AHA/ASA Collaborate on Definition and Evaluation of TIA
June 1, 2009—In Stroke, the American Heart Association/American Stroke Association (AHA/ASA) published a scientific statement for health care professionals on the definition and evaluation of transient ischemic attack (TIA) (2009;40:2276–2293). The statement was authored by Committee Chair J. Donald Easton, MD, et al on behalf of the AHA/ASA Stroke Council, the Council on Cardiovascular Surgery and Anesthesia, the Council on Cardiovascular Radiology and Interventions, the Council on Cardiovascular Nursing, and the Interdisciplinary Council on Peripheral Vascular Disease. The American Academy of Neurology affirms the value of this statement as an educational tool for neurologists.
According to the AHA/ASA, this scientific statement is intended for use by physicians and allied health personnel caring for patients with TIAs. Formal evidence review included a structured literature search of Medline from 1990 to June 2007 and data synthesis using evidence tables, meta-analyses, and a pooled analysis of individual patient-level data. The review supported endorsement of the following tissue-based definition of TIA: a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, without acute infarction. Patients with TIAs are at high risk of early stroke, and their risk may be stratified by clinical scale, vessel imaging, and diffusion magnetic resonance imaging. Diagnostic recommendations include: TIA patients should undergo neuroimaging evaluation within 24 hours of symptom onset, preferably with magnetic resonance imaging, including diffusion sequences; noninvasive imaging of the cervical vessels should be performed, and noninvasive imaging of intracranial vessels is reasonable; electrocardiography should occur as soon as possible after TIA, and prolonged cardiac monitoring and echocardiography are reasonable in patients in whom the vascular etiology is not yet identified; routine blood tests are reasonable; and it is reasonable to hospitalize patients with TIA if they present within 72 hours and have an ABCD2 score of 3, indicating high risk of early recurrence, or the evaluation cannot be rapidly completed on an outpatient basis.
In related news, on June 2, in Neurology, Arvind Chandratheva, MD, et al published findings from the Oxford Vascular Study in which the investigators concluded that about half of all recurrent strokes during the 7 days after a TIA occur in the first 24 hours (2009;72:1941–1947); this highlights the need for emergency assessment. Additionally, they concluded that the ABCD2 score is reliable in the hyperacute phase, which shows that appropriately triaged emergency assessment and treatment are feasible.
According to the investigators, the study was conducted because several recent guidelines recommend assessment of patients with TIA within 24 hours, but it was uncertain how many recurrent strokes occur within 24 hours. It was also unclear whether the ABCD2 risk score reliably identifies recurrences in the first few hours. The Oxford Vascular Study is a prospective, population-based incidence study of TIA and stroke with complete follow-up. The investigators determined the 6-, 12-, and 24-hour risks of recurrent stroke, defined as new neurologic symptoms of sudden onset after initial recovery. Of 1,247 first TIAs or strokes, 35 had recurrent strokes within 24 hours, all in the same arterial territory. The initial event had recovered before the recurrent stroke (ie, was a TIA) in 25 cases. The 6-, 12-, and 24-hour stroke risks after 488 first TIAs were 1.2% (95% confidence interval [CI], 0.2–2.2), 2.1% (0.8–3.2), and 5.1% (3.1–7.1), with 42% of all strokes during the 30 days after a first TIA occurring within the first 24 hours. The 12- and 24-hour risks were strongly related to ABCD2 score (P = .02 and P = .0003). Sixteen (64%) of the 25 cases sought urgent medical attention before the recurrent stroke, but none received antiplatelet treatment acutely, the investigators reported.