Strategy of endovascular versus open repair for patients with clinical diagnosis of ruptured abdominal aortic aneurysm: the IMPROVE RCT

Abstract

Background Ruptured abdominal aortic aneurysm (AAA) is a common vascular emergency. The mortality from emergency endovascular repair may be much lower than the 40–50% reported for open surgery. Objective To assess whether or not a strategy of endovascular repair compared with open repair reduces 30-day and mid-term mortality (including costs and cost-effectiveness) among patients with a suspected ruptured AAA. Design Randomised controlled trial, with computer-generated telephone randomisation of participants in a 1 : 1 ratio, using variable block size, stratified by centre and without blinding. Setting Vascular centres in the UK (n = 29) and Canada (n = 1) between 2009 and 2013. Participants A total of 613 eligible participants (480 men) with a ruptured aneurysm, clinically diagnosed at the trial centre. Interventions A total of 316 participants were randomised to the endovascular strategy group (immediate computerised tomography followed by endovascular repair if anatomically suitable or, if not suitable, open repair) and 297 were randomised to the open repair group (computerised tomography optional). Main outcome measures The primary outcome measure was 30-day mortality, with 30-day reinterventions, costs and disposal as early secondary outcome measures. Later outcome measures included 1- and 3-year mortality, reinterventions, quality of life (QoL) and cost-effectiveness. Results The 30-day mortality was 35.4% in the endovascular strategy group and 37.4% in the open repair group [odds ratio (OR) 0.92, 95% confidence interval (CI) 0.66 to 1.28; p = 0.62, and, after adjustment for age, sex and Hardman index, OR 0.94, 95% CI 0.67 to 1.33]. The endovascular strategy appeared to be more effective in women than in men (interaction test p = 0.02). More discharges in the endovascular strategy group (94%) than in the open repair group (77%) were directly to home (p < 0.001). Average 30-day costs were similar between groups, with the mean difference in costs being –£1186 (95% CI –£2997 to £625), favouring the endovascular strategy group. After 1 year, survival and reintervention rates were similar in the two groups, QoL (at both 3 and 12 months) was higher in the endovascular strategy group and the mean cost difference was –£2329 (95% CI –£5489 to £922). At 3 years, mortality was 48% and 56% in the endovascular strategy group and open repair group, respectively (OR 0.73, 95% CI 0.53 to 1.00; p = 0.053), with a stronger benefit for the endovascular strategy in the subgroup of 502 participants in whom repair was started for a proven rupture (OR 0.62, 95% CI 0.43 to 0.89; p = 0.009), whereas aneurysm-related reintervention rates were non-significantly higher in this group. At 3 years, considering all participants, there was a mean difference of 0.174 quality-adjusted life-years (QALYs) (95% CI 0.002 to 0.353 QALYs) and, among the endovascular strategy group, a cost difference of –£2605 (95% CI –£5966 to £702), leading to 88% of estimates in the cost-effectiveness plane being in the quadrant showing the endovascular strategy to be ‘dominant’. Limitations Because of the pragmatic design of this trial, 33 participants in the endovascular strategy group and 26 in the open repair group breached randomisation allocation. Conclusions The endovascular strategy was not associated with a significant reduction in either 30-day mortality or cost but was associated with faster participant recovery. By 3 years, the endovascular strategy showed a survival and QALY gain and was highly likely to be cost-effective. Future research could include improving resuscitation for older persons with circulatory collapse, the impact of local anaesthesia and emergency consent procedures. Trial registration Current Controlled Trials ISRCTN48334791 and NCT00746122. Funding This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 31. See the NIHR Journals Library website for further project information.

Long-term Outcomes Following Endovascular Aneurysm Repair for Ruptured Abdominal Aortic Aneurysms

“…The incidence of type II endoleaks is expected to be unaffected by compliance with the IFU, however. The IMPROVE trial identified a reintervention rate of 29% at 3 years, 3 which is similar to the 33% 5-year reintervention rate in the current series. However, the reintervention rate determined by the current analysis is higher than in the elective setting, where a large observational study (12,239 EVARs included) reported 1-and 5-year reintervention rates of 1.4% and 6.6%, respectively.…”

“…16,20 A single large study reported 50% mortality at 5 years for eEVAR, 20 and the IMPROVE trial 3-year data showed 48% mortality in the eEVAR cohort, which is comparable to the current series. Comparing this to open repair of rAAA, which had a survival rate of 46% at 3 years in the IMPROVE trial 3 and 42.9% at 5 years in a Swedish study, 21 (12,239 EVARs included) reported 1.5% mortality at 30 days, 8% at 1 year, and 32% at 5 years. 23 The difference in 1-year mortality between emergency and elective EVAR may be explained partly by the higher 30-day rate because survival beyond 30 days to 1 year is more comparable between emergency and elective patients.…”

“…Emergency endovascular aneurysm repair (eEVAR) is now recommended as the first line intervention for patients presenting with a ruptured abdominal aortic aneurysm (rAAA) if anatomically suitable. 1 The use of eEVAR is likely to continue to increase following the results of the IMPROVE trial, 2,3 which showed no significant reduction in early mortality but a trend toward improved 3-year mortality in the endovascular cohort. The trend was more pronounced in patients with a proven rupture.…”

Morphology and Hemodynamics in Isolated Common Iliac Artery Aneurysms Impacts Proximal Aortic Remodeling

“…Interestingly, the IMPROVE Trial recently observed the opposite pattern in AAA, where aortic bifurcation angles were lower in ruptured versus intact AAAs, after diameter matching, implying that wider aortic bifurcation angle was protective of AAA rupture. 9 Subsequently, this finding was further investigated in silico using computational modeling in a hypothetical series of AAAs with varying aortic bifurcation angle. 10 The key finding from that study was that maximum LOS in the AAA decreases with increasing aortic bifurcation angle, creating more favorable hemodynamic conditions that are likely to reduce AAA expansion.…”

“…It is also unclear if and how the hemodynamics influence morphology in the region. Recent work has shown that wider aortic bifurcations are protective of rupture in AAA, 9 which was explained by computational simulations of blood flow and stresses. 10 However, in part due to the rarity of CIAA, we know little about the hemodynamics of CIAA besides single case studies, 11,12 despite the important benefit of a normal or near-normal CIA contralateral to the CIAA to act as a built-in control.…”