How quickly do asymptomatic infrarenal abdominal aortic aneurysms grow and what factors affect aneurysm growth rates? Analysis of a single centre surveillance cohort database

OBJECTIVE/BACKGROUND: Abdominal aortic aneurysm (AAA) maximum antero-posterior diameter (MAPD) is the parameter most commonly used to inform the timing of surgical intervention. However, other factors, such as growth rates and patient comorbidities are likely to be important considerations as they may influence AAA related complications including rupture, operative outcomes, and the clinical and cost effectiveness of continued surveillance.

METHODS: This was a retrospective analysis of a 20 year period of a single centre AAA surveillance database. In total, 5363 AAA measurements in 692 patients were analysed for patient demographics, including comorbidity and drug history, growth and rupture rates, and cause of death.

RESULTS: A significant proportion of patients (n = 73; 11%) were kept under surveillance despite having a MAPD < 30 mm. Overall, mean aneurysm growth rate was 2.3 mm/year. Elective repair was undertaken in 20.1% and those who required surgical intervention had significantly faster growth rates. Only 3.9% of patients in surveillance ruptured, 40.7% of whom had a MAPD <55 mm at their last scan. Of the 214 deaths recorded, only 11.7% were related to AAA. The majority of patients who died in surveillance did so from malignancy. Patients with larger AAA (MAPD > 40 mm) on entry into surveillance were significantly more likely to receive surgical intervention, as were those whose AAA expanded >4 mm/year. Females had significantly higher growth rates, and those with diabetes had significantly smaller growth rates. Other comorbidities and drug history were not associated with AAA growth, or 5 and 10 year surgery free survival.

CONCLUSION: The results highlight several areas for service improvement. Specifically, it is important not to maintain surveillance in patients who are very unlikely to ever grow to a point where AAA surgery would be contemplated on grounds or age and/or comorbidity. Similarly, patients should be discharged from surveillance when this likelihood becomes apparent.