Location of Cerebral Microbleeds May Predict Subsequent Stroke after Transient Ischemic Attack

permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. The prognostic significance of cerebral microbleeds (CMBs) in ischemic stroke has previously been investigated. 1,2 However, there are as yet no reports regarding the detailed relationship between the CMB location and recurrent stroke following a transient ischemic attack (TIA). We thus aimed to investigate the association between CMB location and subsequent stroke following a TIA in detail. We conducted a hospital-based, multi-center, prospective co-hort TIA study (Korean TIA eXpression study, KTX). 2 Consecutive patients with TIA were enrolled from 11 university hospitals from July 1, 2010 through December 31, 2012. TIA was defined using classic time-based criteria as a focal neurologic deficit lasting less than 24 hours. Patients 40 years or older who were admitted within 24 hours of symptom onset and underwent magnetic resonance imaging, including diffusion-weighted imaging and magnetic resonance angiography, were included in the study. This study was approved by the institutional review boards of all participating hospitals. Written informed consent was obtained from all patients or from their legally authorized representatives. The locations of the CMBs were classified according to the Microbleed Anatomical Rating Scale. 3 We further trichotomized the CMBs as strictly lobar, strictly deep, and mixed based on their locations. Along with CMB location, other neuroimaging variables, including acute ischemic lesions in diffusion-weighted images (single or multiple), prior territorial infarction, lacunar in-farction, intracerebral hemorrhage, and white matter hyperin-tensities were also investigated. Crescendo TIA was defined as at least 3 similar attacks occurring within 7 days from the index TIA. 4 Risk stratification scores for ABCD 2 and ABCD 3-I scores were also determined. Detailed descriptions of the clinical and neuroimaging variables were presented in a previous study. 2 The prognostic significance of CMB location was investigated using the primary endpoint of subsequent stroke within 90 days of index TIA occurrence. Subsequent stroke was assessed at an outpatient clinic or by telephone interview using a structured questionnaire. If necessary, we reviewed medical records to confirm the diagnosis of subsequent stroke. Lesion-positive TIA was not included as an outcome event. We analyzed the data using analysis of variances for continuous variables and the χ 2 test and Fisher's exact test for categorical variables. In multivariable analyses, we estimated hazard ratios for subsequent stroke after TIA and calculated 95% confidential intervals (CIs) with adjustments for possible confounders using Cox proportional …