Elsevier

The Lancet

Volume 364, Issue 9437, 4–10 September 2004, Pages 843-848
The Lancet

Fast track — Articles
Comparison of endovascular aneurysm repair with open repair in patients with abdominal aortic aneurysm (EVAR trial 1), 30-day operative mortality results: randomised controlled trial

https://doi.org/10.1016/S0140-6736(04)16979-1Get rights and content

Summary

Background

Endovascular aneurysm repair (EVAR) is a new technology to treat patients with abdominal aortic aneurysm (AAA) when the anatomy is suitable. Uncertainty exists about how endovascular repair compares with conventional open surgery. EVAR trial 1 was instigated to compare these treatments in patients judged fit for open AAA repair.

Methods

Between 1999 and 2003, 1082 elective (non-emergency) patients were randomised to receive either EVAR (n=543) or open AAA repair (n=539). Patients aged at least 60 years with aneurysms of diameter 5·5 cm or more, who were fit enough for open surgical repair (anaesthetically and medically well enough for the procedure), were recruited for the study at 41 British hospitals proficient in the EVAR technique. The primary outcome measure is all-cause mortality and these results will be released in 2005. The primary analysis presented here is operative mortality by intention to treat and a secondary analysis was done in per-protocol patients.

Findings

Patients (983 men, 99 women) had a mean age of 74 years (SD 6) and mean AAA diameter of 6·5 cm (SD 1). 1047 (97%) patients underwent AAA repair and 1008 (93%) received their allocated treatment. 30-day mortality in the EVAR group was 1·7% (9/531) versus 4·7% (24/516) in the open repair group (odds ratio 0·35 [95% CI 0·16–0·77], p=0·009). By per-protocol analysis, 30-day mortality for EVAR was 1·6% (8/512) versus 4·6% (23/496) for open repair (0·33 [0·15–0·74], p=0·007). Secondary interventions were more common in patients allocated EVAR (9·8% vs 5·8%, p=0·02).

Interpretation

In patients with large AAAs, treatment by EVAR reduced the 30-day operative mortality by two-thirds compared with open repair. Any change in clinical practice should await durability and longer term results.

Introduction

Rupture of an abdominal aortic aneurysm (AAA) is usually fatal. For more than 50 years aortic aneurysms have been treated with prophylactic open surgical repair,1 a major surgical procedure done under general anaesthesia, usually consisting of a midline laparotomy and cross-clamping of the aorta for at least 30 min. This technique has an associated 30-day mortality of 4–12%;2 however, graft durability is generally for 20–30 years and sees most patients through to the end of their lives.

In the early 1990s, Volodos in the Ukraine3 and Parodi, Palmaz, and Barone in Argentina4 introduced a less invasive endovascular method for AAA repair. Over time, these pioneering devices were improved, and commercial development of the technology has meant that the technique has spread worldwide. Briefly, the endovascular aneurysm repair (EVAR) procedure can be done percutaneously but usually consists of two small incisions in the groin to expose the femoral arteries. The sheathed Dacron or PTFE (polytetrafluoroethylene) graft and stents are fed through these arteries with catheters and guidewires until the graft is positioned correctly at the top and bottom of the aneurysmal segment of aorta. Removal of the sheath with or without balloon expansion allows barbs or other fixing mechanisms to attach to the artery wall and hold the graft firm, allowing blood to pass through it and remove pressure from the diseased aortic wall.

Two open voluntary registries have proved successful at monitoring the progress and development of EVAR over the past 8 years. The UK Registry for Endovascular Treatment of Aneurysms (RETA) was started in 1996,5 and the European EUROSTAR initiative in 1999.6 These registries have indicated that the 30-day mortality after EVAR could be as high as 2·9% and 3·1%,7, 8 but findings of other studies have estimated lower mortalities.9 Even though technological development of endovascular grafts continues, durability remains uncertain, and therefore the evolving technology should be tested in a randomised trial.

