Atherosclerotic Peripheral Vascular Disease Symposium II: controversies in abdominal aortic aneurysm repair.

Abdominal aortic aneurysms (AAAs) are the result of a progressive degenerative process characterized by elastin depletion and inflammatory changes of the aortic wall. The process leads to gradual enlargement and a localized weakening of the aorta, with eventual rupture. Risk factors include age, sex, family history, and smoking.1 The normal aortic diameter varies with age, sex, and body size. An infrarenal abdominal aorta with a diameter 3 cm is considered aneurysmal. The risk of rupture increases directly with aneurysm size, and the death rate associated with rupture is very high (90%). Surgical repair has been the standard therapy for patients with AAAs but is associated with a risk of death and a high rate of complication. Thus, in considering open repair, the risk of the procedure is weighed against the risk of rupture.2 Patients with AAA, especially those with larger aneurysms at high risk of rupture, are usually elderly, and most have multiple comorbidities that increase the risk of surgical treatment. The treating physician, therefore, must balance the natural history of AAA, the operative risk of treatment, and the life expectancy of the patient. Two prospective, randomized trials of good-risk patients with small AAAs (4.0 to 5.5 cm) found no difference in all-cause death rate between patients who were monitored with ultrasound surveillance and those who underwent early surgical repair3,4; however, despite close surveillance with ultrasound, ruptures occurred in 1% of the monitored aneurysm patients each year. Risk of rupture is higher in women, patients who smoke, and those with a family history of aortic aneurysm. Furthermore, most patients with small AAAs undergoing surveillance in these studies ultimately required surgical repair because of AAA enlargement, development of symptoms, or rupture. Therefore, intervention for AAAs 5.5 cm in diameter may be justified in selected patients, and the treatment of small aneurysms is under continued investigation. Open surgical repair has been performed for more than 50 years and is considered to be the standard of care for patients with AAA. Over the past decade, endovascular aneurysm repair (EVAR) has been introduced as a less invasive treatment alternative for patients with AAA. Several endovascular devices have been approved by the US Food and Drug Administration (FDA) and are available to suitable patients with infrarenal AAA. These devices can be inserted safely and are associated with low death rates,5,6 but questions remain about the long-term durability, reintervention rate, and cost of these procedures. The task of this writing group is to review the evidence that compares open surgical repair and EVAR of AAA and address areas of controversy that need further investigation. This discussion is relevant specifically to infrarenal AAAs that meet appropriate anatomic criteria to allow the option of EVAR.