Risk of stroke after transient ischaemic attack is lower than previously thought, study finds
BMJ 2016; 353 doi: https://doi.org/10.1136/bmj.i2320 (Published 22 April 2016) Cite this as: BMJ 2016;353:i2320
The risk of cardiovascular events, including stroke, after a transient ischaemic attack (TIA) or minor stroke is much lower than previously reported, shows a study whose authors say that this finding may be due to improved risk factor management.1
Researchers set up an international registry to collect data on patients aged over 18 who had had a TIA or minor stroke in the previous seven days. They included centres with dedicated systems for the urgent evaluation and care of patients with TIA that had managed at least 100 patients over the previous three years.
From a total of 4789 patients recruited to the registry from June 2009 to December 2011 at 61 sites in 21 countries, 4583 met the inclusion criteria and had their complete follow-up data included in the analysis. More than three quarters (78%) of these patients were evaluated by a stroke specialist within 24 hours of symptom onset.
The results, published in the New England Journal of Medicine, showed that the Kaplan-Meier estimate of cardiovascular events at one year was 6.2% (95% confidence interval 5.5% to 7.0%) and that the estimated risk of stroke was 3.7% at three months and 5.1% at one year. This compares with previous studies that have estimated the risk of stroke or an acute coronary syndrome at 12-20% in the first three months after a TIA or minor stroke.
“We observed a lower rate of cardiovascular events after a TIA or minor stroke than that in historical cohorts,” said the researchers, led by Pierre Amarenco, of Bichat Hospital in Paris, France. “The lower event rates in our cohort may be explained by better and faster implementation of secondary stroke prevention strategies.”
Further analysis showed that multiple infarctions on brain imaging, atherosclerosis of large arteries, and an ABCD2 score of 6 or 7 (the scoring system for risk of stroke after a TIA based on age, blood pressure, clinical findings, duration of symptoms, and the presence or absence of diabetes) were each associated with more than double the risk of stroke.
The study was supported by an unrestricted grant from Sanofi and Bristol-Myers Squibb.
