Obesity's Dual Role in Abdominal Aortic Aneurysm: Risk Factor and Protective Paradox

Obesity, traditionally recognized as a significant public health threat due to its association with numerous metabolic, inflammatory, and psychosocial conditions, is now emerging as a complex factor in the development and progression of abdominal aortic aneurysm (AAA), according to a review published in Frontiers in Endocrinology.

“Obesity encompasses not only the accumulation of fat cells in the body but, more significantly, is often accompanied by adverse lifestyle choices and various comorbidities,” explained Feng Lu, Department of Anesthesiology, The First Affiliated Hospital of Gannan Medical University, Ganzhou Key Laboratory of Anesthesiology, The First Affiliated Hospital of Gannan Medical University, Ganzhou in Jiangxi, China, and coauthors. “These factors collectively influence the initiation, progression, and prognosis of AAA,” they added.

Studies have shown that individuals with higher body mass index (BMI) and central obesity are at an increased risk of developing AAA, with the condition being more severe among those who are morbidly obese. For example, research involving thousands of AAA patients has demonstrated that morbid obesity (BMI >34 kg/m²) is associated with higher perioperative mortality rates following both open aneurysm repair (OAR) and endovascular aneurysm repair (EVAR). Specifically, for every unit increase in BMI, the risk of 30-day mortality in patients undergoing repair for ruptured AAA rises by 1.08%.

However, the relationship between obesity and AAA is not straightforward. Patients with mild obesity (BMI 25-30 kg/m²) often experience better surgical outcomes and lower mortality rates than those of normal weight. This phenomenon has been referred to as the "obesity paradox." This paradox, which is also observed in other cardiovascular conditions, indicates that while severe obesity exacerbates the risks associated with AAA, mild obesity might offer a protective effect against surgical complications.

The potential mechanisms behind obesity's impact on AAA are multifaceted. Obesity accelerates vascular aging through chronic inflammation, oxidative stress, and the secretion of adipokines from adipose tissue, all of which contribute to the pathogenesis of AAA. Visceral fat has been linked to the enlargement of the abdominal aorta, further supporting the connection between obesity and AAA.

Given these complexities, the role of weight management in the perioperative care of AAA patients has gained attention. Preoperative weight loss, particularly in severely obese patients, has been shown to reduce postoperative complications and improve surgical outcomes. Moderate prehabilitation, involving physical activity and dietary control, may help achieve a healthier weight, potentially delaying surgical intervention and reducing overall healthcare costs.

“Given the significant role of obesity in the development, progression, and treatment of abdominal aortic aneurysms (AAA), it is crucial to develop screening, monitoring, and intervention strategies tailored to the varying degrees of obesity in patients at risk for AAA,” wrote the study authors.

Reference

Lu F, Lin Y, Zhou J, et al. Obesity and the obesity paradox in abdominal aortic aneurysm. Front Endocrinol (Lausanne). 2024;15:1410369. doi:10.3389/fendo.2024.1410369