SWIFT PRIME

Clinical Question

In patients with acute ischemic stroke due to occlusions in the proximal anterior intracranial circulation, does stent-retriever thrombectomy in addition to intravenous t-PA improve long-term functional outcome compared to intravenous t-PA alone?

Inclusion Criteria

• Age 18-80 years
• Patients with acute ischemic stroke
• Moderate-to-severe neurologic deficits (NIHSS ≥8 and <30 at randomization)
• Imaging-confirmed occlusion of the intracranial internal carotid artery, the first segment of the middle cerebral artery, or both
• Met imaging eligibility requirements (initially target-mismatch penumbral profile, later small-to-moderate core-infarct strategy)
• Receiving or had received intravenous t-PA
• Able to undergo initiation of endovascular treatment within 6 hours after the time that they were last known to be well before the onset of acute stroke symptoms

Exclusion Criteria

• Large ischemic-core lesion on imaging (ASPECTS <6 or core volume >50 mL on perfusion).
• Pre-stroke disability (mRS >1).
• No confirmed proximal anterior circulation occlusion on CTA/MRA.
• Not receiving or not eligible for IV tPA (all patients required bridging therapy).
• NIHSS <8 (mild stroke) or NIHSS ≥30 at randomization.
• Posterior circulation occlusion.
• Known hemorrhagic diathesis; warfarin therapy with INR >1.7.
• Platelet count <100,000.
• Blood glucose <50 mg/dL.
• Severe allergy to contrast media.
• Pregnancy or suspected pregnancy.

Baseline Characteristics

Arms

Outcomes

Criticisms

• Mandatory IV tPA in both arms — excludes patients ineligible for thrombolysis (late presenters, anticoagulated, recent surgery), limiting generalizability to the direct thrombectomy population.
• Stopped early at 196/833 patients (24%) — the most extreme early termination among the 2015 trials, potentially overestimating treatment effect.
• Industry-sponsored (Covidien/Medtronic) — the only 2015 thrombectomy trial with full industry sponsorship, raising potential conflict of interest concerns.
• Imaging eligibility changed mid-trial from perfusion-based target mismatch to ASPECTS-based core strategy — introduces heterogeneity in patient selection.
• All sites were tertiary centers with experienced neurointerventionalists and a continuous quality-improvement program — workflow times may not be achievable in community settings.
• Excluded M2 and posterior circulation occlusions — later addressed by trials like ASTER 2 and BASICS.
• No comparison with aspiration-first technique (ADAPT) — only Solitaire stent retriever evaluated.
• 6-hour time window — does not address late-presenting patients, who were later shown to benefit in DAWN and DEFUSE 3.

Subgroup Analysis

No heterogeneity of treatment effect across 8 prespecified subgroups (all reported as Risk Ratios per Figure 2): sex (male RR 1.75 [1.11–2.78], female RR 1.61 [1.03–2.50]; interaction P=0.78), age (≥70 yr RR 1.78 [1.03–3.09], <70 yr RR 1.67 [1.13–2.47]; P=0.88), NIHSS (≤17 RR 1.49 [1.05–2.11], >17 RR 2.21 [1.17–4.19]; P=0.55), occlusion site (ICA RR 2.04 [0.67–6.21], M1 RR 1.74 [1.23–2.46], M2 RR 1.35 [0.41–4.41]; P=0.87), geographic region (US RR 1.63 [1.11–2.39], Europe RR 1.85 [1.05–3.24]; P=0.66), ASPECTS (6–7 RR 1.98 [0.73–5.33], 8–10 RR 1.62 [1.17–2.24]; P=0.94), site of initial tPA administration (study hospital RR 1.61 [1.13–2.30], outside hospital RR 1.77 [0.91–3.45]; P=0.87), time from onset to randomization (<189 min RR 1.62 [1.08–2.42], ≥189 min RR 1.77 [1.07–2.93]; P=0.97). Overall RR 1.70 (1.23–2.33). All subgroups showed consistent benefit. Mid-trial imaging protocol change (target mismatch → ASPECTS-based) yielded positive results under both criteria. Trial underpowered (n=196) for formal interaction tests.

Funding

Covidien