +/- 2.3 ng/ml was similarly elevated as in group 1 and dropped to 2.7 +/- 1.7 and 3.3 +/- 1.5 ng/ml 2 and 4 hours after 5000 IU subcutaneously (p less than 0.05), whereas 6 and 8 hours after subcutaneous heparin bolus the mean FPA levels were 4.2 +/- 1.7 and 5.5 +/- 2.0 ng/ml and no more significantly different from the initial FPA values. BTG and PF4 did not change significantly after the subcutaneous heparin bolus. In group 3 the initially elevated mean FPA level of 4.9 +/- 2.4 ng/ml did not change significantly during the first 8 hours after admission, whereas the FPA level 24 hours after admission was 8.4 +/- 3.9 ng/ml and higher than the initial value (p less than 0.01). We conclude that heparin may reduce the elevated FPA level in plasma found in patients with AMI; however, neither subcutaneous nor intravenous heparin in a dosage frequently used is sufficient to consistently normalize the elevated rate of fibrin formation found in these patients.
D000368:Aged; D001609:Beta-Globulins / Q000032:analysis*; D001780:Blood Coagulation Tests; D005260:Female; D005337:Fibrin / Q000378:metabolism*; D005340:Fibrinogen / Q000032:analysis*; D005344:Fibrinopeptide A / Q000032:analysis*; D006493:Heparin / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D007263:Infusions, Parenteral; D007279:Injections, Subcutaneous; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000188:drug therapy; D010974:Platelet Aggregation; D010978:Platelet Factor 4 / Q000032:analysis; D013997:Time Factors; D001620:beta-Thromboglobulin / Q000032:analysis*
D001609:Beta-Globulins; D001620:beta-Thromboglobulin; D005344:Fibrinopeptide A; D010978:Platelet Factor 4; D005337:Fibrin; D005340:Fibrinogen; D006493:Heparin