New Class of Radially Adjustable Stentrievers for Acute Ischemic Stroke

Primary Results of the Multicenter TIGER Trial

Rishi Gupta, MD, MBA; Jeffrey L. Saver, MD; Elad Levy, MD; Osama O. Zaidat, MD, MS; Dileep Yavagal, MD; David S. Liebeskind, MD; Ahmad Khaldi, MD, MS; Bradley Gross, MD; Michael Lang, MD; Sandra Narayanan, MD; Brian Jankowitz, MD; Kenneth Snyder, MD; Adnan Siddiqui, MD; Jason Davies, MD; Eugene Lin, MD; Ameer Hassan, MD; Ricardo Hanel, MD; Amin Aghaebrahim, MD; Ritesh Kaushal, MD; Ali Malek, MD; Nils Mueller-Kronast, MD; Robert Starke, MD; Hormozd Bozorgchami, MD; Gary Nesbit, MD; Masahiro Horikawa, MD; Ryan Priest, MD; Jesse Liu, MD; Ronald F. Budzik, MD; Peter Pema, MD; Nirav Vora, MD; M. Asif Taqi, MD; Edgar Samaniego, MD; Qingliang Tony Wang, MD, PhD; Erez Nossek, MD; Guilherme Dabus, MD; Italo Linfante, MD; Ajit Puri, MD; Eitan Abergel, MD; Sidney Starkman, MD; Satoshi Tateshima, MD; Ashutosh P. Jadhav, MD, PhD


Stroke. 2021;52(5):1534-1544. 

In This Article

Abstract and Introduction


Background and Purpose: The Tigertriever is a novel, radially adjustable, fully visible, stentriever that permits the operator to align radial expansion with target vessel diameters. This multicenter trial compared the Tigertriever's effectiveness and safety compared with established stent retrievers.

Methods: Single arm, prospective, multicenter trial comparing the Tigertriever to efficacy and safety performance goals derived from outcomes in 6 recent pivotal studies evaluating the Solitaire and Trevo stent-retriever devices with a lead-in and a main-study phase. Patients were enrolled if they had acute ischemic stroke with National Institutes of Health Stroke Scale score ≥8 due to large vessel occlusion within 8 hours of onset. The primary efficacy end point was successful reperfusion, defined as core laboratory-adjudicated modified Thrombolysis in Cerebral Ischemia score 2b-3 within 3 passes of the Tigertriever. The primary safety end point was a composite of 90-day all-cause mortality and symptomatic intracranial hemorrhage. Secondary efficacy end points included 3-month good clinical outcome (modified Rankin Scale score 0–2) and first-pass successful reperfusion.

Results: Between May 2018 and March 2020, 160 patients (43 lead-in, 117 main phase) at 17 centers were enrolled and treated with the Tigertriever. The primary efficacy end point was achieved in 84.6% in the main-study phase group compared with the 63.4% performance goal and the 73.4% historical rate (noninferiority P<0.0001; superiority P<0.01). The first pass successful reperfusion rate was 57.8%. After all interventions, successful reperfusion (modified Thrombolysis in Cerebral Ischemia score ≥2b) was achieved in 95.7% and excellent reperfusion (modified Thrombolysis in Cerebral Ischemia score 2c-3) in 71.8%. The primary safety composite end point rate of mortality and symptomatic intracranial hemorrhage was 18.1% compared with the 30.4% performance goal and the 20.4% historical rate (noninferiority P=0.004; superiority P=0.57). Good clinical outcome was achieved in 58% at 90 days.

Conclusions: The Tigertriever device was shown to be highly effective and safe compared with Trevo and Solitaire devices to remove thrombus in patients with large-vessel occlusive stroke eligible for mechanical thrombectomy.

Registration: URL:; Unique identifier: NCT03474549.

Graphic Abstract: An online graphic abstract is available for this article.


Based on convergent evidence from major clinical trials of reperfusion efficacy and improved clinical outcomes, endovascular thrombectomy with stent retrievers has become the standard of care for patients with large vessel occlusion ischemic strokes.[1–8] A meta-analysis of 5 randomized trials demonstrated the number needed to treat with thrombectomy is 1 in 2.6 to improve 3-month global disability outcome by 1 or more levels on the modified Rankin Scale (mRS).[9] However, while quite substantial, the benefits conveyed by first-generation stent retrievers are constrained by less than maximal reperfusion rates achieved with these devices. In pooled, individual participant data meta-analyses of the pivotal trials, failure to achieve successful reperfusion (modified Thrombolysis in Cerebral Ischemia [mTICI] 2b-3) occurred in 29% of patients and failure to achieve complete reperfusion (mTICI 3) in 67%.[9] Accordingly, developing additional endovascular thrombectomy devices with performance characteristics comparable or better than established stent retrievers is desirable.

The Tigertriever (Rapid Medical) is a novel operator-adjustable stent retriever that affords the interventionalist incremental control over the radial diameter and radial force of the thrombectomy basket. The design is intended to facilitate alignment of the mesh with the anatomy of the occluded vessel and to increase internalization of the thrombus within the device, thereby facilitating retrieval and reducing downstream embolization (Figure 1A; Figure I in the Data Supplement). The device has had CE mark, the European Union certification indicating conformity with health, safety, and environmental protection, since 2016 and has shown promising signals of efficacy and safety in preliminary case series reported by European centers.[10–12]

Figure 1.

Tigertriever device and chart of patient flow through study.
A, Tigertriever device including external handle for the operator to control the degree of expansion of the stent retriever. Fine wire mesh mounted on a flexible shaft. The design of the wire mesh (magnified view) is optimized to penetrate the clot and encapsulate it during retrieval. B, Patient screening, enrollment, treatment, and follow-up. ICH indicates intracranial hemorrhage; LVO, large vessel occlusion; mRS, modified Rankin Scale; and NIHSS, National Institutes of Health Stroke Scale.

The TIGER trial (Treatment With Intent to Generate Endovascular Reperfusion) was a single-arm, multicenter, prospective study assessing the efficacy and safety of the Tiger-21 and Tiger-17 retrievers. The study employed an objective performance criterion, noninferiority design, comparing efficacy and safety of the Tigertriever with performance goals derived from adjudicated outcomes in 6 completed prospective trials of 2 FDA-approved predicate stent retrievers, Solitaire (Medtronic) and Trevo (Stryker).[1–4,13,14]