At what degree of carotid or vertebral artery occlusion is additional screening versus intervention required?

Carotid and Vertebral Artery Stenosis: Thresholds for Screening vs Intervention

For carotid artery disease, intervention (CEA or CAS) is recommended for symptomatic patients with ≥50% stenosis by angiography or ≥70% stenosis by noninvasive imaging, and for asymptomatic patients with ≥70% stenosis by noninvasive imaging, while stenosis <50% requires medical management only. 1

Carotid Artery Disease Thresholds

Symptomatic Patients (Recent TIA or Stroke)

Intervention is indicated when:

• ≥70% stenosis by noninvasive imaging (duplex ultrasound, CTA, or MRA) 1
• ≥50% stenosis by catheter angiography 1
• Perioperative stroke/death risk must be <6% 1
• Intervention should occur within 2 weeks of the index event when feasible 1

Medical management only when:

• <50% stenosis by any imaging modality - intervention is not recommended except in extraordinary circumstances 1

Asymptomatic Patients

Intervention is reasonable when:

• ≥70% stenosis by validated duplex ultrasound 1
• >70% stenosis by noninvasive imaging 1
• Perioperative stroke/death risk must be <3% 1
• Life expectancy and comorbidities favor intervention 1

Screening is reasonable for high-risk patients:

• Age >65 years with multiple cardiovascular risk factors 1
• Patients with carotid bruit who are candidates for revascularization 1
• Patients planned for CABG surgery with risk factors: age ≥65 years, left main coronary stenosis, peripheral arterial disease, history of cerebrovascular disease, hypertension, smoking, or diabetes 1

Medical management only when:

• <50% stenosis - revascularization is not recommended 1
• Chronic total occlusion of the carotid artery 1
• Severe disability (Modified Rankin Scale ≥3) precluding functional benefit 1

Special Carotid Scenarios

Patients undergoing CABG:

• 50-99% symptomatic stenosis with prior TIA/stroke: Consider carotid revascularization in conjunction with CABG 1
• Bilateral 70-99% stenosis or unilateral severe stenosis with contralateral occlusion (asymptomatic): May consider prophylactic revascularization 1

Vertebral Artery Disease Thresholds

Symptomatic Patients (Posterior Circulation TIA or Stroke)

Additional screening is indicated:

• All patients with posterior circulation symptoms should undergo noninvasive imaging (CTA or MRA preferred over ultrasound) 1
• Catheter angiography is reasonable when noninvasive imaging fails to define location or severity of stenosis in revascularization candidates 1

Medical management is the primary approach:

• No specific stenosis threshold for intervention has been established in randomized trials 1
• Aspirin 75-325 mg daily, statin therapy, blood pressure control, and risk factor modification are recommended 1, 2

Intervention may be considered when:

• Symptomatic vertebral artery stenosis with recurrent posterior circulation events despite optimal medical therapy 1
• Subclavian steal syndrome with documented symptoms during arm exercise 2
• Need for ipsilateral internal mammary artery for CABG 2

Asymptomatic Patients

Screening is indicated for:

• Patients with bilateral carotid occlusions or unilateral carotid occlusion with incomplete circle of Willis - should undergo noninvasive imaging for vertebral artery disease 1

Medical management only:

• Asymptomatic retrograde vertebral artery flow should NOT undergo revascularization 2
• Asymptomatic subclavian artery stenosis causing vertebral flow reversal should NOT undergo revascularization unless internal mammary artery is needed for myocardial revascularization 2

Surveillance Strategy

For both carotid and vertebral disease:

• Serial noninvasive imaging at 1 month, 6 months, and annually after revascularization 1
• For asymptomatic disease on medical management: imaging at 6-12 months initially to establish stability, then extended intervals once stability confirmed 2
• Surveillance can be terminated when patient is no longer a candidate for intervention 1

Critical Pitfalls to Avoid

Do not confuse imaging modalities:

• The stenosis threshold differs by imaging method: ≥50% by catheter angiography equals approximately ≥70% by noninvasive imaging 1

Do not delay intervention in symptomatic patients:

• The highest stroke risk is within the first 2 weeks after TIA or minor stroke - intervention should occur during this window 1

Do not screen the general asymptomatic population:

• Mass screening is not cost-effective and has low yield 1
• Target screening to high-risk patients only 1

Do not intervene on vertebral artery disease without clear symptoms:

• Unlike carotid disease, vertebral artery intervention lacks randomized trial evidence and should be reserved for symptomatic patients failing medical therapy 1, 2

Do not forget that carotid occlusion is associated with widespread atherosclerosis:

• 70% of patients with carotid occlusion have disease in at least one additional vascular bed 3
• Comprehensive cardiovascular risk assessment is essential 3