Natural history of 40-50 mm root/ascending aortic aneurysms in the current era of dedicated thoracic aortic clinics.

OBJECTIVE: The natural history of root/ascending aortic aneurysms is based on studies from the 1980s to 1990s. Imaging and follow-up guidelines are based on these studies. Dedicated thoracic aortic clinics (TAC) ensure strict patient/imaging follow-up and tight blood pressure (BP) control. The aim of this study was to evaluate the natural history of medically treated root/ascending aortic aneurysms in the current era of dedicated TAC.
METHOD: Two hundred and fifty-one patients with 40-50 mm root/ascending aneurysms (all other aortic segments of <40 mm) were identified through a prospective collected databank. Patients were followed in a dedicated TAC. Serial (12-18 months interval) thoraco-abdominal computed tomographies (CTs), tight BP control (24 h arterial blood pressure monitoring) and isometric and exercise BP monitoring were performed.
RESULTS: The mean age was 65.4 ± 10.9 years; 29.5% of patients were female. Fifty-nine percent of patients had high BP. Aneurysm aetiology was atherosclerotic in 48.2% of patients, annulo-ectasia in 25.1% of patients, bicuspid valve-related in 21.5% of patients and another aetiology in 5.2% of patients. The initial aneurysm diameter was 46 ± 2.6 mm; 74.1% being between 46 and 50 mm. The mean follow-up (FU) was 4.3 ± 2.5 years, with a mean of 2.8 ± 1.1 CTs/pt. During FU, the increase in aortic size/year was 0.42 ± 0.82 mm/year for the root/ascending aorta (40-45 mm: 0.55 ± 0.77 mm/year vs 46-50 mm: 0.38 ± 0.84 mm/year; P = 0.14), 0.66 ± 1.11 mm/year for the arch, 0.45 ± 1.06 mm/year for the mid-descending aorta, 0.43 ± 1.0 mm/year for the aortic hiatus, 0.39 ± 0.87 mm/year for the suprarenal aorta and 0.41 ± 1.03 mm/year for the infrarenal aorta. Thirty patients (12%) were operated during FU. Surgical indication was disease progression on the aortic valve in 8 patients, root/ascending aorta progression of >50 mm in 14 patients and a root/ascending aorta replacement during FU without progression in 8 patients. One patient was operated emergently for an intramural haematoma after 3 years of follow-up. No patient required operation distal to the aortic arch. Operative mortality was 0/30 (0%). Thirty percent of patients required a concomitant hemiarch replacement. Four patients died during FU, with all deaths resulting from non-aortic causes. Freedom from acute aortic-related event and survival at 5 years were respectively 99.4 and 97.6%.
CONCLUSION: The present study suggests that the growth rate of 40-50 mm root/ascending aneurysms followed in a dedicated TAC aorta is lower than that shown in previously reported series. Freedom from aortic-related events and survival are high, thus necessitating long-term follow-up. These results challenge the current guidelines in terms of interval between imaging examinations and the extent and type of aortic imaging.