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

Cardiovascular risk in patients with small abdominal aortic aneurysms

Background: Abdominal aortic aneurysm (AAA) is a cardiovascular health problem. Ultrasound screening has been shown to reduce the risk of AAA-related, but not all-cause, mortality. The recent introduction of screening in several countries has meant that thousands of patients with a small AAA (<5·5cm) that does not require immediate treatment are diagnosed annually. We sought to investigate the cardiovascular profiles of patients with ectatic aortas and assess whether participation in screening reduces cardiovascular risk. Methods: We used three sets of data: from the National Health Service AAA Screening Programme (NAAASP) during the 2013–14 round that were linked with Health Episode Statistics (HES) (235 409 individuals); a subset of the Framingham Study population who had an abdominal CT scan in 2004–05 and were followed up for 10 years (1383 individuals); and data for patients with a small AAA who had been in surveillance for at least 1 year in the UK Aneurysm Growth Study (UKAGS) (384 individuals) or from a national UK audit (1538 individuals), to assess cardiovascular risk and events. Findings: In the linked NAAASP–HES cohort, cardiovascular mortality was 0·30% (95% CI 0·28–0·32) for individuals with an abdominal aortic diameter of less than 2·5 cm; 0·81% (0·51–1·11) for those between 2·5 and 2·9 cm; and 1·30% (0·90–1·71) for those less than 3·0 cm. Death from a cardiovascular event was more likely for individuals with a small AAA than for those without AAA (risk ratio 4·33, 95% CI 3·15–5·97). In the Framingham cohort, abdominal aortic diameter was independently associated with cardiovascular events (hazard ratio [HR] 1·1, 95% CI 1·02–1·18; p<0·0001). An abdominal aortic diameter of more than 2·5 cm was also associated with cardiovascular events (HR 7·6, 95% CI 5·1–11·3; p<0·0001). In the UKAGS and audit populations, patients were not more likely to take antiplatelet agents or statins after entering screening surveillance; cholesterol concentrations and blood pressure also increased. Interpretation: In these contemporary large cohorts of patients with small AAA, cardiovascular events and death were common and were the leading cause of death. The implication is that patients are not more likely to receive cardiovascular protection if they enter screening or surveillance with existing protocols. Cardiovascular risk reduction interventions should be implemented in screening programmes in the future

Investigation of the effect of genetic polymorphisms on aortic growth in patients with abdominal aortic aneurysm (AAA)

Investigation of the effect of genetic polymorphisms on aortic growth in patients with abdominal aortic aneurysm (AAA

Impact of hospital volume on outcomes following treatment of thoracic aortic aneurysms and type-B dissections

Previous research suggests an association between hospital volume and outcomes in high-risk surgical pathologies. The association between hospital volume and outcomes in patients with isolated descending thoracic aortic aneurysms (DTAAs) and type-B thoracic aortic dissections (TBADs) is conflicting. We aimed to investigate this in a literature review and meta-analysis. A systematic review of the literature was performed to identify studies reporting mortality and morbidity following repair (elective or emergency) of DTAA and/or TBAD using the Medline and Embase Databases (2000-2015). Hospital volume was assessed based on the number of patients treated per institution: low volume (1-5 cases per year), medium volume (6-10) and high volume (>10). The primary outcome of interest was all-cause mortality during inpatient stay and at 30 days. Eighty-four series of non-dissecting DTAA or TBAD were included in data synthesis (4219 patients; mean age: 62 years; males: 73.5%). For all patients (emergency and elective) undergoing DTAA repair, in-hospital mortality was 8% [95% confidence interval (CI): 6-8%]. Results were not superior in high-volume centres (8 vs 6 vs 11% for high-, medium- and low-volume, respectively). Sub-analyses for emergency and elective repairs showed no significant differences. For TBAD repairs, in the combined population (emergency and elective), results reached borderline significance (P = 0.0475), favouring high-volume centres (6 vs 11 vs 14%), but this association disappeared when emergency and elective repairs were analysed separately. Nine series reported outcomes at 1 year and 5 series followed DTAA and 18 TBAD treatment. No meaningful long-term comparisons were possible due to the lack of data. No significant associations were detected between hospital volume and subsequent mortality following DTAA or TBAD treatment. Data were heterogeneous and long-term results were scarcely reported. A well-designed longitudinal study of sufficient size is required to inform future strategies in this area

Cardiovascular risk profile and management of risk factors in patients with small abdominal aortic aneurysm

Cardiovascular risk profile and management of risk factors in patients with small abdominal aortic aneurys