Background and purpose: Cerebral microbleeds (CMBs) are prevalent among stroke patients, and have shown to be the risk factor for the future ischemic or hemorrhagic stroke in several reports. However, the significance of CMBs among acute ischemic stroke patients, especially those with non-valvular arterial fibrillation (NVAF), remains unknown.
Methods: Of 1,192 patients who participated in the SAMURAI-NVAF study (an ongoing prospective, multicenter, observational study), 1,099 patients (77.6±10.0 y.o, 620 men) underwent a T2* weighted image (T2*WI). Association of CMBs detected on T2*WI with the incidence of any hemorrhagic infarction (any HI and PH) and PH2 seven days after the index stroke and symptomatic hemorrhagic events and modified Rankin Scale (mRS) at discharge were assessed.
Results: CMBs were detected in 256 patients (23.2%); single CMB in 96, 2-4 CMBs in 109, and ≥5 CMBs in 51. Hemorrhagic infarction was more frequent as the number of CMBs increased (21.5%, 21.9%, 26.6%, and 33.3% in patients with 0, 1, 2-4, and ≥5 CMBs, respectively: p=0.024, analyzed by Cochran-Armitage test for trend). PH2 was identified in 2.5%, 0%, 2.8% and 3.9%, respectively (p=0.824), symptomatic hemorrhagic event in 1.2%, 1.0%, 0%, and 0%, respectively (p=0.5910), and mRS 3-6 in 51.5%, 54.2%, 54.1%, and 62.7%, respectively (p=0.4370). Presence of CMBs was independently associated with any hemorrhagic infarction [odds ratio (OR) 1.72; 95% confidence interval (CI) 1.18-2.51; p=0.005] after adjustment for age, sex, premorbid mRS, infarct size, infarct number, and intravenous thrombolysis, but not with PH2 (p=0.639), symptomatic hemorrhagic events (p=0.633), or mRS 3-6 (p=0.212). Among 253 patients receiving intravenous thrombolysis or endvascular therapy, CMBs were also independently associated with hemorrhagic infarction (OR 2.75; 95%CI 1.27-6.04; p=0.010), but not with the other outcomes.
Conclusions: CMBs were associated with any hemorrhagic infarction in acute ischemic stroke patients with NVAF regardless of receiving thrombolysis or not. However, they were not associated with PH2, symptomatic hemorrhagic events, or unfavorable vital or functional outcomes.