Background and purpose: The aim of this study was to compare the territory of cerebral infarcts on follow-up with that of the preceding transient ischemic attack or nondisabling stroke.
Methods: The Dutch TIA Trial was a randomized, double-blind, controlled trial, in which the secondary preventive effects of two doses of aspirin were compared in patients with a transient ischemic attack or nondisabling stroke. On the basis of clinical symptoms and computed tomography, qualifying events were classified as pertaining to the left carotid, right carotid, or vertebrobasilar circulation.
Results: In 2,993 patients the territory of the qualifying event was that of the left carotid in 1,281 (43%), the right carotid in 1,090 (36%), and the vertebrobasilar in 444 (15%); the territory was uncertain in 178 (6%). On follow-up (mean, 2.6 years), 184 of the 2,371 patients with a baseline event in the carotid circulation suffered a recurrent ischemic stroke (7.8%), as did 28 of the 444 patients in the vertebrobasilar group (6.3%); 117 of these 212 infarcts (55%; 95% confidence interval, 49-62) occurred in the same territory (108 in the ipsilateral carotid and nine in the vertebrobasilar territory) as the event at baseline, compared with 39% to be expected by chance alone (95% confidence interval, 32-45). In the carotid groups patients were significantly more likely to have a subsequent ischemic event in the same territory as at entry than patients in the vertebrobasilar group (relative risk, 1.8; 95% confidence interval, 1.1-3.2). The average interval between the qualifying event and the subsequent stroke was significantly shorter (mean, 167 days; 95% confidence interval, 77-257) if the vascular territory was the same.
Conclusions: These results suggest that single artery disease accounts for at most one half of the strokes on follow-up, relatively more often in the carotid territory, and that recurrent strokes from the same arterial lesion occur sooner than strokes associated with other lesions.