ISCHEMIC STROKE / PREVENTION
Carotid angioplasty with stenting (CAS)
Created 27/01/2022, last revision 04/02/2023
- approx. 10-20% of ischemic strokes are caused by significant carotid stenosis (TOAST 1)
- the risk of stroke or vascular death with symptomatic ICA stenosis >70% is up to 26%/2 years, depending on symptoms, gender, and severity of the stenosis [Rothwell, 2005]
- risk of stroke in asymptomatic carotid stenosis of >60% is ~11%/5 years
- high-risk plaque characteristics and a higher degree of stenosis are associated with an increased risk
- revascularization procedures reduce the risk of stroke; the benefit is only present when the perioperative risk is < 6% (symptomatic) or 3% (asymptomatic stenosis) → indications for revascularization are discussed here
- endovascular treatment (carotid angioplasty and stenting – CAS) is an alternative to carotid endarterectomy (CEA)
- since 1994, there have been significant improvements in technology (including proximal and distal embolic protection devices – EPD) and experience with stenting
- new coated stents promise additional safety → see here
- Roadsaver, CGuard, Gore stent
- randomized trials showed similar efficacy/safety of CAS and CEA (e.g., SAPPHIRE and CREST)
- trials were designed to demonstrate non-inferiority and focused on patients with high surgical risk due to comorbidities (CAD, heart failure, pulmonary disease, etc.)
- CAS does not pose an increased risk compared to CEA and prevents at least the same number of strokes as CEA
- patients with extensive white matter lesions on CT/MRI (ARWMC score ≥ 7) should undergo CEA (ICSS trial)
Trial | N of patients |
30 days mortality/morbidity |
long-term mortality/morbidity |
CARESS (2003) | 397 | 2 vs. 3% | – |
CAVATAS (2001) | 504 | 10 vs 10% | 14.3 vs. 14.2 |
SAPPHIRE (2004) | 334 | 4.4 vs. 9.9% (stroke+MI+death) |
12.2 vs. 20.1 |
CREST (2010) | 2502 | 5.2 vs. 4.6% (CEA) (stroke+MI+death) 4.1% vs 2.3% (CEA) (perioperative stroke) |
primary endpoint: 7.2 vs 6.8% / 4 years stroke+death 6.4 (CAS) vs 4.7% (CEA) |
Indications
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Contraindications
- significant tortuosity and/or severe atherosclerosis of the aortic arch or proximal CCA/BCT, that prevent safe catheter insertion
- elongated aortic root, bovine arch
- tortuous iliac artery
- large calcified plaques preventing the artery remodeling
- distal ICA diameter < 3 mm preventing the use of distal protection (relative contraindication, proximal protection can be used)
- intracranial aneurysm > 5 mm or AV malformation (relative contraindication)
Procedure
- order standard laboratory tests (CBC, coagulation test, basic metabolic panel) and other examinations required by an anesthesiologist
- insert IV cannula and short-term urinary catheter and shave the groin (if transfemoral access is chosen)
- educate the patient about the risks, benefits, and alternatives of the procedure; the patient must sign an informed consent
Premedication
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Periprocedural monitoring
- the procedure is performed in cooperation with an experienced neuroradiologist, anesthesiologist, and a neurologist
- analgosedation is preferred
- basic monitoring:
- ECG and blood pressure (every 5 minutes)
- correct BP correction is critical throughout the procedure (prevention of hyperperfusion syndrome) → parenteral antihypertensives
- if bradycardia occurs, it may be necessary to administer ATROPIN 0.5 mg IV (which may also be given prophylactically)
- a pulse oximetry
- patient’s neurological status (level of consciousness, speech, visual field, acral motor skills)
- ECG and blood pressure (every 5 minutes)
- TCD/TCCD monitoring (optional)
- hemodynamic information (hyperperfusion syndrome is associated with a significant increase in blood flow velocity in the MCA during the procedure, with a concomitant decrease of PI and RI)
- detection of embolization
- microembolization (MES)
- during contrast administration (dissolved air bubbles)
- detection of particles released during critical phases of the procedure (distal protection filter insertion, pre-dilatation, stent deployment, post-dilatation, and protection withdrawal
- increased risk of stroke with > 5 series of microembolizations
- macroembolization leads to transient or permanent flow restriction in the MCA (vessel occlusion)
- microembolization (MES)
CAS technique
Post-procedural management
