Cerebral microbleeds and recurrent stroke risk: systematic review and meta-analysis of prospective ischemic stroke and transient ischemic attack cohorts.

BACKGROUND AND PURPOSE: To evaluate cerebral microbleeds (CMBs) and future stroke risk (including intracerebral hemorrhage [ICH]) in patients with ischemic stroke (IS) or transient ischemic attack.

MATERIALS AND METHODS: A systematic review and meta-analysis of prospective cohorts with recent IS/transient ischemic attack. We critically appraised studies and calculated pooled odds ratios (ORs), using the Mantel-Haenszel fixed-effects method, for ICH or recurrent IS, in patients with versus without CMBs.

RESULTS: We pooled data from 10 cohorts, including 3067 patients. CMBs were associated with a significant increased risk of any recurrent stroke (OR, 2.25; 95% confidence interval [95% CI], 1.70-2.98; P<0.0001), ICH (OR, 8.52; 95%CI, 4.23-17.18; P=0.007), and IS (OR, 1.55; 95%CI, 1.12-2.13; P<0.0001). When stratified by study population ethnicity (Asian versus Western [mainly white European]), the association of CMBs with ICH was significant for Asian cohorts (5 studies; n=1915; OR, 10.43; 95%CI, 4.59-23.72; P<0.0001) but borderline and of lower magnitude for Western cohorts (4 studies; n=885; OR, 3.87; 95%CI, 0.91-16.4; P=0.066). By contrast, there was a significant association of CMBs with recurrent IS in Western (3 studies; n=899) but not Asian cohorts (4 studies; n=1357; OR, 2.23; 95%CI, 1.29-3.85; P=0.004 compared with OR, 1.30; 95%CI, 0.88-1.93; P=0.192, respectively).

CONCLUSIONS: There is consistent evidence of an increased risk of recurrent stroke after IS or transient ischemic attack in patients with CMBs. The risk for spontaneous ICH appears to be greater than the risk for recurrent IS. Our findings also suggest that the balance of risk for ICH versus IS differs between Asian and Western cohorts.