First pass effect is good indicator of overall outcome with mechanical thrombectomy

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EmboTrap (Neuravi/Johnson and Johnson’s Cerenovus) achieved a high reperfusion rate among acute ischaemic stroke patients with large vessel occlusion. With three, or fewer, passes of the device, 80.2% patients in the study achieved mTICI 2b–3 grade revascularisation in the target vessel. The results were presented at International Stroke Conference (ISC; 24–26 January 2018, Los Angeles, USA)Achieving complete revascularisation from a single Solitaire (Medtronic) thrombectomy device pass can result in significantly higher rates of good clinical outcomes. These are the results from a study carried out by Osama Zaidat et al and published in Stroke. The study also found that the first pass effect was more commonly associated with the use of balloon guide catheters and less likely to be achieved with internal carotid artery terminus occlusion.

Recent technical advances in mechanical thrombectomy have resulted in significantly improved rates of revascularisation and clinical outcome in acute ischaemic stroke patients. Although morbidity and mortality in acute ischaemic stroke patients treated with stent retrievers can be high, achieving complete or near-complete reperfusion has been associated with improved clinical outcomes and reduced adverse effects. Complete reperfusion is achieved in less than 50% of cases, and often requires multiple thrombectomy attempts, use of rescue therapy, and is rarely obtained from the first device pass.

In addition to prolonging procedure time, multiple device passes may promote arterial endothelial injury, potentially reducing clinical efficacy while reducing safety. Hence, achieving complete revascularisation with a single pass should be the primary angiographic goal.

The first pass effect is a new measure for modern devices and is defined as achieving a complete recanalisation with a single stoke thrombectomy pass. It is indicated by single pass or use of the device, complete revascularisation of the large vessel occlusion and its downstream territory (mTICI 3), and no use of rescue therapy.

The North American Solitaire Acute Stroke Registry database was used to identify a first pass effect subgroup. Their baseline features and clinical outcomes were compared with non-first pass effect patients.

Clinical outcome measures included 90-days modified Rankin Scale score, National Institutes of Health Stroke Scale score, mortality, and symptomatic intracranial haemorrhage.

A total of 354 acute ischaemic stroke patients underwent thrombectomy in the registry. The first pass effect was achieved in 89 out of 354 (25.1%) patients. More middle cerebral artery occlusions (64% vs. 52.5%) and fewer internal carotid artery occlusions (10.1% vs. 27.7%) were present in the first pass effect group. Balloon guide catheters were used more frequently with first pass group (64.0% vs. 34.7%) and the median time to revascularisation was significantly faster in the first pass effect group (median 34 vs. 60 minutes; p=0.0003).

The first pass effect was an independent predictor of good clinical outcome with a modified Rankin Scale score of less than 2 seen in 61.3% of the first pass effect patients vs. 35.3% of the non-first pass effect cohort (p=0.013; OR, 1.7; 95% CIl, 1.1–2.7).

The achievement of complete revascularisation from a single Solitaire thrombectomy device pass was associated with significantly higher rates of good clinical outcome. The first pass effect is more frequently associated with the use of balloon guide catheters and less likely to be achieved with internal carotid artery terminus occlusion.

NeuroNews spoke to lead author Osama Zaidat (Mercy Health, Ohio, USA) to discuss the results.

What are the implications of these findings?

The first pass effect sets the new standard for thrombectomy devices in acute ischaemic stroke. It paves a way to push the envelope on how we measure success in treating acute ischaemic stroke patient secondary to large vessel occlusion.

How will these findings effect how or when mechanical thrombectomy is carried out?

The new standards add to “how” versus “when”, we need to optimise the technique and the tools to achieve the safest and fastest clot removal. When I was first asked to talk about new technical advances in Heidelberg, Germany I challenged them on what we want new technology to do and how to achieve the best technical results. The simple idea of the first pass effect came to me and we proved it with data.

Did any of the results surprise you?

It is always important to provide clinical and scientific evidence to what makes sense. It made sense to me that if you remove the clot in a single device attempt or pass it would, in theory, lead to the best safety and clinical outcome results versus the current standard of less complete recanalisation as a good outcome (regaining 50% of the reperfusion back after three passes). We provided the scientific evidence to back it up.

Why did the use of balloon guide catheters improve outcome?

The use of balloon guide catheters indeed led to higher rate of first pass effect, when compared to cases that the balloon guide catheter was not used in. This may be related to the importance of efficient clot removal when the balloon is up as well as more efficient suctioning and aspiration. .

What further study is need to confirm these results?

It is always important to start by validating the concept by other independent investigators using different data set, I am looking forward to see other researchers worldwide look at this important concept. Furthermore, we had a limited number of predictors that we could evaluate in our data set, we could not evaluate whether the size of balloon guide catheter affected the outcome or different technique would have led to different rate of first pass effect.

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