NEW YORK (Reuters Health) – Findings from a new study suggest that contrary to what some researchers have hypothesized, migraine is not associated with atherosclerosis, but it may be a risk factor for venous thromboembolism (VTE) — an indicator of a procoagulant state.

In several prior studies, migraine has been linked to an increased risk of cardiovascular disease, particularly stroke. The underlying mechanisms, however, were unclear, according to the report in the September 16th issue of Neurology.

“The thinking has been that because people with migraine are more likely to have strokes and other cardiovascular problems, that they would also have more severe and early atherosclerosis,” study co-author Dr. Stefan Kiechl said in a statement. “This study is the first to use high-resolution ultrasound to examine this theory, and it provides solid evidence to refute it.”

The results are based on an analysis of data for 574 subjects, 55 to 94 years of age, who participated in the Bruneck Study, a population-based investigation conducted in northern Italy. The subjects, who were followed from 1990 to 2005, were interviewed regarding headaches and VTE and underwent ultrasound assessment of atherosclerosis in the femoral and carotid arteries.

Based on standard criteria, 111 subjects had migraines, including 36 with aura. Patients with and without aura were no more likely than non-migraineurs to have atherosclerosis, and there was no difference in severity or 5-year progression of atherosclerosis between the groups. In fact, there was a tendency for atherosclerosis to be less severe in migraine patients.

As noted, however, migraine patients did seem to be at increased risk for VTE. Overall, 18.9% of migraineurs had VTE compared with 7.6% of non-migraineurs (p = 0.031).

“Procoagulant state is considered an alternative explanation for the increased cardiovascular disease risk among patients with migraine,” the authors note. “As a novel finding, the Bruneck Study obtained a significant association between migraine and lifetime risk of VTE. Extrapolation of these data to arterial thrombosis requires caution even though evidence is growing that patients with VTE are at increased risk for cardiovascular disease.”

Neurology 2008;71:937-943.