Bilateral occlusion of the trunk of the middle cerebral artery. Results of an international randomized trial. The EC/IC Bypass Study Group

EC-IC bypass: The failure of a clinical trial? Applicability to PFO closure trials

Extracranial-to-intracranial (EC-IC) bypass surgery was used to prevent stroke in patients with carotid occlusion and inadequate collateral flow. Because of inappropriate proliferation of EC-IC bypass, a randomized clinical trial was carried out. The failure of the trial may have been related to inappropriate patient selection and all eligible patients not being randomized. Subsequent study has identified criteria for patient selection and new trials are underway. The present patent foramen ovale closure trials share many of the same difficulties, including overuse of the procedure and interventionalists reluctant to randomize patients. If these trials are not properly done we will be in the same situation in 20 years that the EC-IC trialists are facing today. Improvements in patient selection criteria, randomization of all eligible patients, and better statistical parameters will increase the likelihood of future trials getting the correct answer the first time. The importance of carefully done observational trials should not be overlooked.