Flow Diversion Versus Coiling in Small and Medium-sized Unruptured Aneurysms of Proximal Anterior Circulation with Complex Anatomy: a Matched-pairs Study.

Background: The benefits of flow diversion (FD) versus endosaccular coiling (EC) in small and medium-sized proximal saccular aneurysms of anterior circulation, amenable to both methods, remain not well-established. This study aimed to compare the efficacy and safety of FD vs EC and evaluate the triggers of treatment modality choice in the aforementioned setting.

Methods: The study had a retrospective design. Raw sample included 154 FD and 190 EC consecutively enrolled cases. All aneurysms were saccular, sized 4-14 mm, located at intradural ICA or A1/M1, not acutely ruptured and previously untreated. Median lesion size was 6.6 mm (90% < 10 mm), median neck diameter‑3.7 mm. Matched cohorts were 67 cases each, PS difference < 0.1 probit SD, all covariates: size, neck, location, shape, angle, multiplicity, rupture history, age, and incorporated arterial branch. Follow-up DSA available for 94.2% of raw sample at median 9 months.

Results: In both raw and matched samples respectively, FD versus EC demonstrated higher rates of target aneurysm total occlusion (76.4% vs 53.2%, p < 0.001 and 80.3% vs 49.2%, p < 0.001), lower of rates of intraoperative technical adverse events (7.3% vs 21.4%, p < 0.001 and 9% vs 22.4%, p = 0.032) and retreatment (raw‑2.6% vs 15.4%, p < 0.001, matched‑1.5% equal). Rates of neurological morbidity and death were similar. The choice of FD was triggered by neck size and ratio, paraophthalmic location (OR = 2.57), multiplicity (OR = 4.1) and incorporated arterial branch (OR = 4.82), p < 0.001. Incorporated branch was associated with incomplete occlusion in both treatment modalities (p < 0.01).

Conclusion: In this study FD demonstrated higher rates of target aneurysm total occlusion, lower rates of intraoperative technical adverse events and similar rates of neurological morbidity and death, compared to EC.