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DENVER -- The overall mortality 2 years after endovascular repair of abdominal aortic aneurysms remained lower than that seen for open repair in the landmark multicenter randomized Open Versus Endovascular Repair (OVER) trial.

This key finding is at odds with the earlier European DREAM and EVAR-1 trials, Dr. Frank A. Lederle said at the Vascular Annual Meeting.

 In OVER, the endovascular group hasn’t shown any late rise in mortality through the 2 years reported.
Dr. Lederle

In the European randomized trials, as in OVER, 30-day mortality was significantly lower with endovascular aneurysm repair (EVAR)than in the open repair group. In the European studies, however, this early advantage was completely erased during the next year, whereas in OVER, the endovascular repair group hasn't shown any late rise in mortality through 2 years, reported Dr. Lederle, director of the Minneapolis VA Center for Epidemiological and Clinical Research and professor of medicine at the University of Minnesota, Minneapolis.

OVER is an ongoing Veterans Affairs (VA)-funded study involving 881 patients with abdominal aortic aneurysms at least 5.0 cm in diameter. These patients, who were suitable candidates for both open and endovascular repair, were treated at 42 participating centers.

Mortality during the initial procedural hospitalization or within 30 days of repair was 0.5% in the endovascular repair group, significantly better than the 3.0% rate with open repair.

Two-year mortality was 7.0% with endovascular repair and 9.4% with open repair; thus, mortality from 30 days through 2 years was virtually the same in the two groups. No ruptures have occurred to date.

In contrast, in the DREAM (Dutch Randomised Endovascular Aneurysm Management) trial, the promising trend of fewer deaths at 30 days in the endovascular repair group turned into a slight total excess of deaths at 2 years (N. Engl. J. Med. 2005;352:398-405).

Similarly, the Endovascular Aneurysm Repair Trial 1 (EVAR-1) showed no difference between the two procedures with regard to long-term mortality, which was about 28% at 4 years (Lancet 2005;365:2179-86).

Why was OVER different in this regard? Dr. Julie A. Freischlag, OVER co-principal investigator with Dr. Lederle, cited the high quality of surgical care in the VA system, rapid technical evolution in endovascular repair since the time when patients enrolled in the European trials, and the emphasis in OVER on aggressive, long-term medical therapy.

"The great majority of patients are on beta-blockers and lipid-lowering drugs. That's different than in DREAM and EVAR-1," said Dr. Freischlag, Johns Hopkins University, Baltimore.

Perhaps as a result, perioperative mortality rates in OVER were lower than in earlier studies. Moreover, through 2 years there have been fewer cardiovascular than cancer deaths.

"That's fascinating. You'd have expected that it would have been nearly all cardiovascular deaths. It looks like we are protecting the patients not only from perioperative death but also from death in the 2 years following," she continued.

The EVAR-1 trial found higher complication and reintervention rates with endovascular repair, as well as one-third higher costs compared with open repair. Again, OVER is shaping up differently.

"It appears the reintervention rate for the endovascular patients in OVER is lower than what we've seen before. If endovascular therapy actually does lead to lower mortality, the cost may be worthwhile," Dr. Freischlag observed.

A cost-effectiveness analysis based on the prespecified, interim, 2-year OVER results is underway. The 9-year-long study is scheduled to end in October 2011, when 5-year follow-up will be complete.

At 2 years, EVAR-treated patients did relatively better in terms of mortality than did the open repair group in all prespecified subgroups based on patient age, surgical risk, aneurysm diameter, and coronary artery disease. These trends, while consistent, didn't attain statistical significance.

There were 134 endoleaks in 110 patients in the endovascular repair group, resulting in 20 secondary procedures in 17 patients. Thirty-one incisional hernias occurred in the open repair group, triggering secondary therapeutic procedures in 22 patients.

One audience member asked if the OVER findings imply he should now routinely advise endovascular repair for candidates for both endovascular and open repair. "These curves could change over time. We probably won't have the final answer for your patients for another 3 years," Dr. Freischlag replied.

Still, on the basis of the interim analysis, patients can be informed that both procedures have low mortality and low major morbidity rates. Quality of life scores, erectile dysfunction scores, and reintervention rates are similar as well. And the much faster recovery from endovascular repair is widely appreciated.