The Long-Term Outcome of Customized EVAR Follow-Up Primarily Based on Ultrasound AAA Diameters

Abstract

Introduction - Previous studies have suggested that yearly contrast-enhanced CT (CTA) follow-up after EVAR of AAA may be unnecessary and could have negative effects. The objective was to study the long-term outcome of a personalized follow-up program after infrarenal EVAR based on frequent ultrasound AAA diameter measurements for low-risk patients. Methods - All consecutive patients followed-up locally for at least one year after infrarenal EVAR between 2010 and 2015 were included. Pre-, intra-, and post-operative data was retrospectively reviewed. Follow-up included CTA at 1 month post-EVAR in all patients. Depending on this CTA, the patients were divided into 2 groups, ultrasound-based and CTA-based follow-up. When the CTA was uneventful and the patient was considered anatomically at low risk of developing AAA-related adverse events by the operator, the follow-up continued with only ultrasound assessing AAA diameter at 1, 2, 3 and every 5 years postoperatively (group A). When expansion was suspected or ultrasound was inconclusive, CTA was performed. Patients not fulfilling the criteria for group A were followed with yearly 3-phase-CTAs (group B). Crossing-over between groups was permitted. Late re-interventions were analysed by intention-to-treat based on allocation to group A or B. Values are presented as median (IQR) or absolute numbers (%) if not stated otherwise. Non-parametric and log-rank tests were used for comparisons. Results - 204 patients (176 male, age 72 (67-77), 20 ruptured AAAs) with an AAA diameter of 58 (48-66) mm were included. 180 (88 %) were allocated into follow-up in group A and 24 (12%) in group B. Median follow-up time was 36 (24-59) months, during which 78 additional CTAs (0.42/person) were performed in group A and 6 crossovers occurred between the groups. Five year primary and primary assisted success was 83±6% and 95±2% for group A and 59±17% and 91±6% for group B, respectively (p= 0.005 for primary and p= 0.222 for primary assisted success). Primary failures were detected after 22 (12-36) months. 15 late aneurysm-related re-interventions were performed in 12 patients at a median of 40 (27-60) months postoperatively (9 in group A and 6 in group B). In group A, 7 re-interventions were expansion-related (6 detected on ultrasound follow-up and 1 after unrelated abdominal CT-scan) and 2 were after symptomatic lower limb ischemia. All late re-interventions in group B were performed following findings on follow-up imaging due to AAA enlargement or failing sealing zones without expansion. Five-year late re-intervention-free survival was 95±2 % and 85± 8% for groups A and B, respectively (p=0.010). Five-year survival was 81±4% and 75±16% for group A and B, respectively, with no verified aneurysm-related deaths. Conclusion - A customized follow-up program after infrarenal EVAR based on ultrasound AAA diameter measurements in low-risk patients seems to be effective in maintaining a very high 5-year clinical success rate. Ultrasound can be used for the majority of patients. However, yearly CTA is still necessary for high-risk patients. Longer follow-up is needed to determine the ideal frequency of imaging in the long-term.