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

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. (JACC. 2025;85:818-831) (c) 2025 by the American College of Cardiology Foundation.