Acute Neuroimaging and Risk Stratification for Suspected TIA Patients in the Emergency Department

1. Transient Ischemic Attack Patient Update: The Optimal Management of Emergency Department Patients With Suspected Cerebral Ischemia

2. Acute Neuroimaging and Risk Stratification for Suspected TIA Patients in the Emergency Department

3. Andrew Asimos, MDDirector of Emergency Stroke CareDepartment of Emergency MedicineCarolinas Medical Center, Charlotte, NCAdjunct Associate Professor, Department of Emergency MedicineUniversity of North Carolina School of Medicine at Chapel Hill

4. Attending PhysicianEmergency MedicineCarolinas Medical CenterDepartment of Emergency MedicineCharlotte, NC

6. CME Disclosure Statement • Emergency Medicine Advisory Board • Boehringer Ingelheim Pharmaceuticals • Research support from the Foundation for Education and Research in Neurologic Emergencies (FERNE) and Emergency Medicine Foundation (EMF) • Research support from Boehringer Ingelheim Pharmaceuticals

7. Session Objectives • What is the short term ischemic stroke risk for ED patients with suspected cerebral ischemia who are diagnosed with a TIA? • What TIA features or syndromes impart greater stroke risk, and can these patients be identified clinically or with TIA risk stratification tools? • What is the role of MRI in TIA patient risk stratification? • Can and should ED TIA patients be safely dispositioned home with outpatient follow-up and still have an optimal outcome, given the short-term ischemic stroke risk?

8. TIA Conceptual Change • TIA is a process, not an event • Can we reliably predict who is at risk of suffering a completed stroke within the first hours, days, or weeks of a presumed TIA? • Can we acutely intervene in the TIA process and prevent a completed stroke from occurring?

9. Early Risk First Emphasized in 1973

10. Early Risk First Emphasized in 1973

11. 27 Years Later

13. 90-Day Prognosis after ED Diagnosis of TIA • 10.5% will suffer a stroke • 21% will be fatal • 64% will be disabling • Half of these will occur within 1 - 2 days of ED visit • 2.6% will die • 2.6% will suffer adverse cardiovascular events • 12.7% will have additional TIAs Johnston SC et al. JAMA 2000;284:2901-2906.

14. Stroke Risk after TIA 18 independent cohorts 10,126 patients Pooled stroke risk 3.1% (95%CI 2.0-4.1) at 2 days 5.2% (95% CI 3.9-6.5) at 7 days Giles MF et al. Lancet Neurology 2007;6:1063–1072.

15. Which TIA Patients are at Highest Risk? • A risk stratification score could help allocate expensive evaluation and treatment to the highest risk patients • High risk patients might benefit more from hospital admission • If expedited ED evaluation not an option • Outpatient evaluation for low risk patients

16. Independent Risk Factors for Stroke within 90 Days Johnston SC et al. JAMA 2000;284:2901-2906.

17. 90-Day Stroke Risk by Number of Risk Factors No. (%) Johnston SC et al. JAMA 2000;284:2901-2906.

19. ABCD Score Rothwell et al. Lancet 2005;366:29-36.

20. 7-Day Stroke Risk Stratified According to ABCD Score:OXVASC Validation Cohort Rothwell et al. Lancet 2005;366:29-36.

22. ABCD2 Score Johnston SC et al. Lancet 2007;369:283-92.

23. ABCD2 Score andShort-term Stroke Risk 2-Day Risk Low Risk: Score 0-3 → 1% Moderate Risk: Score 4-5→ 4% High Risk: Score 6-7 → 8% Stroke Risk (%) ABCD2 score Johnston SC et al. Lancet 2007;369:283-92.

24. Ability of the ABCD2 Score to Identify Low-Risk TIA Cases in Community-Based ED’s • 4 community-based ED’s • ED-based operational definition of TIA • Dichotomized ABCD2 score at 4 • 358 cases • Definition of a completed stroke unclear Reeves MJ. International Stroke Conference, February, 21, 2008

25. 90-day events by ABCD2 Score Reeves MJ. International Stroke Conference, February, 21, 2008

26. Reeves MJ. International Stroke Conference, February, 21, 2008

27. North Carolina Collaborative TIA Risk Validation Study

29. Benign Recurrent TIAs Johnston SC et al. Neurology 2003;60:280-285.

30. MRI versus CT • DWI imaging on MRI can detect ischemic lesions within minutes of the event

31. 2006 NSA TIA EvaluationConsensus Guidelines

32. 2008 European TIA EvaluationConsensus Guidelines

33. Frequency of Positive Diffusion MRI:5 Reported Series of TIAs Ovbiagele B et al. Stroke 2003;34(4):919-24.

34. Do hyperacute DWI abnormalities in TIA patients signify irreversible ischemic infarction? • 21 consecutive TIA patients with DWI with 6 hours • Half DWI positive • Follow-up MRI at 2-9 days • All initially positive DWI patients with abnormalities on T2/FLAIR images Inatomi Y et al. Cerebrovasc Dis 2005;19:362-368.

35. DWI Negative TIA Patients at Risk of Recurrent Transient Events • 85 TIA patients with DWI MRI within 24 hours • DWI negative patients • 4.6 times (27% versus 6%) more likely to have subsequent TIA (i.e. not a stroke) • 4.3 times (2% versus 9%) less likely to have a stroke within one year Boulanger J et al. Stroke 2007;38:2367-69.

36. MRI as a Tool for Risk Stratifcation • 90-day new stroke rate • 4.3% No DWI lesion • 11% DWI lesion and no vessel occlusion • 33% DWI lesion and vessel occlusion • 60% of DWI+ patients “high-risk” compared with 9% of DWI- patients • OR 15.8 (95% CI 3.7-67.5) Coutts SB et al. Ann Neurol 2005;57:848-854. Cucchiara BL et al. Stroke 2006;37:1710-1714.

37. Association Between Positive DWI Imaging and Clinical Predictors of Early Stroke Redgrave J et al. Stroke 2007;38:1482-1488.

38. Stroke Risk After TIA Urgent Evaluation Associated with Lower Risk Giles MF et al. Lancet Neurology 2007;6:1063–1072.

39. Questions?www.ferne.orgaasimos@carolinas.org ferne_clindec_2008_tia_asimos_image_risk_extended_062508_final