The epidemiology of abdominal aortic aneurysm and natural history of type II endoleak after endovascular aneurysm repair

Abdominal aortic aneurysm is an important cause of death globally, however, its impact is less today than two decades ago due to a decline in AAA mortality. Within the same timeframe changes have occurred to the way that AAA may be treated, for example an increasing use of endovascular surgical techniques. Type II endoleak is one of the most common complication of endovascular aneurysm repair. The sequela of having a type II endoleak is however unknown. My objectives within this thesis were to analyse causes of the decline in aneurysm mortality being seen in many developed countries using data derived from the World Health Organisation and investigate short/medium term outcomes of patients with type II endoleak at a single centre in the United Kingdom. Through these studies I have demonstrated a robust association between trends in established cardiovascular risk factors and mortality from AAA suggesting that a reduction in the global burden of high cholesterol (P=0.0082), hypertension (P=0.028) and smoking (P=0.017) have led to a drop in AAA mortality. Aneurysm rupture in patients with an isolated type II endoleak appears to be rare occurring in less than 1% of all literature reported type II endoleaks and no ruptures were recorded in patients with type II endoleak followed up prospectively. Patients with isolated type II endoleak demonstrate equivalent aneurysm related mortality to those without, however, there is a strong independent association between type II endoleak and 5mm of aneurysm sac expansion (P=0.0001). A conservative strategy to the treatment of type II endoleak appears to be safe and given time isolated type II endoleak appear to have a good chance of spontaneously resolving without the need for invasive intervention. For those patients with type II endoleak and 10mm of aneurysm sac expansion, further research is needed to investigate the risk versus benefit of intervention.