Published date
Thursday, 23 April, 2015

Published: Thursday 23 April 2015

About 85% of all strokes are caused by a blood clot blocking an artery in the brain.

Mechanical clot retrieval (thrombectomy) is a procedure by which the blood clot causing a stroke is pulled out of the brain, typically using a device inserted into an artery called a 'stent retriever'.

To date, the results of seven large trials suggest that early treatment with thrombectomy can reduce the disability caused by strokes that occur in the main, large arteries of the brain. These trials compared standard care (including thrombolysis) alone, with standard care plus thrombectomy.

The latest of these studies are called THERAPY and THRACE. Both presented their results on Sunday 19 April, at the European Stroke Organisation Conference (ESOC) in Glasgow.

They closely follow the presentation of the REVASCAT trial results on Friday 17 April also at the ESO conference.  

The first four of the seven trials are called MR CLEAN, EXTEND-IA, ESCAPE, and SWIFT PRIME. Read further details about these trials.


The THERAPY trial was stopped early after enrolling 108 of an intended 692 patients. This was because of the positive results of the other previously reported thrombectomy trials. This meant that the results were not statistically significant, even though the data showed strong trends towards a better stroke outcome with thrombectomy than without.  

Furthermore, unlike the other trials which focused on the use of 'retrievable stent' devices for thrombectomy, THERAPY used a different type of thrombectomy device called a 'penumbra aspiration system'. This removes the blood clot by continual apsiration (sucking) and debulking the clot, rather than trapping with a metal mesh as used in stent-retrievers.


The THRACE trial presented intermediary results. Although it enrolled 414 patients from 26 centres (in France), only 385 patients had completed their three-month follow up after treatment. Nevertheless, the results showed that more patients who received thrombectomy were functionally independent at three months after their stroke than those who did not. As intermediary results, it’s also still not yet know what the complication rates are from treatment in this study.

Serge Bracard, MD (Central Hospital Nancy, France) presented the study at the (ESO) Conference. Commenting to Medscape Medical Newshe said:

"Ours was a pragmatic study, we didn't have very specific inclusion criteria other than patients had to have a clot in a large artery and a moderate to severe stroke."

He also said the most important requirement was time:

"Interventional treatment had to start within five hours of symptom onset and must be completed within six hours."

This is an extremely exciting time in stroke research and care. We hope the findings of these trials will help us find new and innovative ways to ensure more people make their best possible recovery from stroke.

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