Solitaire Flow Restoration Device Versus the Merci Retriever in Patients With Acute Ischaemic Stroke (SWIFT): A Randomised, Parallel-Group, Non-Inferiority Trial

Study Questions:

What is the efficacy and safety of the Solitaire Flow Restoration Device compared with the standard, predicate mechanical thrombectomy device, the Merci Retrieval System?


In SWIFT (Solitaire With the Intention For Thrombectomy), a randomized, parallel-group, noninferiority trial, the investigators enrolled patients from 18 sites (17 in the United States and one in France). Patients were eligible for inclusion if they had acute ischemic stroke with moderate to severe neurological deficits and were treatable by thrombectomy within 8 hours of stroke symptom onset. The investigators used a computer-generated randomization sequence to randomly allocate patients to receive thrombectomy treatment with either Solitaire or Merci (1:1; block sizes of four and stratified by center and stroke severity). The primary endpoint was Thrombolysis In Myocardial Ischemia (TIMI) scale 2 or 3 flow in all treatable vessels without symptomatic intracranial hemorrhage, after up to three passes of the assigned device, as assessed by an independent core laboratory, which was masked to study assignment. Primary analysis was done by intention to treat. A prespecified efficacy stopping rule triggered an early halt to the trial.


Between February 2010, and February 2011, the investigators randomly allocated 58 patients to the Solitaire group and 55 patients to the Merci group. The primary efficacy outcome was achieved more often in the Solitaire group than it was in the Merci group (61% vs. 24%; difference 37% [95% CI 19-53], odds ratio [OR] 4.87 [95% CI 2.14-11.10]; pnoninferiority < 0.0001, psuperiority = 0.0001). More patients had good 3-month neurological outcome with Solitaire than with Merci (58% vs. 33%; difference 25% [6-43], OR 2.78 [1.25-6.22]; pnoninferiority = 0.0001, psuperiority = 0.02). Ninety-day mortality was lower in the Solitaire group than in the Merci group (17 vs. 38; difference –21% [–39 to –3], OR 0.34 [0.14-0.81]; pnoninferiority = 0.0001, p = 0.02).


The authors concluded that the Solitaire Flow Restoration Device achieved substantially better angiographic, safety, and clinical outcomes than did the Merci Retrieval System.


This study reports that, compared with the Merci Retriever, neurothrombectomy with the Solitaire Flow Restoration device is associated with increased achievement of successful cerebral recanalization without symptomatic intracranial hemorrhage, improved final disability outcomes, and reduced mortality. However, definitive demonstration of benefit of mechanical thrombectomy with Solitaire can only come from the undertaking of randomized trials to directly compare mechanical thrombectomy using Solitaire with intravenous thrombolysis and to supportive medical care alone. Future studies will also need to compare the Solitaire Flow Restoration device with the Trevo retriever.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention

Keywords: Stroke, Myocardial Ischemia, France, Thrombectomy, United States

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