New Appearance of Extraischemic Microbleeds on T2*-Weighted Magnetic Resonance Imaging 24 Hours After Tissue-type Plasminogen Activator Administration
Background and Purpose—It is unknown whether new-extraischemic microbleeds (new-EMBs) develop rapidly after tissue-type plasminogen activator (tPA) infusion. We hypothesized that new-EMBs may develop rapidly after tPA infusion using T2*-weighted MRI (T2*) and investigated the frequency and clinical factors associated with new-EMBs.
Methods—Patients with acute stroke within 3 hours of onset who were treated with tissue-type plasminogen activator (tPA) were studied prospectively. T2* was performed before and 24 hours after tPA therapy. Independent clinical factors associated with new-EMBs development were examined using multivariate logistic regression analysis.
Results—A total of 224 patients (121 men; mean age, 76.2±10.6 years) were enrolled in the present study. MBs before tPA infusion were observed in 72 (32.1%) patients. Within 24 hours after tPA infusion, 6 (2.7%) patients had symptomatic intracranial hemorrhage (extraischemic [n=4], and hemorrhagic transformation [n=2]). Follow-up T2* revealed asymptomatic new-EMBs in 11 (4.9%) patients and hemorrhagic transformation in the infarcted area in 65 (29.0%). The total and mean number of new-EMBs were 23 and 1.6±1.3, respectively. Patients with new-EMBs more frequently had symptomatic extraischemic hemorrhage than those without new-EMBs (27.3% [3/11] versus 0.5% [1/213]; P=0.0003). However, the frequency of hemorrhagic transformation was not different between patients with and without new-EMBs (27.3% versus 29.1%; P=0.9999). Multivariate logistic regression demonstrated that the presence of MBs before tPA infusion was the only independent factor associated with new-EMBs (odds ratio, 10.6; 95% confidence interval, 20.68–54.279; P=0.0046).
Conclusions—New-EMBs occurred rapidly after tPA infusion in 4.9% of patients. The presence of MBs before tPA therapy was associated with new-EMBs. Patients with new-EMBs are likely to have symptomatic extraischemic hemorrhage.
- Received April 16, 2013.
- Revision received May 27, 2013.
- Accepted June 24, 2013.
- © 2013 American Heart Association, Inc.