NIHR Signal Mortality benefits from minimally invasive aneurysm repair aren’t sustained in the long term

Published on 31 January 2017

Minimally invasive surgery to repair abdominal aortic aneurysm (AAA) was associated with fewer aneurysm-related deaths in the short-term, up to six months. From eight years onwards the open surgical procedures were associated with fewer aneurysm-related deaths, suggesting on-going monitoring is required.

An AAA is a swelling due to weakness in the main blood vessel running through the centre of the abdomen. If the aneurysm bursts there is a high chance of death. Earlier trials suggested that the minimally invasive technique of endovascular aneurysm repair (EVAR) gave mortality benefits in the immediate months after the procedure, but this was lost after a few years.

This trial is the longest follow-up trial of aneurysm repair using either endovascular or open surgery techniques. Patient factors including age, health and aneurysm size, may affect the outcome with either procedure. These factors, along with expected recovery time and potential complications, should inform surgical choices and guide the process of informed consent.

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Why was this study needed?

An AAA usually does not cause any symptoms unless it ruptures. This results in massive bleeding which is fatal for 8 out of 10 people. A ruptured aneurysm causes 1 in 50 deaths amongst men aged 65 and over in the UK so men above this age are offered one-off ultrasound screening.

If a small to medium size aneurysm is found (between 3.0 and 5.4cm diameter), regular follow-up monitoring is offered. If the aneurysm is large (5.5cm or more) they will be offered surgery to repair the aneurysm.

There are two main methods for aneurysm repair, either open surgery or minimally invasive endovascular repair (EVAR). Previous trials suggested short-term mortality benefits of EVAR that diminished in the following years. Therefore this trial focused on longer term outcomes.

What did this study do?

The UK endovascular aneurysm repair trial 1 (EVAR-1) recruited 1252 people with large AAA aged 60 years and over from 37 UK hospitals (1999 to 2004). Most participants were men (91%) with average age 74 years.

Participants were randomly allocated to receive either open or minimally invasive endovascular aneurysm repair. They received annual check-ups for an average 12.7 years. The main outcome of interest was overall mortality and aneurysm-related mortality. This included deaths from rupture before or after the primary or subsequent procedures, or other related causes, such as graft infection.

All randomised patients were included in the analysis and the study had sufficient sample size to reliably detect differences in the main outcomes.

What did it find?

  • There were differences in aneurysm-related mortality at different time points.
  • Up to six months after the procedure there were fewer aneurysm-related deaths in the EVAR group, with 4.6 deaths per 100 per year compared with 10 per 100 per year amongst those undergoing open repair (adjusted hazard ratio [HR] 0.47, 95% CI 0.23 to 0.93).
  • There was no significant difference in aneurysm-related mortality between six months and up to eight years. However, from eight years onwards the situation had reversed and the risk of aneurysm-related death was higher among the EVAR group (1.3 per 100 per year) compared with open repair participants (0.2 per 100 per year; adjusted HR 5.82, 95% CI 1.64 to 20.65).
  • From eight years onwards there were also slightly more deaths from any cause in the EVAR group (14.9 vs. 12.7 per 100 per year) but this was on the borderline of reaching statistical significance (adjusted HR 1.25, 95% CI 1.00 to 1.56).

What does current guidance say on this issue?

NICE is in the process of producing a guideline on the diagnosis and management of abdominal aortic aneurysm, which is due for publication in November 2018. NICE has approved EVAR as a procedure. It recommends that the choice between an open or endovascular approach is based on patient factors (such as age and aneurysm size) and that clinicians discuss the uncertainties about longer-term outcomes with patients to ensure their informed consent.

What are the implications?

The findings of this large trial support the findings of earlier trials that there may be short-term advantages to stenting, but these aren’t sustained and open repair has better mortality outcomes in the longer term. The authors suggest this indicates a need for structured surveillance of stent recipients to ensure that further procedures, if needed, can be performed as quickly as possible. They point out that recent changes to the design of these stents may also help.

Previous study found that patients prefer stents due to recovery time and complications, and this is often the procedure of choice. The combined findings highlight the importance of informed patient choice when deciding between open and stenting procedures.

Citation and Funding

Patel R, Sweeting MJ, Powell JT, Greenhalgh RM; EVAR trial investigators. Endovascular versus open repair of abdominal aortic aneurysm in 15-years' follow-up of the UK endovascular aneurysm repair trial 1 (EVAR trial 1): a randomised controlled trial. Lancet. 2016;388(10058):2366-74.

This project was funded by the National Institute for Health Research Health Technology Assessment Programme (project number 11/36/46).

