Patients presenting with anterior circulation acute ischemic stroke eligible using standard criteria to receive IV tPA within 4.5 hours of stroke onset

Patient, family member or legally responsible person depending on local ethics requirements has given informed consent

Patient's age is ≥18 years (no restriction on age)

Intra-arterial clot retrieval treatment can commence (groin puncture) within 6 hours of stroke onset

Arterial occlusion on CTA or MRA of the internal carotid artery, proximal middle cerebral artery, distal middle cerebral artery

Mismatch - Using CT or MRI with a Tmax >6 second delay perfusion volume and either CT-rCBF or DWI infarct core volume. A) Mismatch ratio of greater than 1.2, and B) Absolute mismatch volume of greater than 10 ml, and C) Infarct core lesion volume of less than 70mL

Intracranial hemorrhage, rapidly improving symptoms, pre-stroke modified Rankin score of ≥ 2 inability to access the cerebral vasculature, stenosis proximal to the thrombus site, carotid dissection, terminal illness with less than 1 year life expectancy, pregnant women, previous stroke within last three months, recent past history or clinical presentation of intracranial hemorrhage, subarachnoid hemorrhage, arterio-venous malformation, aneurysm, or cerebral neoplasm, current use of anticoagulants with coagulation prolongation, use of glycoprotein IIb - IIIa inhibitors within the past 72 hours, hypoglycaemia, blood pressure > 185/110, hemorrhagic diathesis, gastrointestinal or urinary bleeding within the preceding 21 days, major surgery within the preceding 14 days, exposure to a thrombolytic agent within the previous 72 hours.

Control Group = Usual care only vs.

Intervention Group = Intra-arterial treatment with a stent retriever (Solitaire FR retrievable stent by Covidien) plus usual care

Reperfusion at 24 hrs post stroke without symptomatic intracerebral hemorrhage.

Recanalization at 24 hrs post stroke

Infarct growth within 24 hrs

Stroke severity (NIHSS) at 24hrs

Symptomatic intra-cranial hemorrhage

Death due to any cause

Modified Rankin Scale (mRS) 0-1 at 3 months

Modified Rankin Scale (mRS) 0-2 at 3 months

Categorical shift in mRS at 3 months

NIHSS reduction ≥8 points or reaching 0-1 at 3 months

The median age was 69 years. The median NIH stroke scale was 15. The median stroke to puncture time was 210 minutes.

Reperfusion at 24 hours for the endovascular intervention group was 89% as compared with the alteplase-only group at 34% (P<0.001).

Early neurologic improvement at 3 days was 80% for endovascular intervention group vs the 37% for the alteplase-only group (adjusted P < 0.001)

71% of patients in the endovascular treatment group had functional independence (modified Rankin score of 0-2) as compared to 40% in the alteplase-only group - absolute difference of 33% (P = 0.01)

Although not statistically significant, at the time of early termination of the study more deaths occurred in the alteplase only group compared to the endovascular plus alteplase group (20% vs 9%).

The median infarct growth at 24 hr was also less with the intervention group (35.3 mL vs 10.9 mL; P = 0.007)

The rate of symptomatic intracerebral hemorrhage was 6% the alteplase only group vs 0% for the intervention group.

This study had no upper limit age restrictions

This study had no restrictions based on NIHSS score.

The investigators had originally planned to enroll 100 patients. 

The EXTEND-IA trial was terminated early after the release of the MR CLEAN results and an unplanned interim efficacy analysis was conducted based on the Haybittle-Peto stopping rule.

This was a poorly powered study