Introduction: Silent brain infarctions (SBI) are asymptomatic lesions whose presence is associated with a two-fold increased risk of future stroke. Though carotid atherosclerosis is responsible for ∼20% of ischemic strokes, the strength of association between carotid disease and SBI is unclear based on estimates from individual studies.
Hypothesis: We hypothesized that a synthesis of the existing literature would show that two separate manifestations of carotid atherosclerosis, carotid intima-media thickening (IMT) and luminal stenosis, are associated with SBI.
Methods: We searched multiple online literature databases from their inception to April 2015. Articles were included if they reported an association between MRI defined SBI and carotid IMT or stenosis, excluding SBI evaluation after a procedure. The association between SBI and IMT or stenosis was estimated using pooled random-effects (RE) standard mean difference (SMD) or odds ratio, respectively.
Results: We pooled 6 IMT studies reporting on 1434 subjects with SBI and 5058 subjects without SBI. Subjects with SBI had a larger mean IMT compared to subjects without SBI (pooled RE SMD, 0.36; 95% CI, 0.21 to 0.51; P<0.0001, Figure Panel A). We pooled 9 carotid stenosis studies reporting on 11,177 subjects (1839 subjects with and 9338 subjects without carotid stenosis). In total, 141 (22.5%) of the subjects with carotid stenosis had SBI, while 1568 (16.8%) of the subjects without carotid stenosis had SBI. Our pooled RE analysis showed a significant positive relationship between carotid stenosis and SBI (OR, 2.62; 95% CI, 2.04 to 3.36; P<0.0001, Figure Panel B).
Conclusions: Both carotid IMT and stenosis are significantly associated with the presence of SBI. Patients with SBI and carotid atherosclerosis may represent a group at higher risk of clinically overt stroke and who may therefore benefit from more intensive stroke prevention measures.