Intracranial arterial stenosis in Ecuadorian Natives/Mestizos. A population-based study in older adults (The Atahualpa Project).

BACKGROUND: Intracranial arterial stenosis (IAS) is more prevalent among Asians, Blacks and Caribbean Hispanics than in Whites. However, there is no information on the importance of this common cause of stroke among Mestizo/Native populations of Latin America. We aimed to assess prevalence and correlates of IAS in an indigenous Ecuadorian population of older adults.

METHODS: Atahualpa residents aged ≥60 years were identified during door-to-door surveys and invited to undergo brain magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) of intracranial vessels for identification of stroke lesions and arterial stenosis. Prevalence of IAS was assessed in patients with strokes as well as in stroke-free individuals. A logistic regression model was constructed with stroke as the outcome, IAS as the exposure, and confounders (demographics and cardiovascular risk factors) as independent variables.

RESULTS: Out of 267 participants (mean age 71 ± 8 years, 57% women), 15 (5.6%) had intracranial arterial stenosis, including 10 out of 52 (19.2%) persons with stroke and five out of 215 (2.3%) without. The multivariate logistic regression model showed significant association of IAS with stroke after adjusting for demographics and cardiovascular risk factors (OR: 7.9, 95% C.I.: 2.2-27.8, p=0.001). Mechanisms underlying stroke in patients with IAS included perforator occlusion, artery-to-artery embolism and hypoperfusion.

CONCLUSIONS: Prevalence of IAS in Ecuadorian Natives/Mestizos is similar to that in Asians. Individuals aged ≥60 years with IAS are almost eight times more likely to have a stroke after adjusting for confounding variables.