Greek Study for Endovascular Repair of Ruptured Abdominal Aortic Aneuryms

Description

Ruptured abdominal aortic aneurysms (rAAAs) remain one of the most emergent medical events, with over 90% mortality if left untreated and a prevalence of a minimum 45 patients per 1000000 population. The 30 day mortality for emergency open repair has remained at around 50%, and there is no consistent improvement in the outcome of the open technique over time. Since its development, endovascular aneurysm repair (EVAR), has been increasingly used even in the emergency setting.

So far there have been 4 randomized controlled trials, comparing EVAR versus open repair for rAAA. The first was a small trial from Nottingham followed by the Dutch trial AJAX and the French ECAR. The last and biggest trial with 613 patients was the UK IMPROVE trial. All these trials showed non inferiority of EVAR, but failed to prove benefit for EVAR with respect to 30 day mortality. Furthermore two meta-analysisof the above RCTs, stated again, that 30 and 90 day mortality is similar between EVAR and open surgery, with the exception of women having a better outcome with an endovascular approach.

On the contrary, multiple observational studies and registries showed even a 50% risk reduction in mortality with EVAR. There has been huge critique and discussion of the results in IMPROVE trial, in which 10% of patients crossed over to the non-allocated treatment group. In both groups, patients who were treated with EVAR had a mortality of 25%, significantly lower than those who received open surgery (38%). Furthermore, two recent published studies that compared mortality of rAAA between Sweden, USA and UK, came to the conclusion that mortality is lower in centers that accept a large number of cases with rAAA, mostly treated with EVAR. There is an argument that these encouraging results are subject of bias, since there is patient selection according to haemodynamic stability and aortic morphology. A valid counter argument stated by Lachat and colleagues is that EVAR for rAAA in their center, in the moderate risk, stable patient with favourable anatomy (aortic neck length >10mm) has a reduced 30 day mortality of 10%, a result never demonstrated with open repair. As EVAR evolves, new technical features of the devices may address the current limitations of the technique. In addition, the anatomic suitability obstacle for EVAR has been revoked by the PROTAGORAS study, which led to CE mark for a commercial stent graft system, allowing treatment of aortic neck lengths as small as 2mm with the use of chimney technique. The authors in the IMPROVE trial acknowledge the fact that: "The suitability of ruptured aneurym for EVAR is subjective and will be defined by the aortic morphology, the experience of the operator and the range of resuscitation, endovascular and anaesthetic techniques available".

It is safe to guess that haemodynamically compromised patients would benefit from a less invasive procedure, with minimum surgical exposure, if any, and local anaesthesia. There is no doubt however that for a center to adopt an EVAR only policy, poses many logistical challenges.

The aim for this research study is that an "EVAR first" approach is feasible in rAAA, even in more complex anatomies and in patients with less physiologic reserve and at the same time prove that short and midterm mortality and morbidity with EVAR is significantly lower than open repair when compared to the mortality and morbidity rates of patients receiving open repair in the latest RCT "IMPROVE". This can be achieved, with implementing a treatment alogorithm for the pre intra and post operative time, based on already established protocols and relevant international standards, with single aim to avoid the factors in patient management that contribute to mortality and morbidity. Furthermore this research study will show increased applicability of EVAR in ruptured AAAs with shorter and larger in diameter proximal neck and with angulation >60 degrees, with the implementation of EndoAnchors (HeliFX). Another aim for this research study is to identify the role of the clotting mechanism in the overall mortality and thus to distinguish patient clotting profiles that can predict or alter the outcome.

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