EARLY-ONSET OF IMMUNOLOGICAL HEPARIN-INDUCED THROMBOCYTOPENIA IN ACUTE MYOCARDIAL-INFARCTION

We studied five patients who developed a decrease in platelet count of more than 30 000 x 10(6)/l within 24 h of heparin treatment and direc t percutaneous transluminal coronary angioplasty and/or intracoronary thrombolytic therapy among 38 consecutive patients with acute myocardi al infarction (AMI). Anti-platelet factor 4 (PF4)-heparin complex anti bodies were detected in the sera of these five patients, although they had never previously been exposed to heparin. These patients might ha ve had specific antibodies before heparin treatment. PF4 might be rele ased from activated platelets and bind to endogenous heparin-like mole cules, and antibodies with cross-reactivity to the PF4-heparin complex may have been generated by the endogenous complex before the first he parin treatment. We conclude that it is worthwhile to check the platel et count and screen for anti-PF4-heparin complex antibody in advance t o prevent thrombotic complications due to heparin treatment in patient s with AMI.