Anatomic Eligibility for Endovascular Aneurysm Repair Preserved Over Two Years of Surveillance.

OBJECTIVE Endovascular aneurysm repair (EVAR) is a widely used option for patients with suitable vascular anatomy who have a large infrarenal abdominal aortic aneurysm (AAA). Patients with small AAAs are managed with careful surveillance and it is a common concern that their anatomy may change with AAA growth, and their option for EVAR may become limited. Device innovation has resulted in expanded ranges of anatomy that may be eligible for EVAR. This study sought to identify changes in anatomic eligibility for repair with contemporary endovascular devices in AAA patients, monitored by computed tomography over the course of two years. METHODS Subjects from the Non-Invasive Treatment of Abdominal Aortic Aneurysm Clinical Trial (N-TA3CT, NCT01756833) were included in this analysis. Females had baseline AAA maximum transverse diameter (MTD) between 3.5-4.5 cm, and males had baseline MTD between 3.5-5.0 cm. Subjects were included in this analysis if they completed pre-enrollment and two year follow-up CT imaging. Pertinent anatomic measurements were performed on a post-processing workstation in a centralized imaging core laboratory. EVAR candidacy was determined by measuring proximal aortic neck diameter, AAA length, and infrarenal neck angulation. Patients were considered to be eligible for EVAR if they qualified for at least one of the 7 studied devices' Instructions for Use (IFU) at baseline and at two years. Paired t-test analysis was used to detect differences in aortic measurements over two years, and McNemar test was used to compare eligibility over two years. RESULTS 192 subjects were included in this analysis, 168 male and 24 female. 85% of patients were eligible for EVAR at baseline and 85% after two years of follow-up (P = 1.00, [95% CI, -0.034 - 0.034]). Of the 164 EVAR candidates at baseline, 160 (98%) remained eligible over two years of surveillance. Insufficient neck length was the most common reason for both ineligibility at baseline (18 of 28 subjects) as well as loss of candidacy over two years (3 of 4 subjects). CONCLUSIONS The majority of patients eligible for EVAR when entering a surveillance program for small AAA remain eligible after two years. Substantial changes in AAA neck anatomy resulting in loss of EVAR treatment options, are infrequent. Patients with anatomical AAA progression beyond EVAR eligibility remain candidates for complex EVAR and open repair.