Background: Symptomatic intracranial hemorrhage (sICH) is the most feared complication of IVT for ischemic stroke, and patients who have cerebral microbleeds (CMBs) can potentially be at greater risk. This study aims to assess the association between the number and location of CMBs on MRI and the incidence of sICH post IVT.
Subjects & Methods: We analyzed consecutive IVT-treated patients during a 5-year period (2010-2014) at a tertiary care stroke center. Patients without pre or within 24-hour post-treatment MRI were excluded from the study. All neuroimaging studies were examined by two independent readers and a third reader as a tie-breaker. CMBs were defined according to recent consensus recommendations for MRI studies as round or oval, hypointense lesions with associated blooming on T2*-weighted MRI and can be up to 10 mm in diameter. Outcome measures in our study were occurrences of sICH and were defined according to European Cooperative Acute Stroke Study (ECASS)-III criteria combined with clinical deterioration of ≥4 points on NIHSS, or death.
Results: Of 589 IVT patients (mean age 61±15 years, 51% men, median admission NIHSS: 6 points [IQR 3-11]), 97 patients had CMBs on T2*-MRI. Ten patients had more than 10, while the remaining 87 patients had 1-10 CMBs on T2*-MRI. The rates of sICH did not differ between patients with and without CMBs (4.1% vs. 3.5%; p=0.75). However, sICH occurred more frequently (p=0.0031) in patients with >10MBs (30 %, 95%CI by the adjusted Wald method: 10%-61%) than in patients with 1-10 CMBs (1 %, 95%CI: 0%-7%). After adjusting for potential confounders, the presence of >10 CMBs on T2*-MRI was independently (p=0.0004) associated with a higher likelihood for sICH [OR: 13.4, 95% CI: 3.2-55.9] in multivariate logistic regression analyses. Among patients with sICH in >10 CMBs group, one patient developed multiple ICHs in different regions and one developed a large thalamic ICH remote from the infarcted area. In both these patients the location of ICHs corresponded to the location of CMBs on T2*-MRI. The third patient developed sub-arachnoid hemorrhage.
Conclusions: Our findings indicate a higher risk of sICH after IVT when more than 10 CMBs are present. However, it does not demonstrate an increased risk of sICH among patients who have ≤ 10 CMBs.