TRANSITORY INFLUENCE OF FIBRINOGEN/FIBRIN DEGRADATION PRODUCTS (FDPs) ON PLATELET AGGREGATION

This paper describes a pilot study to investigate the influence of FDPs on platelet aggregation in a small cohort of patients (N = 12) undergoing systemic thrombolytic therapy with streptokinase (600,000 I.U. or 1,500,000 I.U. delivered over 30 minutes) for acute myocardial infarction.

Serial pre- and post-therapy blood samples were anticoagulated with sodium citrate, and whole blood aggregation studies carried out over 24 hours using a Crono-log 540 aggregometer and the standard adenosine diphosphate (ADP), adrenalin (A), collagen (C) and ristocetin (R) aggregating agents.

Results, in the form of mean percentage voltage change from baseline voltage change, measured at 8 minutes after addition of aggregant, are presented for the cohort at times in Figure 1. Serial aggregometry tracings for one representative patient are shown in Figure 2.

Clearly comparison of the 1 hour and 18 hour results for each aggregating agent shows a variable but consistent return towards baseline (at FDP < 8 μg/ml) as the FDP concentration drops. This implies that, provided the same platelet population is involved, there is no generalised permanent platelet defect consequent on systemic STK therapy. Coulter counter measurements do not indicate the increase in platelet number that would suggest a large influx of new platelets.