American Board of Internal Medicine (ABIM) Certification Practice Exam

Which of the following factors notably increases the risk of stroke after a TIA?

1. A low ABCD2 score

2. Symptomatic internal carotid artery stenosis > 50%

3. Over 75 years of age

4. History of diabetes only

The correct answer is: Symptomatic internal carotid artery stenosis > 50%

The notable increase in stroke risk after a transient ischemic attack (TIA) is closely associated with symptomatic internal carotid artery stenosis greater than 50%. When there's significant stenosis in the internal carotid artery, it indicates a substantial reduction in blood flow to the brain, heightening the likelihood of subsequent cerebrovascular events, including strokes. This occurs because the compromised blood flow may lead to insufficient perfusion or embolization of thrombi formed at the site of stenosis. The ABCD2 score is designed to assess the short-term risk of stroke following a TIA, with a low score indicating a lower risk, which is contrary to an increased risk. Age can influence overall stroke risk due to increased vascular fragility and co-morbidities, but the specific factor of symptomatic internal carotid artery stenosis has a direct impact on the acute risk following a TIA. While diabetes is indeed a risk factor for a range of vascular complications, it is the degree of carotid artery obstruction that most sharply delineates the risk of imminent stroke post-TIA.