ABSTRACT
BACKGROUND: This study was performed to determine the clinical correlates and long-term prognostic implications of microbleed burden and location in Chinese patients with ischemic stroke. METHODS AND RESULTS: We recruited 1003 predominantly Chinese patients with ischemic stroke who received magnetic resonance imaging at the University of Hong Kong. We determined the clinical correlates of microbleeds and the long-term risks (3126 patient-years of follow-up) of recurrent ischemic stroke and intracerebral hemorrhage (ICH) by microbleed burden (0 versus 1, 2-4, and ≥5) and location, adjusting for age, sex, and vascular risk factors and stratified by antithrombotic use. Microbleeds were present in 450 of 1003 of the study population (119/450 had ≥5, 187/450 had mixed location). Having ≥5 microbleeds was independently associated with prior antiplatelet and anticoagulant use, whereas microbleeds of mixed location were independently associated with hypertension and prior anticoagulant use (all P<0.05). Microbleed burden was associated with an increased risk of ICH (microbleed burden versus no microbleeds: 1 microbleed: multivariate hazard ratio: 0.59 [95% confidence interval, 0.07-5.05]; 2-4 microbleeds: multivariate hazard ratio: 2.14 [95% confidence interval, 0.50-9.12]; ≥5 microbleeds: multivariate hazard ratio: 9.51 [95% confidence interval, 3.25-27.81]; Ptrend<0.0001), but the relationship of microbleed burden and risk of recurrent ischemic stroke was not significant (Ptrend=0.054). Similar findings were noted in the 862 of 1003 patients treated with antiplatelet agents only (ICH: Ptrend<0.0001; ischemic stroke Ptrend=0.096). Multivariate analysis revealed that, independent of vascular risk factors, antithrombotic use, and other neuroimaging markers of small vessel disease, having ≥5 microbleeds (multivariate hazard ratio: 6.08 [95% confidence interval, 1.11-33.21]; P=0.037) was identified as an independent predictor of subsequent ICH, but neither microbleed burden nor location was predictive of recurrent ischemic stroke risk. CONCLUSIONS: In Chinese patients with ischemic stroke, a high burden of cerebral microbleeds was significantly associated with an increased risk of ICH; however, neither microbleed location nor burden was associated with recurrent ischemic stroke risk.
