Use of Magnetic Resonance Imaging in Predicting Further Vascular Events Among Patients With Transient Ischemic Attacks

Abstract

To the Editor: In the October 2004 issue of Stroke , Purroy et al reported a higher risk of further vascular events among transient ischemic attack (TIA) patients with diffusion-weighted imaging (DWI) acute ischemic lesions.1 They prospectively studied 83 patients with TIA and suggested that duration of symptoms (>60 minutes), presence of DWI acute ischemic lesion, and large vessels disease were important risk factors for the recurrence of vascular events, including cerebrovascular ones. However, only a minority (9.6%) of patients had their magnetic resonance imaging performed (MRI) within 2 days of symptom onset.1 As quoted by the authors, 10.5% of patients with TIA will have a stroke within the next 90 days of their TIA, and 25% to 50% of these have their stroke within the first 24 to 48 hours.2,3 Therefore, a substantial portion of MRI data may show a second cerebrovascular ischemic event instead of the first stroke/TIA and subsequently do not predict the primary outcome. We would like to know the proportion of clinically defined early/late new vascular events. Second, the inclusion of TIA as a primary endpoint is problematic and not conventional in relation to stroke prevention trials.4–8 The percentage of patients with TIA versus stroke at outcome should be stated. Third, a significant proportion of patients presented with vertebrobasilar (43.4%) TIA. What symptoms were accepted as diagnosis of vertebrobasilar TIA? Isolated “dizziness” of unclear origin, for example, is sometimes diagnosed as possible vertebrobasilar TIA but has multiple alternate differential diagnoses that may not ever be conclusively determined. It would have been interesting to know the proportion of vertebrobasilar and carotid TIA among patients with DWI acute ischemic lesions and further vascular events. Fourth, …