The Nonsyndromic Ascending Thoracic Aorta in a Population-Based Setting: A 5-Year Prospective Cohort Study

Abstract

Background: Prospective data on the clinical course of the ascending thoracic aorta are lacking.

Objectives: This study sought to estimate growth rates of the ascending aorta and to evaluate occurrences of adverse aortic events (AAEs)-that is, thoracic aortic ruptures, type A aortic dissections, and thoracic aortic-related deaths.

Methods: In this prospective cohort study from the population-based, multicenter, randomized DANCAVAS (Danish Cardiovascular Screening trials) I and II, participants underwent cardiovascular risk assessments including electrocardiogram-gated, noncontrast computed tomography (CT) scans. The clinical database was supplemented with outcome data from Danish health care registries. Exclusion criteria were connective tissue disorders, bicuspid aortic valves, and survivors of a prior AAE. To estimate growth rates, participants with consecutive CT scans were followed from inclusion to last scan. To evaluate AAEs, the entire cohort was followed from inclusion to AAE; elective ascending aortic surgery; death; or December 31, 2021.

Results: In 2,026 individuals (77.3% men; mean age: 69.2 ± 3.1 years; median follow-up: 4.5 years [Q1-Q3: 3.4-4.7 years]), 4,897 CT scans were obtained, encompassing 1,374 individuals with baseline ascending aortas of <40.0 mm (68.3% men), 388 with baseline ascending aortas between 40.0 and 44.9 mm (94.5% men), 188 with baseline ascending aortas between 45.0 and 49.9 mm (98.4% men), and 76 men with baseline ascending aortas of ≥50 mm. The mean ascending aortic growth rates in men and women were 0.07 ± 0.5 mm/year and 0.13 ± 0.3 mm/year (P = 0.012), respectively. Growth rates did not increase with larger diameters, and no differences were observed between small (<39.9 mm; 0.11 ± 0.5 mm/year) and large (≥50 mm; 0.07 ± 0.6 mm/year) (P = 0.60) aortas. In men with dilated aortas between 45.0 and 49.9 mm, 3.2% progressed to ≥50.0 mm over 4.6 years (Q1-Q3: 4.0-5.6 years). Among all 14,962 nonsyndromic participants (95.0% men; mean age: 67.7 ± 3.7 years; median follow-up: 5.0 years [Q1-Q3: 4.1-5.8 years]), 23 (0.2%) encountered AAEs (31/100,000 person-years), and 26 (0.2%) underwent elective ascending aortic surgery. In size groups of <40.0, 40.0 to 44.9, 45.0 to 49.9, and ≥50.0 mm, proportions of AAEs were 10 of 11,382 (0.1%), 5 of 2,997 (0.2%), 7 of 493 (1.4%), and <3 of 90, respectively. Adjusted HRs for AAE were 1.24 (95% CI: 1.16-1.33; P < 0.001) for each 1-mm increase in diameter and 5.43 (95% CI: 1.99-14.82; P = 0.001) for a family history of aortic aneurysms.

Conclusions: In men aged 60 to 74 years, growth of the ascending aorta was slow, questioning the currently recommended (bi)annual surveillance scan intervals. Additionally, 95% of AAE case patients presented with diameters of <50.0 mm upon the event, highlighting the need for individualized risk stratifications in addition to diameter. Larger prospective studies in aneurysmal women are warranted.

Keywords: aortic aneurysm; ascending thoracic aorta; dissection; epidemiology; growth; population-based.