The physiological and clinical importance of cardiorespiratory fitness in people with abdominal aortic aneurysm

An abdominal aortic aneurysm (AAA) is an abnormal enlargement of the aorta, below the level of renal arteries, where the aorta diameter increases by over 50%. As an aneurysm increases in size there is a progressive increase in the risk of rupture, which ranges from 25% to 40% for aneurysms larger than 5.5 cm in diameter. People with AAA are also at a heightened risk of cardiovascular events and associated mortality. Cardiorespiratory fitness is impaired in people with AAA, and is associated with poor (post-operative) clinical outcomes, including increased length of hospital stay and post-operative mortality following open-surgical or endovascular AAA repair. While cardiorespiratory fitness is a well-recognised prognostic marker of cardiovascular health and mortality, it is not routinely assessed and it is not included in current clinical practice guidelines for the management of people with AAA. In this novel review we discuss the physiological impact of AAA on cardiorespiratory fitness, as well as the consequences of low cardiorespiratory fitness on clinical outcomes in people with AAA. Finally, this review summarises current evidence of the effect of exercise training interventions on cardiorespiratory fitness in people with AAA, including the associated improvements in post-operative mortality, AAA growth and cardiovascular risk. Based on this review we propose that cardiorespiratory fitness should be considered as part of the routine risk assessment and monitoring of people with AAA, and that targeting improvements in cardiorespiratory fitness with exercise training may represent a viable adjunct treatment strategy for reducing post-operative mortality and disease progression.