The EVAR 1 trial started recruitment in September, 1999. The underlying hypothesis, based on annual mortality rates of 7·5% and 5%, allows the possibility that EVAR may improve survival after 3 years from 79% to 86%. Subsequently, other similar trials, including the Dutch DREAM trial,10 have commenced, but most of these studies are powered on shorter-term combined mortality and morbidity outcomes. Here, we report the first results from EVAR 1 of 30-day operative mortality. The important long-term outcomes of all-cause mortality, graft durability, quality of life, and cost-effectiveness for EVAR 1 and the associated EVAR 2 trial (a randomised trial of EVAR with best medical treatment versus best medical treatment alone in patients unfit [anaesthetically and medically not well enough] for open repair) are scheduled for release in 2005.

Section snippets

Methods

Detailed methods for the EVAR 1 trial have been published elsewhere.11 In summary, recruitment into the trial began on Sept 1, 1999, with just 13 eligible UK centres. During the subsequent 4 years, the number of centres that showed sufficient experience with EVAR rose to 41, although only 34 of these had entered patients into the trial by the end of planned recruitment in December, 2003. National experience was monitored by the RETA registry in Sheffield and centres were invited to submit their

Patients

During the recruitment phase (September, 1999, to December, 2003), eligible patients of both sexes aged at least 60 years were identified in whom computed tomography had indicated the presence of an aneurysm 5·5 cm or more in diameter, which was regarded as anatomically suitable for EVAR. After clinical assessment, patients were assessed locally for their fitness (ie, anaesthetically and medically well enough) for elective (non-emergency) open aneurysm repair, with guidelines provided for

Procedures

We randomly allocated patients to either open AAA repair or EVAR. Randomisation used a 1/1 ratio in randomly permuted block sizes constructed by the STATA version 8 (Stata Corporation, TX, USA). Randomisation was stratified by centre and was done centrally by the trial manager only when all necessary baseline data had been received at the trial coordinating centre at Imperial College, London, UK.

Surgery was done according to typical local procedures, and we encouraged centres to undertake the

Statistical analysis

The primary outcome measure for EVAR 1 is all-cause mortality with target recruitment of 900 patients.11 The trial also had 90% power, at the 5% significance level, to detect a difference in 30-day operative mortality of 5·8% for open repair versus 1·5% for EVAR.

During the course of the trial, a closed and confidential data monitoring and ethics committee reviewed results and, to date, stopping rules have not been implemented. Neither the trialists nor any other person had access to the

Role of the funding source

The sponsor of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report. The corresponding author had full access to all the data in the study and had final responsibility for the decision to submit for publication.

Results

Between September, 1999, and December, 2003, 2068 patients were identified with an aneurysm measuring at least 5·5 cm that was judged anatomically suitable for EVAR and 1342 (65%) of these were regarded as fit for elective open aneurysm repair (figure). Signed consent for randomisation was obtained from 1082 (81%) patients. 543 were randomised to EVAR and 539 to open repair. 512 (94%) patients in the EVAR group received their intended elective treatment compared with 496 (92%) in the open

Discussion

We have shown a clear short-term survival benefit of EVAR, with 1·7% of patients dying by 30 days compared with 4·7% of those allocated open repair. EVAR had at least two-thirds lower 30-day and in-hospital mortality compared with open repair. Whether this early benefit will be sustained is not yet known, particularly since (according to EUROSTAR)6 further interventions might be needed in at least 25% of patients who have undergone endovascular repair, and a 1% annual risk of AAA rupture

References (24)

  • MEAPM Adriaensen et al.

    Elective endovascular versus open surgical repair of abdominal aortic aneurysms: systematic review of short-term results

    Radiology

    (2002)
  • M Prinssen et al.

    The Dutch Randomised Endovascular Aneurysm Management (DREAM) Trial: background, design and methods

    J Cardiovasc Surg

    (2002)
  • Cited by (1728)

    View all citing articles on Scopus

    Listed at end of report

    View full text