Transient Ischemic Attack Treatment & Management

Rapid transport is essential to evaluate the patient who may have fleeting or stuttering symptoms. Fingerstick glucose can quickly rule out hypoglycemia. Intravenous (IV) access can be established, although transport should not be delayed for this. Collect all the patient's prescription bottles.

The family or witnesses should be instructed to go to the ED, or contact information for these individuals should be obtained. Some communities may have EMS preferentially transfer patients with high-risk stroke symptoms to centers with specific stroke expertise.^[21]

Global CNS depression and airway or cardiac compromise are not typically features of a transient ischemic attack (TIA). In fact, the level of consciousness and neurologic examination are expected to be at the patient's baseline. Initial assessment is aimed at excluding emergent conditions that can mimic a TIA, such as hypoglycemia, seizure, or intracranial hemorrhage.

Laboratory studies, including CBC, coagulation studies, and electrolyte levels, should be obtained. Obtain an electrocardiogram (ECG) and evaluate for symptomatic rhythms or evidence of ischemia. Brain imaging is recommended within 24 hours of symptom onset. While MRI with diffusion-weighted imaging (DWI) is preferred, a noncontrast head CT is a reasonable first choice when MRI is not readily available.^{[2, 3]}

Although controversy exists regarding the need for admission, there is no controversy regarding the need for urgent evaluation, risk stratification, and initiation of stroke prevention therapy.^{[2, 22, 23, 24]}

When one community implemented a strategy to ensure patients were seen within an average of 1 day, compared with an average of 3 days, the 90-day stroke risk fell from 10% to 2%.^[25] Others have initiated programs to admit patients to a "rapid evaluation unit" or "observation unit", which drops the 90-day stroke risk from approximately 10% to 4-5%.^{[26, 27]} Others have suggested similar benefits from rapid follow-up.^[28]

The availability of local resources determines whether this urgent evaluation should occur as an inpatient, in an ED observation unit, or in rapid follow-up. To determine appropriate disposition, the emergency physician should decide on the necessary workup, then discuss with the neurologist or primary care physician how best to ensure that this occurs promptly.^[29] In addition to the rapidity of the risk stratification workup, the emergency physician should consider the potential benefit of decreased time to thrombolysis in hospitalized patients diagnosed with TIA who develop a new stroke in the first 24-48 hours after diagnosis.

One randomized controlled trial of an ED diagnostic protocol found that they could reduce cost, length of stay, and provide appropriate risk stratification by performing this workup in an ED observation unit (with neurology consultation) rather than in an inpatient unit.^[30]

Risk stratification scores

A number of patients present to the ED with a "transient neurological disturbance" that does not represent a true TIA, and distinguishing between these can be difficult for the busy emergency practitioner. In addition, an emergent and comprehensive workup of all patients with "possible TIA" may not be the most cost-effective or appropriate use of limited local resources. The emergency practitioner should use appropriate risk stratification to ensure that emergent diagnostic and therapeutic interventions are targeted to the highest-risk patients. A number of risk stratification scores are available to assist in this task, but the most widely validated is the ABCD² score (see Table 2, below).^{[17, 31, 24]}

Table 2. ABCD² Score (Open Table in a new window)

Individuals with an ABCD2 score higher than 6 had an 8% risk of stroke within 2 days, while those with an ABCD2 score less than 4 had a 1% risk of stroke within 2 days. Some of these patients with lower scores may well have non-TIA events rather than true TIAs.^[32] It has been proposed that this scoring system can be used to risk-stratify ED patients for emergent workup and predict the severity of recurrent stroke after TIA.^{[31, 33, 34, 35]} Others have suggested that when a comprehensive workup can be obtained routinely in the ED, the value of the ABCD score diminishes significantly.^[36] Some groups have noted, however, that the short-term stroke risk after TIA can be worrisome, even in those with low ABCD² scores.^{[37, 38]}

Additionally, abnormalities on brain imaging can highlight patients diagnosed with a TIA who are at increased risk of early stroke and also should be taken into consideration. It has been shown that patients with transient neurological deficits who are found to have infarcts on DWI have a worse prognosis with higher rates of recurrent TIA and stroke compared to patients suffering either an ischemic stroke or a TIA without evidence of infarction on DWI.^{[17, 18]}

