Summary
The aim of this study was to determine the association of tPA antigen levels with
CAD and ischaemic stroke and whether associations are independent of levels of PAI-1
antigen. In subjects with CAD (n = 247) tPA was associated with the number of coronary
arteries with ≥50% stenosis, but this association was lost after adjustment for PAI-1,
which was found to be the largest determinant of tPA levels in linear regression models
and accounted for as much as 38% of the variation in levels. Levels of tPA were significantly
higher in patients with a history of MI compared with those without, even after adjustment
for covariates and PAI-1 (MI: 10.0 [9.4-10.6] ng/ml; no MI: 8.9 [8.5-9.4] ng/ml, p
= 0.004). In a logistic regression model comparing patients with MI to patients without
MI, the odds ratio for tPA levels in the upper quartile compared with the lowest quartile
was 2.03 (1.33-3.10). Levels of tPA in subjects with ischaemic stroke (n = 338) were
significantly higher than age matched healthy control subjects (n = 366) and again
this difference remained after adjustment (patients: 10.4 [9.9-10.9] ng/ml; controls:
9.0 [8.7-9.3] ng/ml, p <0.0001). In a logistic regression model comparing patients
with ischaemic stroke to healthy control subjects the odds ratio for tPA in the upper
quartile compared with the lowest quartile was 4.23 (3.02-5.92). These data suggest
that the associations of tPA with acute thrombosis are independent of levels of PAI-1
but the mechanisms whereby enhanced fibrinolysis may predis-pose to thrombosis remain
unclear.