Trevo NXT Retriever

Early data confirm Trevo NXT Retriever as an effective tool for mechanical thrombectomy

Initial data pooled from four high-volume European stroke centres indicate that Stryker's Trevo NXT Retriever is an effective and safe tool for mechanical thrombectomy, especially when used for combined approaches. This was the finding of Manina Etter, Alex Brehm and Marios-Nikos Psychogios (Department of Neuroradiology, University Hospital Basel, Basel, Switzerland) alongside researchers from University Hospital Heidelberg (Heidelberg, Germany), Hospital Clínico San Carlos, (Madrid, Spain), Careggi University Hospital, (Florence, Italy) and University Hospital RWTH Aachen, (Aachen, Germany), who reported initial experience with the device for mechanical thrombectomy of large- and medium vessel occlusions in the journal Frontiers in Neurology. 1

the ICA-T and one for the M1/M2) and the groin to reperfusion time (median 51 minutes for ICA-T vs. 34/35 minutes for M1/M2) were higher for ICA-T occlusions. Discussing the findings, Psychogios et al highlight that the rate of first-pass complete or near complete reperfusion was achieved in 54% of cases, comparing favourably to previously published data of the predecessor device, while final mTICI ≥2c was achieved in 83% of cases and final complete reperfusion (mTICI 3) in 56% of the cases. Regarding the technical aspects of using the Trevo NXT Retriever as a first-line device, they write that advancing the stent retriever within the microcatheter was “easy” in the majority of cases and target placement was achieved in all cases. “Our impression after using the 4mm Trevo NXT with 0.021” microcatheters is that the pushability of the stent retriever is given even in tortuous proximal vessels. While treating distal occlusions with the 3mm MECHANICAL THROMBECTOMY Trevo NXT, pushing the device is the standard of care for ischaemic stroke through a 0.017” microcatheter caused by large vessel occlusion (LVO). was feasible,” they write. “In our The main techniques include use of a stent subjective opinion, pushing the retriever and withdrawal of the device with or new 3mm device through a 0.017” without flow arrest by a balloon- microcatheter was easier compared to guide catheter; direct aspiration previous Trevo generations, although we did technique using a large-bore not compare the two devices in this study.” aspiration catheter (ADAPT), As for the retrieval of the device into the placed at the face of the clot; or, aspiration catheter or balloon-guide catheter, primary combined approaches using the authors received positive feedback. These a stent retriever and an aspiration findings are consistent with the development catheter intracranially, with of a hydrophilic coated polymer jacket, additional extracranial aspiration designed to enable smoother and easier through the guide catheter. delivery and improved retraction. The authors

Stryker’s Trevo stent retriever is a well- write that the device can be regarded as safe, established mechanical thrombectomy device, with complication rates comparable to those with earlier iterations of the device having of the literature. In sum, the findings lead the been the most frequently used devices in authors to conclude that, based on initial data, the MR CLEAN trial,2 and the only stent the Trevo NXT Retriever is an effective and retriever used in the interventional arm of safe tool for mechanical thrombectomy— the DAWN randomised trial. Psychogios especially when using combined approaches. et al assessed the new-generation Trevo NXT, Retriever focusing on the efficacy and References: peri-interventional safety of the device, from 1: Etter M, Möhlenbruch M, Weyland C, et al. Initial experience with October 2020 to February 2021. the Trevo NXT stent retriever. Front Neurol. Forthcoming 2021.

The study’s primary endpoint was first-pass 2: Berkhemer O, Fransen P, Beumer D, et al. A Randomized Trial of Intraarterial Treatment for Acute Ischemic Stroke. N Engl J Med. complete or near-complete reperfusion, 2015;372.(1):11–20. defined as a modified thrombolysis in cerebral infarction (mTICI) score ≥2c. Secondary endpoints included final reperfusion, National Institutes of Health Stroke Scale (NIHSS) at 24 hours and discharge. Interventionalists gave subjective ratings based upon their experience of delivering and retracting the catheter compared to previous generations.

In total, 80 patients were enrolled in the study, with a mean age of 74±14 years, and 39 patients (49%) were female. The median NIHSS at admission was 15 (interquartile range [IQR] 8–19) and median Alberta Stroke Program Early CT Score (ASPECTS) on initial imaging was 9 (IQR 8–10). First-pass or near-complete reperfusion was achieved in 43 (54%) patients, with complete reperfusion (mTICI 3) seen in 34 (43%). Final complete, or nearcomplete reperfusion (mTICI ≥2c) was observed in 66 patients (83%) and complete reperfusion (mTICI 3) Marios-Nikos Psychogios in 45 (56%) patients, after a median of 1.5 passes (IQR 1–3). The study’s authors note that the rate of successful reperfusion was 64% after one pass, and 96% at the end of the procedure. A total of 158 passes were performed, and no device malfunctions were observed. Four complications were seen; two subarachnoid haemorrhages, and two vasospasms. A subgroup analysis of the angiographic results after stratification by occlusion site indicated higher first-pass complete or nearcomplete reperfusion results in the M1 and M2 segments compared to the internal carotid artery terminus (ICA-T; 53%/46% vs. 29%), while the number of passes (median three for

Per Pass Reperfusion Results1 Pass # Number of patients mTICI <2b, n (%) mTICI ≥2b, n (%) mTICI ≥2c, n (%) mTICI 3, n (%)

1

80 29 (36%) 51 (64%) 43 (54%) 34 (43%)

