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Why do I use EVAR in preference to open surgery for the treatment of Abdominal Aortic Aneurysms?

Few operations have been subjected to the scrutiny of Endovascular Abdominal Aortic Aneurysm Repair (EVAR). In Europe, two large randomised control trials the EVAR 1 trial and the DREAM trial, have shown without a shadow of doubt, that 30-day mortality is significantly lower for those patients treated with EVAR  as opposed to open surgery. If one goes through the papers with a fine comb, it will become apparent that the difference in in-hospital mortality (which is definitely more important than the 30-day mortality) is even more strikingly in favour of EVAR. Further studies from the USA including the Medicare Data and data from the Veterans Affairs Hospitals corroborate these findings. On the basis of the above studies a unit who offers EVAR to all suitable patients will have an in-hospital mortality of 3 to 4 % less than a unit that only offers EVAR to patients considered “unfit” for open surgery.

 

In the past, one of the concerns with EVAR was the rate of long-term complications and the need for re-intervention. When the EVAR 1 paper was published all patients who had a type 2 endoeak were classified as having some form of complication. We now know that the majority of type 2 endoleaks are benign and only those that are associated with an expanding aneurysm need treatment. From the recent Medicare data we know that only 9% of patients need re-intervention over a 4 year period. By re-intervention one means an endovascular procedure performed as a day case in the angiosuite under local anaesthetic. In contrast, the Medicare data also showed us that during the same period of time 9.7% of patients treated by open repair required surgery (requiring an in-patient admission) for laparotomy-related complications. This data was not looked at in the UK EVAR trials. The need for hospitalization without surgery during the 4 year follow-up period was also much higher for the open repair group. Another important factor that was not looked at in the EVAR trials is the risk of impotence, which has been shown to be extremely low with EVAR but occurring in up to 83% of patients after open repair. This is an extremely important factor to consider in younger patients especially when one notes that sub-analysis of the EVAR 1 data shows that the benefits of EVAR are sustained in the younger and fitter patient. If one looks at series of EVAR by Tim Chuter and Roy Greenberg (two of the world’s most prominent vascular surgeons), using the Zenith stent graft system, the long term re-intervention rate was less than 3%. Since a sub-analysis of the UK EVAR trials suggested that patients treated with this system have a better outcome, I mainly use the Zenith system. To date none of the patients I treated with this system have required any re-intervention.

 

 

Although the EVAR 1 trial showed that overall mortality was equal at 4 years between EVAR and open surgery, one should keep in mind that the study was not powered enough to show a difference in overall mortality, and the benefit in favour of EVAR for aneurysm related mortality was still sustained. Interestingly, even if this were not the case, if one had to look at the life-table analysis of overall survival in the EVAR 1 trial, the area between the plots for the two groups represents the difference in survival between the two groups in patient years. Not offering EVAR to all those suitable, would negate a number of retired patients the opportunity to live for up to 4 years post-procedure (as opposed to dying in hospital after the procedure). There are a number of important, priceless events that happen during this time in life, such as becoming a grandparent or seeing one’s son or daughter get married. By not routinely offering EVAR as a first option to all suitable patients we would deny this experience to a significant number of our patients.

 

When one reviews the literature with regards to the cost-effectiveness of EVAR, the results may at first seem conflicting. A population-based study from Sweden concluded that there was no significant difference in total cost between the two procedures. A trial from Ireland in higher risk patients shows that EVAR is the most cost-effective option when compared to open surgery. A recent cost-effectiveness analysis published in the British Journal of Surgery concluded that EVAR is unlikely to be cost-effective when compared to open repair. This publication is however based on the EVAR 1 data. This data is now a couple of years old and is obsolete for a cost-effectiveness analysis since:

1. In the trial a number of patients who had EVAR had unnecessary re-interventions

2. During the trial EVAR patients were still recovered in HDU and kept in hospital for longer periods of time than today since clinicians were still on their learning curve for the procedure

3. Since the trial, the cost of stents has come down and the cost of ICU, HDU and ward beds has gone up

4. EVAR patients are now followed up with Ultrasound as opposed to CTA.

 

I therefore beleive that EVAR provides patients with AAA, with a suitable alternative to open surgery which is less likely to have an adverse outcome. Patients treated with EVAR are now needing less post-operative work up prior to their surgery, having a procedure with much lower mortality and morbidity, not requiring any intensive post-operative support and going home within 3 days of having their procedure. They also return to their pre-morbid state much quicker.

