Basilar Artery Tortuosity and Elongation and Risk of Ischemic Stroke and Death: The Northern Manhattan Study.

Background: Basilar artery (BA) dolichoectasia is defined as dilatation, tortuosity, and/or elongation of the basilar artery. Hospital-based studies have demonstrated an association between BA dilatation and risk of death and stroke. We hypothesized that BA tortuosity and elongation increase risk of death and stroke independent of BA dilatation. Methods: We included stroke-free participants in the Northern Manhattan Study, a population-based prospective cohort study, with an available time of flight MRA. BA tortuosity was defined as BA localization lateral to margin of the clivus, and BA elongation as BA tip distal to margin of the sella. BA diameters were obtained with semi-automated in-house software. Primary outcomes were any death and ischemic stroke. Cox proportional hazards models were used to obtain hazards ratios [HR] and 95% confidence intervals [CI] after adjusting for demographics and vascular risks. Results: Participants (N=1032, mean age 70.7 years, 39.5% men, 65.7% Hispanic) were followed on average for 10.4 ± 3.1 years after their MRA. Among these, 97 (9.4%) had BA tortuosity, 294 (28.5%) had BA elongation, and 98 (9.5%) had both tortuosity and elongation. Participants with BA tortuosity were more likely men, and participants with BA elongation were older, more likely women, non-Hispanic white and were more likely hypertensive. There was no association between BA tortuosity (HR 0.89; 95% CI 0.73 – 1.09, P=0.27), BA elongation (HR 1.12; 0.96 – 1.31, P=0.14), or BA dilatation (HR 1.03; 95% CI 0.84 – 1.27, P=0.76) and risk of death. There was an interaction between BA tortuosity and elongation (P for interaction=0.02); BA elongation was associated with an increased risk of death only among those with BA tortuosity (HR 2.06; 1.29 – 3.29; P=0.002). Adjusting for BA dilatation attenuated the association (HR 1.66; 0.99 – 2.81, P=0.05). We found no association between BA tortuosity (HR 0.92; 95% CI 0.77 – 1.10) or elongation (HR 1.07; 95% CI 0.92 – 1.23), or their combination, and ischemic stroke. Conclusion: Stroke-free individuals with both basilar elongation and tortuosity may have a higher risk of death, but not stroke. Further studies of vasculopathy seen in dolichoectasia and its relationship to systemic vascular disease and mortality are warranted.