Morphological factors associated with progression of subaneurysmal aortas.

BACKGROUND: The aim of this population-based cohort study was to assess the association between aortic morphological baseline factors in 65-year-old men with subaneurysmal aortic diameter (25-29 mm) and risk of later progression to abdominal aortic aneurysm (AAA) generally considered to be at a diameter for repair (at least 55 mm). METHODS: Men with a screening-detected subaneurysmal aorta between 2006 and 2015 in mid-Sweden were re-examined using ultrasonography after 5 and 10 years. Cut-off values for baseline subaneurysmal aortic diameter, aortic size index, aortic height index, and relative aortic diameter (with respect to proximal aorta) were analysed using receiver operating characteristic (ROC) curves, and their associations with progression to AAA diameter at least 55 mm evaluated by means of Kaplan-Meier curves and a multivariable Cox proportional hazard analysis adjusted for traditional risk factors. RESULTS: Some 941 men with a subaneurysmal aorta and median follow-up of 6.6 years were identified. The cumulative incidence of AAA diameter at least 55 mm at 10.5 years was 28.5 per cent for an aortic size index of 13.0 mm/m2 or more (representing 45.2 per cent of the population) versus 1.1 per cent for an aortic size index of less than 13.0 mm/m2 (HR 9.1, 95 per cent c.i. 3.62 to 22.85); 25.8 per cent for an aortic height index of at least 14.6 mm/m (58.0 per cent of the population) versus 2.0 per cent for an aortic height index of less than 14.6 mm/m (HR 5.2, 2.23 to 12.12); and 20.7 per cent for subaneurysmal aortic diameter 26 mm or greater (73.6 per cent of the population) versus 1.0 per cent for a diameter of less than 26 mm (HR 5.9, 1.84 to 18.95). Relative aortic diameter quotient (HR 1.2, 0.54 to 2.63) and difference (HR 1.3, 0.57 to 3.12) showed no association with development of AAA of 55 mm or greater. CONCLUSION: Baseline subaneurysmal aortic diameter, aortic size index, and aortic height index were all independently associated with progression to AAA at least 55 mm, with aortic size index as the strongest predictor, whereas relative aortic diameter was not. These morphological factors may be considered for stratification of follow-up at initial screening.

Long Term Outcome of Screen Detected Sub-Aneurysmal Aortas in 65 Year Old Men: a Single Scan After Five Years Identifies Those at Risk of Needing AAA Repair.

OBJECTIVE: The epidemiology of sub-aneurysmal aortic dilatation (SAA) 25 - 29 mm is not fully understood, and the management of SAA is debated. Lack of evidence is particularly problematic in the screening setting. This study aimed to evaluate the long term outcome of men with screen detected SAAs, focusing on progression to an abdominal aortic aneurysm (AAA), and on the AAAs reaching the threshold diameter for surgical repair. METHODS: Between 2006 and 2015, all 65 year old men with a screen detected SAA in middle Sweden were re-examined with ultrasound after five and 10 years. The primary outcomes were expansion to AAA ≥ 30 mm and progression to AAA ≥ 55 mm. Secondary outcomes were risk factors for progression, repair rate, and mortality. RESULTS: A total of 1 020 65 year old men with a SAA were identified, of whom 940 (92.2%; 95% confidence interval 91.0 - 93.8) had follow up. The Kaplan-Meier estimated incidence of AAA ≥ 30 mm development after the five year follow up (which was de facto carried out after a mean of 4.9 years) was 65.8% (61.6 - 69.4), all < 55 mm. The corresponding KM-estimated incidence after the 10 year follow up (carried out after a mean of 11.9 years) was 95.1% (90.1 - 97.4), and 29.7% (18.0 - 39.7) reached ≥ 55 mm. All 41 SAAs eventually expanding to ≥ 55 mm were ≥ 30 mm at the five year follow up. Of these, 32 had surgical repair with 100% survival, six have scheduled repairs, and three (7.3%) were unfit for repair. The KM estimated all cause mortality rates at five and 10 years were 7.0% and 17.9%, respectively, with no proven AAA related deaths. CONCLUSION: A majority of SAAs eventually progress to an AAA, of which 30% are estimated to eventually reach the threshold for repair within 10 years. A follow up policy with an ultrasound examination after five years can safely and effectively identify those SAAs at risk of developing into clinically significant AAAs needing repair and may be considered for anyone with reasonably good life expectancy.

Prevalence and natural history of and risk factors for subaneurysmal aorta among 65-year-old men.

Background: The aims of this study were to determine the prevalence of screening-detected subaneurysmal aorta (SAA), i.e. an aortic diameter of 2.5-2.9 cm, its associated risk factors, and natural history among 65-year-old men. Methods: A total of 14,620 men had their abdominal aortas screened with ultrasound and completed a health questionnaire containing information on smoking habits and medical history. They were categorized based on the aortic diameter: normal aorta (<2.5 cm; n = 14,129), SAA (2.5-2.9 cm; n = 258), and abdominal aortic aneurysm (AAA) (≥3.0 cm; n = 233). The SAA-group was rescanned after 5 years. Associated risk factors were analyzed. Results: The SAA-prevalence was 1.9% (95% confidence interval 1.7%-2.1%), with 57.0% (50.7%-63.3%) expanding to ≥3.0 cm within 5 years. Frequency of smoking, coronary artery disease, hypertension, hyperlipidemia, and claudication were significantly higher in those with SAA and AAA compared to those with normal aortic diameter. Current smoking was the strongest risk factor for SAA (odds ratio [OR] 2.8; P < 0.001) and even stronger for AAA (OR 3.6; P < 0.001). Men with SAA expanding to AAA within 5 years presented pronounced similarities to AAA at baseline. Conclusions: Men with SAA and AAA presented marked similarities in the risk factor profile. Smoking was the strongest risk factor with an incremental association with disease severity, and disease progression. This indicates that SAA and AAA may have the same pathophysiological origin and that SAA should be considered as an early stage of aneurysm formation. Further research on the cost-effectiveness and potential benefits of surveillance as well as smoking cessation and secondary cardiovascular prevention in this subgroup is warranted.