Abdominal aortic aneurysms (AAA) are still known as a ‘silent killer’ as they remain largely asymptomatic until they present with a leak or rupture. Ruptured AAA still have a high prehospital and in-patient mortality despite the advances in technology.
Focus has shifted to the early detection of AAA, management of risk factors that contribute to a faster rate of growth, higher rupture risk and the appropriate mode of intervention when an aneurysm reaches intervention threshold. These factors have been addressed in the recent 2024 European Society of Vascular Surgery guidelines.
Vascular Surgeons, Nedlands
An AAA is defined as an aortic diameter of 3cm or more. The prevalence of AAA has significantly decreased over the past two decades mainly due to the decline of smoking, better management of blood pressure and a rise in the use of antiplatelets and statins, all of which have been shown to decrease aneurysm degeneration and rate of growth.
Non-modifiable risk factors in developing an aneurysm include being a male, age and family history. Large population studies had demonstrated the effectiveness of screening for AAA in particular in men at the age of 65 years. Sweden and the United Kingdom screen 65-year-old men while the US taskforce recommends screening for men aged 65 to 75 years who are current or ex-smokers.
However, the Western Australian screening trial failed to demonstrate any benefit in the population due to the high rates of imaging or detection of AAA during routine clinical care.
The heritability of AAA is thought to be up to 70%, with a family history of AAA increasing the prevalence of AAA up to threefold. Therefore, screening is recommended in all men and women aged 50 or older with a first degree relative with AAA. Patients with known popliteal and femoral aneurysms should have routine screening at any age, as prevalence of AAA is up to 40% in this subgroup.
Ultrasound remains the mainstay in aneurysm detection, screening and surveillance of AAA. Aneurysms grow at a mean rate of 2.2 mm/year and this rate is increased in smokers and with increasing AAA size. Ultrasound surveillance of AAA differs in males and females as aneurysms in women tend to rupture earlier than men (see table).
Patients with AAA have a high incidence of cardiovascular disease and management of the underlying risk factors has demonstrated to decrease the risk of cardiovascular morbidity and mortality. Therefore, all patients with AAA should undergo smoking cessation, antiplatelet therapy, statin therapy, BP control and lifestyle advice (exercise and diet).
It is not necessary to restrict exercise or sexual activity in patients with small AAAs, however, restricting vigorous activity in patients with large AAA may be advisable.
Treatment of AAA is offered when risk of intervention is significantly less than the risk of rupture. In men, elective repair should be considered at 55mm whereas in women the threshold is 50mm. The rate of increase of the diameter is another factor for rupture, therefore, patients with aneurysms which grow >10mm/year should also be considered for repair.
Although endovascular aortic repair (EVAR) remains the primary treatment option in most patients, open repair is an effective option, particularly in young patients with a long-life expectancy.
Due to risk of late complications with EVAR, long-term yearly surveillance with ultrasound is recommended (usually by the vascular surgeon). Patients who have undergone open AAA repair usually require a CT scan at 5 years to assess for synchronous aneurysms.
Key messages
- Abdominal aortic aneurysms remain a silent killer. The heritability is up to 70%
- Screening approaches vary around the world. In WA no benefit was found.
- Risk factor management is critical where AAA is detected.
– References on request
Author competing interests – nil