Trevo versus Merci retrievers for thrombectomy revascularisation of large vessel occlusions in acute ischaemic stroke (TREVO 2): a randomised trial

Abstract

Background: Present mechanical devices are unable to achieve recanalisation in up to 20-40% of large vessel occlusion strokes. We compared efficacy and safety of the Trevo Retriever, a new stent-like device, with its US Food and Drug Administration-cleared predecessor, the Merci Retriever.

Methods: In this open-label randomised controlled trial, we recruited patients at 26 sites in the USA and one in Spain. We included adults aged 18-85 years with angiographically confirmed large vessel occlusion strokes and US National Institutes of Health Stroke Scale (NIHSS) scores of 8-29 within 8 h of symptom onset. We randomly assigned patients (1:1) with sequentially numbered sealed envelopes to thrombectomy with Trevo or Merci devices. Randomisation was stratified by age (≤68 years vs 69-85 years) and NIHSS scores (≤18 vs 19-29) with alternating blocks of various sizes. The primary efficacy endpoint, assessed by an unmasked core laboratory, was thrombolysis in cerebral infarction (TICI) scores of 2 or greater reperfusion with the assigned device alone. The primary safety endpoint was a composite of procedure-related adverse events. Analyses were done by intention to treat. This study is registered with ClinicalTrials.gov, number NCT01270867.

Findings: Between Feb 3, 2011, and Dec 1, 2011, we randomly assigned 88 patients to the Trevo Retriever group and 90 patients to Merci Retriever group. 76 (86%) patients in the Trevo group and 54 (60%) in the Merci group met the primary endpoint after the assigned device was used (odds ratio 4·22, 95% CI 1·92-9·69; p(superiority)<0·0001). Incidence of the primary safety endpoint did not differ between groups (13 [15%] patients in the Trevo group vs 21 [23%] in the Merci group; p=0·1826).

Interpretation: Patients who have had large vessel occlusion strokes but are ineligible for (or refractory to) intravenous tissue plasminogen activator should be treated with the Trevo Retriever in preference to the Merci Retriever.

Funding: Stryker Neurovascular.

Figure 1. Example angiography and devices

(A–H) Angiography images of a 67-year-old woman presenting with left hemiplegia and dysarthria (NIHSS 12). Intravenous recombinant tissue plasminogen activator was given 115 min after symptom onset without improvement. (A–B) Angiography before treatment showing complete occlusion of the M1 segment of the right MCA (arrows). (C–E) Angiography after deployment of the Trevo Retriever across the occluded segment showing a perfusion channel with contrast opacification of the distal MCA territory (arrowheads). Black arrows in panels C–E show the proximal Trevo markers and white arrows show the distal Trevo markers. (E) Magnified native image of panel C. (F–G) Angiography after treatment showing near complete reperfusion of the right MCA territory (TICI 2b). At 90 days, the patient’s NIHSS was 0 and modified Rankin scale score was 1. (H) Trevo device and retrieved complex thromboembolic material. (I–J) Thrombus incorporation by the Trevo (I) and Merci (J) retrievers. NIHSS=National Institutes of Health Stroke Scale. MCA=middle cerebral artery. TICI=thrombolysis in cerebral infarction grading scale score.

Figure 2. Trial profile

NIHSS=National Institutes of Health Stroke Scale. mRS=modified Rankin scale. *Modified Rankin scores were not obtained for three patients at 90 days, but survival status was known for all patients. †Modified Rankin scores were not obtained for three patients at 90 days, but survival status was known for all but one patient, who was lost to follow-up after discharge.

Figure 3. 90 day modified Rankin scale scores

Data were available for 85 (97%) of 88 patients in the Trevo group and 87 (97%) of 90 patients in the Merci group.

Figure 4

Kaplan-Meier survival analysis