CT Flags TIA Patients at High Stroke Risk

December 05, 2014

In patients with transient ischemic attack (TIA) or a nondisabling stroke, subtle findings on computed tomography (CT) indicating acute ischemia can identify patients at high risk for impending stroke, a new study has shown.

"Acute ischemia is associated with a high risk of stroke after TIA/nondisabling stroke and the risk increases, especially within the first 2 days, with the addition of chronic ischemia and microangiopathy," the researchers conclude.

The study, led by Jason K. Wasserman, MD, The University of Ottawa, Ontario, Canada, is published online December 4 in Stroke.

"Neuroimaging needs to be conducted within 24 hours of TIA/nondisabling stroke," co-senior author Jeffrey J Perry, MD, Ottawa Hospital Health Research Institute, commented to Medscape Medical News. "If there are acute changes, and especially if these are associated with previous damage or microvascular disease, the patient needs prompt attention from a stroke physician to prevent a subsequent stroke from occurring."

Dr Perry said current management of patients with TIA/nondisabling stroke varies widely.

"In Canada most of these patients are managed as outpatients," he said. "Most do get followed up but this can take days or weeks. Many patients have a subsequent stroke before being seen again. We are saying we need to prioritize certain patients — those with the CT changes we found were associated with high risk. These patients need to be seen by a stroke physician while they are still in the emergency department."

He explained that it has been known previously that patients with acute ischemia are at higher risk but what is new in this study is the degree of risk.

Higher Risk Than Previously Thought

"If the ischemia is associated with a previous area of disease and small vessel disease the risk is much greater than we thought before," he said. "If these patients are seen immediately and treated appropriately this should lead to less death and disability from stroke."

The study included 2028 patients with TIA or nondisabling stroke who had CT within 24 hours. Result showed that 814 patients had ischemic changes on CT. The subsequent stroke rate in the whole population was 1.5% at 2 days and 3.4% at 90 days.

Stroke risk was greater if baseline CT showed acute ischemia alone (10.6%); it was even higher if this was accompanied by chronic ischemia (17.4%) or microangiopathy (17.6%). All three risk factors together were associated with a stroke rate of 25.0%.

The researchers report that 4.2% of patients had evidence of an acute ischemia and that the rate of stroke within 2 days was 3-fold higher in these patients than in those without evidence of acute ischemia. This confirms that much of the early risk for stroke appears to be attributable to patients with progression of a nondisabling stroke, they say.

"We show for the first time that those with evidence of acute ischemia and chronic ischemia and/or microangiopathy are at highest risk within two days, while those with acute ischemia alone or acute ischemia and chronic ischemia and/or microangiopathy are at highest risk within the first 90 days.

"These associations were independent of factors previously associated with stroke after TIA/non-disabling stroke and thus add to the value of the clinical data already available," they add.

Noting a proposal to add acute imaging to the ABCD2 (Age, Blood pressure, Clinical features of TIA, Duration, and Diabetes) score to form a new ABCD2I score, they say, "Our study confirms the value of adding imaging to the clinical data for predicting which patients are at high risk for stroke after TIA."

They add that while most patients with CT evidence of ischemia or microangiopathy had a higher ABCD2 score than those without similar findings, many who went on to have a stroke, were still classified as low or medium risk.

The study was funded by the Canadian Institutes for Health Research. The authors disclosed no relevant financial relationships.

Stroke. Published online December 4, 2014. Abstract

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