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Addressing Aortic Disease in Younger Individuals at Risk for Aortic Aneurysm – A Conversation with Wilson Szeto, MD

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In mid-December 2022, Grant Wahl, a young, fit, apparently healthy commentator at the FIFA games in Qatar collapsed in the press room and subsequently succumbed to an aortic rupture secondary to an aneurysm of the ascending aorta. Mr. Wahl's unfortunate and tragic demise echoed that of another commentator, Tim Russert, about whom the New York Times wrote "People are not supposed to die this way anymore, especially not smart, well-educated professionals under the care of doctors." All of these things and ten years younger than Mr. Russert, Mr. Wahl had no known risk factors for the condition that killed him.

Several weeks after Mr. Wahl's death, we spoke to Wilson Szeto, MD, Chief of Cardiovascular Surgery at Penn Presbyterian Medical Center and Surgical Director of Transcatheter Cardio-Aortic Therapies at the Penn Aortic Center. Founded in 1993, the Aortic Center is the vortex for surgical innovation and research, particularly in aortic root disease, bicuspid aortic valve repair, and their associated threats, aortic aneurysm and dissection.

Mr. Wahl was relatively young and fit and it's clear that his death was completely unanticipated. Do we know how many younger adults — people under the age of 50 — are at risk for the aortic aneurysm and rupture that caused his death?

The passing of Mr. Wahl in December was tragic, but I don't think there was any fault in his care. His case illustrates a concern I have about the incidence of sudden catastrophic aortic rupture. I suspect it's higher than what's reported. We have some figures, but the fact is, we really don't know the denominator here because we can't possibly screen everyone with our current tools, particularly people with no known risk factors.

What, then, are the known risk factors for aneurysm in younger people?

There are several — for example, poorly controlled hypertension. The hope today is that patients with malignant hypertension are aware of their condition, but there are young people walking around with very high blood pressure who don't know it because hypertension is largely asymptomatic. Also, there are certain genetic aortopathies that are well known to clinicians, including Marfan's, Ehlers-Danlos Syndrome, Loeys-Dietz aneurysm syndrome and other genetic syndromes. Finally, there's bicuspid aortic valve, or BAV, which occurs in between one and two percent of the population and can be congenital or acquired. The data suggests that BAV is a risk factor for both aortic aneurysm and dissection.

How does BAV contribute to the risk for aortic aneurysm?

BAV reduces the aperture through which the blood moves, increasing pressure at both the valve and on the tissues of the aorta. There are differences in the way that BAV manifests in older and younger persons. BAV in older persons tends to be symptomatic and to occur with stenosis, a narrowing at the valve caused by calcification. Younger people with bicuspid valve and aneurysm — people in their 20 and 30s — tend not to have stenosis, but to have severe regurgitation as a result of incomplete closure or prolapse of the valve.

The symptoms of aortic regurgitation are generally nonspecific — things like fatigue or shortness of breath, and for this and other reasons, younger patients with the regurgitant phenotype are a source of great concern. It's been my experience that something about the tissue quality of the aorta associated with the regurgitant lesion makes them more prone to aortic emergency.

You've noted that it's impossible to diagnose aneurysmal disease in everyone at potential risk. What, then, is the approach at the Penn Aortic Center to younger people either fortunate enough to have discovered an aneurysm at the aortic root or ascending aorta, or with a known genetic risk factor?

The recent AHA Guidelines — whose contributors included one of our cardiology fellows, Dr. Norrisa Haynes, and Dr. Fleicher, the former Chair of Anesthesiology and Critical Care here at Penn Medicine — include recommendations for both screening and the trigger for surgery for BAV. We generally bear these recommendations in mind at the Penn Aortic Center.

Among the guidelines is to consider surgery at 5 cm of aortic dilation for both bicuspid and tri-leaflet aortic valves. There are two caveats, though. The first is the condition that the patient be relatively low-risk for surgical intervention; the second is that the patient be cared for by an aorta team at a center where outcomes for surgery are good. As you know, our outcomes are among the best in the region. The 5 cm trigger is in response to some of the data we currently have, and in response to the population of young, asymptomatic patients that would otherwise do well with elective surgery.

What surgeries are you performing at the Aortic Center for aortic and aneurysmal disease in younger populations?

