Transient ischemic attacks (TIAs) act as a warning sign for stroke, preceding full ischemic stroke 25% of the time. And 43% of these strokes occur within one week of the TIA event.

TIAs should be treated aggressively, but when weighing treatment options — and particularly the question of hospitalization — one must first determine whether the TIA in question is of high or low risk. High-risk TIAs can be characterized by the recently validated rating scale called ABCD2 (see table 1). The most important variables are C and D1: long duration, unilateral weakness and speech impairment. Patients with these features should be evaluated immediately.

The ABCD2 scale is designed to predict stroke risk in the crucial first 48 hours after TIA. The British and American researchers who created this scale hospitalized all patients with scores of four or higher, and discharged most with lower scores.

Atrial fibrillation — the leading cause of stroke

The CHADS2 scoring system (table 2) can help predict annual stroke risk in patients with sustained or paroxysmal atrial fibrillation. Atrial fibrillation is the number one cause of stroke, responsible for approximately 1 in every 6 attacks. One high-risk subgroup is those patients who have symptomatic carotid artery disease (50-90% stenosis) and present with a TIA. They compose about 10–20% of all ischemic strokes. Carotid endarterectomy is highly beneficial for individuals with > 70% stenosis when performed within two weeks of the TIA event. The efficacy and safety of carotid angioplasty, on the other hand, is currently under review.

A patient who’s had a high-risk TIA with speech impairment or unilateral deficit should immediately go to an emergency room for rapid evaluation of their TIA similar to acute coronary syndrome. A timely evaluation is crucial, and should include a carotid ultrasound, a CT scan, and an ECG.

References

1. Lancet 2007;369 (9558):283-92
2. Circulation 2004;110:2287-92