Recurrent stroke after transient ischaemic attack or minor ischaemic stroke: Does the distinction between small and large vessel disease remain true to type?

The incidence and vascular type of recurrent ischaemic stroke was studied in patients with supratentorial transient ischaemic attacks or non-disabling ischaemic strokes, who were treated with aspirin (30 or 283 mg). Patients were divided into groups with small vessel disease (SVD) (n = 1216) or large vessel disease (LVD) (n = 1221) on the grounds of their clinical features and CT at baseline. Patients with evidence of both SVD and LVD (n = 180) were excluded from further analyses. During follow up (mean 2 6 years) annual stroke rate was 3-6% in both groups. Of the 107 patients with SVD at baseline who had recurrent strokes, 83 proved to have an identifiable infarct: 30 (28%) again had a small vessel infarct, 39 (36%) had a large vessel ischaemic stroke and in 14 (13%) the recurrent ischaemic stroke was in the posterior fossa. Of the 110 patients with LVD at baseline and recurrent stroke, 91 had an identifiable infarct: 67 (61%) again had a large vessel ischaemic stroke, 16 (15%) had a small vessel ischaemic stroke, and eight (7%) had the recurrent ischaemic stroke in the posterior fossa. Thus patients with a transient ischaemic attack or non-disabling ischaemic stroke caused by LVD were more likely to have an ischaemic stroke of the same vessel type during follow up than patients with SVD (relative risk 2-2; 95% confidence interval 1-5-3-4). Possible explanations for this difference are: (1) patients with a small vessel ischaemic stroke at baseline had both SVD and LVD or were misdiagnosed; (2) recurrent small vessel ischaemic strokes may have occurred more often than reported, because they were silent or only minimally disabling; (3) recurrent large vessel ischaemic strokes occurring in patients initially diagnosed as having SVD might have been related to potential cardiac sources of emboli that had not been previously recognised; (4) the antiplatelet drug aspirin (30 or 283 mg) prescribed in this patient group may have prevented thrombosis in small vessels better than in large vessels.