2

34 18 (53%) 16 (47%) 12 (35%) 7 (21%)

3

20 12 (60%) 8 (40%) 5 (25%) 2 (10%)

4

14 8 (54%) 6 (46%) 3 (23%) 2 (15%)

5

8 5 (63%) 3 (37%) 1 (12%) 0 (0%)

Trevo NXT Retriever

6

5 3 (60%) 2 (40%) 1 (20%) 0 (0%)

Minutes matter: Lessons from an aspiration-first pioneer

Minutes matter. That is the message of Alejandro Spiotta (Department of Neurosurgery, Medical University of South Carolina [MUSC], Charleston, USA), detailing the philosophy for the treatment of stroke at MUSC. The institution is a busy centre in what is known as the ‘stroke belt’ in the southeast of the USA, as well as being a pioneer of ADAPT—A direct aspiration first pass technique. In this interview, Spiotta discusses the continued development of ADAPT, evolution in the design—and size—of aspiration catheters, and his experience using the AXS Vecta® Aspiration Catheter platform (Stryker).

MUSC SEES A HIGH VOLUME OF

stroke cases every year, according to Spiotta, who describes it as one of the top five-to-10 centres in the USA for thrombectomies— with 237 having been carried out in 2020. Collaboration between neurology and neurosurgery departments is an important aspect of the hospital’s stroke strategy, as well as a streamlined protocol for treating ischaemic stroke patients, he explains. “When it comes to stroke: time is brain— so everything must happen very quickly, especially in the middle of the night. It is not the time to be pondering decisions,” Spiotta says. “Everything should already be part of the protocol, so the patient comes in and there is not much of a debate or a discussion among the stroke team.”

Cases are discussed in detail, but only during daylight hours. The stroke team agrees on inclusion criteria, and the process is standardised so as not to rely solely on the judgement of individual team members who are under immense pressure when a patient arrives.

As well as being a high-volume stroke centre, MUSC is known for its pioneering of the ADAPT technique of revascularisation. “We have done the most ADAPT procedures of any centre—currently around 1,200 since

The ASSIST Registry compares the four most commonly-used thrombectomy techniques for anterior LVOs AXS Vecta Aspiration Catheter

2013,” explains Spiotta.

According to Spiotta, the biggest advantages of ADAPT are its potential savings in time and cost, as well as generating less pain for the patient. Prior to the advent of ADAPT, many procedures were performed under general anaesthesia. However, ADAPT has changed this paradigm. Spiotta says: “What we found with ADAPT is that, not only was it painless, it was so fast that often our procedures were done faster than it took the anaesthesiology team to put the patient to sleep.”

One important arm to Spiotta’s research— and that of the team at MUSC—is his contribution to the Stroke thrombectomy and aneurysm registry (STAR). STAR is a multicentre initiative to track patient outcomes after thrombectomy or endovascular aneurysm treatment using realworld data. Spiotta describes STAR as the largest research network in the neurovascular space, begun out of the need to compile and analyse data to improve patient outcomes. The registry has grown to include more than 55 sites across five continents, enrolling 10,000 patients so far.

“A recent finding is that aspiration during posterior circulation stroke was actually associated with superior functional outcomes compared to stentrievers, and that was over the largest dataset that has ever been studied,” comments Spiotta. “With a dataset this large, and such high-quality data, we are able to answer clinical questions that were not really able to be answered before.”

Evolution of ADAPT

Importantly, ADAPT continues to develop. Spiotta and colleagues at MUSC now consider the strategy to be in its third generation—what they term ADAPT 3.0. A big development has been the use of larger-bore aspiration catheters over time—a paradigm shift, according to Spiotta. “It is not just a refinement of the technique, but also the introduction of larger and more supple catheters,” he says. “At the time of ADAPT 1.0 we were using what we considered then to be ‘large’ catheters, but now would be considered an intermediate-sized catheter. It was a new concept at the time, and a paradigm shift to place these large-bore catheters distally in the brain arteries.

“Over time, the catheters have gotten larger and have been designed to be delivered to more distal locations, to the arteries in the brain more safely and more readily, so it is faster to deliver these catheters and to navigate them from the neck through the skull and into the brain.” Larger-bore catheters with a larger cross-sectional lumen provide a greater aspiration force at the thrombus, Spiotta says, which can contribute to easier removal of the thrombus, requiring fewer passes, improving procedure times and potentially improving patient outcomes. “The catheter technology has improved dramatically, in becoming larger bore, and also the technique itself has been refined, with regards to where we place the catheter in relation to the thrombus that is obstructing the artery,” he says.

AXS Vecta Aspiration Catheter experience

Stryker’s AXS Vecta Aspiration Catheter is among the latest iterations of such devices launched for direct aspiration thrombectomy. Spiotta and colleagues at MUSC are contributing to the prospective ASSIST registry headed by Rishi Gupta and Markus Mohlenbruch, which is comparing treatment of ischaemic stroke patients using various interventional techniques with Stryker Neurovascular devices for the first pass. Around 1,500 patients are planned to be enrolled, with over 90% of these already included.

“We started using AXS Vecta Aspiration Catheter in the setting of the ASSIST study,” comments Spiotta. “We have been very impressed with the results that we have obtained with the Vecta 71 as well as the 74. We found that our experience is nicely in line with the storyline of the evolution of ADAPT—with increasing catheter size, resulting in shorter procedure times and