Published online before print March 16, 2006, doi: 10.1161/01.STR.0000209255.66933.3b
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(Stroke. 2006;37:1137.)
© 2006 American Heart Association, Inc.
Controversies in Stroke |
Patients With Transient Ischemic Attack or Minor Stroke Should Be Admitted to Hospital
For
From the University of Calgary, Department of Clinical Neuroscience, Calgary, Alberta, Canada; and University of Toronto, Division of Neurology, Department of Medicine, and Regional Stroke Centre, Sunnybrook and Women’s College Health Sciences Centre, Toronto, Ontario, Canada.
Correspondence to Michael D. Hill, University of Calgary, Department of Clinical Neuroscience, Room 1242A, Foothills Medical Centre, 1403 29th St NW, Calgary, Alberta, T2N 2T9, Canada. E-mail michael.hill{at}calgaryhealthregion.ca
Key Words: transient ischemic attack
Transient ischemic attacks (TIAs), like other vascular diseases, whether acute limb ischemia or acute coronary syndromes, are high-risk, unstable conditions. TIA heralds a relatively high risk of stroke, variably estimated to range between 10% and 20% in the ensuing 90 days.1–4 This has been known for several decades.5–8 What is new are reports that show that at least half of the risk of early stroke accrues in the first 2 days after TIA. Necessarily then, any protective strategy needs to be implemented rapidly.
It is surprising that for a condition as common and serious as TIA, there remains so much variability in acute management. Whereas in some institutions, TIA patients are admitted routinely, in other jurisdictions, TIA patients are frequently discharged from the emergency department with suboptimal management, and many discharged TIA patients are unlikely to obtain adequate evaluation or treatment on an outpatient basis within 30 days.4
What Are the Potential Benefits of Hospitalization?
Although the value of inpatient stroke units is well established, little is known about the value of acute observation and investigation units for patients with TIA or minor stroke. Some potential benefits of a short-stay hospital admission include: (1) expedited diagnostic evaluation; (2) monitoring of fluctuating patients with ready access to thrombolysis if they deteriorate; (3) facilitation of early carotid revascularization; and (4) greater opportunity for risk factor modification.9
What Evidence Is There That We Should Apply Stroke Prevention Strategies Rapidly?
The benefit of carotid endarterectomy for stroke prevention in symptomatic patients is time dependent. Pooled analysis of the European Carotid Surgery Trial and North American Symptomatic Carotid Endarterectomy Trial studies has demonstrated that surgery is most effective when performed within 2 weeks of the index ischemic event (number-needed-to-treat [NNT] to prevent 1 stroke in 5 years=5), and this benefit declines dramatically over time (NNT=125 if surgery is delayed >12 weeks after the ischemic event).10 Thus, once carotid endarterectomy is considered for an appropriate patient, surgery should not be delayed. In Calgary, among patients admitted to hospital, we have been able to improve our rates of fast carotid revascularization for inpatients (within 2 weeks) from 72% in 2002 to 92% in 2004 (Hill MD, unpublished data, 2004).
In contrast, there is little evidence that patients with atrial fibrillation require immediate anticoagulation. Stroke recurs at a rate of &5% in the first 2 to 4 weeks, and anticoagulation does not seem to prevent recurrence.11 Despite this result, some have argued in favor of early anticoagulation of TIA patients with atrial fibrillation including immediate use of low molecular weight heparin as a bridging therapy until the International Normalized Ratio can be adjusted to a target of 2.5.
Unfortunately, all of the stroke prevention studies investigating antiplatelet therapies have enrolled patients late after stroke or TIA onset. Only the International Stroke Trial and Chinese Acute Stroke Trial (CAST) studies showed a reduced recurrence of stroke in the first 2 weeks, with an absolute risk reduction of &1% when acetylsalicylic acid was given in the first 48 hours.12 Among patients in the recent Management of ATherothrombosis with Clopidogrel in High-risk patients (MATCH) study who were enrolled within a week, the risk of recurrent stroke appeared to be substantially (but not significantly attributable to small numbers) reduced with double-antiplatelet therapy versus clopidogrel alone, compared with no risk reduction when patients were enrolled later.13 The ongoing Fast Assessment of Stroke and TIA to Prevent Early Recurrence (FASTER) study will provide direct evidence of whether double-antiplatelet therapy and a statin are useful in the hyperacute stage after TIA or minor stroke.14
Can We Select Patients at Highest Risk?
There is some evidence that patients with motor or speech deficits, TIA duration >10 minutes, age >60 years, or diabetes are at the greatest risk of early stroke. A clinical risk stratification model developed in northern California has now been validated.15 A similar risk score has been developed based upon the Oxvase study.16 However, it seems likely that the patients with clear neurological symptoms (eg, witnessed hemiparesis or aphasia, with or without residual signs) are at the highest risk. Other patients with pure sensory events have a more benign prognosis. One reason may be that they may have an alternate diagnosis such as simple partial sensory seizure or a sensory migrainous event.
Brain imaging and vascular imaging performed early after an acute TIA are important predictors of patients who are higher-than-average risk. Computed tomography (CT) data suggest that patients with evidence of new infarction after TIA (despite a lack of symptoms) are at high risk.17 However, CT is insensitive to small volumes of ischemia. Diffusion-weighted magnetic resonance imaging may provide better prognostic value.18,19 Recent work confirms that TIA or minor stroke patients with diffusion-weighted imaging lesion on MRI are at substantially higher risk than those without. This observation may allow the use of MRI to triage patients to admission or home with clinic follow-up.
Is It Cost-Effective?
The cost of admitting a patient to hospital is governed largely by the length of stay. In a global budget system, as in Canada, short stays resulting in higher up-front costs may be cost-effective if future costs are curtailed.
What Is the Calgary Approach?
We modified the Johnston risk factors1 and will admit TIA patients who have had a motor or speech event (high-risk TIA). Patients with pure sensory events, pure vertigo, or clear amaurosis fugax are discharged home to be followed in the stroke outpatient clinic. Pitfalls in this approach have emerged in that many nonstroke physicians fail to note that key words or phrases such as "numbness," "dead," "limp," "swollen," and "my arm was not my own" may imply true weakness rather than simply a sensory disturbance. Dysarthria may be impossible to distinguish from aphasia historically. Careful history taking is required to ensure that patients who have had weakness or speech impairment are identified. Failure to recognize this has resulted in recurrent stroke on several occasions.
Once admitted, patients are preferably enrolled in a clinical trial (eg, FASTER), and they are imaged. Over the past 2 years 12% of admitted TIA patients have required carotid revascularization (Hill MD, unpublished data, 2005 ). The remainder have had a presumed stroke mechanism identified and a logical stroke prevention strategy implemented with a 3-month clinic visit for medical follow-up and lifestyle interventions.
Conclusions
There is a dearth of evidence on exactly what to do with the TIA in the emergency department. Randomized trials are clearly needed. In the interim, our preference is to admit and investigate for stroke mechanism those who we believe are most likely at the highest risk.
References
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