Summary
Ninetyseven men with unstable coronary artery disease (CAD), i.e. unstable angina or a non Q-wave myocardial infarction, entered a double-blind placebo-controlled study with heparin intravenously 30,000-40,000 U daily. Platelet function was evaluated as ex vivo aggregation toward collagen and ADP and as the platelet inhibitory effect of prostacyclin, before and after 5 days of treatment. Heparin increased aggregation induced by ADP 1 εM from 39.6 ± 3.1% to 52.1 ± 4.1% (p = 0.014) and reduced the inhibition of aggregation by prostacyclin 1.0 ng/ml from 59.6 ± 3.7% to 39.3 ± 5.6% (p <0.001). No changes occurred in the placebo group.
Thus, treatment with heparin enhances the platelet sensitivity to ADP and decreases the platelet inhibitory effect of prostacyclin in men with unstable CAD. Concomitant treatment with acetylsalicylic acid abolishes the increased reponse to ADP, but does not seem to influence the interaction between heparin and prostacyclin.
