Risk stratification of aortic aneurysms : Predictors of natural and clinical course

Abstract

Rupture of an abdominal aortic aneurysm (AAA) is a dramatic and often fatal process with an overall risk of mortality that ranges from 79 to 94%. The risk of AAA rupture increases strongly with increasing diameter of the AAA. Approximately 14,000 persons die each year due to aortic aneurysm rupture or dissection in the United States (US), making this condition the 14th leading cause of death. Every year, 200,000 AAAs are diagnosed in the US and the estimated overall number of people with AAAs is 1.5 to 2 million. These numbers are likely to increase in future due to an increasing population age. The main objective of this thesis is to evaluate the prognosis of patients with aortic aneurysms and to provide more insight in predictors of the natural course of patients with AAA and complications after elective and ruptured aortic aneurysm repair. The results of our studies have several implications for treatment strategies. The risk of rupture of small abdominal aortic aneurysms (<55 mm) is low, which pleads for watchful waiting. Statins appear to reduce AAA growth rates, which may prevent aneurysm rupture and surgery. Mortality risks after elective or ruptured AAA repair are clearly age- and gender-related. Age, gender and the presence of co-morbidities should be taken into account when deciding on elective AAA repair or watchful waiting. A general threshold of 55 mm for elective AAA repair may not be justified for all patients, especially for elderly patients. The value of surgical repair of ruptured AAA is very limited in patients aged 85 years or older. To improve prevention of AAA rupture after endovascular AAA repair (EVAR), surveillance should focus on the first 2-3 years of follow-up, especially in patients with increased risk of early rupture, such as a large initial AAA diameter or presence of endoleak or graft migration. Better stent-graft durability and longevity is required to further reduce the AAA rupture risk after EVAR. Prior AAA repair is an important risk factor for complications after thoracic endovascular aortic aneurysm repair (TEVAR) and open thoracic or thoracoabdominal aortic aneurysm repair. Patients with prior AAA repair should therefore be provided maximum care to protect their spinal cord when thoracic aortic repair is required. We have introduced the feasibility of dynamic imaging of the thoracic aorta and cardiac structures and function with one ECG-gated Computed Tomography (CT) scan. The obtained images can be successfully assessed for thoracic aorta pathology, cardiac disease and extracardiac pathology. This new imaging technique may become the initial imaging modality for pre-operative cardiac risk stratification in many patients with thoracic aortic aneurysms or dissections. A more accurate prediction of the natural and clinical course on the basis of our results allows for “custom-made” treatment strategies. With increasing insight in predictors of the natural and clinical course of patients with aortic aneurysms, it will be more and more possible to tailor treatment to each patient’s unique predictors which will subsequently lead to an improved prognosis.