Microbleeds as a predictor of intracerebral haemorrhage and ischaemic stroke after a TIA or minor ischaemic stroke: a cohort study.

OBJECTIVES: We examined whether patients with cerebral microbleeds on MRI, who started and continued antithrombotic medication for years, have an increased risk of symptomatic intracerebral haemorrhage (ICH).

DESIGN: Prospective cohort study.

SETTINGS: Multicentre outpatient clinics in the Netherlands.

PARTICIPANTS: We followed 397 patients with newly diagnosed transient ischaemic attack (TIA) or minor ischaemic stroke receiving anticoagulants or antiplatelet drugs. 58% were men. The mean age was 65.3 years. 395 (99%) patients were white Europeans. MRI including a T2*-weighted gradient echo was performed within 3 months after start of medication. 48 (12%) patients had one or more microbleeds. They were followed every 6 months by telephone for a mean of 3.8 years.

PRIMARY AND SECONDARY OUTCOME MEASURES: Primary outcome was a symptomatic ICH. Secondary outcome were all strokes, ischaemic stroke, myocardial infarct, death from all vascular causes, death from non-vascular causes and death from all causes.

RESULTS: Five patients (1%) suffered from a symptomatic ICH. One ICH occurred in a patient with microbleeds at baseline (adjusted HR 2.6, 95% CI 0.3 to 27). The incidence of all strokes during follow-up was higher in patients with than without microbleeds (adjusted HR 2.3, 95% CI 1.0 to 5.3), with a dose-response relationship. The incidences of ischaemic stroke, vascular death, non-vascular death and death of all causes were higher in patients with microbleeds, but not statistically significant.

CONCLUSIONS: In our cohort of patients using antithrombotic drugs after a TIA or minor ischaemic stroke, we found that microbleeds on MRI are associated with an increased risk of future stroke in general, but we did not find an increased risk of symptomatic ICH.