A series of preoperative risk factors—including currently smoking, chronic kidney disease (CKD), congestive heart failure (CHF), aneurysm size greater than 7cm, more advanced age (75 or over), Crawford extent I–III thoracoabdominal aortic aneurysms (TAAAs), known chronic obstructive pulmonary disease (COPD), and anemia at baseline—were found to be predictive of one-year mortality among patients undergoing fenestrated and branched endovascular aneurysm repair (F/BEVAR) for complex AAAs and TAAAs with custom-made devices.
That is the key finding from one of the latest papers to come out of the U.S. Aortic Research Consortium (U.S. ARC) of investigational device exemption (IDE) trials set to be presented at the 2024 Southern Association for Vascular Surgery (SAVS) annual meeting in Scottsdale, Arizona (Jan. 24–27).
The 10-center, more than 3,000-patient research conglomerate aims to use the data generated to create a risk stratification calculator to help inform a preoperative decision-making process that balances risk of aneurysm rupture if no intervention takes place, and mortality risk at one year if the disease is operated upon, Adam Beck, MD, a U.S. ARC investigator and vascular surgery division director at the University of Alabama at Birmingham in Birmingham, Alabama, told Vascular Specialist ahead of the SAVS 2024 meeting.
“The typical discussion when we are in clinic talking to patients about whether or when they should repair their aneurysm always focuses on the risk of rupture,” he said. “And that risk of rupture is usually put into the context of annual rupture risk. We did this project because we wanted to give a counterpoint to that risk of rupture. That was the idea behind this one-year mortality risk. So, you can say, ‘This is the risk of doing nothing, and here is the risk of doing something,’ in the setting of the patient’s overall state of health and quality of life.”
Operative mortality can be very low—from 1–2%—depending on the extent of the aneurysm and complexity of the repair, Beck observed. “But the mortality when you go out to a year can be much higher than that. So, something is happening to these patients after they get repaired. It’s not rupture of their aneurysm. Many of them are dying of their other medical comorbidities.”
The U.S. ARC researchers looked at the full range of preoperatively available risk factors—gender, race, age, coronary disease, CHF, emphysema, cerebrovascular disease, diabetes, renal disease, hypertension, as well as both smoking and preoperative functional status. They were stratified by Crawford extent of their aneurysm: one complex AAA (juxtarenal/suprarenal) and two separate TAAA groups—one comprising Crawford type IV and V and the other the particularly high-risk extent I–III group, Beck explained.
“The things that we found that were predictive of one-year mortality in a multivariable Cox regression was if they were a current smoker, if they had CKD, CHF, a very large aneurysm (greater than 7cm), more advanced age (75-plus), extent I–III TAAAs, patients with known COPD, and those who were anemic at baseline,” he said.
“The aneurysm size is a tough one. That one always falls out in an analysis like this: the bigger your aneurysm, the higher your risk of one-year mortality. It’s an interesting thing because the bigger your aneurysm, the more likely we are to offer you a repair—even in the setting of higher-risk patients, because we’re weighing that risk-benefit with rupture.”
During SAVS 2024, the research team will break down what the risk looks like in their predictive model by increasing risk factors. The risk calculator the U.S. ARC investigators hope to generate would enable individual patient data to be plugged in to gauge their one-year mortality risk.
“Hopefully this could be something that will allow you to discuss with the patient in clinic and say, ‘Here is your risk of rupture, and here is your risk of mortality at one year. I think that it makes sense to proceed with your repair.’ Or you could say, ‘It really doesn’t make sense at your current size for us to put you at the risk of the operation,’” explained Beck. “This could also help you with your discussions about smoking cessation. If we could show patients on our phones apps and say, ‘This is your risk of mortality at a year with you being a current smoker. If I take this risk factor out, here is your risk factor at one year, and it will be a sizable difference.’ I think that will really help that discussion with the patient and our clinical decision-making.”
Further down the road, U.S. ARC is set to continue building on its body of work with additional analyses in areas such as target-vessel outcomes based on type of stent graft used, the impact of aortic aneurysm sac behavior after repair, the impact of renal insufficiency on outcomes, and the impact of endoleaks on mortality. The group has also recently completed a pilot study for a randomized controlled trial (RCT) for prophylactic spinal drains in patients with extent I–III TAAAs. The latter particularly excites Beck owing to his long-standing interest in preventing spinal cord ischemia as a complication of complex aortic aneurysm repairs.
Another recent development saw U.S. ARC include aortic arch procedures in its registry. “A few of the centers are capturing data for their endovascular aortic arch reconstructions,” Beck noted. “This is still in its infancy, but we’ll have some consortium data to publish in the next year or two, once we have more patients.”
Despite being only about six years old, U.S. ARC is having a big impact on evolving the arena of complex repair of TAAAs and AAAs, Beck said. “In our group, we have each changed our practices based on our publications,” leading to quality improvement, he added. “I’m biased because of my personal academic interests, but I think if we can actually get a [large, nationwide] RCT going for spinal cord ischemia, that would be one of the biggest contributions that we could make to the aortic surgery world. It will take a few years to enroll the number of patients we will need, so successfully initiating the trial may be one of our next big landmarks.”
