ArticlesTrevo versus Merci retrievers for thrombectomy revascularisation of large vessel occlusions in acute ischaemic stroke (TREVO 2): a randomised trial
Introduction
Intravenous recombinant tissue plasminogen activator (rt-PA) is the standard of care for treatment of acute ischaemic stroke. However, rt-PA has limitations, including a short therapeutic window that restricts more widespread adoption and poor reperfusion rates in the setting of extensive clot burden.1, 2, 3, 4, 5, 6 Use of mechanical clot retrieval devices in acute ischaemic stroke might result in increased reperfusion rates compared with intravenous or intra-arterial thrombolysis.7 However, mechanical devices are unable to achieve recanalisation in as many as 20–40% of large vessel occlusion strokes.8, 9, 10
Presently available thombectomy devices work through application of different degrees of retrieval force on the thrombus with either a proximal approach (eg, thromboaspiration devices) or distal approach (eg, snare-like devices). The Merci Retriever (Stryker Neurovascular, Mountain View, CA, USA; figure 1) is a flexible nitinol wire with distal corkscrew-shaped coil loops with attached filaments. The device is deployed distally to the clot through a microcatheter and is used to ensnare and remove the thrombus into a balloon-guide catheter placed in the cervical internal carotid or vertebral arteries. The Trevo Retriever (Stryker Neurovascular; figure 1) is a novel thrombectomy device belonging to a category increasingly known as stent retrievers because of their resemblance to intracranial stents. Unlike their predecessors, stent retrievers apply a radial retrieval force in the centre of the thrombus and along its whole length. A microcatheter is placed distal to the thrombus and the closed-cell stent-like nitinol device is delivered via the microcatheter. The retriever is deployed by unsheathing the microcatheter, resulting in opening of the stent and radial displacement of the thrombus against the blood vessel wall with incorporation of the clot material into the stent struts. The device is subsequently retrieved into a catheter placed in the internal carotid or vertebral arteries. In animals, Trevo was very effective at achieving immediate reperfusion of occluded arteries without causing any clinically significant disruption of the vascular integrity.11 In the multicentre, prospective, single-group TREVO trial12 of 60 patients with stroke at seven European centres, treatment with the Trevo Retriever had a recanalisation rate of 92% with a rate of independent functional outcome (90 day modified Rankin scale [mRS] score of ≤2) of 55%.
In this trial, TREVO 2, we aimed to compare the efficacy and safety of mechanical thrombectomy with the Trevo Retriever with that of the Merci Retriever in the arterial revascularisation of patients with acute ischaemic stroke.
Section snippets
Study design and patients
TREVO 2 was a randomised, prospective, controlled, multicentre, open-label, adaptive, non-inferiority trial. The study used an executive committee, an independent clinical events committee, a CT and MRI imaging core laboratory, a separate angiography core laboratory, and an independent data safety and monitoring board (DSMB) to ensure appropriate oversight and analysis of the study data. The independent DSMB, which was made up of investigators who were not actively participating in enrolment in
Results
Figure 2 shows the screening, enrolment, and follow-up profile of the trial. No patients crossed over or were incorrectly randomised. 178 (19%) of 930 patients presenting with stroke-like symptoms were screened within 8 h of symptom onset between Feb 3, 2011, and Dec 1, 2011. Table 1 shows baseline characteristics of the 88 patients randomly assigned to the Trevo group and 90 patients to the Merci group. The mean age was 67·2 years (SD 14·2), 43% of patients were men, median baseline NIHSS
Discussion
Our trial showed that the Trevo Retriever was superior to the Merci Retriever for arterial revascularisation in terms of reperfusion to TICI 2 or greater in the setting of acute ischaemic stroke. Notably, increased frequency and extent of reperfusion was associated with improved clinical outcomes at 24 h, shorter hospital stays, and improved independence.
Overall safety profiles (composite events) were much the same with both devices (table 3); however, vessel perforations were almost ten times
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