Prediction of Ischemic Stroke in Patients with Tissue-Defined Transient Ischemic Attack

Background: The risk of future stroke after transient ischemic attack (TIA) has been widely studied, but most findings were obtained for classically defined TIA (time-defined TIA). A new definition of TIA, that is, tissue-defined TIA, which requires the absence of fresh brain infarction on magnetic resonance imaging, could change stroke risk assessments. We, therefore, aimed to evaluate the risk of future stroke in patients with tissue-defined TIA. Methods: We retrospectively reviewed 74 patients with tissue-defined TIA, who could be followed for 2 years. Clinical, laboratory, and radiological data were collected and compared between groups that did and did not develop ischemic stroke within the 2-year period. Results: Ischemic stroke occurred in 11 patients (14.9%). Increased age, hemiparesis, and/or dysarthria during the TIA, old cerebral infarction revealed by magnetic resonance imaging, and large-artery stenosis detected by magnetic resonance angiography and/or ultrasonography tended to increase the risk of future stroke, but no individual factor showed statistically significant effect. TIA etiology did not significantly affect the risk. ABCD2 score, an established score for predicting stroke after time-defined TIA, showed only a weak association with future stroke. In contrast, new scores that we created reliably predicted future stroke; these included the APO (age, paresis, and old cerebral infarction) and APOL (age, paresis, old cerebral infarction, and large-artery stenosis) scores. The areas under the receiver operating characteristic curves were .662, .737, and .807 for ABCD2, APO, and APOL, respectively. Conclusions: Compared with the established measures, our newly created scores could predict future stroke for tissue-defined TIA more reliably.