Endovascular Retreatment of Previously Clipped Intracranial Aneurysms: An Individual Patient Data Meta-analysis.

Abstract

To evaluate the effectiveness and safety of endovascular retreatment of previously clipped intracranial aneurysms (IAs). Systematic searches of Medline, Embase and Cochrane Central were performed. The primary outcome was good functional outcome (modified Rankin Scale 0-2) at the last follow-up. Secondary outcomes included complete occlusion, and perioperative complications. One-stage individual patient data meta-analysis was performed, adjusted using generalized linear mixed models with prespecified covariables and study as a random effect. Twenty-six studies reporting 413 patients with 414 previously clipped IAs retreated endovascularly were included. Totally, 249 (60.1%), 39 (9.4%), 39 (9.4%), 81 (19.6%) and 6 (1.4%), underwent simple coiling, balloon-assisted coiling, stent-assisted coiling, flow diversion, and disruption, respectively. Of these, 88.6% and 11.4% IAs were located anteriorly and posteriorly. Mean size of the IAs at retreatment was 6.8 mm. Most (70.4%) of previously clipped IAs were unruptured at retreatment, mainly due to regrowth (n = 48), remnants (n = 49) or recurrences (n = 41), when reported. With clinical follow-up of 26.8 months, proportions of good functional outcomes, improved/unchanged neurological outcomes, and deaths were 77.3% (95%CI: 72.15; 81.74), 88.2% (95%CI: 64.57; 96.85), and 6.9% (95%CI: 4.19; 11.18), respectively. With angiographical follow-up of 19.4 months, the proportion of complete occlusion was 74.4% (95%CI: 64.38; 82.29). Multivariate analyses showed that a prolonged interval (>1 month) between clipping and endovascular retreatment was associated with good functional outcome (odds ratio 7.37, 95%CI: 2.16; 29.94) whereas posteriorly located IAs were associated with perioperative complications (odds ratio 8.05, 95%CI: 1.45; 50.48). Endovascular retreatment of previously clipped IAs can be accomplished safely and effectively in well-selected patients. The indications for retreatment need to be carefully weighed against the natural history of a previously clipped IA.