Image: PD. Abdominal Aneurysm
Study author, Dr. Frank A. Lederle, MD talks to 2 Minute Medicine: Professor of Medicine, University of Minnesota School of Medicine
“The study is most important as a reminder that whatever our enthusiasm for new treatments, we need always to check the facts. Endovascular repair has been eagerly accepted in part as a way to extend the indications for AAA repair to those who aren’t candidates for open repair – people with medical contraindications to surgery or small AAA (less than 5.5 cm). But while EVAR is a very good technique for the same patients who are candidates for open repair, it is not better in the long run and should not be used in these other populations. This comes from a number of randomized trials (including EVAR-2, PIVOTAL, and CAESAR), our study is the latest to confirm and extend our understanding of this principle.”
Key study points:
1. Patients under 70 with an asymptomatic abdominal aortic aneurysm receive a survival benefit from elective endovascular repair, while those over 70 have longer survival with an open repair.
2. Endovascular repair reduces perioperative mortality, but there is no significant difference in long-term all cause mortality between EVAR and open repair.
Primer: Abdominal aortic aneurysm (AAA) is an abnormal dilation of the wall of the aorta that can result in the acutely life-threatening complication of rupture. Predisposing risk factors for an AAA include age, male gender, smoking, hypertension and family history. AAAs are predominantly infrarenal and are commonly discovered on physical exam or incidentally during an evaluation of an unassociated abdominal problem. Size is the major determinant in the decision to proceed with operative repair. Asymptomatic AAAs under 5cm are followed for growth with serial ultrasounds. Aneurysms over 5cm or those that grow at a rate over 4mm/year are repaired electively depending on the medical condition of the patient. Open repair involves suturing a graft to the normal aorta and then wrapping the aneurysm wall around the graft. Endovascular repair (EVAR) entails threading a catheter through peripheral access such as the femoral artery and placing a graft intravascularly at the aneurysm site. To proceed with EVAR, the patient must have a minimally angulated aneurysm neck below the renal arteries that’s at least 1-1.5 cm long and at least one suitable common iliac for fixation of the graft at the site. Endovascular repair was introduced as a less invasive method for intervention and has been shown to reduce perioperative mortality, but has also been associated with higher rates of late deaths due to AAA rupture. Traditionally, due to the decreased perioperative mortality EVAR has been preferred for patients with a worse prognosis.
This [randomized controlled] trial divided 881 patients to either endovascular or open repair with up to 9 years of follow-up. Mean patient age was 70 and almost all were men with a maximum AAA diameter of 5.7 cm. The primary outcome of the study was all-cause mortality – with 146 deaths occurring in each cohort. Perioperative mortality, defined as death during hospitalization or within 30 days of the surgery, was significantly lower in the EVAR group vs. open repair (0.5% vs. 3.0%, p = 0.0004). EVAR also resulted in better survival in patients less than 70 years old. This treatment interaction disappeared for patients over 70 years old, who had marginal benefit with open repair, as opposed to EVAR (p=.06).
In sum: This trial supports previous evidence that EVAR has reduced perioperative mortality that extends to up to three years. Although EVAR carries a higher risk for late death due to rupture, this trial demonstrates that open and endovascular repair have similar long-term mortality. Endovascular repair provided more survival benefit for patients under 70, while patients at or over 70 years of age had longer survival with open repair. This finding contradicts traditional views that the less invasive EVAR is more beneficial for older, higher-risk patients.
By [AO] and [AH]
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