Aberrant Right Subclavian Artery: Demographics, Morphological Features and Follow up CT Scans Dynamics

Introduction: Aberrant right subclavian artery (ARSA) is the most common of the aortic arch anomalies, occurring in .5% to 1% of the population. There is no standardized follow up protocol, especially in the asymptomatic cases. The purpose of the present study was to evaluate the natural history of ARSA and the role of serial CT scans. Methods: This is a single-center retrospective study of patients with ARSA depicted on chest computed tomography (CT) scans between February 2013 and July 2022. Data were collected from their medical records. Measurements of the aorta at different segments including the aortic diameter at the orifice of ARSA, and ARSA at ostium followed by 1 cm intervals were collected, as well as for follow-up CT scans. Results: 65 patients were diagnosed with ARSA, 70.8% of whom were women. The average age for the cohort was 58.569 ± 16.99 years. The median follow up time was 4 years (range 0-10 years), KM estimated survival after ARSA diagnosis at 1 and 5 years as 97% and 93%, respectively. Nineteen patients had a second CT scan and were included in the morphological CT dynamic analysis, on average of 29 ± 27 months apart (range 7-108). The mean ARSA diameter at origin was larger in the second scan 16.91 ± 4.31 mm compared to the initial scan 16.31 ± 4.96 mm, (P = .04).The mean aortic arch diameter in the first and second CT were 28.54 ± 4.24 and 29.64 ± 5.14 (P = .10), respectively. All other measurements did not disclose any significant enlargement over time. Conclusions: Our cohort demonstrate a benign natural history of ARSA with slow growth rates. However, due to our small sample size we can't draw a clinically sound recommendation on the need for imaging follow up, and further larger cohort with longer follow up interval are required.