Outcomes following endovascular vs open repair of abdominal aortic aneurysm: a randomized trial
Lederle FA, Freischlag JA, Kyriakides TC, Padberg FT Jr, Matsumura JS, Kohler TR, Lin PH, Jean-Claude JM, Cikrit DF, Swanson KM, Peduzzi PN; Open Versus Endovascular Repair (OVER) Veterans Affairs Cooperative Study Group.
JAMA. 2009 Oct 14;302(14):1535-42.
Reviewers: Yong G. Peng MD, PhD
University of Florida
Hong Liu, MD
UC Davis Health System
There exists limited data to assess whether endovascular repair of abdominal aortic aneurysms (AAA) improves short-term outcomes compared with traditional open repair. This study is the planned interim report of a 9-year trial comparing postoperative outcomes 2 years after either endovascular or open repair of an AAA.
This study is a randomized, multicenter, clinical trial of 881 veterans from 42 Veterans Affairs Medical Centers with an AAA who were candidates for both elective endovascular repair or open repair of their AAA. The trial is ongoing and this report describes the period between October 15, 2002, and October 15, 2008. The cohort was divided into two groups: those receiving elective endovascular (n = 444) or open (n = 437) repair of their AAA. The main outcome measures of the study include: procedure failure, secondary therapeutic procedures, length of stay, quality of life, erectile dysfunction, major morbidity, and mortality.
Perioperative mortality (defined as within 30 days or while an inpatient) was lower for the endovascular repair (0.5% vs 3.0%; P = .004), but there was no significant difference in mortality at 2 years (7.0% vs 9.8%, P = .13). Patients in the endovascular repair group had a reduced median procedure time (2.9 vs 3.7 hours), blood loss (200 vs 1000 mL), transfusion requirement (0 vs 1.0 units), duration of mechanical ventilation (3.6 vs 5.0 hours), hospital stay (3 vs 7 days), and intensive care unit stay (1 vs 4 days). However, they required substantial exposure to fluoroscopy and contrast. There were no differences between the 2 groups in major morbidity, procedure failure, secondary therapeutic procedures, aneurysm-related hospitalizations, health-related quality of life, or erectile function.
In this report of short-term outcomes after elective AAA repair, while perioperative mortality was low for both procedures it was lower for endovascular than open repair. The early advantage of endovascular repair was not offset by increased morbidity or mortality in the first 2 years after repair. Longer-term outcome data are needed to fully assess the relative merits of the 2 procedures.
The use of endovascular stent-grafts for the repair of AAAs was first reported in 1991. In last two decades, the obvious superior early postoperative outcome, including lower morbidity and mortality, compared with traditional open repair has supported its popularity. Studies have demonstrated that there is a significant reduction of early postoperative morbidity, length of intensive care and hospital stay, and improved hospital resource utilization and cost. Because of these early encouraging reports, many vascular surgeons switched from traditional open repair to endovascular stents. This therapeutic approach has been widely accepted as a valid treatment option for repairing AAAs both by academic and community practices, particularly for high-risk patients. Recently however, both observational trials and case control studies have questioned the long-term advantage of endovascular repair versus open repair regarding quality of life and survival. The results of the currently reviewed randomized, multicenter clinical trial in the early postoperative period are not much different than those previously reported by the European trial, except that the overall morbidity and mortality rate in both endovascular and open repair groups were even lower than previously reported. The overall lower morbidity and mortality reported in this study can be attributed to several factors:
- Patient selection and relative small diameter of AAA. (Majority of cases < 5.5cm)
- Surgical skill and postoperative care improvement compared to early stage of AAA repair
- Continued evolving new generation of endovascular systems.
What some may find surprising from this study is that there was no observed difference in survival rate, quality of life and erectile dysfunction after a two-year follow up in both groups. However, these findings are not totally unexpected, since two earlier published studies that compared the endovascular stent versus open surgical repair on descending thoracic aortic aneurysms have reported similar results.
Despite being a well-designed and multicenter randomized trial, this study also has a number of limitations:
- Patients selected in this study were not from a heterogeneous population, since all patients were veterans.
- The fact that there was no difference between the two groups associated with secondary therapeutic procedure was misleading, since the endovascular group of procedure failures (4.1%) was all due to surgical failure (endoleaks), whereas procedure failures (incision hernia) in the open repair group (4.9%) may have been associated with collagen defects or the disease itself.
- The study did not address whether the choice of anesthesia had any impact on the overall outcome (regional versus general anesthesia).
In our opinion, there is still insufficient evidence to suggest the endovascular approach has long-term superior benefit compared to open surgical repair for the patient with AAA. Several major problems must be resolved (e.g. endoleaks, stent fractures, stent migration and visceral organ vessel branch revascularization) before the endovascular method can claim to be the primary therapeutic choice for repair of AAA. Continued research and long-term follow up are necessary to validate the preferred therapeutic options for patients with AAA.