Transient Ischaemic Attack in the Acute Setting – Diagnosis, Management and Treatment

Abstract

More than 700,000 acute strokes1 and 300,000 transient ischaemic attacks (TIAs)2,3 occur annually in the US. It is estimated that between 15 and 26% of acute stroke cases have a prior history of TIA.4 TIAs are important because they are associated with high short-term risk of both stroke and cardiac events. In a widely quoted emergency department (ED) study of over 1,700 TIA cases from California, the three-month stroke risk was found to be 10.5%.5 A recent meta-analysis of 11 TIA cohort studies found that the summary estimate for the 90-day stroke risk was 9.2% ‐ very similar to the Californian study.6 This meta-analysis also confirmed that most of this stroke risk occurs in the first few days after the TIA event; the risk of stroke was 3.5% at two days and 8.0% at 30 days.6 Similar findings were found in another recent meta-analysis of 18 cohort studies, which estimated that the seven-day risk of stroke was 5.2%.7 Patients with TIA are also at high risk of other cardiovascular events. In a meta-analysis of 39 cohort studies, the annual risk of myocardial infarction and non-stroke vascular death following TIA was 2.2 and 2.1%, respectively.8 These studies, which serve to illustrate the high risk of cardiovascular events following a TIA, suggest that patients suspected of having a TIA event require an expedited clinical work-up. Historically, TIA has been defined on the basis of focal neurological deficits due to transient and reversible cerebral or retinal hypoperfusion lasting for less than 24 hours.9 However, because the duration of symptoms for most TIAs is much less than 24 hours ‐ typically less than TIA10 ‐ there has been a proposed change in the definition of TIA to include only cases with a symptom duration of less than one hour.11,12 The advent of diffusion-weighted imaging (DWI) technology adds further challenges to the traditional definition of TIA ‐ up to 50% of TIA patients have DWI abnormalities indicating ischaemic changes.13‐15 The presence of positive DWI changes in TIA cases has been shown to be associated with longer symptom duration (>60 mins), the presence of speech disturbance, atrial fibrillation and ipsilateral carotid stenosis.13