For patients with isolated aortic aneurysmal disease with a relatively normal functioning valve, an aortic replacement or valve-sparing root replacement is an ideal option because you can preserve the native valve. Another option, and one we're doing with increasing frequency at Penn, is aortic valve repair. In the right hands, this is an option even if there's a valvular lesion — that is, a younger person with a leaky or regurgitative valve. If a patient has a valve that's primarily leaking — bicuspid or otherwise — and has no stenotic profile and an aneurysm, we also do valve-sparing aortic root replacement surgery. This has the benefit of resolving the aortic aneurysm and preserving the native valve so that it doesn't leak. Finally, aortic valve replacement is an option in patients with emergent concerns.

In aortic valve replacement there's some concern about the available alternatives. Mechanical valves, for example, have a lifetime requirement for blood thinners. The other option, bioprosthetic valves, have durability concerns. How do you address these issues?

My perspective is that just because you have an aneurysm and a leaky valve doesn't necessarily mean you have to have a valve replacement. As I mentioned, you can have an aortic replacement only and a valve-sparing operation. The caveat, again, is that these procedures should take place at centers of excellence because the younger you are, the more that longer life expectancy and long-term prognosis are important factors to consider. Patients with emergent need may not have this luxury, though, and for these patients, we have to consider our available options for valve replacement, which include mechanical and bioprosthetic valves. Both have advantages and drawbacks in younger patients. The mechanical valves require lifelong anticoagulation, which isn't a popular option in younger people, and the bioprosthetic valves have limited durability, ranging from 10-15 years, before they have to be replaced.

In part due to these and other issues, we now also offer the Ross procedure at Penn for younger patients with aortic disease.

Introduced in the 1970s, the Ross procedure involves replacing the aortic valve with a pulmonary autograft, which is then replaced with a bioprosthetic valve or homograft. The procedure was performed for a time across the country, including at Penn, then disappeared. Why did this happen, and why is it now being performed again at Penn?

The reason there's been a nationwide resurgence in the Ross is that there's been technical refinement in the procedure — so the surgery we were doing 15-20 years ago isn't what we're doing today. We're not using the same conduits, for example, that we were a couple of decades ago, and the implantation technique has changed.

The problem with the Ross as it was originally performed had to do with failure at the autograft pulmonic valve. The native pulmonic valve is accustomed to 30 mL mercury of blood pressure. When it's suddenly subjected to the 120-150 mL mercury of blood pressure typical of the aortic valve, it dilates out quickly, stretches the valve, and you have regurgitation. So what we do now is offer strategies including support for the pulmonic valve with external wrapping — an anuloplasty — to keep it from stretching out, and impose very tight blood pressure control. Stabilization with an ascending aortic replacement using a synthetic dacron graft is another technical refinement. With these new approaches, some institutions — including Penn — have demonstrated very good outcomes.

Another reason the procedure survived is that there are places in the United States that never stopped doing the Ross — Dr. El-Hamamsy at the Montreal Heart Institute, for example. Dr. Michael Ibrahim, who's here now, trained with Dr. El-Hamamsy, and it was really his enthusiasm for the Ross and his persistence that brought it back to Penn.

Finally, let's talk about graft durability and life expectancy following valve replacement or repair, and the future of aortic surgery.

The Dacron grafts when you replace an aorta have very long durability. The valve repairs — in small studies we're starting to get some robust 10 - 15 years data that suggests these procedures, when done well, are durable. The valve sparing procedure, which has been around since the '90s when Tirone David starting doing them up at the University of Toronto, have very good 15 to 20 year outcomes data. Again, the caveat is that these are small series studies performed by expert surgeons.

What we're trying to achieve for the future involves avoiding tragic and catastrophic events like the one that resulted in the death of Mr. Wahl. We are pursuing investigations in biomarkers and blood tests now, and I think the research are going to help us, ultimately, in the next decade or so to bring along earlier diagnosis for these younger people at risk. There are many intelligent researchers working on this here and elsewhere, and we're hoping we can move the needle and change the narrative on this topic in the years ahead.

Penn Medicine, Philadelphia, PA 800-789-7366 © , The Trustees of the University of Pennsylvania

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