Abstract 4342198: Real-world Surveillance and Follow up for Incidentally Detected Ascending Thoracic Aortic Aneurysms on LDCT for Lung Cancer Screening

Background: Ascending thoracic aortic aneurysms (aTAAs) carry a risk of dissection and rupture, which increases with aTAA diameter. While the 2022 AHA/ACC guidelines recommend follow-up imaging at 6-12 months following detection to determine the rate of aortic enlargement, little is known regarding patterns of aTAA follow up and recognition in clinical practice. Methods: We reviewed radiology reports from 5000 consecutive low dose computed tomography (LDCT) scans for lung cancer screening at the Milwaukee VA Medical Center (WI) as of January 2025 to identify patients with aTAAs. Patients were queried for TAA-related ICD codes over the previous 5 years or during the follow-up period. Manual chart review determined whether aTAAs were incidental (i.e., not previously noted in clinic or radiology reports) and whether aTAAs ≥4.5 cm received follow-up CT chest imaging within 6 months and 1 year (+/- 3 months), dedicated aortic imaging (CT angiography), or referral to a cardiovascular specialist during the follow-up period. Results: Among 5000 LDCTs (3836 unique patients), 369 aTAAs ≥4.0 cm (9.6%) were identified, including 88 aTAAs ≥4.5 cm (2.3%). Among individuals with aTAA, 88 (24%) had an ICD code over the previous 5 years. Of aTAAs ≥4.5 cm, 30 (34%) had an ICD code. Of the aTAAs ≥4.5 cm, 27 (31%) were incidentally detected. Eleven (41%) had a follow-up CT chest for any indication within 9 months, with 6 (55%) ordered for aTAA surveillance. Seventeen (63%) incidentally detected aTAAs ≥4.5 cm had >1 year of follow up available (mean follow-up: 491 +/- 127 days; aortic size: 4.6 +/- 0.14 cm; age: 74.9 +/- 8.5 years; all male). Of these, 6 (35%) had evidence of documentation in outpatient clinic notes and 3 (17.6%) had an appropriate ICD code. Fourteen (82%) underwent follow-up CT chest imaging within 15 months—2 (12%) for aTAA surveillance, and 12 for lung cancer screening. Only 2 (12%) patients had dedicated CT angiography and 1 (6%) was referred to a cardiovascular specialist. Conclusion: aTAAs were common in a Veteran LDCT patient population but were often not documented with ICD codes. Incidentally detected aTAAs lacked clinical documentation, follow-up, and specialist referral. Dedicated aortic imaging was rarely used. Further work is needed to determine whether similar patterns exist at other institutions. Low adherence rates to aTAA monitoring guidelines may reflect the limited evidence base that restricts widespread acceptance of these guidelines.