Four randomized, controlled trials have just been completed demonstrating a very significant improvement in patient outcomes with endovascular intervention for acute ischemic stroke. Endovascular intervention was typically used in addition to IV tPA, though some trials included patients ineligible for IV tPA as well.
MR CLEAN (Multicenter Randomized Clinical trial of Endovascular Treatment in the Netherlands)
- 500 patients randomized
- Subjects had proximal arterial occlusion in the anterior cerebral circulation, enrolled < 6 hours from symptom onset.
- Outcome: modified Rankin Scale (mRS) of 0-2 at 90 days (indicating functional independence) was 33% in thrombectomy patients vs. 19% in controls (p<0.001, number needed to treat [NNT]=8)
ESCAPE (Endovascular treatment for Small Core and Anterior circulation Proximal occlusion with Emphasis on minimizing CT to recanalization times)
- 316 patients randomized
- Subjects had NIHSS > 5, CTA confirmed occlusion of the carotid or the middle cerebral artery, good collaterals on CTA, no extensive CT hypodensity, enrolled < 12 hours
- Outcome: mRS of 0-2 at 90 days was 53.0% in thrombectomy vs. 29.3% in controls (p<0.001, NNT=4), mortality 10% in thrombectomy vs 19% in control (p=0.04)
SWIFT PRIME (Solitaire™ With the Intention For Thrombectomy as PRIMary treatment for acute ischemic strokE)
- 196 patients randomized
- Subjects received IV tPA < 4.5 hours, had NIHSS between 8 -29, CTA or MRA showing an occlusion of the intracranial carotid or MCA, CT hypodensity < 1/3 of the MCA territory, and treatable < 6 hours.
- Outcome: mRS of 0-2 at 90 days was 60.2% in thrombectomy patients vs. 35.5% in controls (p < 0.001, NNT=4)
EXTEND-IA (EXtending the time for Thrombolysis in Emergency Neurological Deficits with Intra-Arterial therapy)
- 70 randomized patients
- Subjects received IV tPA < 4.5 hours, had CTA/MRA showing occlusion of the intracranial carotid or MCA, significant mismatch and limited core on MR- or CT perfusion, treatable <6 hours.
- Outcome: mRS 0-2 at 90 days was 71% in thrombectomy patients vs 40% in controls (p<0.01, NNT =3).
Based on our review of the specific details of the above trials, we currently recommend:
- Patients with acute ischemic stroke and significant neurologic deficit presenting within 4.5 hours should receive IV tPA, consistent with current criteria.
- Acute vascular imaging with CTA is recommended to detect large proximal arterial occlusions (intracranial internal carotid artery and middle cerebral artery trunk) in patients with acute ischemic stroke, especially those with NIHSS>10.
- Acute endovascular intervention should be offered to patients presenting within 6 hours of major anterior circulation stroke who have a large artery occlusion and who do not have evidence of major early infarct signs on CT, regardless of whether they have received IV tPA.
Areas of Ongoing Uncertainty
- The role of endovascular therapy in the 6 to 12 hour window has not been well established, but could be considered in select patients with favorable brain imaging.
- The relative benefits and risks for patients with branch occlusions rather than proximal arterial occlusions has not been determined, but should be considered when the clinical deficits are severe.
- The role of endovascular therapy in occlusions of the vertebrobasilar system was not evaluated in these trials, but has often been considered a viable target for similar intervention.