What are the recommended prognostic tests for Transient Ischemic Attack (TIA)?

Recommended Prognostic Tests for Transient Ischemic Attack (TIA)

All patients with suspected TIA should undergo immediate risk stratification using the ABCD2 score, followed by urgent brain imaging (CT or MRI), vascular imaging, and cardiac evaluation to determine stroke risk and guide management decisions. 1, 2

Initial Risk Stratification

ABCD2 Score Assessment

• Age: ≥60 years (1 point)
• Blood Pressure: ≥140/90 mmHg (1 point)
• Clinical Features: Unilateral weakness (2 points) or speech impairment without weakness (1 point)
• Duration: ≥60 minutes (2 points) or 10-59 minutes (1 point)
• Diabetes: Present (1 point)

Risk Categories Based on ABCD2 Score 1, 3

• High Risk (6-7 points): ~8.1% 2-day stroke risk
• Moderate Risk (4-5 points): ~4.1% 2-day stroke risk
• Low Risk (0-3 points): ~1.0% 2-day stroke risk

Essential Diagnostic Workup

Immediate Imaging (within 24 hours for high-risk patients) 1, 2

• Brain Imaging:

  • CT or MRI brain (MRI with diffusion-weighted imaging preferred when available)
  • DWI-MRI detects silent infarcts in up to 31% of TIA patients 1

• Vascular Imaging:

  • CTA from aortic arch to vertex (preferred when available)
  • Alternatives: MRA or carotid ultrasound for extracranial vessels

Laboratory Tests 1

• Complete blood count
• Electrolytes and renal function
• Coagulation studies (aPTT, INR)
• Random glucose and HbA1c
• Lipid profile (fasting or non-fasting)
• Troponin

Cardiac Evaluation 1, 2

• 12-lead ECG for all patients
• ECG monitoring for >24 hours to detect paroxysmal atrial fibrillation
• Echocardiography for patients with suspected cardioembolic source

Additional Investigations for Embolic Stroke of Undetermined Source (ESUS)

• Extended Cardiac Monitoring: Long-term rhythm monitoring (≥2 weeks) for patients ≥55 years without identified atrial fibrillation 1
• Advanced Cardiac Imaging: TEE, cardiac CT, or cardiac MRI to identify cardioaortic sources 1
• Transcranial Doppler: With embolus detection to screen for right-to-left shunt in patients where PFO closure would be considered 1

Management Timeline Based on Risk

High-Risk Patients (ABCD2 ≥4) 1, 2

• Immediate evaluation and brain imaging (within 24 hours)
• Urgent carotid imaging for patients with carotid territory symptoms
• Admission to stroke unit or urgent TIA clinic assessment within 24-48 hours

Lower-Risk Patients (ABCD2 <4) 1

• Brain imaging within 48-72 hours
• Outpatient management with specialist follow-up within 7-10 days

Important Considerations

• The ABCD2 score performs better for anterior circulation TIAs compared to posterior circulation TIAs 4
• Some studies have questioned the positive predictive value of ABCD2 in emergency department settings 5
• Carotid stenosis is an independent predictor of 90-day stroke risk regardless of ABCD2 score 6
• Up to 24% of stroke recurrences occur in patients with low ABCD2 scores (0-3), suggesting caution when using the score in isolation 6

Pitfalls to Avoid

1. Delaying imaging in high-risk patients: Urgent evaluation (within 24-48 hours) can reduce stroke risk by up to 80% 1
2. Relying solely on ABCD2 score: Some patients with low scores still experience recurrent strokes 6
3. Missing atrial fibrillation: Extended cardiac monitoring significantly increases detection rates 1
4. Overlooking posterior circulation TIAs: These may have different risk factors and ABCD2 may be less predictive 4
5. Neglecting carotid imaging: Carotid stenosis is a powerful independent predictor of recurrent stroke 6

By following this systematic approach to TIA evaluation, clinicians can effectively stratify risk, identify underlying causes, and implement appropriate preventive strategies to reduce the risk of subsequent stroke.