Unruptured Giant Intracranial Aneurysms: Risk Factors for Mortality and Long-Term Outcome

This study aims to investigate the long-term outcomes of unruptured giant intracranial aneurysms (GIAs) with different treatment modalities and to analyze the factors affecting prognosis. We performed a retrospective medical record review of patients with unruptured GIAs treated at our institution from 2011 to 2018. Prognosis was compared to the best medical treatment without intervention (conservative treatment, CT) and surgical (ST) or endovascular (ET) treatment. Risk factors for mortality were investigated. A total of 276 patients were included in this study. Patients received CT in 16.3%, ST in 30.1%, and ET in 53.6% of cases. After an average 7-year follow-up, the rupture rate after CT was 22.2%, accounting for an annual rupture rate of 7.3%. The postoperative complication rate was 30.1% and 8.1% after ST and ET, respectively. The recurrence rate after ET was 10.1%, compared with ST which was 1.2%. The follow-up mortality in unruptured GIAs was 26.7% after CT, 7.2% after ST, and 5.4% after ET. Older age (50~59, HR 5.877; 60~69, HR 8.565), size ≥ 40 mm (HR 3.916), and posterior circulation location (HR 6.411) were associated with increased mortality. ET significantly decreased mortality (HR 0.191). Unruptured GIAs warrant treatment if feasible due to the high rupture rate and mortality of the natural history. Older age, posterior circulation location, and larger size are risk factors for poor prognosis. Both ST and ET showed a lower mortality rate than CT. ST showed less likely recurrence compared to ET, while ET had a lower complication rate than ST.