- retrieve filter (aspirate filter prior to retrieval if slow flow occurs)
- remove the sheath and secure the groin (use Angioseal or other devices)
- observe the patient in the ICU
- continue monitoring of vital signs with careful BP control (check it every 15 minutes in the first hour, then every 30 minutes for at least 24 hours)
- careful correction of BP is the key to the prevention of hyperperfusion syndrome
- careful correction of BP is the key to the prevention of hyperperfusion syndrome
- check for complications and monitor neurological status (GCS, NIHSS)
- perform control Doppler ultrasound (neurosonography) within 24 hours
- record PSV in the proximal, mid, and distal portions of the stent and in the segment distal to the stent
- stent artifactually increases flow velocities
- after the procedure, continue dual antiplatelet therapy (DAPT; aspirin 100 mg + clopidogrel 75 mg) for at least 4 weeks (1-3 months)
- then switch the patient to monotherapy (either ASA or CLP)
Complications
- only complications related to stenting are discussed below
- common adverse events related to endovascular procedures and diagnostic DSA are discussed elsewhere → overview of complications during endovascular procedures
Central complications
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1.1 Distal complications
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1.2 In-stent complications |
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1.3 Proximal complications | |
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Peripheral (access-site) complications Femoral arterial access is commonly used for CAS, but radial or brachial approaches may be considered. Complications range from asymptomatic to life-threatening conditions |
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Systemic complications | |
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- microembolization (most common) x microembolization
- responsible for a substantial portion of the 30-day mortality/morbidity
- distal and proximal protection devices prevent cerebral embolization
- a meta-analysis of approximately 2400 patients showed that the 30-day mortality and morbidity were 5.5% and 1.8% (without and with protection) [Kastrup, 2003]
- use of distal protection is debated; many centers have comparable results without it
- its insertion is associated with additional manipulation in carotid bifurcation, which itself increases the risk of embolization or vasospasm
- other complications such as filter thrombosis, stent entrapment, and damage must be considered
- mechanical recanalization or intraarterial thrombolysis may be performed in the case of symptomatic distal embolization
- the main mechanism of acute stent thrombosis is the platelet activation
- the highest risk in the first 72h
- the incidence of acute and subacute carotid stent thrombosis is 0.5-2%
- besides occlusion, mural thrombi occur and can embolize to the brain
- any change in the patient’s neurological status after the procedure should raise suspicion of acute stent thrombosis and requires urgent diagnosis (most easily by duplex ultrasound) and therapy with Ilb/IIIa receptor inhibitors
- proper premedication (see above) and stent placement are key to the prevention of such complication
- prophylactic add-on therapy with IV abciximab reduces the risk of ischemic complications while increasing the risk of bleeding
- prophylactic add-on therapy with IV abciximab reduces the risk of ischemic complications while increasing the risk of bleeding
- therapy → IV or IA abciximab
- endovascular microsnare loops have been developed to remove the migrated stent (stentectomy) (Oh, 2012)
- deformation is more common with balloon-expandable stents compared to self-expandable stents
- uncorrectable stent deformation may require surgical revision
- stent rupture may result in dissection with possible pseudoaneurysm formation
- difficulties with distal protection retrieval can usually be resolved percutaneously
- careful manipulation is crucial
- it may be helpful to move the patient’s head, have the patient swallow, or choose a more torquable retrieval sheath. In case of filter fracture, it is recommended to ‘jail’ the filter against the arterial wall with an additional stent
Follow-up
- neurosonology – method of choice; always examine the velocities within the stent and in proximal and distal segments
- MR angiography may be subject to artifacts
- CT angiography