What is the role of shunts and Dual Antiplatelet Therapy (DAPT) with medications like aspirin and clopidogrel in managing cerebrovascular conditions?

Shunts and Dual Antiplatelet Therapy in Cerebrovascular Neurosurgery

For patients with cerebrovascular conditions requiring shunts, dual antiplatelet therapy (DAPT) with aspirin and clopidogrel should be administered prior to stenting and continued for at least 3-6 months following the procedure to prevent thrombotic complications.1

Types of Shunts in Cerebrovascular Conditions

• Venous sinus stents are commonly used in patients with idiopathic intracranial hypertension (IIH) to relieve pressure gradients and improve symptoms 1
• Various stent types are used in cerebrovascular conditions, including Zilver, Precise, Wallstent, Protégé, and SMART stents, with no evidence suggesting superiority of any particular device 1
• For patients with refractory symptoms after stenting, cerebrospinal fluid (CSF) shunting (such as ventriculoperitoneal shunts) may be considered as an alternative treatment option 1

Antiplatelet Therapy for Cerebrovascular Stenting

Recommended Regimens

• DAPT with aspirin and clopidogrel should be administered prior to stenting and continued for at least 3-6 months following the procedure 1
• For carotid artery stenting specifically, DAPT with aspirin (81-325 mg daily) plus clopidogrel (75 mg daily) is recommended before and for a minimum of 30 days after the procedure 1
• After intracranial artery stent implantation, DAPT with aspirin and clopidogrel is recommended for at least 1 month 2
• For symptomatic carotid stenosis not undergoing revascularization, DAPT with low-dose aspirin and clopidogrel is recommended for the first 21 days or longer, followed by clopidogrel or aspirin monotherapy 2

Duration of Therapy

• After carotid endarterectomy (CEA), DAPT is typically continued for 1-3 months, after which it should be transitioned to single antiplatelet therapy indefinitely 2
• For drug-eluting stents, DAPT may be required for 6-12 months or longer (up to 24 months) to prevent delayed stent thrombosis 1
• For bare metal stents, DAPT is typically recommended for 3-4 weeks 1
• After the recommended DAPT duration, long-term aspirin or clopidogrel monotherapy is recommended for continued prevention 2

Efficacy and Safety Considerations

• DAPT with aspirin and clopidogrel has been shown to reduce the risk of total stroke by 20% and ischemic stroke by 23% compared to aspirin monotherapy without increasing the risk of intracranial hemorrhage 3
• In patients with cerebral infarction or transient ischemic attack combined with intracranial and extracranial arteriostenosis, both standard dose (75 mg) and lower dose (50 mg) clopidogrel plus aspirin were superior to aspirin alone for stroke prevention 4
• Thromboembolic complications have been reported with aspirin monotherapy in stent procedures, suggesting the importance of dual therapy 1
• Post-stenting manometry should be performed to confirm resolution of pressure gradients and document procedural success 1

Monitoring and Procedural Considerations

• Diagnostic venography and manometry should be performed with the patient awake during stenting procedures 1
• A large diameter microcatheter is recommended for venous sinus stenting procedures 1
• Heparin is commonly administered during stenting procedures, with lower doses (50 U/kg vs 70 U/kg) potentially associated with fewer neurological complications 5
• Platelet function testing may be considered, as clopidogrel resistance occurs in 4-50% of patients 5

Alternative Antiplatelet Agents

• Ticagrelor plus aspirin has shown significantly lower thromboembolic events compared to clopidogrel plus aspirin for endovascular intervention of intracranial aneurysms without increasing hemorrhagic events 6
• Ticagrelor may be considered as an alternative to clopidogrel in patients with clopidogrel resistance 5
• For patients who cannot tolerate clopidogrel, ticlopidine (250 mg twice daily) may be substituted 1

Common Pitfalls and Considerations

• Premature discontinuation of DAPT after stenting significantly increases the risk of stent thrombosis 2
• Failure to transition from DAPT to single antiplatelet therapy after the recommended duration may unnecessarily increase bleeding risk 2
• Not considering individual bleeding risk when prescribing long-term antiplatelet therapy is a common pitfall 2
• In patients with high bleeding risk, shorter durations of DAPT may be considered 1
• For patients with cerebrovascular stents who also require anticoagulation for atrial fibrillation, consultation with the interventional cardiologist is essential before stopping antiplatelet therapy 1

Follow-up Recommendations

• Non-invasive imaging of extracranial carotid arteries is reasonable at 1 month, 6 months, and annually after revascularization to assess patency and exclude development of new lesions 1
• Once stability has been established over an extended period, surveillance at longer intervals may be appropriate 1
• During follow-up, it is recommended to assess neurological symptoms, cardiovascular risk factors, and treatment adherence at least yearly 2