carotid artery stenosis

Pathology

• at 70-75% stenosis, lesions become hemodynamically significant
• low-flow ischemic events may occur
  • left carotid artery stenosis may be associated with cognitive decline
• thrombi may form at origin of ICA, which may propagate or embolize
• coexisting atherosclerosis elsewhere is the rule
• mortality more frequently due to MI than stroke
• stroke rarely occurs with asymptomatic carotid stenosis that progresses to total carotid occlusion*

* the circle of Willis usually maintains cerebral blood flow despite unilateral, or even bilateral carotid occlusion

Clinical manifestations

• paresthesias/weakness of hand, arm & face
• aphasia (dominant hemisphere)
• dysarthria
• unilateral neglect
• carotid bruit
• 80% of large artery strokes occure without warning

Radiology

• non-invasive techniques adequate for screening*
  • carotid ultrasound (Doppler) 89%/84%
  • magnetic resonance angiography (MRA)
    • contrast-enhanced MRA (CEMRA) 94%/93%
  • spiral CT, CT angiography (CTA) 77%/95%
• angiography
  • candidates for carotid endarterectomy
  • long-term anticoagulation considered for patient with probable large vessel disease
  • recurrent TIAs & inconclusive noninvasive evaluation
  • suspected carotid or cerebral dissection
• progression of carotid artery intimal thickness does not predict cardiovascular risk

* sensitivity/specificity

Complications

• 60% asymptomatic stenosis: 5 year stroke rate reduced from 11% to 5% by carotid endarterectomy
• 90% stenosis plus ulceration, 73% incidence of stroke
• 50-99% asymptomatic stenosis: 10 year stroke rate 9% with medical management alone

Management

• intensified medical management seems to be better choice than carotid endarterectomy for asymptomatic extracranial carotid artery stenosis
  • same appears to be true for intracranial atherosclerosis (see cerebrovascular disease)
  • incidence of ipsilateral carotid-related acute ischemic stroke in patients with severe carotid stenosis is 4.7% over 5 years
• the Asymptomatic Carotid Atherosclerosis Study demonstrated that asymptomatic individuals with > 60% stenosis of the internal carotid artery stenosis were at low risk for stroke
  • 5.1% risk over 5 years with medical management plus carotid endarterectomy (CEA)
  • 11% risk over 5 years for medical management alone
• platelet inhibition:
  • aspirin* 75-325 mg PO QD
  • clopidogrel
  • Aggrenox
  • combination of aspirin plus clopidogrel increases risk of hemorragic stroke
  • rivaroxaban 2.5 mg BID + aspirin 100 mg/day decreases cardiovascular events (RR=0.72) at the cost of increased risk of bleeding (mostly GI bleeding) (RR=1.6)
• control of atherosclerotic risk factors (see atherosclerosis)
  • aerobic exercise may slow progression of atherosclerosis
  • statin therapy may be as effective as aerobic exercise
    • stroke risk for asymptomatic patients treated with high- intensity statin therapy is < 2%/year
    • reduce LDL cholesterol to < 100 mg/dL
    • reduce LDL cholesterol to < 70 mg/dL with diabetes
  • niacin more effective as adjunct to statin than ezetimibe
• tight glycemic control in diabetics (Hgb A1c < 7%) of no proven benefit for stroke prevention
• carotid endarterectomy:
  • symptomatic carotid stenosis
  • beneficial for patients with > 70% stenosis
    • threshold for revascularization may be > 80% stenosis or rapid progression
    • less benefit in patients with stenosis of 50-69%
    • no benefit in patients with stenosis of < 50%
  • absolute risk reduction = 16% {without near occlusion}
  • preferable to stenting in elderly [14, 21]
    • less risk of stroke
  • lower procedural complication rate than angioplasty with carotid stenting in 1st week after ischemic stroke
• angioplasty with carotid artery stenting
  • higher risk for perioperative stroke than with endarterectomy (MKSAP19)
  • avoid in patients >= 70 years of age
  • may be alternative to CEA in younger patients
  • aggressive medical management better than angioplasty with stenting in patients with intracranial stenosis
  • medical therapy better than carotid stenting for asymptomatic carotid stenosis
• carotid endarterectomy equivalent to carotid stenting in younger patients & older ones up to age 80 years
• combining carotid endarterectomy with cardiac surgery in patients with > 70% but asymptomatic carotid stenosis is associated with more perioperative strokes than cardiac surgery alone
• no clear benefit of carotid endartectomy or carotid artery stenting vs best medical management for 60-99% asymptomatic carotid artery stenosis
• carotid atherectomy has not been adequately studied [NEJM knowledge+]
• USPSTF recommends against screening for carotid artery stenosis

* No benefit to more than 162 mg QD

* No indication to switch from aspirin to clopidogrel

Clinical trials

• DNASCO study
• Carotid Occlusion Surgery Study randomized trial
  • extracranial-intracranial bypass for symptomatic carotid artery occlusion of no benefit

More general terms

• carotid artery disease
• arterial stenosis

Additional terms

• atherosclerosis
• vertebrobasilar disease

Patient information

carotid artery stenosis patient information