Thrombus age does not differentiate between cardiogenic and atherosclerotic strokes

Interventional stroke therapy made thrombi available for histological analysis. Unfortunately, simple composition aspects such as erythrocyte versus fibrin/platelet rich did not allow a feasible allocation to thrombi's cardiac or carotid origin. Since the mentioned criteria represent characteristics of thrombus age, we used established histological criteria for determining thrombus age in patients who had an atherosclerotic (TOAST (Trial of Org 10172 in Acute stroke Treatment) 1) stroke versus patients who had a cardioembolic (TOAST 2) stroke.

We assessed prospectively data from stroke patients presenting with occlusion of the middle cerebral artery eligible for catheter-based intervention. Besides patient characteristics and stroke workup, extracted thrombi were classified into different age categories according to their cellular to fibrotic transition. Thrombi were collected in an erythrocyte lysing solution to reduce acute clotting effects. Statistics were done with a non-parametric Kolmogorov-Smirnov test.

170 patients were included, of which 50 (38 men; 73±12 years) had a TOAST 1 and 99 (59 women; 75±10 years) had a TOAST 2 categorised stroke. Age, National Institutes of Health Stroke Score (13±7 vs 15±7), Alberta Stroke Program Early CT Score (9±3 vs 9±2), Thrombolysis in Cerebral Infarction Score (2.9±0.2 vs 2.9±0.3), modified Rankin Score on discharge (3.2±2 vs 3.2±2), number of vascular risk factors (0.9±1.4 vs 1.0±1.1) or time span between symptom onset to reperfusion (266±115 vs 260±128 min) remained non-significant. Also, thrombus age did not differ between the groups. The mean age of thrombi was 5-8 days. However, the male-female ratio differed significantly (p<0.0005) between groups, with more men in TOAST 1 group and more women in TOAST 2 group.

Age aspects of thrombi seem not feasible to allow reliable source allocation. However, the young age of thrombi points to a rapid detachment. The difference in sex relation is in line with previous reports.