PeRforation EVents During ENdovascular Therapy for Acute Ischemic Stroke

A large, worldwide study called PREVENT is looking at a complication that can happen during a stroke treatment called thrombectomy. This complication is a perforation of a blood vessel. The investigators aim to: 1. Find what factors make this perforation more likely. 2. Understand why the perforation happens by looking closely at images taken during the procedure. 3. Create a simple way to classify these perforations to help doctors decide how to treat them right away. 4. Improve the emergent treatment of vessel perforation to stop the bleeding rapidly. 5. Provide data to guide decision whether thrombectomy should be continued or aborted after the event of vessel perforation. 6. Develop a safer way to perform thrombectomy. Investigators will compare the results collected for patients where perforation happened with those where perforation did not happen.