Intracranial Aneurysms: Recurrences More than 10 Years after Endovascular Treatment-A Prospective Cohort Study, Systematic Review, and Meta-Analysis

Purpose: To assess the efficacy of endovascular treatment (EVT) of intracranial aneurysms for recurrence, bleeding, and de novo aneurysm formation at long-term follow-up (> 10 years after treatment) with magnetic resonance (MR) angiography and to identify risk factors for recurrence through a prospective study and a systematic review of the literature.

Materials and methods: Clinical examinations and 3-T MR angiography were performed prospectively 10 years after EVT of intracranial aneurysms in a single institution. Ethics committee approval and informed consent were obtained. PubMed, EMBASE, and Cochrane databases were searched to identify studies in which authors reported bleeding and/or aneurysm recurrence rates in patients who received follow-up more than 10 years after EVT. Univariate and multivariate subgroup analyses were performed to identify risk factors (midterm MR angiographic results, aneurysm characteristics, retreatment within 5 years).

Results: In the prospective study, sac recanalization occurred between midterm and long-term MR angiography in 16 of 129 (12.4%) aneurysms. Grade 2 classification on the Raymond scale at midterm MR angiography (relative risk [RR], 4.16; 99% confidence interval [CI]: 2.12, 8.14) and retreatment within 5 years (RR, 4.67; 99% CI: 1.55, 14.03) were risk factors for late recurrence. In the systematic review (15 cohorts, 2773 patients, 2902 aneurysms), bleeding, aneurysm recurrence, and de novo lesion formation rates were, respectively, 0.7% (99% CI: 0.2%, 2.7%; I(2), 0%; one of 694 patients), 11.4% (99% CI: 7.0%, 18.0%; I(2), 21.6%), and 4.1% (99% CI: 1.7, 9.4%; I(2), 54.1%). Raymond grade 2 initial result (RR, 7.08; 99% CI: 1.24, 40.37; I(2), 82.6%) and aneurysm size greater than 10 mm (RR, 4.37; 99% CI: 1.83, 10.44; I(2), 0%) were risk factors for late recurrence.

Conclusion: EVT of intracranial aneurysm is effective for prevention of long-term bleeding, but recurrences occur in a clinically relevant percentage of patients, a finding that may justify follow-up of selected patients for 10 years or more, such as patients with aneurysms larger than 10 mm or classified as Raymond grade 2 at midterm MR angiography.