Findings from an analysis of risk factors in almost 15,000 patients support current guidelines for aortic diseases in recommending a full screen of the aorta when a focal aortic dilation is discovered, say those behind the study.
Published online Monday and in the July 20 issue of the Journal of the American College of Cardiology, data from the population study showed that risk factors for aortic dilation differ across various aortic segments but that the most dominant predictor for having a dilation at any aortic segment is the presence of an aortic dilation elsewhere.
The authors, led by Lasse Obel, MD, from the Odense University Hospital and University of Southern Denmark, said their findings support current guidelines to recommend a full screening of the aorta if a focal aortic dilation is discovered.
Additionally, the iliac arteries should be scanned when an aortic arch, descending, or abdominal aortic dilation is discovered, they recommended.
“In this large, population-based, cross-sectional study including randomly selected participants aged 60-74 years, we sought to identify the most dominant predictors for having an aortic dilation at any aortic segment,” said Obel and colleagues.
Alongside the dominant risk factor of other aortic dilation, they added that other noteworthy predictors to be considered include hypertension, increasing body surface area (BSA), male sex, familial disposition, atrial fibrillation (AFLI), smoking, and acute myocardial infarction (AMI), “which were present in various combinations for different parts of the aorta.”
Alongside its study of risk factors, the publication also provides a reference for aortic diameters and offers clinically applicable prediction formulas for calculating expected normal ascending, arch, descending, and abdominal aortic diameters, respectively, when measured on non-contrast computed tomography (CT) scans.
“As expected, male participants had significantly larger aortic diameters on all aortic segments compared with women,” said Obel and colleagues, noting that the overall ascending, arch, descending, and abdominal aortic diameters from the CT scans were 37.3, 30.6, 28.3, and 20.3 mm, respectively, and that male participants were significantly larger, by 2.5-4.0 mm, on each aortic segment compared with women.
The new analysis comes from two comprehensive Danish population-based screening trials, DANCAVAS I and II (Danish Cardiovascular Multicenter Screening Trials), which included participants aged 60-74 years from the national civil registry.
The study population consisted of 14,989 participants (14,235 men, 754 women) with an average age of 68 years, said the team, noting that the highest adjusted odd ratios (OR) for having any aortic dilation were observed when co-existing aortic dilations were present.
The highest adjusted OR for thoracic aortic dilations was found when a dilated ascending or descending aorta occurred, the researchers noted, adding that in these cases, the risk of having a co-existing aortic arch dilation was increased by a factor of between 6 and 8.
They added that when a focal dilation at the descending or abdominal aorta was present, the risk of having a coexisting dilation at the opposite site was increased by a factor of 4 – potentially explained by the common pathology for descending and abdominal aneurysms.
Meanwhile when an abdominal aortic dilation was exposed, the risk of having a co-existing dilation on the common iliac arteries was increased by a factor of 10, the authors revealed – stressing that such a finding emphasizes the importance of screening the iliac arteries, particularly when an abdominal aortic dilation is found.
“Not surprisingly, the different aortic sites shared several risk factors, including hypertension, increasing BSA, AFLI, and familial disposition, which were present in various combinations for different parts of the aorta,” they said – adding that diabetes was a mutual protective factor for all thoracic aortic sites.
However, other risk factors appeared diversely associated to different segments, they said, noting that smoking and AMI increased risk for abdominal dilations “remarkably,” while they reduced risk for ascending dilations.
Writing in an accompanying editorial, John Elefteriades, MD, PhD, from the Yale University School of Medicine, and Joshua Beckman, MD, MS, from Vanderbilt University Medical Center, noted that the new publication also provides “valuable fundamental data” on the prevalence of aortic disease, normal aortic diameters at different anatomic levels and prediction of the presence of aneurysm.
However, the editorialists suggested that the authors’ high ORs for having an arch aneurysm when a patient has an ascending or descending aneurysm be taken “with a grain of salt,” noting that it is very rare, anatomically, to have an arch aneurysm without an ascending or descending dilatation.
"Although very high ORs were calculated for association of adjacent segments with arch aneurysms, these are misleading because they merely represent anatomic continuity, not a ‘second’ aneurysm,” they said.
Elefteriades and Beckman also noted the importance of providing a reference for aortic diameters within the dataset, adding that the detailed imaging assessments will be an important backdrop both for clinical care and for future research.
“We believe that a significant contribution of this study is the cataloging of normal aortic dimensions, based on careful calculations in thousands of patients from the general population,” they said.
Obel LM, Diederichsen AC, Steffensen FH, et al. Population-Based Risk Factors for Ascending, Arch, Descending, and Abdominal Aortic Dilations for 60-74–Year-Old Individuals. J Am Coll Cardiol 2021;78:201-11.
Elefteriades JA, Beckman J. The Normal Aorta Characterization Based on 15,000 CT Scans. J Am Coll Cardiol 2021;78:212-5.