What is the clinical utility of a 6-month computed tomography in the follow-up of endovascular aneurysm repair patients?

Objective A drawback of endovascular aneurysm repair (EVAR) is the need for ongoing surveillance. Follow-up schedules including 1-, 6-, and 12-month computed tomography (CT) established by regulatory trials have been carried into clinical practice without critical assessment. The utility of a 6-month CT, with its associated radiation exposure and contrast toxicity, obtained after a normal result at 1-month CT has not been established. Methods All EVAR patients from 1996 to 2004 at one institution with complete local 1-year follow-up were reviewed for clinically significant CT findings at 1, 6, and 12 months. Before 2000, all patients underwent 1-, 6-, and 12-month CT. In 2000, a policy of omitting the 6-month CT in patients who had a normal result on the 1-month scan was adopted. Results During the study period, 573 patients underwent EVAR, and 376 patients who had complete local 1-year follow-up were included in this review. All had a 1-month CT scan and the result was abnormal in 40 (10.6%): five had type 1 leaks (1.3%), 34 had type 2 leaks (9.0%), and one had a type 3 leak (0.3%); all were followed with 6-month CT. The 1-month CT scan result was normal for 336 (89.4%) patients. Of these, group I (130 patients, 67 treated after 2000) underwent routine 6-month CT, with only two abnormalities noted (1.5%); both were type 2 endoleaks not associated with sac growth. No 6-month CT in this group demonstrated findings warranting intervention. The 6-month CT was omitted in group II (206 patients, all treated after 2000), and follow-up was only at 1 year. In this group, no patient's management would have been altered by findings on a 6-month CT. No patient in either group experienced aneurysm sac growth by 1 year. Clinical complications occurred in three group I patients (2.3%): seroma, limb occlusion, and main body thrombosis. Only one group II patient (0.5%) experienced a complication ≤1 year, a limb occlusion at 9 months. Conclusions After EVAR, a 6-month CT after a normal 1-month CT result does not identify any clinically significant findings warranting intervention and can be omitted safely from the follow-up schedule.