Purpose: To determine the risk of aneurysm rupture in patients with persisting proximal type Ia endoleaks following endovascular aneurysm repair (EVAR) in comparison to the risk of rupture of untreated abdominal aortic aneurysms (AAA) of similar size.
Methods: Among 400 patients who where treated with EVAR from 1996 to 2003 at a single center, 21 (5.3%) patients (13 men; mean age 78.0±5.0 years, range 67-86) with large (≥5.5 cm) aneurysms had imaging evidence of type Ia endoleaks that persisted >10 months (type Ia group) despite secondary endovascular treatment. These patients were compared to 24 untreated AAA patients (17 men; mean age 73.8±5.2 years, range 64-88) with large aneurysms from a separate geographic region with a well-established aneurysm treatment program before EVAR became available (1990-1998).
Results: There were no significant differences between the type Ia and the untreated AAA patients with regard to age (79±8 vs. 74±5 years), gender (38% vs. 29% women), baseline aneurysm diameter (6.1±0.7 vs. 6.4±0.9 cm), or length of follow-up (32±23 vs. 29±40 months). During the follow-up period, the rate of aneurysm enlargement was significantly lower in type Ia patients (0.19 cm/y) than in untreated AAA patients (0.54 cm/y, p = 0.03). One (4.8%) patient with a persisting type Ia endoleak and 2-cm aneurysm enlargement (0.8 cm/y) had aneurysm rupture after 2.5 years, while 12 (50%) of the 24 untreated aneurysms ruptured (p = 0.001), which was the primary cause of death in this group. The rupture rate was 1.8 per 100 patient-years in the type Ia group and 20.7 per 100 patient-years in the untreated AAA group. Aneurysm-related mortality was significantly reduced in the type Ia group compared to the untreated AAA group at 36 months (11% vs. 52%, p = 0.004). In the multivariate analysis, factors associated with death were an untreated AAA (odds ratio 97, p = 0.004), female gender (odds ratio 9.7, p = 0.02), and baseline aneurysm size (odds ratio 4.7/cm, p = 0.03).
Conclusion: This study suggests that EVAR may reduce the risk of rupture and aneurysm-related death despite the presence of a persisting type Ia endoleak. This finding is limited to patients with aortic endografts that are in good position. The mechanism of protection from rupture is unclear but may be related to reducing the rate of aneurysm enlargement.