Gurmeen Kaur, MBBS
@kaurgurmeen
Endovascular intracranial procedures have seen significant advances over the past 3-4 years as reflected in all the recent stroke thrombectomy trials. Given that the last scientific review by the American Heart Association was in 2009, this Scientific Statement document updates the review of outcomes data for the efficacy and safety of these procedures and provides new recommendations for the use of these therapies.
A highly selected writing group did a computerized search of the National Library of Medicine database of literature (PubMed) from July 2007 to January 2016 to come up with these recommendations.
Acute ischemic stroke recommendations: The technical goal of the thrombectomy procedure should be a TICI grade 2b/3 angiographic result to maximize the probability of a good functional clinical outcome. Use of salvage technical adjuncts, including intra-arterial fibrinolysis, may be reasonable to achieve these angiographic results if completed within 6 hours of symptom onset.
- IV tPA: Based on the poor rates of recanalization in LVOs (namely 4.4% in ICA and 30% average in MCAs), likely a result of clot composition and clot length (>8mm), there should be no delays after administration of intravenous r-tPA to vascular imaging and endovascular therapy.
- Intra-arterial thrombolysis: Though prourokinase data had shown early promise, multiple RCTs showed that modern thrombectomy devices are more efficient and hence intra-arterial thrombolysis remains a second line or adjunctive therapy for M2/3 clots but should be used with caution in patients with contraindications to systemic IV tPA.
- Mechanical thrombectomy: The newer generation thrombectomy devices, including Penumbra vacuum aspiration system and the Solitaire/Trevo stent retrievers, demonstrated progressively improving TICI (Thrombolysis in Cerebral Infarction) grade 2 to 3 recanalization rates as compared to the MERCI devices.
- Negative RCTs: In 2013, there were 3 negative RCTs, SYNTHESIS, IMS3 and MR RESCUE, which failed to demonstrate efficacy of endovascular treatment in stroke. The authors have discussed each of the studies to explain the role of patient selection, advanced imaging studies and newer embolectomy devices which further led to the positive trials in 2015. It is interesting to note that while both DEFUSE 2 and MR RESCUE used CT/ MR perfusion imaging selection with standardized RAPID post processing software, MR RESCUE used parameters to select oligemia in the later time window versus the real ischemic core.
- Positive RCTs: 2015 was marked by a major paradigm change in practice with development of level 1A evidence for endovascular stroke intervention: MR CLEAN, which used ASPECTS rather than a tissue perfusion imaging modality; ESCAPE, which used a multiphase CTA/CTP imaging; ESCAPE IS, which used CTP or MR DWI-PWI; SWIFT PRIME, which used RAPID and was designed for the solitaire device and REVASCAT again with RAPID for advanced imaging. The meta-analysis of all these trials (the HERMES group) also showed overwhelmingly positive results.
- Extending time window and the concept of the tissue window: Over 2017-18, stroke care was further revolutionized with DAWN and the DEFUSE trials the benefit of endovascular thrombectomy in patients presenting 6 to 24 or 6 to 16 hours from symptom onset or last seen normal, respectively, but with advanced CTP or MR DWI-PWI imaging selection strategies.
Endovascular treatment of intracranial stenosis: While the evidence is still incomplete and trials are ongoing, intracranial stenting procedures seem to have a grim future. WASID, SAMMRIS and VISSIT indicate that among patients with symptomatic intracranial arterial stenosis, treatment with a balloon-expandable stent resulted in an increased 30-day and 12-month risk of recurrent stroke or TIA compared with medical therapy. Guidelines now recommend medical therapy for 50-69%; optimal medical therapy for 70-99% including aspirin, clopidogrel for 90 days, maintenance of systolic BP <140 mm Hg, statin therapy, and aggressive risk factor modification. The use of Wingspan or Pharos stents are limited to 22-80 years with severe >70% symptomatic stenosis only after failing medical therapy with >2 strokes while making good recovery from the strokes with mRS >3. Additionally, the recent stroke has to be more than 7 days before the stent placement. The utility of angioplasty alone or placement of stents other than Wingspan or Pharos is unknown and is considered investigational.
Cerebral aneurysms:
- Endovascular treatment: A number of endovascular methods are now available for treatment of intracranial aneurysms with coils, stent assisted coils and flow diverters and pipeline devices being the newest. Endoluminal flow diversion may be considered as an alternative to coil embolization in carefully selected cases, but there is insufficient evidence at this time to recommend this strategy as a treatment for most aneurysms.
- Subarachnoid hemorrhage: SAH carries very high mortality and two trials, ISAT and BRAT, both showed coiling was associated with decreased death or dependence at 1 year compared with neurosurgical clipping in patients with SAH in both trials.
Intracranial AVMs: While AVMs carry a very mortality rate in case of rupture, ruptured AVMs are treated but evidence is controversial regarding unruptured AVMs. ARUBA trial showed a lower incidence of stroke or death in the group receiving conservative management. When intervention is chosen, embolization alone is reasonable to consider as a strategy for select ruptured or unruptured AVMs.
Dural AV fistulas: The natural history of DAVFs depends on the venous drainage pattern. Fistulas with retrograde cortical venous drainage, tinnitus or ocular symptoms are the most common ones with high risk of hemorrhage. Several classification systems exist based on the venous drainage. For asymptomatic low grade DAVFs, conservative management is recommended but for asymptomatic higher grade and symptomatic ones, endovascular therapy alone may be curative, or endovascular therapy may be used with other therapies such as surgery or radiosurgery.
Cerebral Venous Thrombosis: CVT may be related to both congenital and acquired pro-thrombotic states. First line therapy continues to be systemic anticoagulation. However, in patients with CVT who are at high risk for deterioration (severely depressed mental status, coma, straight sinus thrombosis at presentation; those with neurological deterioration or increasing intracranial hemorrhage despite systemic anticoagulation), the use of endovascular techniques, including direct intra-sinus thrombolysis or mechanical thrombectomy, may be considered.
Idiopathic intracranial hypertension: For patients with IIH, medical therapy with acetazolamide, symptom management and weight loss continue to be the main stay of treatment. However, various procedures like optic nerve sheath fenestration, surgical CSF diversion and transverse sinus stenting with angioplasty followed by self-expanding stents have been explored. A meta-analysis showed that the procedure had produced self-reported improvements in headache, vision, and papilledema of 83%, 78%, and 97%, respectively. It may be reasonable to offer transverse sinus stenting in medically refractory patients with disabling headache and pulsatile tinnitus.
Head and neck tumor embolization: While there are no RCTs showing benefit, preoperative embolization is a common adjunct for select vascular tumors like meningioma, hemangiopericytoma, hemangioblastoma, paraganglioma, juvenile angiofibroma, neurogenic tumors, esthesioneuroblastoma, and benign and malignant bone tumors of the skull and spine.
These AHA scientific guidelines provide a comprehensive framework of what the evidence stands for and what procedures can be safely considered for various intracranial procedures.
