Small-vessel disease has uncertain impact on large-vessel stenosis outcomes

By Eleanor McDermid, Senior medwireNews Reporter

Research shows that small-vessel disease (SVD) is common among patients with intracranial arterial stenosis, but that its effect on stroke risk cannot be separated from the effect of associated risk factors.

The study, which is published in JAMA Neurology, included 313 patients who received intensive medical management, with or without intracranial stenting, in the randomised SAMMPRIS trial. Almost half (49.5%) of these patients had SVD, report Hyung-Min Kwon (Seoul Metropolitan Government–Seoul National University Boramae Medical Center, Korea) and co-researchers.

During follow-up, the 2-year probability of patients with SVD having an ischaemic stroke in the territory of the stenotic artery was 16.3% and the probability of a stroke in any territory was 22.8%. This was markedly higher than in patients without concurrent SVD, who had corresponding probabilities of 9.9% and 11.1%.

However, SVD was not associated with stroke after accounting for baseline cognitive performance and the presence of diabetes, which were the only factors that varied between the SVD and non-SVD groups and were also significantly associated with outcomes.

Diabetes was significantly more common in patients with than without SVD, at 56.8% versus 39.9%, and this was also true for a number of other risk factors, including older age and history of coronary heart disease or stroke, and systolic blood pressure was higher.

In a linked editorial, Louis Caplan (Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA) says: “It is not surprising that the sheer weight of risk factors in patients with coexistent small and large artery disease might lead to more strokes”.

Also, he points out that lacunar infarcts and microbleeds – two of the SVD used in SAMMPRIS, alongside white matter hyperintensities – can have causes other than SVD, diluting a possible effect of SVD on outcomes in patients with large-vessel disease.

Caplan suggests that future research should focus specifically on the size of brain infarcts in patients who have plaques within the stenotic artery that obstruct the smaller perforating vessels, or who have intrinsic disease within these perforators.

“Neither of these important questions is answerable from the SAMMPRIS trial database but could be addressed in future trials if the correct imaging examinations and follow-up are planned”, he says.

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