Background Thromboembolic events are recognized complications of endovascular aneurysm coil embolization. The routine use of peri-procedural antiplatelet therapy is usually limited to patients undergoing stent or flow diverters placement. However, there is some evidence to suggest a protective effect of peri-procedural antiplatelet therapy even when stent placement is not anticipated. We performed a systematic review and meta-analysis to investigate the effects of routine use of antiplatelet therapy in the peri-procedural period for coiling-only aneurysm endovascular embolization.

Methods We conducted a systematic review and meta-analysis of clinical studies in English language published up to March 2018 in the MEDLINE and EMBASE databases. Searches were supplemented by scanning bibliographies of key articles. We included retrospective and prospective studies published in full and reported original data on symptomatic thromboembolic events (clinical ischemic stroke or TIA) in patients with unruptured aneurysms treated using coiling-only techniques (primary coiling or balloon-assisted) and received peri-procedural oral antiplatelet therapy (single, dual, or multiple). Studies reporting only on stent-assisted coiling or flow diverters were excluded. Two authors independently selected eligible studies and extracted data.

Results Out of 466 retrieved studies, we identified 14 eligible studies published between 2007 and 2017 and included 2431 patients. Only four studies had a prospective design. All studies were single center. There was one randomized trial that compared two antiplatelet regimens but did not include a control arm. The antiplatelet therapy regimen varied as some studies used single antiplatelet (ASA, clopidogrel, or prasugrel) while others used dual or multiple antiplatelet agents. Three studies had a control group which did not receive any antiplatelet therapy. In these studies, the pooled relative risk for symptomatic thromboembolic events in patients with versus without peri-procedural antiplatelet therapy was 0.33 (95% CI 0.17 to 0.92). We calculated the cumulative incidence (thromboembolic event rate at the end of the study) in all 14 studies. The overall incidence of symptomatic thromboembolic events in patients who did not receive any antiplatelet therapy was 11% (95% CI 4.3% to 17.7%), compared to 4.7% (95% CI 1.2% to 8.2%) in those on a single antiplatelet agent, and 2% (95% CI 1.0% to 3.0%) in patients on dual or multiple antiplatelet agents. Seven studies included data on the incidence of new lesions on diffusion-weighted imaging (DWI). In these studies, incidence of DWI lesions in patients on a single antiplatelet agent was 50.6% (95% CI 7.3% to 93.9%) compared to 43.9% (95% CI 25.9% to 61.9%) in patients on dual or multiple antiplatelet agents. There was no difference in the frequency of major hemorrhagic complications between the groups: control 1.8% (95% CI 0.2% to 3.5%), single antiplatelet 1.1% (95% CI 0.2% to 1.9%) and dual antiplatelet 1.5% (95% CI 0.7% to 2.4%).

Conclusion In electively-treated patients with unruptured brain aneurysms undergoing endovascular coiling-only embolization, available evidence suggests that peri-procedural primary prophylaxis with antiplatelet therapy is associated with lower symptomatic and DWI thromboembolic events. Routine use of this approach warrants further investigation in a randomized control setting.

Disclosures M. Almekhlafi: None. A. Alsultan: None. A. Kuczynski: None. B. Menon: None. M. Hill: None. M. Goyal: None.