SOLITAIRE FR With the Intention For Thrombectomy as PRIMary Endovascular Treatment for Acute Ischemic Stroke - SWIFT PRIME

Contribution To Literature:

The SWIFT PRIME study on eligible patients presenting with an acute ischemic stroke suggests that endovascular therapy is superior in improving perfusion, neurological, and functional outcomes compared with IV thrombolysis alone.

Description:

The goal of the trial was to compare the role of endovascular therapy as an adjunct to intravenous (IV) thrombolysis in patients presenting with acute ischemic stroke within 6 hours of symptom onset, compared with IV thrombolysis alone.

Study Design

Patients with acute ischemic stroke presenting within 6 hours of symptom onset were randomized to endovascular thrombectomy with the Solitaire FR stent retriever along with IV tissue plasminogen activator (t-PA) (n = 98) or IV t-PA alone (n = 98).

Patient Population:

  • Total number of enrollees: 196
  • Duration of follow-up: 90 days
  • Mean patient age: 66 years
  • Percentage female: 50%
  • National Institutes of Health Stroke Scale (NIHSS) score (median): 17
  • Onset to emergency room (ER) arrival time: 110 minutes
  • ER arrival to qualifying imaging followed by randomization: 45 minutes
  • Symptom onset to groin puncture: 224 minutes

Inclusion criteria:

  • Acute ischemic stroke
  • Age 18-80 years
  • Pre-stroke Modified Rankin Score ≤1
  • NIHSS score 8-29 at randomization
  • Received IV t-PA within 4.5 hours of stroke onset
  • Computed tomography angiography (CTA) or magnetic resonance angiography (MRA) confirmation of large vessel occlusion (intracranial internal carotid artery [ICA], middle cerebral artery [MCA]-M1, or carotid terminus)
  • Groin puncture within 6 hours of stroke onset and within 90 minutes of qualifying imaging

Exclusion criteria:

  • CT/magnetic resonance imaging (MRI) evidence of hemorrhage
  • CT hypodensity or MRI hyperintensity less than one third of the MCA territory (or in other territories, >100 cc of tissue)
  • Carotid dissection or complete cervical carotid occlusion requiring stenting at the time of the mechanical thrombectomy procedure
  • ASPECTS score <6

Principal Findings:

The study stopped early due to efficacy. The primary outcome, modified Rankin score of 0-2 at 90 days, was observed in 60% in the endovascular + t-PA group versus 35% of the t-PA group (p = 0.0002). The shift toward better outcomes was consistent in direction across all the score levels of the modified Rankin scale.

Secondary outcomes:

  • In the endovascular group, Thrombolysis in Cerebral Infarction (TICI) 2B/3 perfusion rate was 88%.
  • Mortality: 9% vs. 12%, p = 0.5
  • Improvement in NIHSS at 27 hours: 8.5 vs. 3.9, p < 0.0001
  • Symptomatic intracranial hemorrhage: 0% vs. 3%, p = 0.12
  • Parenchymal hemorrhage: 5.1% vs. 7.2%, p = 0.57
  • Subarachnoid hemorrhage: 4.1% vs. 1.0%, p = 0.37

CT-perfusion (n = 139) vs. MRI (n = 34) imaging prior to randomization:

  • Time from stroke onset to randomization was longer in MRI patients compared with CT-perfusion patients (235.5 vs. 179 minutes, p = 0.003), driven by a higher transfer-in rate for MRI patients.
  • Time from emergency room arrival to randomization was similar between the two groups.
  • Modified Rankin Scale score 0-2 at 90 days for MRI vs. CT-perfusion was similar, p = 0.8. TICI 2B/3 perfusion rate was 60.7% vs. 69.7%, p = 0.37.

Interpretation:

Among patients with acute ischemic stroke presenting within 6 hours of symptom onset due to proximal large arterial occlusion, the use of endovascular treatment with the Solitaire FR stent retriever as an adjunct to IV thrombolysis is superior to IV thrombolysis alone in improving distal perfusion, neurological outcomes, and functional recovery. Benefits of endovascular therapy were similar irrespective of receiving MRI or CT-perfusion as qualifying study prior to randomization. This trial initially required functional perfusion imaging like EXTEND-IA for inclusion, but then simplified imaging criteria to include patients with a small to moderate ischemic core to accommodate a larger number of sites and to expedite randomization. Risk stratification needs to be standardized prior to greater utilization.

In combination with other recent trials such as MR CLEAN and EXTEND-IA, the results indicate that adjunctive endovascular treatment should be first-line therapy for eligible patients presenting with an acute ischemic stroke.

References:

de Champfleur NM, Saver JL, Goyal M, et al. Efficacy of Stent-Retriever Thrombectomy in Magnetic Resonance Imaging Versus Computed Tomographic Perfusion–Selected Patients in SWIFT PRIME Trial (Solitaire FR With the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke). Stroke 2017;48:1560-6.

Saver JL, Goyal M, Bonafe A, et al., on behalf of the SWIFT PRIME Investigators. Stent-Retriever Thrombectomy after Intravenous t-PA vs. t-PA Alone in Stroke. N Engl J Med 2015;372:2285-95.

Presented by Dr. Jeffrey Saver at the International Stroke Conference (ISC), February 11, 2015, Nashville, TN.


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