An incidental diagnosis of intracranial atherosclerotic stenosis in stroke-free individuals should trigger a thorough assessment of vascular health, according to the authors of a study identifying risk factors and vascular event risk in asymptomatic ICAS.

That conclusion emerged from data collected on more than 1,000 stroke-free participants in NOMAS (Northern Manhattan Study), a trial that prospectively followed participants who underwent a brain magnetic resonance angiogram (MRA) during 2003-2008.

In ICAS patients with stenosis of at least 70%, even with aggressive medical therapy, the annual stroke recurrence rate is 10%-20% in those with occlusions and at least three or more vascular risk factors. This high rate of recurrent vascular events in patients with stroke caused by ICAS warrants greater focus on primary prevention and targeted interventions for stroke-free individuals at highest risk for ICAS-related events, the investigators concluded.

Identify High-Risk ICAS

Using NOMAS data, the investigators, led by Jose Gutierrez, MD, MPH, tested the hypothesis that stroke-free subjects at high risk of stroke and vascular events could be identified through the presence of asymptomatic ICAS. NOMAS is an ongoing, population-based epidemiologic study among randomly selected people with home telephones living in northern Manhattan.

During 2003-2008, investigators invited participants who were at least 50 years old, stroke free, and without contraindications to undergo brain MRA. The 1,211 study members were followed annually via telephone and in-person adjudication of events. A control group of 79 patients with no MRA was also identified with similar rates of hypertension, diabetes, hypercholesterolemia and current smoking.

Mean age was about 71 years (59% female, 65% Hispanic, 45% any stenosis). At the time of MRA, 78% had hypertension, 25% had diabetes, 81% had hypercholesterolemia, and 11% were current smokers.

Researchers rated stenoses in 11 brain arteries as 0, with no stenosis; 1, with less than 50% stenosis or luminal irregularities; 2, 50%-69% stenosis; and 3, at least 70% stenosis or flow gap. Outcomes included vascular death, myocardial infarction, ischemic stroke, cardioembolic stroke, intracranial artery disease stroke (which combined intracranial small and large artery disease strokes), and any vascular events (defined as a composite of vascular death, any stroke, or MI).