Mortality rates of ruptured abdominal aortic aneurysm repair have not changed despite increasing utilisation of EVAR

Christopher Washington

Ruptured abdominal aortic aneurysms (rAAA) are associated with an overall mortality rate of over 80%, and, according to the US Centers for Disease Control and Prevention, were the primary cause of death in over 11,000 patients in 2009. Historically, ruptured abdominal aortic aneurysms have been repaired by open surgical methods, approaches which carry significant morbidity and mortality. Recently, endovascular repair of ruptured abdominal aortic aneurysms (EVAR) has gained in popularity with evolving technology. While retrospective studies have demonstrated that EVAR is associated with decreased morbidity, in-hospital mortality and length of stay, to date randomised trials have failed to show early mortality benefit of EVAR over open repair.

In a recent retrospective study from the University of Pittsburgh Medical Center there were 330 patients that presented with a de novo ruptured abdominal aortic aneurysm from 2003 to 2014. These patients where stratified into two groups based on year of presentation. The first group (presenting from 2003 to 2008) included 163 patients, while the second group (from 2009 to 2014) included 167 patients. Our goal was to compare these two time periods, the first with open surgery as the mainstay of therapy, while in the second endovascular therapy was becoming more common.

In the first group, 16/163 patients underwent EVAR, whereas in the second group 70/167 underwent EVAR. When comparing baseline demographics such as age, sex, and comorbidities between the two groups, we noted no differences. Likewise, there were no differences in operative mortality (12.9% Group 1 vs. 13.8% Group 2) or 30-day mortality (33.1% Group 1 vs. 36.5% Group 2) between the two groups.

Our team did find that there was a significant difference in patients with blood transfusion requirements of less than 500ml (6.9 % Group 1 vs. 28.4% Group 2), need for bowel resection (11.3% Group 1 vs. 4.9% Group 2), and respiratory complications (32.6% Group 1 vs. 18.9% Group 2). Using a multivariate analysis we found that age older than 80 years, anatomy requiring an open repair, heart rate greater than 110 beats per minute, cardiopulmonary resuscitation, and hypotension were all predictors of increased mortality following repair of ruptured abdominal aortic aneurysm.

When comparing outcomes following open and endovascular repair throughout the entire cohort we found there was a significant decrease in operative mortality (open 16% vs. endovascular 5.8%, p=0.017) and 30-day mortality (open 38.8% vs. endovascular 23.3%, p=0.008) associated with endovascular repair. We also found that endovascular repair is associated with decreased post-operative morbidity. Tracheostomy (open 22.5% vs. 3.8% endovascular, p=0.0002), pneumonia (open 22.5% vs endovascular 11.2%, p=0.0302), post-operative haemodialysis (open 17.2% vs. endovascular 6.2%, p=0.0175) and length of stay (open 12.2 days vs. endovascular 7.5 days, p=0.007) were all lower following endovascular repair. We found that this decrease in morbidity and mortality following endovascular repair of ruptured aneurysms did not translate to improved outcomes in Group 2 despite the increasing number of EVAR being performed.

Next, we looked at open surgical mortality based on surgeon experience at time of operation, using years since graduation from fellowship as a marker. When we compared the open surgical mortality results we found that there was a difference, though not significant, in mortality between the two time periods in those surgeons with less than five years’ experience, and with 5–10 years’ experience. There was no difference in mortality between those surgeons with more than 10 years.

In summary, EVAR is associated with a significant decrease in mortality rates, as well as morbidity and length of stay. Over the course of a 12-year period there was a shift in the practice pattern from open surgical repair towards EVAR. Haemodynamic instability and the need for open repair predicted increased in-hospital mortality. Despite this paradigm shift toward increasing EVAR in the later group, there was no demonstrated change in mortality. This could be due to selection bias toward healthier patients undergoing EVAR, or possibly due to diminished surgeon experience with open aortic surgery.

Christopher B Washington is a vascular surgeon at the University of Pittsburgh Medical Center, Pittsburgh, USA