Effect of anticoagulation on the age distribution of thrombi in stroke patients with non-valvular atrial fibrillation

Objective: Atrial fibrillation (AF) is an important risk factor for cerebral stroke. We studied whether anticoagulation affected histological age aspects of thrombi retrieved from patients with AF-related stroke. Methods: In this monocentric study, AF patients according to criteria (Trial of Org 10 172 in Acute Stroke Treatment) with occlusion of the middle cerebral artery were prospectively and consecutively included. They were assigned to three groups: anticoagulation naïve, adequately anticoagulated, and with paused anticoagulation. In addition to patient characteristics and stroke workup, extracted thrombi were histologically classified into different age categories according to their cellular to fibrotic transition. Results: A total of 244 patients were studied, from which 136 (58 females; 78±9 years) were drug naïve, 34 (15 females; 78±8 years) had paused anticoagulation, and 74 (29 females; 79±9 years) were adequately anticoagulated. Groups did not differ regarding stroke severity at admission (modified Rankin Score, mRS: median, IQR: 5 (1); 5 (0.75); 5 (1), respectively; National Institutes of Health Stroke Scale (NIHSS): median, IQR: 16 (8); 16 (8); 16 (7), respectively). Due to thrombectomy, median scores declined in all groups without differences between groups (mRS: 3.5 (4); 4 (4); 4 (4); NIHSS: 5 (16); 11 (31); 7 (18)). With a small but significant effect (p=0.043), thrombus age differed between the groups due to significantly younger thrombi in the paused medication group as compared with the adequately anticoagulated patients. Conclusions: Thrombus age distribution seems not to be affected by anticoagulation. The younger thrombi in patients with paused anticoagulation possibly point to a rebound effect needing further investigations.