One group has developed 2 variations of the ABCD2 score, one based on preclinical information and the other on secondary care assessments. In this multicenter observational study, they found that use of the ABCD3-imaging score can improve risk stratification after TIA in secondary settings; however, further validation and study is needed before use of the ABCD3-imaging can be recommended.^[39]

The American Heart Association^[2] comments that "It is reasonable to hospitalize patients with TIA if they present within 72 hours of the event and any of the following criteria are present:"

• ABCD² score of 3 (Class IIa, level of Evidence C)
• ABCD² score of 0 to 2 and uncertainty that diagnostic workup can be completed within 2 days as an outpatient (Class IIa, level of Evidence C)
• ABCD² score of 0 to 2 and other evidence that indicates the patient's event was caused by focal ischemia (Class IIa, level of Evidence C)

The National Stroke Association consensus guidelines for the management of TIAs recommend considering patient hospitalization if it is the first TIA within the previous 24 to 48 hours. This would facilitate possible early treatment with tissue plasminogen activator (tPA) and other medical management for recurrent symptoms, and it would expedite risk stratification and implementation of secondary prevention (category 4). For patients with a recent (within 1 week) TIA, the guidelines recommend a timely hospital referral with hospitalization for the following:

• Crescendo TIAs
• Duration of symptoms longer than 1 hour
• Symptomatic internal carotid stenosis greater than 50%
• Known cardiac source of embolus such as atrial fibrillation
• Known hypercoagulable state
• Appropriate combination of the California score or ABCD score (category 4).^[24]

Vital signs must be obtained promptly and addressed as indicated. Cardiac monitoring can capture a relevant dysrhythmia. Pulse oximetry can evaluate for hypoxia. Intravenous access (if not already established by EMS) should be obtained. Obtain a fingerstick glucose level, and treat the patient accordingly.

Patients may be significantly hypertensive. Unless there is specific concern for end-organ damage from a hypertensive emergency, blood pressure should be managed conservatively while ischemic stroke is being ruled out.

For acute ischemic stroke, the American Heart Association recommends initiating antihypertensive therapy only if blood pressure is higher than 220/120 mm Hg or if mean arterial pressure is greater than 130 mm Hg. Unless there is a concerning comorbid cardiac or other condition requiring blood pressure lowering, allowing the patient's blood pressure to autoregulate at a higher level (during the acute phase) may help maximize cerebral perfusion pressure.^[40]

Medical management is aimed at reducing both short- and long-term risk of stroke. Antithrombotic therapy should be initiated as soon as intracranial hemorrhage has been ruled out, given the high short-term risk of stroke following TIA. The AHA/ASA guidelines for the prevention of stroke in patients with stroke or transient ischemic attack, issued in 2006^[41] and updated in 2010^[42] , are summarized below.^[41]

Noncardioembolic transient ischemic attack

Antiplatelet agents are recommended rather than oral anticoagulation as initial therapy. Aspirin (50-325 mg/d), combination aspirin/extended-release dipyridamole, and clopidogrel are all reasonable first-line options (class I recommendation).

Combination aspirin/extended-release dipyridamole (Aggrenox) may be superior to aspirin alone (class IIa recommendation)^[43] and can be started within 7 days of the event.^[44]

Clopidogrel may be considered instead of aspirin alone (class IIb recommendation). Aspirin in combination with clopidogrel increases the risk of hemorrhage and is not routinely recommended for patients with TIA (class III recommendation).

Cardioembolic transient ischemic attack

In patients with atrial fibrillation after TIA, long-term anticoagulation with warfarin (goal INR, 2-3) is typically recommended. Aspirin, 325 mg/d, is recommended for those unable to take oral anticoagulants. The 2010 AHA/ASA guidelines on stroke prevention after TIA or stroke state that clopidogrel should not be used in combination with aspirin therapy, as the bleeding risk of clopidogrel plus aspirin is similar to that of warfarin.^[42]

The 2010 AHA/ASA guidelines also state that it is reasonable for patients with atrial fibrillation who require temporary interruption of oral anticoagulation, but are at high risk for stroke, to be given low molecular weight heparin subcutaneously as bridging therapy.^[42]

In acute MI with left ventricular thrombus, oral anticoagulation with warfarin (goal INR 2-3) is reasonable. Aspirin up to 162 mg/d should be used concurrently for ischemic coronary artery disease.

