Aortic calcification is associated with decreased abdominal aortic aneurysm growth

Abdominal aortic aneurysm (AAA) rupture remains a significant cause of morbidity and mortality, but predictors of continued growth and rupture risk remain limited. The aim of this study was to investigate the relationship between abdominal aortic calcification and AAA growth via a secondary cohort analysis of the Non-Invasive Treatment of Abdominal Aortic Aneurysm Clinical Trial (N-TA3CT), a prospective multicenter randomized study. Arterial calcification Agatston scores and maximum transverse diameter were measured in non-contrast computed tomography (CT) scans in patients enrolled in N-TA3CT. Uni- and multi-variable linear regression were used to assess the association of anatomic calcium burden and comorbid conditions with rate of aneurysm growth. Of the 261 randomized patients in the trial, 136 patients met inclusion criteria for analysis. On univariable analysis, baseline calcium score at all assessed anatomic locations- the superior mesenteric artery (spearman correlation coefficient (SCC) -0.20, p = 0.0176), renal artery (-0.22, p = 0.0120, infrarenal aorta (-0.26, p = 0.0020), common iliac artery (-0.19, p = 0.024), external iliac artery (-0.26, p = 0.003), and sum of all measured sites (-0.28, p = 0.001)- was significantly associated with lower AAA diameter growth rates. Of individually measured sites, baseline infrarenal aortic calcification had the strongest negative association with aneurysm growth. Interestingly, infrarenal calcium score was not significantly associated with baseline aneurysm diameter (R² 0.0001, spearman correlation p = 0.94), or diabetes status (p = 0.59). In a multivariable regression model, factors significantly associated with faster diameter growth included baseline volume and current tobacco use. Factors associated with reduced growth rate included diabetes and baseline infrarenal aorta calcium score thereby establishing aneurysmal calcification as a marker for slower aneurysm growth.