Betathromboglobulin And Fibrinopeptide A In Exercise-Induced Myocardial Ischemia

Abstract

To investigate the role of platelet release and thrombin activity in exercise-induced myocardial ischemia, plasma betathromboglobulin (BTG) (mean ± SD, ng/ml) and plasma fibrinopeptide A (FpA) (pmol/ml) were measured before and after treadmill testing using the Bruce Protocol in normal subjects and 77 patients with suspected coronary artery disease (CAD). In normals, there was no difference between pre and post-exercise BTG (31 ± 9 v 27 ± 9) nor FpA (1.0 ± 0.8 v 0.8 ± 1.3). In 31 patients with a negative exercise test there was no difference in mean pre and postexercise BTG conc (36 ± 14 v 41 ± 33; p>0.1), but there was an increase in mean FpA. Ten of the patients with negative exercise tests had documented CAD by coronary angiography and their FpA rose from 2.1 ± 1.8 to 4.3 ± 4.4 (p < 0.05) after treadmill testing; 6 had a significant increase in FpA and 4 in BTG. In 46 patients with an abnormal exercise test (>1 mm ST-segment depression) there was an increase in mean BTG post-exercise (pre 42 ± 17 v post 60 ± 60; (p<0.005) and the increase was significant in 32%. The increase was more common in those patients who developed chest pain during the test. Plasma FpA increased from 1.6 ± 1.2 to 4.1 ± 4.6 in the patients with a positive test (p<0.005) with an increase in 33% of patients. These data indicate that exercise-induced myocardial ischemia is associated with platelet release and thrombin activity in patients with CAD. Increase in BTG after treadmill testing occurred mainly in patients with a positive test who developed chest pain. The FpA in patients with CAD increased in patients with either positive or negative treadmill tests. Increase in FpA post-exercise appears to be a more sensitive indicator of CAD than BTG.