Too few patients are being screened for abdominal aortic aneurysm (AAA), resulting in severe morbidity and mortality. Many patients with AAA aren’t identified until they present with rupture, leading to mortality as high as 90%.1 Early detection is critical.
Medicare offers one-time free screening to eligible individuals > 65 years of age, and several professional organizations promote screening with published guidelines, which we discuss later in this article.
So who is at risk, who should be screened, and what is the best way to screen your patients?
Risk factors and sex differences
AAA has a prevalence of between 1% and 5% in men > 65 years old,2,3 and it is 4 to 6 times more common in men than women.4 Major risk factors include smoking, older age, family history, and genetic factors, while hypertension, history of coronary artery disease, hyperlipidemia, and peripheral arterial disease have weaker associations.3,4 Exercise and diabetes seem to have protective effects.5
The incidence and mortality of AAA increased between the 1950s and the mid-1990s; however, both indicators have decreased in numerous countries in the 21st century.6 Although the prevalence is much lower in women, they have a higher risk of rupture than men at equivalent lesion diameters.3 The prevalence of AAA in women who smoke and are > 70 years of age is > 1%.3
Silent but deadly
Most patients with AAA are asymptomatic. Their lesions are often detected incidentally on magnetic resonance imaging of the spine obtained for back pain, on an abdominal ultrasound (US) for gallstones, or on a routine computed tomography (CT) scan for the evaluation of abdominal pain. Some patients will experience vague abdominal discomfort from rapid expansion of an aneurysm prior to rupture, necessitating urgent repair. Also, some large aneurysms can erode into the spine and cause chronic back pain prior to rupture. An infrarenal abdominal aortic diameter > 30 mm defines an aneurysm,7 and once the diameter reaches 55 mm, the threat of rupture often justifies operative repair. (See “The preferred approach to repair.”)
The preferred approach to repair
Since the introduction of endovascular aneurysm repair (EVAR) in the latter part of the 20th century, it has become the standard of care for the surgical management of aneurysmal disease. Currently, > 80% of patients with an abdominal aortic aneurysm (AAA) who undergo repair are treated with EVAR.23
Typically, the AAA diameter is assessed via ultrasound. If repair is indicated, a computed tomography arteriogram is obtained to define the anatomy and help determine if the AAA is amenable to endografting. The most common contraindications to EVAR are either a short proximal neck (not enough distance below the renal arteries to safely anchor the stent graft) or an iliac artery diameter that is too small to allow delivery of the device. The operation can be performed under local, regional, or general anesthesia, and patients are usually discharged on the first postoperative day. These patients require lifelong surveillance due to the risk of delayed endoleak and reperfusion of the aneurysm sac.24
Ruptured aneurysms will classically manifest with severe abdominal and/or back pain. Often a ruptured aneurysm will be contained in the retroperitoneum, allowing the patient to remain hemodynamically stable for a period of time and thus providing a window of opportunity for emergent repair.
Continue to: What is the evidence that screening is effective?