The Solitaire Flow restoration device achieved substantially better angiographic, safety and clinical outcomes than did the Merci Retrieval System, according to the small, randomized SWIFT trial presented Aug. 27 at the European Society of Cardiology Congress in Munich. Thus, the study authors suggested that Solitaire might be a future treatment of choice for endovascular recanalization in acute ischemic stroke.
The results were presented simultaneous to publication in the Lancet.
The Solitaire Flow restoration device (Covidien/ev3, Dublin), approved by the FDA in March, is a self-expanding stent retriever designed to restore blood flow in patients with ischemic stroke due to large intracranial vessel occlusion. In this trial, Jeffrey L. Saver, MD, director of the University of California, Los Angeles Stroke Center, and colleagues sought to compare the efficacy and safety of Solitaire with the current standard mechanical thrombectomy device, the Merci Retrieval system (Stryker), which was the first mechanical thrombectomy device cleared by the FDA for use in acute ischemic stroke in 2004.
In this randomized, parallel-group, non-inferiority trial, the researchers enrolled patients from 18 sites (17 in the U.S. 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 eight hours of stroke symptom onset. They 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 lab, which was masked to study assignment. Saver and colleagues conducted a primary analysis by intention to treat.
And, of note, pre-specified efficacy stopping rule triggered an early halt to the trial.
Between February 2010 and February 2011, the researchers 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 percent vs. 24 percent). More patients had good three-month neurological outcome with Solitaire than with Merci (58 percent vs. 33 percent).
The 90-day mortality rate was lower in the Solitaire group than it was in the Merci group (17 percent vs. 38 percent).
“Accordingly, when endovascular recanalization is undertaken in patients with acute ischemic stroke, initial treatment with Solitaire might be a preferred approach,” the authors wrote. “However, for the benefit of this treatment to be definitively shown, randomized trials are needed to compare mechanical thrombectomy with Solitaire to intravenous thrombolysis alone (in rt-PA-eligible patients) and to supportive medical care alone (in rt-PA-ineligible patients).”
They noted that this is the first acute ischemic stroke trial to undertake a direct, randomized comparison of one endovascular recanalization technique with another.
Saver et al acknowledged some study limitations, including that the design was open-label, but they added that the “potential for bias was mitigated by the use of a masked core imaging laboratory and a masked adjudication committee.” Also, the early halt of the trial resulted in a smaller than planned number of study participants, limiting the precision of treatment effect estimates.
The study authors concluded that their trial’s results “provide supportive evidence for a benefit of endovascular reperfusion on clinical outcomes in patients with acute ischemic stroke. As far as we are aware, this trial is the first randomized trial to find a beneficial effect of increased achievement of endovascular reperfusion on mortality.”
“This new device is significantly changing the way we can treat ischemic stroke," Saver said in a release. “We are going from our first generation of clot-removing procedures, which were only moderately good in reopening target arteries, to now having a highly effective tool.”
Furthermore, Saver et al said that their trial results are “highly generalizable to all centers that do endovascular reperfusion for acute ischemic stroke,” because the participating sites included both academic