The Source for Neurovascular News and Education

November 29, 2022


Time from symptom onset stretched to 24 hours, and age over 80 years no longer considered a barrier to treatment in the new SNIS recommendations.


A new report from the Society of NeuroInterventional Surgery (SNIS) expands the indications for the use of thrombectomy in acute ischemic stroke from emergent large vessel occlusion (ELVO). The update was published online January 4, 2019, ahead of print in the Journal of NeuroInterventional Surgery.


“Since 2015, there have been an almost continuous set of clinical trials and new information on thrombectomy,” senior author Justin F. Fraser, MD, (University of Kentucky, Lexington), told Neurovascular Exchange in a telephone interview. “There is this rapidly growing body of literature looking at many procedures across the interventional space and general surgical space. . . . As an individual practitioner, it is tough to synthesize all of that literature in an effective way that can ensure you are practicing evidence-based medicine.”


The update is one of a series related to thrombectomy released by the SNIS and is aimed at helping interventionalists absorb and utilize this new information. “This is a laser-guided focus on the indications as they sit right now,” explained Fraser.


Highlights of the new recommendations include:


1. Time from symptom onset: Thrombectomy is now indicated in select patients up to 16 to 24 hours after symptom onset, based on recent clinical trials, particularly DAWN and DEFUSE 3.

2. Imaging: The recommendations clarify how specific imaging findings, notably mismatch profile, can be used to identify good thrombectomy candidates. Notably:

a. Within the first 6 hours of symptom onset, imaging findings considered favorable for thrombectomy include CT ASPECTS ≥ 6, MRI DWI ASPECTS ≥ 6, moderate-to-good collateral status on multiphase CTA, small core infarct volumes, and/or significant penumbral-to-core mismatch on advanced perfusion imaging. Thrombectomy may also be reasonable in patients with CT ASPECTS < 6 or MRI DWI/CTP-estimated core volume > 70 mL.

b. Six to 24 hours after symptom onset, thrombectomy remains indicated in patients who meet the advanced MRI DWI-PWI or CTP imaging criteria for DAWN or DEFUSE 3, as well as in patients who do not meet these criteria but who otherwise have a ‘favorable’ imaging profile.

3. Location of ELVO: Thrombectomy is now indicated in patients with occlusions of the internal carotid artery, including intracranial, cervical segments or tandem occlusion and M1/M2 middle cerebral artery. It may also be reasonable for more distal occlusions.

4. Stroke severity: Thrombectomy is indicated in patients with an NIHSS score ≥ 6 and may also be considered in patients with lower scores if they have disabling symptoms, provided complications and hemorrhage risk can be kept low.

5. Age and baseline level of functioning: Age > 80 should not be a contraindication for thrombectomy, but the benefits of this procedure in patients with a baseline mRS > 1 are unknown.



More Patients Eligible Now Than in the Past


“We’re seeing a general expansion of this procedure,” said Fraser. “In years past, the question was who should get thrombectomy? And now the philosophy is switching to asking, who shouldn’t get thrombectomy? [Because] we are finding out that more and more patients can benefit from it.


“I’m hopeful that this will help providers to feel comfortable offering thrombectomy to more and more patients where the data support it, which I think will lead to an expansion of the volume of patients getting it, which I think will help improve outcomes,” he continued.


Fraser also highlighted the importance of maintaining a high level of quality of care.


“Making decisions about indications and treating these patients is very dependent upon your ability to minimize complications. The risk-benefit ratio [of thrombectomy] changes dramatically if your complication rates are high,” he observed, adding, “As more providers are doing this service, it is critical to remember that if you are going to do thrombectomy, you need to be able do it with minimal complications. And trials suggest we can do that.”




Mokin M, Ansari SA, McTaggart RA, et al. Indications for thrombectomy in acute ischemic stroke from emergent large vessel occlusion (ELVO): report of the SNIS standards and guidelines committee. J NeuroInterv Surg. 2019;Epub ahead of print.



Fraser reports no relevant conflicts of interest.