Rationale and design of the extracranial Carotid artery Aneurysm Registry (CAR)

Background: Aneurysms of the extracranial carotid artery (ECAA) are rare. Although most ECAA are identified in asymptomatic patients, serious neurological complications may occur. Current literature on treatment outcome contains mainly case reports and small case series with incomplete data and lack of long-term follow-up. There is clear lack on natural follow-up data, and there is no clear treatment algorithm. An international web-based registry to collect data on patients with ECAAis designed to provide clinical guidance on this scarce pathology. Methods: The Carotid Aneurysm Registry (CAR) is open for inclusion of all patients with a fusiform or saccular ECAA. Patients with primary or secondary ECAA can be enrolled in CAR independent of the type of treatment (conservative or invasive). CAR participation does not interfere with the local physician's treatment policy. Follow-up and imaging can also be scheduled according to local clinical practice. The primary endpoint of the CAR in conservative patients is occurrence of symptoms related to the aneurysm at 30 days, one, three, and five years. The primary endpoint in invasively treated patients is freedom from symptoms of the aneurysm at 30 days, one, three, and five years. Results: Analyses will relate outcome to etiology, imaging characteristics, ECAA growth patterns, and (if applicable) revascularization technique applied. The aim of the registry is to prospectively collect follow-up data on patients with an ECAA, being either treated conservatively or by invasive aneurysm exclusion strategies. The CAR database will be used to address diagnostic and therapeutic research questions. Conclusions: Collecting and analyzing the data gained from the registry could be the first step towards development of treatment guidelines and expert consensus for the management of ECAA