A 9-Year Longitudinal Study of Basilar Artery Diameter.

Background Dilatation of the basilar artery ( BA ) has been recognized as a predictor of cardiovascular events ( CVE s). However, it is unclear if the longitudinal change in BA diameter (Δ BA ) is associated with CVE s. Methods and Results In a cohort of Japanese participants with vascular risk factors in an observational study, we evaluated the relationship of Δ BA to CVE s and the time course of the BA diameter. The short axis of the BA diameter was measured at the midpons level in T2-weighted images. Brain magnetic resonance imaging measurements included cerebral small-vessel disease, lacunars, and white matter hyperintensities. First, 493 patients were analyzed by the time-dependent Cox proportional hazards model to evaluate the association between Δ BA and CVE s, with adjustment for age, sex, vascular risk factors, and magnetic resonance imaging parameters. Second, we assessed the longitudinal Δ BA in 164 patients who underwent long-term follow-up magnetic resonance imaging, by linear regression analysis. In the mean follow-up of 8.7 years, 105 patients developed CVE s. A smaller Δ BA was independently associated with the high incidence of CVE s (hazard ratio, 0.36; 95% CI, 0.16-0.78; P=0.010; n=493). After a mean interval of 9.4 years, the average Δ BA was 0.41±0.46 mm (excluding patients with fetal-type circle of Willis). Progression of BA dilatation was associated with men but inversely associated with initial BA diameter and fetal-type circle of Willis (n=164). Conclusions BA diameter increased over time (excluding the patients with fetal-type circle of Willis), whereas Δ BA was inversely associated with the incidence of CVE s.