  

With regards to EVAR in the emergency setting, a meta-analysis has just been published in the Journal of Vascular Surgery. This identified 23 studies, and even though only one was a randomized controlled trial, when one appreciates the difficulty of trying to randomize such patients in extremis, the data is compellingly in favor of EVAR. The total number of patients identified was 7040 with 730 having emergency EVAR. Emergency EVAR was associated with a significant reduction in mortality (pooled odds ratio 0.624; 95% confidence interval [CI] 0.518 to 0.752; P < .0001). Besides, in the EVAR group intensive care stay was reduced by 4 days, hospital stay by 8.6 days, there was a significant reduction in blood loss and reduced procedure time.  The biggest problem is with providing such a service. At Manchester Royal Infirmary I am fortunate to have both the man power and technology available round the clock to provide such a service when I am on-call. Unfortunately not all hospitals offer such a service since some surgeons beleive that a randomised control trial is necessary before routinely offering this service. As a result not all primary care trusts fund stent-grafts for these patients. In my opinion, performing a randomized trial in such an urgent situation when there is sufficient evidence from non randomized trials to show a benefit is a clear case of throwing common sense out of the window. We must not let the clout around randomized controlled trial (leading to publications in high impact journals and touring of the international conference circuit) cloud our judgment based on common sense. If this happens it shall not be long before we are asked to enroll individuals into a randomized control trial assessing the need of parachutes when jumping out of the plane, since at the moment there is definitely no type 1 evidence (evidence based on a randonised control trial) for wearing one.

References

Lancet. 2004 Sep 4-10;364(9437):843-8. 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. Greenhalgh RM, Brown LC, Kwong GP, Powell JT, Thompson SG; EVAR trial participants.

N Engl J Med. 2004 Oct 14;351(16):1607-18. A randomized trial comparing conventional and endovascular repair of abdominal aortic aneurysms. Prinssen M, Verhoeven EL, Buth J, Cuypers PW, van Sambeek MR, Balm R, Buskens E, Grobbee DE, Blankensteijn JD; Dutch Randomized Endovascular Aneurysm Management(DREAM)Trial Group.

N Engl J Med. 2008 Jan 31;358(5):464-74. Endovascular vs. open repair of abdominal aortic aneurysms in the Medicare population. Schermerhorn ML, O'Malley AJ, Jhaveri A, Cotterill P, Pomposelli F, Landon BE.

J Am Coll Surg. 2006 Apr;202(4):577-87. Open versus endovascular abdominal aortic aneurysm repair in VA hospitals. Bush RL, Johnson ML, Collins TC, Henderson WG, Khuri SF, Yu HJ, Lin PH, Lumsden AB, Ashton CM.

Lancet. 2005 Jun 25-Jul 1;365(9478):2179-86. Endovascular aneurysm repair versus open repair in patients with abdominal aortic aneurysm (EVAR trial 1): randomised controlled trial. EVAR trial participants.

Ann Vasc Surg. 2000 Jan;14(1):13-9. Incidence of erectile dysfunction after open abdominal aortic aneurysm repair. Lee ES, Kor DJ, Kuskowski MA, Santilli SM.

Br J Surg. 2007 Jun;94(6):709-16. Patient fitness and survival after abdominal aortic aneurysm repair in patients from the UK EVAR trials. Brown LC, Greenhalgh RM, Howell S, Powell JT, Thompson SG.

J Vasc Surg. 2007 Mar;45(3):461-5; discussion 465-6. Epub 2007 Jan 24. Long-term outcome and reintervention after endovascular abdominal aortic aneurysm repair using the Zenith stent graft. Hiramoto JS, Reilly LM, Schneider DB, Sivamurthy N, Rapp JH, Chuter TA.

Eur J Vasc Endovasc Surg. 2007 Sep;34(3):281-90. Secondary interventions and mortality following endovascular aortic aneurysm repair: device-specific results from the UK EVAR trials. Brown LC, Greenhalgh RM, Kwong GP, Powell JT, Thompson SG, Wyatt MG.

J Endovasc Ther. 2008 Feb;15(1):1-11. Similar cost for elective open and endovascular AAA repair in a population-based setting. Mani K, Björck M, Lundkvist J, Wanhainen A.

J Endovasc Ther. 2007 Dec;14(6):763-76. A prospective clinical, economic, and quality-of-life analysis comparing endovascular aneurysm repair (EVAR), open repair, and best medical treatment in high-risk patients with abdominal aortic aneurysms suitable for EVAR: the Irish patient trial. Hynes N, Sultan S.

Br J Surg. 2008 Feb;95(2):183-90. Modelling the long-term cost-effectiveness of endovascular or open repair for abdominal aortic aneurysm. Epstein DM, Sculpher MJ, Manca A, Michaels J, Thompson SG, Brown LC, Powell JT, Buxton MJ, Greenhalgh RM.

J Vasc Surg. 2008 Jan 31 [Epub ahead of print] Endovascular vs open repair of acute abdominal aortic aneurysms - A systematic review and meta-analysis. Sadat U, Boyle JR, Walsh SR, Tang T, Varty K, Hayes PD.