Aneurysm sac shrinkage after endovascular repair: predictive factors and long-term follow-up.

BACKGROUND

The aim of this study was to determine the predictive factors of reduction in diameter ≥10 mm of the aneurysm sac after endovascular treatment and analyze evolution in these patients.

METHODS

Between December 1997 and December 2008, all patients electively treated at our center for an infrarenal abdominal aortic aneurysm (AAA) were included in a prospective registry. We did a retrospective study between patients whose aneurysm was reduced by at least 10 mm in diameter on computed tomography scan during follow-up (Group 1) and the other patients who did not (Group 2). A univariate and multivariate statistical analysis was performed.

RESULTS

The files of 197 patients (mean age 74.8 years) with a mean follow-up of 54.8 months were reviewed. One hundred two patients (51.8%) had a reduction of ≥10 mm of AAA diameter (Group 1); this reduction was achieved after an average follow-up of 23.6 months. The delay to obtain at least a 10-mm diameter reduction was not influenced by any preoperative characteristics of patients or characteristics of the AAA. Patients in Group 1 were younger (74 vs. 76 years, P = 0.039), with a longer (31 vs. 27.7 mm, P = 0.038) and narrower upper neck (23.1 vs. 24.0 mm, P = 0.02) compared with Group 2. After multivariate analysis, these 3 variables were independently predictive of reduction in AAA diameter. In Group 1, secondary procedures were performed in 13 patients after a diameter reduction of ≥10 mm, including 3 type 1 endoleaks treated after 36 months (1 case) and after 123 months (2 cases) and 1 type 3 endoleak treated after 78 months. In Group 2, secondary procedures were performed in 28 patients, including 9 type 1 endoleaks treated after a median time of 26 months and no type 3 endoleak. Secondary procedures were significantly more frequent in Group 2 than in Group 1 (29.4% vs. 12.7%, respectively; P = 0.005). Freedom from secondary procedure at 5 years was 87.9% in Group 1 and 65.4% in Group 2 (P = 0.003). Freedom from AAA rupture at 8 years was significantly superior in Group 1 than in Group 2 (100% vs. 83.5%, P = 0.008).

CONCLUSIONS

Sac shrinkage after endovascular aortic aneurysm repair is more likely observed in younger patients with long and small proximal neck anatomy and is associated with better long-term outcomes. However, late failures do occur even in those with significant sac shrinkage; therefore, follow-up should continue lifelong.