Either oral anticoagulation with warfarin (goal INR 2-3) or antiplatelet therapy may be considered in dilated cardiomyopathy. In rheumatic mitral valve disease, oral anticoagulation with warfarin (goal INR 2-3) is reasonable. Antiplatelet agents would not normally be added to warfarin unless patients experience recurrent embolism despite a therapeutic INR.

According to the 2010 AHA/ASA guidelines, the benefit of warfarin after stroke or TIA in patients with sinus rhythm and cardiomyopathy characterized by systolic dysfunction has not been established.^[42]

In mitral valve prolapse, long-term antiplatelet therapy is reasonable. In mitral annular calcification, antiplatelet therapy can be considered. Those with mitral regurgitation can be considered for warfarin or antiplatelet therapy.

In aortic valve disease, antiplatelet therapy may be considered. For mechanical prosthetic valves, oral anticoagulation with warfarin (goal INR 2.5-3.5) is recommended. For those with TIAs despite therapeutic INR, aspirin, 75-100 mg/d, can be added to the regimen. For bioprosthetic valves, patients with TIA and no other source of thromboembolism can be considered for oral anticoagulation with warfarin (goal INR 2-3).

Intracranial Atherosclerosis

The 2010 AHA/ASA guidelines state the following for patients with stroke or TIA due to 50-99% stenosis of a major intracranial artery:

• Aspirin at 50-325 mg/d, rather than warfarin, is recommended.
• Maintenance of blood pressure of less than 140/90 mm Hg and total cholesterol less than 200 mg/dL is recommended.
• Extracranial/intracranial bypass surgery is not recommended.
• Angioplasty or stent placement is investigational and of unknown utility.

Patients with TIA and ipsilateral carotid artery stenosis may be candidates for urgent (< 2 wk) carotid endarterectomy. In certain patients, carotid artery stenting is a reasonable alternative. This can be discussed acutely or rapid follow-up arranged.

Patients with symptoms attributable to extracranial vertebral stenosis may be candidates for endovascular treatment, and again, this should be arranged expediently if available.

According to the AHA/ASA 2010 guidelines, optimal medical treatment for these patients includes antiplatelet and statin therapies as well as risk factor modification. This is also optimal medical treatment for patients with symptomatic extracranial carotid disease.^[42]

Neurologist

There is clear consensus on the need for rapid evaluation, and patients who undergo neurologic evaluation and risk stratification within 24 hours (versus within a few days) appear to have a significantly decreased short-term risk of stroke. Therefore, decisions regarding ED evaluation, and inpatient versus rapid outpatient follow-up, ideally are made in concert with a neurologist. International recommendations also note that immediate consultation is more cost-effective than outpatient follow-up.^[15]

It may be that the only way to access expedited evaluation and workup is via interfacility transfer to the hospital with the appropriate resources. The National Stroke Association consensus guidelines recommend that "Hospitals and general practitioners should agree on a local admissions policy and a local protocol for referral to specialist assessment clinics for patients with TIA who do not require hospital admission" (category 4).^[24]

Primary care physician

This is the most important consultation that can occur, as the primary care physician will monitor the patient over the long term and ensure risk-factor and lifestyle modification. In addition, a rapid neurology consultation is not available in many communities, and the primary care doctor may be primarily responsible for managing urgent risk stratification.

Cardiologist

This consultation can be considered for those with clear findings that influence stroke risk, such as atrial fibrillation, patent foramen ovale, intracardiac thrombus, or valvular abnormalities.

Vascular surgeon

This consultation should be considered for those with significant vessel stenosis or occlusion, with a goal of specialist assessment within 1 week and treatment within 2 weeks of symptom onset.^{[15, 45, 46]} In many centers, some vascular interventions can be performed by other specialists including interventional radiologists, neuroradiologists, and cardiologists.

Patients selected for outpatient care should have a clear follow-up plan and stroke prevention initiated as above, including antiplatelet medication and risk-factor modification. Antiplatelet agents typically should be initiated as soon as intracranial bleeding is ruled out. As above, the agent to be used varies with the patient and the specific indication.

The following should be included in any long-term monitoring of TIA patients:

• Antihypertensive control should be optimized for patients with hypertension.
• Lipid control should be initiated, potentially including a statin agent.
• Blood glucose control should be optimized for patients with diabetes.
• A smoking-cessation strategy, which may include medication, should be initiated.
• Heavy drinkers should eliminate or reduce alcohol consumption.
• Overweight patients should be encouraged to lose weight.
• All patients should be encouraged to exercise.