Clinical Pearls & Morning Reports
Since the introduction of endovascular aortic aneurysm repair (EVAR) in 1991, the number of abdominal aortic aneurysm repairs in the United States has increased dramatically, and more than 80% of these procedures are now performed with the use of EVAR. Read the NEJM Clinical Practice Article here.
Q: What factors predispose to the development of an abdominal aortic aneurysm?
A: Predisposing factors include advanced age, family history, previous or current tobacco use, hypercholesterolemia, and hypertension; diabetes mellitus is associated with reduced risk.
Q: What diameter represents an appropriate threshold for repair of an abdominal aortic aneurysm?
A: Randomized trials showing no survival advantage with surgery over close surveillance for abdominal aortic aneurysms measuring less than 5.5 cm have supported the view that this diameter represents an appropriate threshold for repair and that surveillance for aneurysms with a diameter that is less than 5.5 cm is safe and cost effective. An important limitation of the studies on which the threshold of 5.5 cm is based is that the overwhelming majority of patients enrolled were White men; thus, the generalizability of the findings to women and other races and ethnic groups is unclear. Given the smaller native size of the aorta and the higher incidence of rupture of small abdominal aortic aneurysms among women, most experts and guidelines suggest that a smaller diameter of 5.0 cm is an appropriate threshold for repair in women.
A: The three largest randomized, controlled trials performed to date in which the outcomes of elective open surgical repair were compared with outcomes of EVAR have yielded consistent results. All three trials showed that 30-day morbidity and mortality were significantly lower with EVAR than with open surgical repair (0.5 to 1.7% vs. 3.0 to 4.7%). However, the short-term survival advantage of EVAR diminishes during follow-up, such that among the patients who survived beyond 2 to 3 years, survival rates associated with the two procedures were similar, and they remained so during 8 to 10 years of follow-up. Reintervention rates after EVAR were higher than those observed after open surgical repair, but most follow-up procedures were performed with catheter-based techniques; overall, the costs of EVAR were higher than those associated with open surgery.
A: The choice of repair strategy should involve shared decision making and should include consideration of the patient’s anatomical suitability, operative risk, and willingness to adhere to the lifelong requirement for annual follow-up imaging. Multiple guidelines recommend lifelong follow-up imaging after EVAR in order to identify and correct aortic or other device-related complications, such as persistent blood flow within the aneurysm sac (e.g., endoleaks) or residual aortic sac enlargement. Postprocedural imaging surveillance is intended to identify serious complications and to prevent death from aneurysm rupture. Imaging often includes computed tomographic angiography in the first months after EVAR, followed by duplex ultrasonography annually. Rupture of an abdominal aortic aneurysm after EVAR has been documented in 5.4% of patients. In contrast, with open surgical repair, lifelong follow-up is not critical owing to the greater durability of repair and the lesser need for reintervention. After open repair, most vascular surgeons follow patients until they have completely regained their preoperative baseline. Thereafter, patients are typically seen only if a new problem arises, since rupture after open repair is extremely rare.