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.