Microembolic signals at 48 hours after stroke onset contribute to new ischaemia within a week

Background and aim: We investigated whether new ischaemic lesions (NIL) on follow-up diffusion weighted magnetic resonance imaging (DWI) are associated with microembolic signals (MES) within 24 h or at 48 h after stroke onset. Methods: Patients had acute ischaemic stroke and were studied within 24 h of onset. Transcranial Doppler ultrasonography (TCD) was prospectively examined twice, within 24 h and at 48 h after onset. DWI was conducted twice, on admission and on day 7. NIL were defined as the presence of hyperintense lesions undetected on initial DWI. Results: 125 patients were consecutively enrolled from November 2004 to March 2006. TCD detected MES in 49% within 24 h and in 29% at 48 h after onset. In 27 patients with small vessel disease, MES were found in 8 (30%) patients within 24 h and in 5 (19%) patients at 48 h after stroke onset. In contrast, in 20 patients with large vessel disease, 11 (55%) patients within 24 h and 7 (35%) at 48 h had MES. Follow-up DWI detected NIL in 28 of 125 patients (22%) and NIL were significantly more frequent in MES positive patients (42%) than in MES negative patients at 48 h (15%; p= 0.002). MES at 48 h (OR 3.9; 95% CI 1.5 to 10; p= 0.005), atrial fibrillation (OR 3.6; 95% CI 1.3 to 11; p= 0.013) and arterial lesions (OR 4.3; 95% CI 1.5 to 12; p= 0.007) represented independent factors for NIL. Conclusion: The presence of MES at 48 h, atrial fibrillation and arterial lesions were associated with recurrence of cerebral ischaemia on DWI.