http://frankmagliochetti.com/2016/mechanical-thrombectomy/

Ischemic stroke is one of the most frequently encountered neurologic emergencies. It can be a truly debilitating diagnosis, and yet classically, there has only been one treatment available for small and large vessel occlusions alike – tPA. Now, with the widespread availability of CT angiography and the advent and maturation of interventional techniques such as mechanical thrombectomy, the management of large vessel occlusion (LVO) strokes is rapidly evolving and is increasingly distinct from the management of other strokes. This is truly an exciting time in stroke care, so for this month’s journal club we focused on three questions relevant to the emergency provider:

What is the utility of prehospital clinical scales for rapidly identifying LVO strokes?
Should patients with suspected LVO be taken to the nearest stroke center or bypass smaller hospitals to reach a comprehensive stroke center?
How effective is mechanical thrombectomy vs. tPA alone?

ARTICLES REVIEWED

1. Hastrup S, Damgaard D, Johnsen SP, Andersen G. Prehospital acute stroke severity scale to predict large artery occlusion: design and comparison with other scales. Stroke. 2016;47:1772–1776.[Pubmed]

2. Gerschenfeld, G., Muresan, I. P., Blanc, R., Obadia, M., Abrivard, M., Piotin, M., & Alamowitch, S. (2017). Two paradigms for endovascular thrombectomy after intravenous thrombolysis for acute ischemic stroke. JAMA Neurology, 74(5), 549-556.[Pubmed]

3. Badhiwala, JH, et al. Endovascular Thrombectomy for Acute Ischemic Stroke A Meta-analysis. JAMA. 2015;314(17):1832–1843.[Pubmed]

HASTRUP ET AL.

This retrospective cohort study out of Denmark developed and internally validated the Prehospital Acute Stroke Severity Scale (PASS) for prediction of LVO and compared its performance with other widely used scales – RACE, LAMS, 3ISS, and the CPSS. The PASS was 64% sensitive and 83% specific for identifying LVO stroke. All of the clinical scales examined performed similarly. The PASS is the simplest of these scales, although only the RACE score has been externally validated.

Hastrup S, Damgaard D, Johnsen SP, Andersen G. Prehospital acute stroke severity scale to predict large artery occlusion: design and comparison with other scales. Stroke. 2016;47:1772–1776

Bottom line: While pre-hospital stroke scales may be helpful in the early identification of possible LVO stroke, they all lack sufficient sensitivity and specificity to rule in or rule out the diagnosis.

GERSCHENFELD ET AL

Hot off the presses from France, this retrospective analysis of acute ischemic stroke registries compared the outcomes patients with LVO who were first taken to the nearest primary stroke center, treated with tPA, and then transferred to a comprehensive stroke center (“drip-and-ship”) for thrombectomy vs. patients who were taken directly to a comprehensive stroke center (“mothership”). Measured outcome was 3-month functional independence as evaluated by modified Rankin scale ≤ 2.All patients received IV tPA followed by mechanical thrombectomy. Patients in the drip-and-ship group had a small but statistically significantly lower NIHSS (15 vs. 17). No statistically significant difference in 3 month outcomes, rate of recanalization, NIHSS at 24 hours or at discharge, or infarct complications was found.

GERSchenfield main out comes and clinical evolution.jpg

Bottom Line: Taking patients with LVO stroke directly to a comprehensive stroke center does not produce better outcomes than presenting to the nearest stroke center for tPA prior to transfer for thrombectomy.

BADHIWALA ET AL.

Subgroups with Better Functional Outcomes:

**- Confirmed proximal arterial occlusion (OR 2.24; 95% CI, 1.72- 2.90)**
**- Combined IV tPA AND endovascular therapy (OR 2.07; 95% CI, 1.46-2.92)**
**- Use of stent retriever device (OR 2.39; 95% CI, 1.88-3.04)**

This meta-analysis of RCTs comparing endovascular therapy for acute ischemic stroke to standard therapy was published in JAMA in 2015, aiming to answer whether endovascular therapies lead to improved outcomes and to identify factors associated with said improved outcomes. Data was pooled from 8 different trials totaling 2423 patients. Endovascular therapy was associated with significantly higher rates of functional independence at 90 days compared to standard therapy (44.6% vs. 31.8%) with NNT = 8. No significant difference in rates of symptomatic intracerebral hemorrhage or mortality was found.

Bottom line: Endovascular therapy does seem to be of benefit for patients with LVO. These patients should still get tPA. Better outcomes are seen if the occlusion is proximal and if the newer stent retriever devices are used for thrombectomy.

Summary: We are now managing LVO stroke patients much differently than their small vessel counterparts. Like with any emergent diagnosis, rapid identification and early definitive management are the key goals. Based on these articles, we learned:

Clinical stroke scales may be useful, especially pre-hospital, but cannot rule out or rule in the diagnosis.
There is no benefit to bypassing a primary stroke center to reach a comprehensive stroke center for suspected LVO.
Endovascular therapy does benefit properly selected patients with LVO, but they should still receive tPA.

This topic is sure to continue to evolve over the coming years – stay tuned!