Wasserman JK, Perry JJ, Sivilotti MLA, Sutherland J, Worster A, Émond M, et al. Computed Tomography Identifies Patients at High Risk for Stroke After Transient Ischemic Attack/Nondisabling Stroke: Prospective, Multicenter Cohort Study. Stroke. 2014
Wasserman et al evaluate the predictive value of CT findings and risk of stroke. Specifically, they evaluate 2028 patients who presented to the hospital within 48 hours of symptoms, who had either a TIA or non-disabling stroke, receiving a scan within 24 hours. Head CT’s were evaluated by local neuro-radiologist as either being present or absent for evidence of acute ischemia, chronic ischemia and microagniopathy. Do these aforementioned patients with recent TIA or non-disabling stroke predict a higher likelihood of stroke in the forthcoming days? Wasserman et al answer: Yes! Stroke risk at 90 days was greater if baseline CT showed acute ischemia alone (10.6%; p = 0.002), acute + chronic ischemia (17.4%; p = 0.007), acute ischemia + microangiopathy (17.6%; p=0.019), or acute + chronic + microangiopathy (25.0%; p =0.029). The average age of patient’s was 67.9 +/- 14.5.
Limitations of this study include the fact that only CT’s were used. CT’s are known to be less sensitive at detecting ischemia as compared to MRI’s. However some may argue that this models real world practical evaluation of strokes in the acute and early sub-acute strokes. A second limitation is that there was no distinction made between symptomatic and non-symptomatic acute lesions on head CT. Although acute ischemia seen on imaging in those with TIA symptoms or non-disabling stroke was shown to have higher risk of repeat ischemic event, from the data, we are unable to determine if patient’s new event was secondary to a new stroke or progression of the original stroke. This potentially may skew the data.
This study nonetheless, does show that imaging is useful in predicting future stroke in 90 days. Some may argue that imaging used as single parameter in this clinical setting may not be too useful. However, if used in conjunction with the ABCD2 score (as is seen in the new ABCD2I score), there may be clinical application. As with the ABCD2 score which stratifies risk of an immediate stroke, using imaging as a stroke risk marker will act to dictate management. Should a patient be admitted for expedited stroke work up inpatient, or can the patient have an outpatient work up? For those who mull over this question, imaging can act as an additional data point. It does seem intuitive otherwise that having a prior stroke would increase the risk of a subsequent stroke. However, now we can quantify that risk within 90 days and specify that to imaging findings.