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Evevident
Original paper
2015NEJMNeurology

MR CLEAN

A randomized trial of intraarterial treatment for acute ischemic stroke

RCTStroke thrombectomy

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Overview

Endovascular therapy improved functional outcome in anterior-circulation large-vessel stroke treated within 6 hours.

Clinical takeaway

MR CLEAN was the first major modern positive thrombectomy trial and changed acute LVO stroke care.

Key result

Functional independence (mRS 0-2) at 90 days was 32.6% with endovascular therapy vs 19.1% with usual care.

Practice impact

Mechanical thrombectomy became standard for eligible anterior-circulation LVO strokes.

Evidence

Study design

Randomized, open-label, blinded-endpoint trial.

Enrollment

500

Follow-up

90 days.

Geography

Netherlands

Clinical question

Does intraarterial/endovascular treatment improve outcomes in acute anterior-circulation LVO stroke?

Population

  • Patients with acute ischemic stroke due to proximal anterior-circulation arterial occlusion treatable within 6 hours of onset.

Intervention

Endovascular therapy (predominantly stent retriever) plus usual care.

Comparator

Usual care alone, including IV alteplase when eligible.

Primary outcome

Functional outcome on the modified Rankin Scale at 90 days (ordinal shift).

Endovascular treatment within 6 hours improved functional outcome, increasing functional independence at 90 days from 19.1% to 32.6%.

Adjusted common odds ratio / 1.67 / CI 95% CI 1.21-2.30 / p=0.002 (functional independence difference)

Key results

  • Adjusted common odds ratio for a shift toward better mRS was 1.67 (95% CI 1.21-2.30) favoring intervention.
  • Functional independence (mRS 0-2) at 90 days: 32.6% with endovascular therapy vs 19.1% with usual care (absolute difference 13.5 percentage points).
  • There was no significant difference in mortality or symptomatic intracranial hemorrhage.
  • Nearly all patients (~89%) received IV alteplase before randomization.

Harms

  • New ischemic strokes in a different vascular territory occurred more often with intervention (5.6% vs 0.4%).
  • Symptomatic intracranial hemorrhage did not differ significantly between groups (7.7% vs 6.4%).

Clinical Use

When to cite

  • When activating endovascular therapy pathways for large-vessel occlusion stroke rather than relying on IV thrombolysis alone.

Practice impact

  • Mechanical thrombectomy became standard for eligible anterior-circulation LVO strokes.

Applicability

  • Most applicable to patients with acute ischemic stroke from a proximal anterior-circulation occlusion treatable within 6 hours of onset.

Limitations

  • Early-generation devices and workflow compared with current systems.
  • Restricted to early-window anterior-circulation large-vessel occlusion.
  • Open-label design, though the primary outcome was assessed by blinded raters.

Common misinterpretations

  • MR CLEAN complemented rather than replaced IV thrombolysis; most patients received alteplase before thrombectomy.
  • It launched a wave of confirmatory trials (ESCAPE, SWIFT PRIME, EXTEND-IA, REVASCAT) that together established thrombectomy as standard of care.

Related evidence

NINDS tPA - Earlier TrialDAWN - Later TrialDEFUSE 3 - Later Trial

Citation

Berkhemer OA, Fransen PS, Beumer D, et al. A randomized trial of intraarterial treatment for acute ischemic stroke. N Engl J Med. 2015;372(1):11-20. doi:10.1056/NEJMoa1411587

In patients with acute ischemic stroke caused by a proximal intracranial occlusion of the anterior circulation, intraarterial treatment administered within 6 hours after stroke onset was effective and safe.