Bibliography

NHS Choices. Abdominal aortic aneurysm. London: Department of Health; 2014.

NHS Choices. Abdominal aortic aneurysm screening. London: Department of Health; 2014.

NICE. Abdominal aortic aneurysm: diagnosis and management. GID-CGWAVE0769. London: National Institute for Health and Care Excellence; Expected publication date November 2018.

NICE. Endovascular aneurysm sealing for abdominal aortic aneurysm. IPG547. London: National Institute for Health and Care Excellence; 2016.

NICE. Endovascular stent–grafts for the treatment of abdominal aortic aneurysms. TA167. London: National Institute for Health and Care Excellence; 2009.

NICE. Laparoscopic repair of abdominal aortic aneurysm. IPG229. London: National Institute for Health and Care Excellence; 2007.

NICE. Stent-graft placement in abdominal aortic aneurysm. IPG163. London: National Institute for Health and Care Excellence; 2006.

Reise JA, Sheldon H, Earnshaw J, et al. Patient preference for surgical method of abdominal aortic aneurysm repair: postal survey. Eur J Vasc Endovasc Surg. 2010;39:55–61.

Why was this study needed?

An AAA usually does not cause any symptoms unless it ruptures. This results in massive bleeding which is fatal for 8 out of 10 people. A ruptured aneurysm causes 1 in 50 deaths amongst men aged 65 and over in the UK so men above this age are offered one-off ultrasound screening.

If a small to medium size aneurysm is found (between 3.0 and 5.4cm diameter), regular follow-up monitoring is offered. If the aneurysm is large (5.5cm or more) they will be offered surgery to repair the aneurysm.

There are two main methods for aneurysm repair, either open surgery or minimally invasive endovascular repair (EVAR). Previous trials suggested short-term mortality benefits of EVAR that diminished in the following years. Therefore this trial focused on longer term outcomes.

What did this study do?

The UK endovascular aneurysm repair trial 1 (EVAR-1) recruited 1252 people with large AAA aged 60 years and over from 37 UK hospitals (1999 to 2004). Most participants were men (91%) with average age 74 years.

Participants were randomly allocated to receive either open or minimally invasive endovascular aneurysm repair. They received annual check-ups for an average 12.7 years. The main outcome of interest was overall mortality and aneurysm-related mortality. This included deaths from rupture before or after the primary or subsequent procedures, or other related causes, such as graft infection.

All randomised patients were included in the analysis and the study had sufficient sample size to reliably detect differences in the main outcomes.

What did it find?

  • There were differences in aneurysm-related mortality at different time points.
  • Up to six months after the procedure there were fewer aneurysm-related deaths in the EVAR group, with 4.6 deaths per 100 per year compared with 10 per 100 per year amongst those undergoing open repair (adjusted hazard ratio [HR] 0.47, 95% CI 0.23 to 0.93).
  • There was no significant difference in aneurysm-related mortality between six months and up to eight years. However, from eight years onwards the situation had reversed and the risk of aneurysm-related death was higher among the EVAR group (1.3 per 100 per year) compared with open repair participants (0.2 per 100 per year; adjusted HR 5.82, 95% CI 1.64 to 20.65).
  • From eight years onwards there were also slightly more deaths from any cause in the EVAR group (14.9 vs. 12.7 per 100 per year) but this was on the borderline of reaching statistical significance (adjusted HR 1.25, 95% CI 1.00 to 1.56).

What does current guidance say on this issue?

NICE is in the process of producing a guideline on the diagnosis and management of abdominal aortic aneurysm, which is due for publication in November 2018. NICE has approved EVAR as a procedure. It recommends that the choice between an open or endovascular approach is based on patient factors (such as age and aneurysm size) and that clinicians discuss the uncertainties about longer-term outcomes with patients to ensure their informed consent.

What are the implications?

The findings of this large trial support the findings of earlier trials that there may be short-term advantages to stenting, but these aren’t sustained and open repair has better mortality outcomes in the longer term. The authors suggest this indicates a need for structured surveillance of stent recipients to ensure that further procedures, if needed, can be performed as quickly as possible. They point out that recent changes to the design of these stents may also help.

Previous study found that patients prefer stents due to recovery time and complications, and this is often the procedure of choice. The combined findings highlight the importance of informed patient choice when deciding between open and stenting procedures.

Citation and Funding

Patel R, Sweeting MJ, Powell JT, Greenhalgh RM; EVAR trial investigators. Endovascular versus open repair of abdominal aortic aneurysm in 15-years' follow-up of the UK endovascular aneurysm repair trial 1 (EVAR trial 1): a randomised controlled trial. Lancet. 2016;388(10058):2366-74.

