Proximal Type I Endoleak After Endovascular Abdominal Aortic Aneurysm Repair: Predictive Factors

Abstract

Proximal type I endoleaks after endovascular abdominal aortic aneurysm repair (EVAR) are associated with a high risk of rupture. Risk factors for developing this complication are not fully elucidated. We aimed to define preoperative predictors for proximal type I endoleak and describe its clinical outcome. From a consecutive series of 257 patients who underwent EVAR, we selected 202 who had available pre- and postoperative CT scan studies. Proximal neck diameter, length, angulation, calcification, thrombus load (thickness, percentage of neck circumference coverage, percentage of neck area occupancy), and maximum aneurysm diameter were evaluated on preoperative CT scans. All postoperative CT and duplex ultrasound scans, supplemented with angiograms in selected cases, were reviewed for the presence or absence of endoleak. Device overlap and oversizing (relative to the proximal neck) were also determined. Type I proximal endoleak rates were estimated using the Kaplan-Meier method. The associations between the variables listed above and proximal type I endoleak were evaluated by use of Cox proportional hazards models. Proximal type I endoleak occurred in eight patients, corresponding to a 3-year incidence rate of 4% (SE = 1.5%). The median follow-up was 340 days (range, 22-1954). Univariate analyses found significant associations between proximal type I endoleak and the following variables: percentage of calcified neck circumference (hazards ratio = 2.19 for a 25% increase, p = 0.019), aneurysm maximum diameter (hazards ratio = 1.98 for a 1-cm increase, p = 0.006) and proximal neck and device overlap (hazards ratio = 0.53 for a 5-mm increase, p = 0.007). The mean overlap among cases with and without type I proximal endoleak was 15.6 mm and 29.3 mm, respectively. When these variables were included in a multivariate model, all remained statistically significant. No significant association could be documented for neck thrombus-related variables. Thirty-nine (19.3%) patients had a beta neck angle inferior to 120 degrees . There was a trend toward a higher incidence of proximal type I endoleaks in these patients (p = 0.057). Device oversize relative to proximal neck diameter did not affect the probability of this type of endoleak. One patient survived an emergency open repair of a ruptured aneurysm after significant expansion. Six patients underwent endovascular reinterventions (4 additional proximal cuff placements, 2 proximal angioplasties). The mean interval for reintervention was 389 days. Distal migration (>or=5 mm) was identified in four cases (50%). Proximal type I endoleak is a rare complication after EVAR, but it is associated with a high number of reinterventions and potentially serious consequences. Patients with short and heavily calcified aneurysmal necks and large aneurysms are at increased risk of proximal type I endoleaks.