Abdominal aortic aneurysm sac behavior following Cook Zenith graft implantation: a five-year follow-up assessment of 212 cases.

AIM

Aneurysm shrinkage is an expected outcome after stent-grafting for abdominal aortic aneurysm (AAA). A worrying problem following repair is progressive enlargement indicating persistent sac pressurization: in this setting not all grafts are equal. The Cook Zenith device (CZ) became available on the European market in 1999. While multicenter studies on the device have shown favorable clinical results at mid-term follow-up, few have focused on sac behavior. This study evaluated AAA sac behavior and predictive factors of its evolution by assessing the five-year results obtained with the CZ graft in a single-institution experience.

METHODS

All consecutive elective surgery patients treated with a CZ graft for infrarenal aortic or aortoiliac aneurysm repair from January 2000 to November 2004 in our institution were included prospectively in the study and followed at 1, 6, 12, 18, 24 months and yearly thereafter. Pre-, intra- and postoperative data were recorded in a computerized database. Computed tomography (CT) scans were reviewed by a senior radiologist to identify any abnormalities including endoleak and graft malfunction. Pre- and postoperative maximum sac diameters were derived from measurements of CT findings and then compared. A change of at least 8 mm in sac size was considered significant. Overall results are expressed according to the Committee on Reporting Standards of AAA treatment. Factors that may have influenced sac behavior were analyzed by dividing the patients into 3 groups according to whether the sac diameter remained unchanged (group 1), had increased (group 2) or regressed (group 3). Statistical analysis of the demographic and CT-scan data was then performed.

RESULTS

The study sample was 212 consecutive patients (mean age 72.8+/-9.0 years); the mean aneurysm diameter before treatment was 55.5+/-9.8 mm. All stent grafts were successfully implanted. The 30-day mortality rate was 0.94% (2/212); the morbidity rate was 11.7% (25/212). The primary technical success rate was 93.40%; the assisted primary technical success and secondary technical success rates were 96.63% and 99.52%, respectively. The mean follow-up period was 17.7+/-14.7 (1-60) months. The cumulative survival probability was 94%, 84.2%, and 72.9% at 12, 24, and 36 months, respectively. The endoleak-free survival probabilities at 12 and 24 months were 75.7% and 62.8%, respectively. The free of intervention survival rates were 82.1%, 68.9% and 60.6% at 12, 24 and 38 months, respectively. At five years follow-up, the overall clinical success rate was 49.5%. If changes in sac diameter occurred, they were noted at 13 months on average. Sac size remained unchanged in 115 (54.3%) patients (group 1), increased in 9 (4.2%) (group 2), and regressed in 88 (41.5%) (group 3). Neither preoperative patient demographics nor aneurysm characteristics were found to be predictive of sac behavior. Aortouniliac graft configuration was predictive of sac shrinkage (P=0.020). Endoleak was more frequent among patients in groups 1 (27/115; 23%) and 2 (5/9; 56%) than among those in group 3 (9/88;10%) (P=0.001). Reduction in aneurysm sac diameter was less marked in patients with any type of endoleak (P=0.0003).

CONCLUSION

The CZ grafts offered satisfactory overall results up to five years of follow-up; nevertheless, sac diameter increased in 4.25% of patients. Endoleak was a predictive factor of a lack of sac shrinkage, while aortouniliac graft configuration was predictive of sac shrinkage.