This project was funded by the National Institute for Health Research Health Technology Assessment Programme (project number 11/36/46).

Bibliography

NHS Choices. Abdominal aortic aneurysm. London: Department of Health; 2014.

NHS Choices. Abdominal aortic aneurysm screening. London: Department of Health; 2014.

NICE. Abdominal aortic aneurysm: diagnosis and management. GID-CGWAVE0769. London: National Institute for Health and Care Excellence; Expected publication date November 2018.

NICE. Endovascular aneurysm sealing for abdominal aortic aneurysm. IPG547. London: National Institute for Health and Care Excellence; 2016.

NICE. Endovascular stent–grafts for the treatment of abdominal aortic aneurysms. TA167. London: National Institute for Health and Care Excellence; 2009.

NICE. Laparoscopic repair of abdominal aortic aneurysm. IPG229. London: National Institute for Health and Care Excellence; 2007.

NICE. Stent-graft placement in abdominal aortic aneurysm. IPG163. London: National Institute for Health and Care Excellence; 2006.

Reise JA, Sheldon H, Earnshaw J, et al. Patient preference for surgical method of abdominal aortic aneurysm repair: postal survey. Eur J Vasc Endovasc Surg. 2010;39:55–61.

Endovascular versus open repair of abdominal aortic aneurysm in 15-years' follow-up of the UK endovascular aneurysm repair trial 1 (EVAR trial 1): a randomised controlled trial

Published on 14 October 2016

R Patel, M Sweeting, J Powell, R Greenhalgh

The Lancet , 2016

Background Short-term survival benefits of endovascular aneurysm repair (EVAR) versus open repair of intact abdominal aortic aneurysms have been shown in randomised trials, but this early survival benefit is lost after a few years. We investigated whether EVAR had a long-term survival benefit compared with open repair. Methods We used data from the EVAR randomised controlled trial (EVAR trial 1), which enrolled 1252 patients from 37 centres in the UK between Sept 1, 1999, and Aug 31, 2004. Patients had to be aged 60 years or older, have aneurysms of at least 5·5 cm in diameter, and deemed suitable and fit for either EVAR or open repair. Eligible patients were randomly assigned (1:1) using computer-generated sequences of randomly permuted blocks stratified by centre to receive either EVAR (n=626) or open repair (n=626). Patients and treating clinicians were aware of group assignments, no masking was used. The primary analysis compared total and aneurysm-related deaths in groups until mid-2015 in the intention-to-treat population. This trial is registered at ISRCTN (ISRCTN55703451). Findings We recruited 1252 patients between Sept 1, 1999, and Aug 31, 2004. 25 patients (four for mortality outcome) were lost to follow-up by June 30, 2015. Over a mean of 12·7 years (SD 1·5; maximum 15·8 years) of follow-up, we recorded 9·3 deaths per 100 person-years in the EVAR group and 8·9 deaths per 100 person-years in the open-repair group (adjusted hazard ratio [HR] 1·11, 95% CI 0·97–1·27, p=0·14). At 0–6 months after randomisation, patients in the EVAR group had a lower mortality (adjusted HR 0·61, 95% CI 0·37–1·02 for total mortality; and 0·47, 0·23–0·93 for aneurysm-related mortality, p=0·031), but beyond 8 years of follow-up open-repair had a significantly lower mortality (adjusted HR 1·25, 95% CI 1·00–1·56, p=0·048 for total mortality; and 5·82, 1·64–20·65, p=0·0064 for aneurysm-related mortality). The increased aneurysm-related mortality in the EVAR group after 8 years was mainly attributable to secondary aneurysm sac rupture (13 deaths [7%] in EVAR vs two [1%] in open repair), with increased cancer mortality also observed in the EVAR group. Interpretation EVAR has an early survival benefit but an inferior late survival compared with open repair, which needs to be addressed by lifelong surveillance of EVAR and re-intervention if necessary. Funding UK National Institute for Health Research, Camelia Botnar Arterial Research Foundation.

Expert commentary

EVAR-1 compared endovascular aortic stenting with surgery. Initial results suggested stenting was safer than surgery. Later results showed an increase in mortality in the stented group. This is attributed to excess cancer deaths (radiation from surveillance CT scans) and late ruptures from aneurysms treated by early stents.

Will screening without radiation reduce cancers and will improved stents reduce late ruptures? Other work from the same study shows a reduction in quality of life and an increase in treatment cost for EVAR patients.

We are using last century’s research and technology to guide current treatment. Notwithstanding, this study provides some of the best information we have.

Mr Harvey Chant, Consultant Vascular Surgeon, Royal Cornwall Hospitals

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