1. Previous research established the risk of stroke or acute coronary syndrome (ACS) following transient ischemic attack (TIA) or minor stroke in the realm of 12% to 20%.
2. The TIAregistry.org project establishes the risk closer to 6% and also identifies 3 independent variables predicting stroke at 1 year: multiple cerebral infarctions on imaging, higher scores on a previously established stroke risk-stratification system, and large-artery atherosclerosis.
Evidence Rating Level: 2 (Good)
Study Rundown: Previous research established the risk of stroke or ACS following TIA or minor stroke in the realm of 12% to 20%. The TIAregistry.org project involved patients who had had a TIA or minor stroke within the last 7 days and were enrolled in a prospective, observational registry. The primary study outcome was a composite measure including death from cardiovascular cause, nonfatal stroke, and nonfatal ACS.
The study reported a lower-than-previously-reported risk of stroke or ACS following TIA or minor stroke of 6.2% at 1-year of follow-up. The authors examined the predictors of outcomes in a series of multivariate models, ultimately showing that three factors were independently associated with more than doubling of 1-year stroke risk: multiple acute cerebral infarctions on brain imaging, an ABCD2 score (risk-stratification score for TIA triage, rated from 0 to 7) of 6 or 7, and large-artery atherosclerosis (e.g. carotid artery stenosis).
A primary drawback, which limits the generalizability, is that the results are biased towards clinic populations involving stroke specialists and specific TIA clinics.
Relevant Reading: Short-term prognosis after emergency department diagnosis of TIA
In-Depth [prospective cohort]: The TIAregistry.org project involved 4789 patients from 61 sites in 21 countries, 87% of whom sought medical attention within 24 hours of TIA or minor stroke symptom onset. Primary outcome events were adjudicated by study authors on the basis of narrative descriptions. At time of analysis, there was a median follow-up period of 27.2 months; 91% of patients had either died or had at least 1 year of follow-up. There was a primary outcome rate (composite of death from cardiovascular cause, nonfatal stroke, and nonfatal ACS) of 6.2% (95% [CI], 5.5 to 7.0); the one-year rates for death from any cause, stroke or TIA, and ACS were 1.8%, 12.0%, and 1.1%, respectively. Examining a series of Cox regression models including a number of potential predictors of one-year stroke risk, three variables emerged as independently associated with 1-year stroke risk: multiple cerebral infarctions on brain imaging (HR for comparison with no infarctions = 2.16, 95% [CI], 1.46 to 3.21; p<0.001) an ABCD2 score of 6 or 7 (compared to a score of 0 to 3, HR=2.20, 95% 1.41 to 3.42; p<0.001), and large-artery atherosclerosis (compared to no specific etiology discovered, HR=2.01, 95% [CI], 1.29 to 3.13; p=0.002). Importantly, 22% of stroke outcomes occurred in patients with an ABCD2 score of less than 4.
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