A randomized trial comparing platinum and hydrogel-coated coils in patients prone to recurrence after endovascular treatment - The PRET trial

Purpose: The PRET trial aims compares hydrocoils to bare platinum coils in patients with aneurysms prone to recurrence, i.e. in patients with large aneurysms (≥10 mm; PRET-1 patients) or in patients with a major recurrence after previous coiling (PRET-2 patients). We aim at reporting an update of the randomization rate and results of the interim analysis from the DMSC. Materials and Methods: PRET is a RCT with single-blind allocation. 500 subjects are followed for 18 months. PRET-1 (250) and PRET-2 (250) cases are randomized separately. Interventions are: a/bare coil embolization, or b/hydrocoil embolization. Primary endpoint is recurrence rate. Secondary end-points include procedural complications, clinical outcome, safety of hydrogel coiling and overall M&M. Results: 264 PRET subjects were randomized by 30 sites in Canada, US, France, UK, Japan and Chile. Baseline characteristics of PRET subjects were (mean (SD)): Age = 59 (11) years; 73% had only one aneurysm; 16% presented with acute rupture of the aneurysm; Aneurysm parameters for PRET1 subjects (53%) were: size = 14(5) mm and in 57% of cases located in the anterior circulation. Aneurysm parameters for PRET2 subjects (47%) were: size = 13(11) mm and in 57% of cases located in the anterior circulation. An interim safety analyses carried out on 234 subjects did not reveal any significant difference in SAEs or clinical outcome (mRS>2 at discharge and 1-month follow-up) between treatment arms. Conclusion: We hope that PRET will show that for the treatment of aneurysms prone to recurrence, Hydrocoils provide an equal or higher efficacy than bare platinum coils with no difference in safety profile.