Early risk of stroke after transient ischemic attack: back to the future.

T ransient ischemic attack (TIA) has long been recognized by stroke investigators as both an immediate and a long-term precursor of stroke. Fisher, writing in 1951 about a series of stroke patients, noted the presence of " transitory attacks before the major stroke … commonly occurring once or twice in the preceding week or month. " 1 In 1964, Marshall reported that nearly half of stroke patients who had experienced TIAs beforehand had their stroke in the subsequent month. He commented: " The appearance of TIAs … is clearly a serious matter and the decision as to what investigation and treatment should be carried out is a matter of some urgency. " 2 Other early studies of patients presenting with TIAs reported a significant short-term risk of stroke. In 1974, Whisnant calculated a 7.6% risk of stroke within 1 month after a TIA. 3 Data subsequently published in 1987 by Whisnant and colleagues suggested a stroke risk of 5% within the first 5 days after a TIA. 4 In a 1978 study, 40% of patients with a single TIA had a stroke within 1 month. 5 About 10 years later, 2 studies demonstrated a 9% risk of stroke within 6 days after a TIA, 6 and a 4.4% risk at 30 days. 7 The authors of these 2 studies respectively concluded that " patients with recent TIAs are at high risk for … brain infarction " and that " [t]he risk of stroke is greater immediately after TIA, which has important implications for clinical practice. " The authors of the latter study recently recalculated the risk of stroke at 5% within 2 days after a TIA, 8 identical to the risk reported in another recent publication. 9 Still another recent report showed a 30-day risk of stroke of 9.2% after TIA. 10 Two studies published in this issue of CMAJ add robust data to the previous reports concerning the early risk of stroke following TIA. In one, Gladstone and colleagues examined data collected in a multicentre registry of patients with an emergency department diagnosis of TIA or stroke (page 1099). 11 They report a 2-and 90-day risk of stroke following a TIA of 3% and 6% respectively. They found that clinical features similar to those previously reported 9 were predictors of an increased risk of stroke and death. In addition, the authors found that, compared with the stroke patients, those …