TIA
- TIA carries a 5-year stroke risk of 30-50%, and up to 25% stroke risk within first few weeks of TIA episode.
- However, only about 50% of patients with TIAs will have a hemodynamically significant carotid stenosis.
Carotid bruits
- Carotid bruits is not a reliable exam for significant carotid stenosis. The presence of bruits is associated with significant carotid stenosis about one-third to two-thirds of the time.
- The overall sensitivity of catching carotid stenosis with carotid bruits on exam is about 60%
NASCET- North American Symptomatic Carotid Endarterectomy Trial
- High grade stenosis 70%-99%
- 26% of fatal or nonfatal ipsilateral stroke by 24 months after randomization in medical group, compared to 9% in surgical group. The absolute risk reduction for stroke is 17%. Benefits persist after 8 years.
- For patients with 50%-69%, NASCET reveals a smaller but statistically significant reduction from 22.2% to 15.7%.
ACAS – Asymptomatic Carotid Atherosclerosis Study
- 1600 patients with >60% stenosis randomized to medical management vs. surgery.
- Combined stroke and death risk at 5 years for surgery arm is 5.1% vs 11% in medical arm
- Carotid endarterectomy effectively cuts stroke risk by half, but it does so by needing 5 years of longevity to realize the benefit
Intervention
Criteria for Asymptomatic Intervention
- Conventional carotid angiogram demonstrating >60% stenosis or 70-80% stenosis based on carotid duplex
Criteria for symptomatic intervention
- Angiogram demonstrating > 50% stenosis
- If patient had a stroke, you should wait until neurologic recovery stabilizes
- The literature states for symptomatic carotid stenosis, window of operation should be 3-14 days. Doing it in the first 2 days is associated with combined 11% stroke and mortality rate, compared to 3% in the 3-14 day window.
Techniques
- Carotid endarterectomy (CEA) and carotid artery stenting (CAS) are both acceptable forms of intervention. Although CAS is traditionally reserved for patients with surgically-difficult anatomy or high medical risk patients, its popularity and experience are growing among surgeons
- In CEA, patch angioplasty is superior than primary repair lower incidence of stroke, recurrent stenosis, and occlusion.
- With CEA, the percentage of patients needing intraoperative shunting is estimated to be around 20% on the high end. If internal carotid back pressure is used as criterion for shunting, 50 mmHg or below is a safe threshold for selective shunting, although some argue that it is too high and may subject more patients to unnecessary shunting.
- Aspirin or other antiplatelet therapy, although popular among surgeons, has NOT demonstrated effectiveness at preventing carotid restenosis.
- In CAS, dual antiplatelet therapy is mandatory
Re-Interventions
- Restenosis is generally attributed to neointimal hyperplasia in the first 2 years
- Restenosis rates of CEA and CAS are both extremely low. In large trials, restenosis rate in CAS at 5 years is between 6 – 10%, with re-interventions rates of 2% yearly
- However, if restenosis is present, post-CEA restenosis rate is significantly higher than that of post-CAS
- It is reasonable to re-intervene on symptomatic re-stenosis of >70% or asymptomatic re-stenosis >80%
- There is no data to suggest that re-intervention for asymptomatic re-stenosis of either CAS or CEA has improved long-term patency rate or neurologic benefits