Endovascular repair of ruptured abdominal aortic aneurysm (AAA) was associated with improved midterm survival and quality of life and reduced costs compared with open surgery in long-term follow up of the IMPROVE trial[1].
“The main message from our study is that the endovascular procedure is more likely to give you 3 good years. That is very important. It also appears highly cost-effective. So our findings support the increasing use and wider availability of emergency endovascular repair,” lead author Dr Janet Powell (Imperial College London, UK) commented to theheart.org | Medscape Cardiology.
“At present we estimate that about a quarter of emergency aneurysm repairs are performed endovascularly, but we hope this will change after this study,” she added. “New NICE guidelines are coming out next year on abdominal aortic aneurysm and we hope they will take our findings on board.”
Long-term results from the IMPROVE trial were published online in the BMJ on November 14, 2017.
In an accompanying editorial[2], Dr Martin Björck (Uppsala University, Sweden) says the 3-year results of the IMPROVE trial “are convincing” and “will change clinical practice in favor of endovascular repair for patients with suspected ruptured abdominal aortic aneurysms.”
Powell stressed that mortality from ruptured aneurysm is very high. “In the UK alone, this causes about 6000 deaths a year. Patients require immediate surgery to repair the rupture if they are to have a chance of survival.”
The traditional approach of open surgery is associated with a mortality rate of around 45% within 90 days, she noted. “Observational studies have suggested the newer endovascular procedure may have a lower mortality rate, but patients in these studies have been selected for the endovascular procedure, so it’s hard to know if this morality reduction is real.”
There have been three recent European randomized trials of endovascular vs open repair for ruptured aneurysm, including the IMPROVE trial, none of which showed a significant survival benefit during the acute period (0–90 days) with endovascular repair, the researchers report. However, there are few data on outcomes beyond a year after rupture.
The IMPROVE trial randomized 613 patients with symptoms of a suspected rupture to repair with open surgery or an endovascular procedure and has followed patients long term.
The mean follow-up for mortality was 4.9 years, with no significant difference in total mortality between the two groups (hazard ratio 0.92, 95% CI 0.75–1.13; P=0.41).
However, the survival curves diverged after the acute phase, with lower mortality in the endovascular strategy group between 3 months and 3 years (48% vs 56%; HR 0.57, 95% CI 0.36–0.90; P=0.015), before converging again by 7 years.
Powell noted that patients were randomized at the point of suspected diagnosis, but not all patients had aneurysms repaired, as some died before they got to surgery and others were found not to have a ruptured aneurysm when they were scanned.
Results for the 502 patients who actually had repaired ruptures were more pronounced, with 3-year mortality of 42% in the endovascular group vs 54% in the open surgery group (HR 0.62, 95% CI 0.43–0.88). However, after 7 years there was no clear difference between the groups again (HR 0.86, 95% CI 0.68–1.08).
Powell commented: “We have data on some patients out to 7 years, and we are seeing the survival curves moving together again, but I think that is probably due to patients dying of other things—you have to remember the average age of patients at baseline in this study was 77, and everyone has to die sometime.”
Previous studies have suggested that patients receiving the emergency endovascular procedure need more subsequent hospitalizations for corrective repairs. Powell explained that the endovascular procedure consists of inserting a stent to fix the new aortic graft into place. Under emergency conditions with the patient in shock and often having very low blood pressure, it can be difficult to image and place the stent accurately to get the best seal, whereas in open surgery the graft is sewn in, which tends to give a more permanent fix.
However, in this study, the rate of reintervention was similar in the two groups, which Powell said was “reassuring.”
The average quality of life was higher in the endovascular group in the first year but by 3 years was similar across the two groups.
The early higher average quality of life in the endovascular strategy vs open repair group, coupled with the lower mortality at 3 years, led to a gain in average quality-adjusted life-years (QALYs) at 3 years of 0.17.
The endovascular group spent fewer days in the hospital and had average costs lower by £2605. The probability that the endovascular strategy is cost-effective was >90% at all levels of willingness to pay for a QALY gain.
The researchers point out that endovascular repair of abdominal aortic aneurysm has not been shown to be cost-effective in the elective setting and the reasons for the different results between emergency and selective situations remain speculative.
“The shock associated with rupture probably kills many patients irrespective of the type of repair, but endovascular repair is less invasive and can be conducted under local anesthesia so that patients recover more rapidly than after open repair,” they write.
They also suggest that less acute kidney injury and shorter stays in critical care may also contribute to the better midterm mortality with endovascular repair in the emergency setting.
The IMPROVE trial was funded by the UK National Institute for Health Research (NIHR) Health Technology Assessment (HTA) program. The authors report no relevant financial relationships.
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