# Long-term clinical follow-up of intracranial aneurysms treated with flow diverter devices: a bicentric retrospective study

## TL;DR

This study analyzes long-term outcomes of intracranial aneurysm treatments using flow diverter devices, showing high safety and effectiveness beyond 18 months.

## Contribution

The study provides comprehensive long-term clinical follow-up data across multiple flow diverter device platforms, identifying 18 months as a critical threshold for complications.

## Key findings

- Beyond 18 months, FDD treatment showed exceptional safety with no delayed complications.
- Multiple overlapping FDDs significantly increased the risk of delayed complications.
- At 24 months, 81% of patients achieved complete aneurysm occlusion.

## Abstract

Flow diverter devices (FDDs) have revolutionized the treatment of intracranial aneurysms. However, comprehensive long-term outcome data across multiple device platforms remain limited, with most prior studies focusing exclusively on Pipeline embolization device (PED) outcomes. This study reports extensive long-term clinical follow-up of patients treated with various types of FDDs, providing critical safety and efficacy data for contemporary practice.

We conducted a retrospective analysis of intracranial aneurysms treated with FDDs from February 2011 to July 2016 in two tertiary care centers in France. The study included 209 patients with 216 cerebral aneurysms (91.2% anterior circulation, 8.8% posterior circulation; 66.2% unruptured, 31.0% recanalized, 2.8% ruptured). The duration of clinical and angiographic follow-up ranged from 24 to 156 months. Kaplan–Meier analysis performed for complication-free survival and aneurysm occlusion durability. Multivariate analysis showed risk factors for delayed complications.

Long-term follow-up data were available for 202/209 (96.7%) patients. The early permanent morbidity and mortality rates were 3.8% and 1.4%, respectively. Between 12 and 18 months, procedure-related complications occurred in 5 of 202 patients (2.5%): two ischemic events, one delayed rupture, one silent intrastent stenosis, and one case of seizures following antiplatelet withdrawal. Only three patients (1.5%) were symptomatic. At the 24-month follow-up, complete aneurysm occlusion achieved in 81.0% of the patients, with adequate occlusion in 93.3%. Kaplan–Meier analysis revealed 97.5% complication-free survival at 18 months, with sustained durability thereafter. Multiple FDDs were the only significant independent predictor of delayed complications (OR: 7.066, 95% CI: 1.049–47.606, P < 0.045). No procedure-related complications or deaths occurred after 18 months.

Beyond 18 months of follow-up, FDD treatment for intracranial aneurysms proves exceptional safety with no delayed complications, regardless of device type. However, the findings of this study also show 18 months as a critical threshold for complication risk assessment, a key implication that clinicians and researchers need to be aware of. The study also underscores the need for modified management strategies when multiple overlapping FDDs are deployed, which significantly increases the risk of delayed complications.