Intervention on thoracic and thoracoabdominal aortic aneurysms: can the UK offer a service?
Authors: Mark L Field, Debbie Harrington, Mohamad Bashir, Manoj Kuduvalli, Aung Oo
Journal: Journal of the Royal Society of Medicine (2012)

Descending thoracic aortic aneurysms and thoracoabdominal aortic aneurysms are classified according to their longitudinal extent, at their greatest reaching from left subclavian artery to iliac vessels and involving two body cavities.1 The natural history of thoracoabdominal aortic aneurysms is difficult to determine accurately; however, several studies have estimated survival in patients followed up after having been turned down for surgery or declining intervention.1,2 The outlook for these patients is poor.

In Crawfords original series (1986)1 of 94 unoperated patients, the two-year survival was 24%. A larger study by Perko et al. (1995)2 documented similarly poor outcomes with five-year survival of 0.39 ± 0.07, 0.23 ± 0.06 and 0.18 ± 0.05 for isolated thoracic aneurysms, thoracoabdominal aneurysms and abdominal aortic aneurysms, respectively. This has not improved despite current optimal medical therapy; however, predicting annual risk of rupture has become accurate allowing timely intervention in an elective setting.3,4 Risk of rupture is most strongly related to diameter with the so-called ‘hinge point’ being around 7 cm in the descending thoracic aorta, at which point 43% of those under follow-up will have ruptured or dissected.5 In asymptomatic patients the indication for surgery occurs roughly when the annual risk of rupture is greater than the perioperative risk of death.4

Intervention is a major undertaking for surgeon and patient. Open surgery has improved significantly over recent years; however, even in high-volume reference centre risks remain substantial for the largest of aneurysms (death [10%], paraplegia [7.5%] and renal failure [15.9%]6). However, data from this same group6 suggest much improved survival following surgery, with five-year survivals between 66% and 75%, depending on the severity of the aneurym, significantly better than that estimated in natural history studies. Relatively recently, endovascular approaches have been pioneered to circumvent the need for extensive high-risk surgery; however, these approaches have not been without their problems, including high cost and re-intervention rates.7 Hybrid approaches with endovascular stenting and re-routing of visceral vessels have been published by several groups, including some in the UK,8 but seem to offer no clear advantage. The literature remains controversial and no randomized trial has been performed comparing best medical therapy with surgery, stent or a hybrid procedure. American Heart Association guidelines9 and international consensus statements7 exist and provide a comprehensive comparison of these various approaches and we do not intend to reproduce the arguments here.

The picture in the UK remains particularly unclear with respect to prevalence, intervention, outcome and arrangement of services. This essay attempts to estimate the consumption of medical services by patients with this condition within the UK, attempts to understand the intervention rate and form and asks whether the UK can offer a service with adequate outcomes at acceptable costs.