Ascending Thoracic Aortic Aneurysm Growth is Minimal at Sizes That Do Not Meet Criteria for Surgical Repair

Objective: Historic studies of nonsyndromic ascending thoracic aortic aneurysms (aTAAs) suggested that aTAA growth rate was approximately 0.6mm/year, but data were limited, with relatively few studies using computed tomography (CT) imaging. Our objective was to reevaluate the annual growth rate of nonsyndromic ATAAs that do not meet criteria for surgical repair in the contemporary era. Methods: Nonsurgical patients (ATAA diameter<5.5cm) undergoing aTAA surveillance with repeat CT imaging taken 3-5 years apart were identified. Maximum aTAA diameter was determined by a single radiologist using centerline measurements. Average growth rate was evaluated based on longest available follow-up. Results: Seventy-four patients were included. Average follow-up time was 3.98±0.86 years. Patients were primarily male (n=74, 100%), with average age of 67.4±7.7 years and a history of smoking (n=57, 77%), hypertension (n=54, 73%), and dyslipidemia (n=54, 73%). Average baseline aTAA diameter was 43.2±4.2 mm and average growth rate was 0.11±0.34 mm/year, with a rate of 0.12±0.33 mm/year in patients with tricuspid aortic valves (n=68) and 0.08±0.22 mm/year in patients with bicuspid valves, excluding one outlier with a negative growth rate of -0.79mm/year (Figure 1). There was no difference in growth rate between patients with initial diameter ≤45mm vs. >45mm. Only 5 patients experienced clinically significant changes in diameter with magnitude >5% of baseline. Conclusions: In this population, most patients did not experience annual aneurysm growth over 5 years, regardless of initial aTAA diameter. Thus, in the modern era, aTAAs may not grow as quickly as previously described, which is important in determining appropriate intervals for aneurysm surveillance based upon risk:benefit ratio. Figure 1. Comparison of average annual growth rate distributions between overall population and patients with tricuspid vs. bicuspid aortic valves