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 (CVEs). However, it is unclear if the longitudinal change in BA diameter (Delta BA) is associated with CVEs. Methods and Results-In a cohort of Japanese participants with vascular risk factors in an observational study, we evaluated the relationship of Delta BA to CVEs 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 Delta BA and CVEs, with adjustment for age, sex, vascular risk factors, and magnetic resonance imaging parameters. Second, we assessed the longitudinal Delta 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 CVEs. A smaller DBA was independently associated with the high incidence of CVEs (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 DBA 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 DBA was inversely associated with the incidence of CVEs.