London, UK -A clearer idea of which patients with abdominal aortic aneurysm should receive endovascular repair rather than open surgery or no repair has come from further results of two major studies: EVAR-1 and EVAR-2 [1,2].

Both studies are published in the June 25, 2005, issue of the Lancet. EVAR-1 is comparing endovascular repair with open surgical repair in older patients with aneurysms of at least 5.5 cm in diameter. Early results showed a significant reduction in postoperative mortality at 30 days in the endovascular group. In the current paper, the researchers report that aneurysm-related mortality remained 3% lower with endovascular repair at four years of follow-up, but there was a much higher rate of complications and reintervention in the endovascular group, and there was no significant difference in overall survival between the two groups. These results are similar to those of the DREAM study, published earlier this month.

EVAR-2, which is comparing endovascular repair with no repair in patients judged to be unsuitable for open surgery, found a high rate of operative mortality (9%) in the endovascular group and no difference in aneurysm-related mortality or overall survival at four years. However, there were some biases in this study that favored the no-repair group.

The EVAR investigators, led by Prof Roger Greenhalgh (Imperial College London, UK), say in the papers that endovascular repair cannot displace open repair, "and the skills of open repair should be maintained in the training of vascular surgeons." But in an interview with heartwire, Greenhalgh said he believed the endovascular approach still had a role in lower-risk patients. "Even though the overall survival at four years was the same in both groups in EVAR-1, the reduction in postoperative mortality will be important for many patients. You have to remember that the average age in this trial is 70 years and the next four years are important years. Most patients will still choose a lower-risk procedure over a higher-risk one if the long-term outcome looks similar." But he added that he would not be offering endovascular repair to his higher-risk patients such as those included in EVAR-2.

In an accompanying editorial, Dr Jack Cronenwett (Dartmouth-Hitchcock Medical Center, Lebanon, NH) addresses how the results of these two studies should affect clinical practice [3]. First of all, he notes that only about half of patients will have aneurysms that are anatomically suitable for endovascular repair. After this has been taken into account, he says the issue of life expectancy should be assessed. Noting that, because the rate of reintervention after endovascular repair increases with time, this procedure will be most costly and probably less effective for patients with long life expectancy, Cronenwett thus recommends that the current practice of open repair for patients with long life expectancy be continued until even longer follow-up is available. And he says the results of EVAR-2 suggest that for many older high-risk patients it may be best not to attempt repair at all.

"Patients with low operative risk, who are usually younger with longer life expectancy, are the best candidates for open repair and should not be considered for endovascular repair unless they have excellent anatomical suitability. Patients at higher operative risk are better candidates for endovascular repair, if anatomical suitability is adequate. However, there are many high-risk patients with marginal anatomical suitability for endovascular repair who have short life expectancy and will not benefit from repair of their abdominal aortic aneurysm; they are best managed medically," Cronenwett writes.

He adds: "Finally, there is still a large gray area where patients' preference should influence the choice of endovascular vs open repair, given their similar outcomes. Current results from the EVAR-1 trial have shifted the choice point slightly toward the endovascular option, but ultimate clarity will await the long-term results of this trial." Cronenwett concludes that until even longer-term results are available, "patients are best advised to select well-informed surgeons with good results to assist their decision making."

The EVAR-1 study included 1082 patients aged 60 years or older who had aneurysms of at least 5.5 cm in diameter that were anatomically suitable for endovascular repair. They were randomized to open repair or endovascular repair. Early results showed a lower 30-day operative mortality in the endovascular group. The current paper deals with follow-up of up to four years.

Results showed that, at four years, all-cause mortality was similar in the two groups (about 28%). Although there was a persistent reduction in aneurysm-related deaths in the endovascular-repair group, many more patients in this group had postoperative complications.

After 12 months, there was negligible difference in health-related quality of life between the two groups; by four years, the endovascular group was associated with higher hospital costs (mean £13 257 per patient vs £9946 for the open-repair group).

The EVAR investigators conclude, "Compared with open repair, endovascular repair offers no advantage with respect to all-cause mortality and health-related quality of life. It is more expensive and leads to a greater number of complications and reinterventions. However, it does result in a 3% better aneurysm-related survival. The continuing need for interventions mandates ongoing surveillance and longer follow-up of EVAR for detailed cost-effectiveness assessment."

The EVAR-2 trial involved 338 patients aged 60 years or older who had aneurysms of at least 5.5 cm in diameter and who were judged unfit for open repair. They were randomized to receive endovascular repair or no intervention. Results as of December 2004—a median follow-up of 2.4 years—showed that neither aneurysm-related mortality nor all-cause mortality differed between groups.

In those followed for four years, the overall mortality was 64%, and costs were vastly increased for the endovascular group (mean £13 632 vs £4983 in the no-intervention group). In addition, there was no difference in quality of life between the two groups.

The researchers point out that more than a quarter of patients assigned to no intervention for their aneurysm underwent aneurysm repair that could have biased the results against the endovascular group, but they say that per-protocol analysis indicated that these crossovers did not alter the main conclusions of the trial.

Greenhalgh et al note that the patients in EVAR-2 had significantly worse health than those in EVAR- 1, and the results show that endovascular repair is not a safe procedure in such high-risk patients. They conclude: "We have shown no survival benefit from endovascular aneurysm repair in patients unfit for open repair. Endovascular repair is costly, has little effect on health-related quality of life, and involves a continuing need for surveillance and reintervention."