Survival advantage maintains for EVAR vs. open repair, but choice isn't clear-cut

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 - Abdominal aortic aneurysm (AAA) stents with bilateral iliac arteries
Digital CT showing endovascular stenting of an abdominal aortic aneurysm with bilateral iliac aneurysms, using a techniques that preserves flow into both internal iliac arteries (purple arrows)
Source: The Cleveland Clinic

Endovascular repair and open repair resulted in similar long-term survival, and the perioperative survival advantage with endovascular repair was sustained for several years. But rupture after repair remained a concern, according to the OVER Veterans Affairs Cooperative Study .

The study was published Nov. 22 in the New England Journal of Medicine.

Each year in the U.S., 40,000 patients undergo elective procedures to repair abdominal aortic aneurysms, which result in approximately 1,250 perioperative deaths—more than for any other general or vascular surgical procedure, with the exception of colectomy (N Engl J Med 2009;361:1368-1375). Endovascular repair was introduced in the 1990s as a less invasive method than traditional open repair. Some randomized trials have shown that endovascular repair reduces perioperative mortality, but in the United Kingdom’s EVAR 1 trial and the Dutch DREAM trial, this advantage was lost within two years owing to excess late deaths in the endovascular-repair groups, according to the OVER study authors.

In the OVER (Open versus Endovascular Repair) Veterans Affairs Cooperative Study, excess late deaths were not observed in the endovascular-repair group at two years (JAMA 2009;302:1535-1542). These findings are the long-term results of that study.

For the study, Frank A. Lederle, MD, of the Veterans Affairs Medical Center in Minneapolis, and colleagues randomly assigned 881 patients with asymptomatic abdominal aortic aneurysms who were candidates for both procedures to either endovascular repair (444) or open repair (437) and followed them for up to nine years (mean, 5.2 years). They selected patients from 42 Veterans Affairs medical centers who were 49 years of age or older at the time of registration.

More than 95 percent of the patients underwent the assigned repair. For the primary outcome of all-cause mortality, 146 deaths occurred in each group. The previously reported reduction in perioperative mortality with endovascular repair was sustained at two years and at three years but not later.

There were 10 aneurysm-related deaths in the endovascular-repair group (2.3 percent) versus 16 in the open-repair group (3.7 percent), according to the authors. They confirmed six aneurysm ruptures in the endovascular-repair group versus none in the open-repair group and observed “significant interaction” between age and type of treatment. In fact, survival was increased among patients less than 70 years old in the endovascular-repair group but tended to be better among those 70 years of age or older in the open-repair group.

“The clinical implications of this age effect must be reconciled with our finding that late rupture occurred only in the endovascular-repair group,” Lederle et al wrote. “The procedure associated with late failures would seem to be less desirable for use in younger patients,” even though the late-rupture rate was low, with only six during 4,576 patient-years of follow-up. This finding is one-third less than the rate found in the EVAR 1 trial.

Concerning the mortality findings, the study authors wrote that “excess late deaths that resulted in loss of the perioperative survival advantage in the endovascular-repair group occurred later in our study than in the EVAR 1 and DREAM trials, but they occurred nevertheless. Although this convergence of survival curves could be attributed to chance, its occurrence in all three studies argues otherwise.”

Based on the findings, they concluded that endovascular repair “continues to improve and is now an acceptable alternative to open repair even when judged in terms of long-term survival. However, our results also indicate that late rupture remains a concern and that endovascular repair does not yet offer a long-term advantage over open repair, particularly among older patients, for whom such an advantage was originally expected.”

The study was funded by the Department of Veterans Affairs’ Office of Research and Development.