Safety and Efficacy of Solitaire Stent Thrombectomy: Individual Patient Data Meta-Analysis of Randomized Trials

Abstract

Background and purpose: Recent positive randomized trials of endovascular therapy for ischemic stroke used predominantly stent retrievers. We pooled data to investigate the efficacy and safety of stent thrombectomy using the Solitaire device in anterior circulation ischemic stroke.

Methods: Patient-level data were pooled from trials in which the Solitaire was the only or the predominant device used in a prespecified meta-analysis (SEER Collaboration): Solitaire FR With the Intention for Thrombectomy as Primary Endovascular Treatment (SWIFT PRIME), Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion With Emphasis on Minimizing CT to Recanalization Times (ESCAPE), Extending the Time for Thrombolysis in Emergency Neurological Deficits-Intra-Arterial (EXTEND-IA), and Randomized Trial of Revascularization With Solitaire FR Device Versus Best Medical Therapy in the Treatment of Acute Stroke Due to Anterior Circulation Large Vessel Occlusion Presenting Within Eight Hours of Symptom Onset (REVASCAT). The primary outcome was ordinal analysis of modified Rankin Score at 90 days. The primary analysis included all patients in the 4 trials with 2 sensitivity analyses: (1) excluding patients in whom Solitaire was not the first device used and (2) including the 3 Solitaire-only trials (excluding ESCAPE). Secondary outcomes included functional independence (modified Rankin Score 0-2), symptomatic intracerebral hemorrhage, and mortality.

Results: The primary analysis included 787 patients: 401 randomized to endovascular thrombectomy and 386 to standard care, and 82.6% received intravenous thrombolysis. The common odds ratio for modified Rankin Score improvement was 2.7 (2.0-3.5) with no heterogeneity in effect by age, sex, baseline stroke severity, extent of computed tomography changes, site of occlusion, or pretreatment with alteplase. The number needed to treat to reduce disability was 2.5 and for an extra patient to achieve independent outcome was 4.25 (3.29-5.99). Successful revascularization occurred in 77% treated with Solitaire device. The rate of symptomatic intracerebral hemorrhage and overall mortality did not differ between treatment groups.

Conclusions: Solitaire thrombectomy for large vessel ischemic stroke was safe and highly effective with substantially reduced disability. Benefits were consistent in all prespecified subgroups.

Keywords: endovascular treatment; intra-arterial therapy; ischemic stroke; mechanical thrombectomy; meta-analysis; randomized controlled trial; stent retriever device; thrombolysis.

Figure 1.

Functional outcome (modified Rankin Scale [mRS] at 90 days) in the primary and sensitivity analysis populations. Odds ratios (OR) and 95% confidence intervals (CI) for ordinal analysis of mRS (both unadjusted and adjusted for age, sex, baseline stroke severity, site of occlusion, intravenous alteplase treatment, Alberta Stroke Program Early CT Score (ASPECTS), and time from onset to randomization) and for independent functional outcome (mRS 0–2), both unadjusted and adjusted.

Figure 2.

Distribution of modified Rankin scores (mRS) at 90 days in the primary analysis: SWIFT PRIME, EXTEND-IA, ESCAPE, and REVASCAT. Overall results (A) comparing age dichotomized at 70 years (B), comparing age dichotomized at 80 years (C), comparing those who did or did not receive intravenous alteplase before endovascular stent thrombectomy (D). NB mRS 5 and 6 were combined for the ordinal analysis. ESCAPE indicates Endovascular Treatment for Small Core and Anterior Circulation Proximal Occlusion With Emphasis on Minimizing CT to Recanalization Times; EXTEND-IA, Extending the Time for Thrombolysis in Emergency Neurological Deficits—Intra-Arterial; REVASCAT, Randomized Trial of Revascularization With Solitaire FR Device Versus Best Medical Therapy in the Treatment of Acute Stroke Due to Anterior Circulation Large Vessel Occlusion Presenting Within Eight Hours of Symptom Onset; and SWIFT PRIME, Solitaire FR With the Intention for Thrombectomy as Primary Endovascular Treatment.

Figure 3.

Treatment effect in predefined subgroups (Forest plot), analyses adjusted for age, sex, baseline stroke severity, site of occlusion, intravenous alteplase treatment, tandem cervical carotid occlusion, Alberta Stroke Program Early CT Score (ASPECTS), and time from onset to randomization. CI indicates confidence interval; ICA, internal carotid artery; MCA, middle cerebral artery; and NIHSS, National Institutes of Health Stroke Scale.

Figure 4.

Relationship of time from stroke onset to reperfusion (modified Treatment in Cerebral Ischemia [mTICI] 2b/3) and independent functional outcome (modified Rankin scores [mRS] 0–2) with 95% confidence interval (scatter represents individual predicted outcomes in the endovascular group only). Estimates were adjusted for age, sex, baseline stroke severity on the National Institutes of Health Stroke Scale (NIHSS) score, site of occlusion, intravenous alteplase treatment, Alberta Stroke Program Early CT Score (ASPECTS), and time from onset to TICI 2b/3 flow among the patients treated with Solitaire as the first device in all 4 trials and achieving mTICI 2b/3 at end of procedure. The onset-to-TICI 2b/3 time was a significant predictor of outcome (odds ratio [OR] 0.99 per minute; P=0.011) with the probability of independent functional outcome declining 1% per 23 minute delay.