RS04 - Embolization Outcomes of Well-defined vs. Indistinct Type II Endoleaks After Endovascular Aortic Aneurysm Repair (EVAR)

Objectives: Outcomes and natural history of type II endoleaks (T2ELs) remain poorly understood and the management remains controversial. Our experience indicates that T2ELs with a well-defined cavity or nidus and feeding vessels have a different evolution compared to indistinct endoleaks in which contrast appears scattered within the sac thrombus without a defined cavity (Figs 1 & 2). The aim of this study was to assess the outcomes of well-defined vs. indistinct T2ELs and compare the effectiveness of treatment.

Methods: Over a 15-year period, 79 patients were treated for T2ELs. Indication, route of embolization, complications, subsequent interventions, endoleak patency and aneurysm size changes were recorded and assessed with CT angiography and/or ultrasound. The primary endpoint included clinical success defined as complete resolution of the endoleak after embolization and absence of sac growth. Secondary outcomes included sac growth, number and type of reinterventions, rupture, conversion to open repair and patient survival.

Results: Sac enlargement was indication for treatment in 59 patients (75%). Median follow-up was 54 months (interquartile range [IQR], 26-84). 39 T2ELs (62%) were well-defined and 40 (38%) were indistinct. Median preoperative aneurysm sac size was greater in the indistinct group (61 mm [IQR, 56-72] vs. 56 [IQR, 52-68]; P=.007). Overall, clinical success rates of embolization were 72% and 22% for well-defined and indistinct endoleaks, respectively (P <.001). After the initial embolization, patients with indistinct endoleaks had more reinterventions (1.7±0.8 vs 1.3±0.5; P=.014) and greater aneurysm sac growth (7.2±17 vs. 0.14±8 mm; P=.020), compared to well-defined endoleaks. Significant aneurysm sac growth (>5 mm) was more frequent among indistinct endoleaks (50% vs. 25%; P=.037). The presence of an indistinct T2EL was an independent predictor of treatment failure (odds ratio [OR], 10.5; IQR, 4.5-32, P<.001) and significant aneurysm sac growth (OR, 2.9; 95%CI, 1.12-7.49.7; P=.0.028). Four (9%) open conversions and two aortic-related deaths occurred, all in patients with indistinct endoleaks.

Conclusions: Among patients treated for type II endoleaks, the absence of definitive nidus is an independent predictor of treatment failure. Despite multiple embolizations, indistinct endoleaks tend to persist and are frequently associated with greater aneurysm sac growth, which may lead to open conversion. Larger series and enhanced characterization are required to define the outcomes and best management of indistinct endoleaks.