by Debra L. Beck
Hollywood, FL (January 23, 2020) – Acute type A aortic dissection is a “total catastrophe in all segments” said Joseph Bavaria, MD, Director of the Thoracic Aortic Surgery Program at the University of Pennsylvania. “So, when we think about where we’re going with treatment of acute aortic dissection, we really have to think about it this way.”
As well, based on autopsy evidence from Japan that showed a “stunning” 8.07% prevalence of Type A aortic dissection in post-mortem CT scans in patients with out-of-hospital cardiac arrest, the prevalence is likely much higher than previously appreciated, he told International Symposium on Endovascular Therapy (ISET) attendees.
“Do we really know the best therapy for acute A dissection?” asked Dr. Bavaria rhetorically. The classic ascending hemi-arch or root hemi-arch operation actually offers really good results in patients less than 80 years of age, as seen in a recent paper by Kawahito et al (Annals of Thoracic Surgery, 2018). In their series, in-hospital mortality was 7.4% for those under 80 years of age and overall postoperative survival was 89.1%, 85.6%, and 82.1% at 1, 3, and 5 years, respectively.
“The treatment is [also] pretty good from a proximal reoperation standpoint,” said Bavaria, and the aortic root is stable after acute type A dissection repair.
The problem is the significant risk of late attrition from distal aortic disease after standard hemi-arch repair, he said, and the attendant high need for reintervention—20% at 10 years.
“We can expect a really high incidence of reoperation in survivors, but a lot of them are not survivors [given the huge competing risk of mortality],” he added. “Most patients are dying late of distal aortic disease and complications in the untreated segment.”
“So, while these surgical repairs have “served us well over the past 15 years,” there are major problems associated with class type 1 repair. These issues have to be addressed in order to improve outcomes, and, in his opinion, this will happen with treatment of the distal aorta with “TEVAR [thoracic endovascular aortic repair] enabling solutions in the acute or subacute phases.”
Possible solutions include the frozen elephant trunk, which has gone through its clinical trial and should be FDA approved by late 2020, said Bavaria. Another option is a zone 2 arch with sequential branched TEVAR completion, which can address the most complex arch tears and eliminate flap in the proximal heel vessels, and allows for definitive TEVAR options in the future. It also has less attendant risk of recurrent laryngeal nerve injury.
“Here's my prediction based on what we think the new technology will allow us to do. And the big shtick here as far as a concept, is that we are taking the type A aortic dissection operation and we are changing it based on the availability of new technology…” he said.
“So, the future based on our data, and our increased sophistication, and the availability of new technology is that in patients with less than 10 to 15 years of life expectancy, we use the classic hemi-arch operations. In those with an arch tear or distal malperfusions who need immediate reconciliation of their distal aortic problems, they’ll get a frozen elephant trunk procedure. And basically, in everyone else, which is the majority of patients and patients less than 65 and stable, we'll be doing Zone 2 arch operations with sequential in about 60% of the patients, arch branch TEVAR using either zone one or zone two cases.”
Dr. Bavaria ended by hinting at the findings of the Acute Type A Dissection Repair with Ascending (ARISE) trial, from which he presented results the following day.
ARISE is a multicenter, early feasibility study evaluating the endovascular ASG, a purpose-built investigational device specifically designed to treat type A dissections of the ascending aorta.
Currently, the trial has enrolled 31 “highly selected” ASG cases, 11 in the acute type A arm (feasibility) and 18 emergent/compassionate use cases, which includes both type As and other ascending pathologies, reported Dr. Bavaria. The study is being conducted at 8 U.S. sites.
While a proper assessment of the new graft will have to await final results, Dr. Bavaria reported [the following day] that, “we've been very, very pleased with the ability, just like in TAVI, to get very close to the valve without getting into the valve.” He added that the technical characteristics of the ASG graft “are pretty reasonable”.