What is the recommended immediate management of a transient ischemic attack according to Harrison's?

Management of Transient Ischemic Attack (TIA)

All patients with suspected TIA within 48 hours require immediate emergency department evaluation with advance notification to the stroke team—this is a medical emergency, not an outpatient problem. 1, 2

Immediate Risk Stratification and Disposition

Speed is the single most critical factor in TIA management. Without urgent specialized care, the 7-day stroke risk reaches 10-11%, but immediate evaluation reduces this to approximately 2.1%—an 80% relative risk reduction. 1, 2

Mandatory Immediate ED Referral (Within 48 Hours)

Hospitalize immediately if ANY of the following are present: 3, 4

• First TIA within past 24-48 hours (to facilitate thrombolytic therapy if symptoms recur) 3, 4
• Crescendo TIAs (multiple, increasingly frequent episodes)—this is an absolute contraindication to outpatient management under any circumstances 3, 2
• Symptom duration >1 hour at presentation 3
• Unilateral motor weakness (face, arm, or leg) 1, 2
• Speech or language disturbance 1, 2
• Symptomatic carotid stenosis >50% (known or suspected) 3, 2
• Known cardiac embolic source (atrial fibrillation, mechanical valve) 3, 4
• Known hypercoagulable state 3

Timing for Lower-Risk Patients

• 48 hours to 2 weeks after onset with motor/speech symptoms: evaluation by stroke specialist within 24 hours (can occur in certified rapid-access TIA clinic) 1
• 48 hours to 2 weeks after onset with non-motor symptoms (sensory changes, monocular vision loss, diplopia, ataxia): comprehensive evaluation within 2 weeks 1
• >2 weeks after onset: neurologist evaluation within 1 month 1

Mandatory Diagnostic Workup (Complete Within 24 Hours)

Brain Imaging

MRI with diffusion-weighted imaging (DWI) is strongly preferred over CT because it detects acute infarction in approximately 31% of TIA patients, identifying those at highest stroke recurrence risk. 3, 1 CT is acceptable only when MRI is unavailable. 3

Vascular Imaging

CT angiography from aortic arch to vertex is the first-line vascular imaging modality and should be performed immediately at the time of initial brain CT. 1 This single study evaluates both extracranial and intracranial vessels simultaneously. 1

Alternative vascular imaging options (when CTA unavailable or contraindicated): 3, 1

• Carotid duplex ultrasound (evaluates extracranial vessels only) 3, 1
• MR angiography 3, 1
• Transcranial Doppler (complementary examination for intracranial vessels) 3

Critical caveat: When duplex ultrasound and MRA results are discordant, proceed immediately to CTA or catheter angiography to resolve the discrepancy. 1 Correlation of findings from at least two imaging modalities is a quality-assurance requirement. 1

Cardiac Evaluation

• 12-lead ECG immediately upon arrival to detect atrial fibrillation, atrial flutter, or structural heart disease 3, 1, 2
• Continuous cardiac monitoring for >24 hours during initial hospitalization to detect paroxysmal atrial fibrillation 1
• Prolonged ECG monitoring for ≥2 weeks in embolic stroke of undetermined source when initial monitoring is negative 1
• Echocardiography when vascular imaging is insufficient to explain the event 1

Laboratory Studies

Immediate laboratory panel: 3, 1

• Complete blood count 3
• Basic metabolic panel (electrolytes, creatinine/eGFR) 3, 1
• Coagulation studies (aPTT, INR) 1
• Random glucose or HbA1c 3, 1
• Cardiac troponin 1

Outpatient follow-up testing: 3, 1

• Fasting lipid profile 3
• Comprehensive diabetes screening (fasting glucose, 2-hour glucose, HbA1c, or oral glucose tolerance test) 1

Immediate Medical Management

Antiplatelet Therapy (Non-Cardioembolic TIA)

Start antiplatelet therapy immediately upon TIA diagnosis—never delay while awaiting diagnostic workup. 4, 5

First-line regimen: Aspirin 50 mg plus extended-release dipyridamole 200 mg twice daily reduces stroke risk more effectively than aspirin alone without increasing bleeding risk. 4

Alternative regimen: Clopidogrel 75 mg daily, particularly for patients with peripheral arterial disease or prior myocardial infarction. 4

Critical pitfall: Never combine aspirin and clopidogrel long-term after TIA—bleeding risk outweighs any potential benefit. 4

Anticoagulation (Cardioembolic TIA)

When atrial fibrillation or other cardiac embolic source is identified, start oral anticoagulation instead of antiplatelet therapy. 1, 4

• Atrial fibrillation: Target INR 2.5 (range 2.0-3.0) 4
• Mechanical prosthetic heart valves: Target INR 3.0 (range 2.5-3.5) 4

Blood Pressure Management

Start antihypertensive therapy 7-14 days after TIA (unless symptomatic hypotension present) with target <140/90 mmHg, or <130/80 mmHg for diabetics. 4

First-line agents: ACE inhibitor alone or combined with thiazide diuretic; use angiotensin receptor blocker if ACE inhibitor not tolerated. 4

Lipid Management

Initiate statin therapy immediately for all patients with atherothrombotic TIA, targeting LDL <100 mg/dL, regardless of baseline cholesterol levels. 4, 5 Immediate statin initiation substantially reduces 90-day stroke risk. 5

Urgent Revascularization

For symptomatic carotid stenosis 70-99%, perform carotid endarterectomy within 2 weeks at centers with perioperative complication rates <6%. 3, 4 The benefit of revascularization declines rapidly after this 2-week window because the highest recurrent stroke risk occurs early. 3, 1

For symptomatic stenosis 50-69%, surgery may be indicated for older men with recent hemispheric symptoms and irregular/ulcerated plaque, but only at experienced centers with complication rates <6%. 4

Emergency carotid endarterectomy is generally not performed for acute stroke with large deficits because of high risk of hemorrhagic transformation with acute reperfusion. 3 The exception is when DWI suggests small infarct with large penumbra. 3

Rapid-Access TIA Clinic Model (Alternative to ED for Lower-Risk Patients)

A certified rapid-access TIA clinic can safely evaluate moderate- and lower-risk patients within 24-48 hours, provided it offers: 1, 2

• Immediate neuroimaging (MRI with DWI preferred, CT acceptable) 1
• Vascular imaging (CTA or carotid duplex) 1
• Access to stroke specialists 1, 2
• Same-day initiation of antiplatelet, statin, and antihypertensive therapy 1
• Protocols for immediate hospitalization if high-risk features are identified 1, 2

Evidence: The EXPRESS study demonstrated that patients accessing such clinics experienced 90-day stroke risk reduction from 10.3% to 2.1% compared with delayed evaluation. 1

Critical Pitfalls to Avoid

• Never discharge patients with crescendo TIAs under any circumstances—they require immediate hospitalization 3, 2
• Do not rely solely on ABCD2 scores for disposition decisions—they supplement but do not replace comprehensive evaluation 1, 2
• Do not delay carotid imaging in anterior circulation TIAs—urgent revascularization may be needed within 2 weeks 1, 4
• Never discharge without confirming outpatient follow-up arrangements 1
• Do not attempt outpatient workup for patients with known high-risk features (symptomatic carotid stenosis >50%, atrial fibrillation, hypercoagulable state) 2, 4

Patient Education

All patients managed in outpatient settings must be fully educated about the need to return immediately if symptoms recur, as this may represent evolving stroke requiring thrombolytic therapy. 3, 1, 4