One-Year Risk of Stroke After TIA or Minor Stroke
What is the risk of stroke and acute coronary syndrome for patients 1 year after minor stroke or transient ischemic attack (TIA) in contemporary practice?
This study reports 1-year follow-up from the TIAregistry.org project. This study is a prospective, observational, international registry of patients with minor stroke or TIA, defined as modified Rankin scores of 0 and 1 (no symptoms = 0, no disability = 1). Patients were enrolled at high-volume centers that had a system of care for rapidly evaluating TIA patients by stroke specialists. Follow-up occurred at 1, 3, and 12 months after the qualifying event, and then yearly. The primary outcome was a composite of cardiovascular death (defined as fatal stroke or acute coronary syndrome followed by death within 30 days), stroke (ischemic or hemorrhagic), and acute coronary syndrome. Any event after the index event was classified as an outcome event, even if it occurred prior to enrollment. Ischemic stroke was defined as a new neurologic deterioration that lasted at least 24 hours, not attributable to a nonischemic cause or a new neurologic deterioration with neuroimaging evidence of brain infarction. Event curves were calculated using the Kaplan-Meier method. Subgroup analyses were performed to examine how the following related to outcome: time to evaluation, ABCD2 score (a risk stratification paradigm), presence of infarction, and mechanism (using TOAST classification). Since ABCD2 and TOAST are associated with stroke recurrence, a Cox proportional-hazards regression model was used to determine if these were independent predictors of new stroke.
There were 4,583 patients enrolled between June 2009 and December 2011, and most patients sought medical attention within 24 hours of symptom onset (89.5%). Patients seen by a stroke specialist more than 24 hours after onset had lower ABCD2 scores (3.8 ± 1.6 vs. 4.7 ± 1.5). After evaluation, 5% of patients received a new diagnosis of atrial fibrillation and 15.5% were found to have >50% carotid stenosis. The median follow-up time was 27.2 months (interquartile range, 12.4-27.2). The primary outcome event rate was 6.2% (95% confidence interval [CI], 5.5-7.0). Recurrent stroke or TIA occurred in 12%, any bleeding in 2%, death from any cause in 1.8%, and acute coronary syndrome in 1.1%. After the index event, the risk of stroke was 1.5% at 2 days, 2.1% at 7 days, 2.8% at 30 days, 3.7% at 90 days, and 5.1% at 1 year. ABCD2 score predicted stroke risk, though 22% of patients had a stroke despite an ABCD2 score <4. The following findings were associated with an increased 1-year stroke risk: multiple acute infarctions on neuroimaging (hazard ratio [HR], 2.16; 95% CI, 1.46-3.21), ABCD2 score of 6 or 7 (HR compared with ABCD2 score of 0-3, 2.20; 95% CI, 1.41-3.42), and large artery atherosclerosis as an etiology (HR compared with undetermined etiology, 2.01; 95% CI, 1.29-3.13).
In contemporary practice, with urgent evaluation and management by a stroke specialist, the risk of stroke after minor stroke or TIA is less than previously reported.
Prior studies have reported that the risk of stroke or acute coronary syndrome is about 16% in the 90 days after minor stroke or TIA. Current practice emphasizes rapid evaluation of patients after minor stroke or TIA for expedited diagnostic testing and risk factor modification/optimization. The older estimates of risk were calculated before expedited evaluation of these patients was common. This study suggests that rapid evaluation and management decreases the risk of stroke and acute coronary syndrome in patients with minor stroke or TIA. While the population enrolled in this trial may not generalize to the entire population of patients with minor stroke or TIA, it is likely similar to patients who are enrolled in stroke clinical trials. Additionally, since all patients were evaluated by stroke specialists, the decrease in risk may not be seen in community practice where there is a shortage of stroke specialists.
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