INVERSE CORRELATIONS BETWEEN PLASMA BETA-THROMBOGLOBULIN LEVEL AND: (1) TIME FROM ONSET OF ACUTE MYOCARDIAL INFARCTION (2) MEAN TIME TO CLOT LYSIS FOLLOWING SYSTEMIC STREPTOKINASE

The platelet specific protein, beta-thromboglobulin (²-TG) is released into the circulation when blood platelets undergo the release reaction as in platelet aggregation and clotting. This paper describes a study of a cohort of patients (N = 40) in which ²-TG was serially assayed by a radioimmunassay technique at various times from the onset of acute myocardial infarction.

It shows a negative correlation (R = -0.76, p = 0.01) between initial ²-TG level and time elapsed since the onset of symptoms. Furthermore, patients fell into two groups - those with high initial or rising levels, and those in whom the levels were not elevated and did not rise. Both groups underwent thrombolytic therapy with intravenous streptokinase, the former manifesting significantly earlier ECG evidence of re-perfusion. Respective mean lysis times and standard errors of the mean (hours) were 0.798 (0.139) and 3.490 (0.498) with p = 0.001 on t-testing. Clearly when the clotting process is well established it is much more difficult to lyse the clot. ²-TG is a marker for the age of the clot in that it reflects the platelet secretion in vivo that accompanies the early stages of clot formation.

We conclude that ²-TG assay is not purely an esoteric research technique but has everyday clinical application in differentiating between early streptokinase-induces lysis, when some at-risk myocardium is still viable, and later spontaneous recanalization. Angiography cannot make this distinction.