Conversations with Experts: Spencer King and Christopher White on Peripheral Interventions

In the past two decades, technology for peripheral vascular interventions has greatly advanced, to the point that interventional cardiologists have surpassed vascular surgeons and interventional radiologists as the specialty responsible for performing the majority of these endovascular procedures. Interventional cardiologists are in the process of redefining themselves as “vascular specialists,” not just heart specialists. In this edition of Conversation with Experts, Spencer B. King, III, MD, editor-in-chief of JACC: Cardiovascular Interventions, and Christopher White, MD, director of the John Ochsner Heart & Vascular Institute and past-president of the Society for Cardiac Angiography and Interventions (SCAI), discuss the current role of the interventional cardiologist in the peripheral arena, as well as future directions interdisciplinary collaboration in this growing area of cardiology.

Spencer B. King, III, MD: I want to start by saying, Chris, that when I took my ABIM certification, I took the cardiovascular medicine boards—which means not only the heart, but all the blood vessels connected to it. For a long time there was this perception that cardiologists had not paid adequate attention to the second part of their boards, namely the vascular part.

However, I’ve noticed that there’s a growing interest in the vascular system. The ABIM has weighed in and now study of the peripheral vessels is very much required for board exams and competence and training programs. It’s clear that the peripheral arterial and vascular systems have become part of the interventional training and practice.

Chris, in your experience, how much are interventional cardiologists involved in the practice of peripheral vascular interventions?

Christopher White, MD: Well, first, I think the terminology is important here. When we talk about peripheral vascular, my definition includes the cardiovascular system—cardiac vessels and non-cardiac vessels—so the distribution becomes very broad. Other times when we mention noncardiac or peripheral interventions, people tend to think of infrainguinal or lower extremity disease, but I think today we should be talking about a broader spectrum.

In the most recent Medicare billing data by specialty, which is from 2008, cardiologists were the single largest provider of peripheral vascular endovascular procedures, compared with any other subspecialty. Vascular surgery was number two, and radiology was number three. The majority of procedures is performed on the cardiology side.

Dr. King: Right, and interventional cardiologists are major players in peripheral interventions, and, in fact, it’s a requirement for ABIM certification that they be trained in this arena. It’s not that every interventional cardiologist is specializing in both structural heart disease and peripheral disease, but many are.

I wanted to know your opinion: is this a serious focus in the training programs? Do you have a feel for how many training programs are really emphasizing and effectively training cardiologists in peripheral vascular interventions?

Dr. White: Our training programs need to be recognizing the “vascular” part of our cardiovascular training. There’s no reason to only focus on heart issues when many other vascular distributions contribute significantly to our patients’ morbidity and mortality.

At the most fundamental level, Spencer, a cardiologist has to be able to manage their vascular access, which includes, among other things, managing the femoral and iliac arteries for either bleeding or vascular complications. Even if you never want to be a peripheral vascular interventionalist, you at least owe it to your patients to be able to manage their access sites.

Dr. King: Chris, I think many people would be surprised by the penetration of cardiology in the peripheral space, but I certainly concur with you because, in reviewing the interventional cardiology training programs I would say that almost all of them require training in interventional cardiology.

Dr. White: There is quite a bit of regional variation, I believe. The perception that any single cardiologist might have would be based on what they see in their region or their city. But, overall, I see very broad participation of interventional cardiology with peripheral vascular interventions.

This participation, I think, comes from necessity and the nature of atherosclerosis. Atherosclerosis is not solely a “heart disease;” atherosclerosis is a disease of the vascular system that affects every organ. Patients with coronary disease also have leg, renal, and carotid disease, and vice versa. It doesn’t obey the rules of medical school departments and specialties, so when we treat patients with vascular disease, we have to treat the whole patient, whether that be stroke prevention or claudication or renovascular hypertension.

Dr. King: You bring up a very interesting point about interdisciplinary collaboration based on the presenting patient’s condition, rather than based on a strict delineation by specialty. What’s your view of collaboration between cardiologists and other specialties?

Dr. White: I am totally in favor of a collaborative approach. Each of our specialties brings something to the table. Say, for instance, that I’m going to collaborate with an interventional nephrologist in dialysis access: I may be able to show him drug-eluting stents that I use in the superficial femoral artery (SFA) or something that may be appropriate for a subclavian vein that he wouldn’t necessarily know about. We cross-pollinate very well, I think.

As we continue to see health care evolve, and as we see ACOs developing, I think they are going to really feed this collaborative approach, particularly as our focus shifts from volume of care to value of care. To manage populations as effectively and efficiently as possible, we’ll need all hands on deck, working together to bring the best talent to the patient’s bedside.

The concept of the “heart team” and working with surgeons has recently gained a lot of popularity, but I do think there’s a great opportunity for most cardiologists to be collaborative with a vascular surgeon or a radiologist or a neurologist or an interventional nephrologist. There are many areas where we do better work as a group than we do off by ourselves.

Dr. King: So, we’ll call this the “vascular team” as opposed to the “heart team.”

Dr. White: Exactly, and they need us as much as we need them.

Dr. King: Well said. There are many areas that might lend themselves to collaboration. Also newly developing areas and new devices are becoming available, like procedures that don’t rely on stents. I’ve been impressed by the many papers I’ve seen in JACC: Interventions from foreign authors and researchers working with drug-eluting balloons. For instance, treatment of problems in the leg, particularly in the SFA and the femoral popliteal area, has had kind of a rocky road so far, but the drug-eluting balloon shows some promise. What’s your view on these drug-eluting balloons?

Dr. White: It is very exciting. The SFA and popliteal areas are some of the most unforgiving locations in the body to put a stent, due to the constant twisting, rotating, and compressing. Obviously, one of the roadblocks to delivering the anti-restenotic drug to these locations is the mechanical burden of a metal scaffold. Any device that removes that scaffolding and lets us just apply the anti-restenotic material holds a lot of promise for treating leg disease.

Dr. King: What about the biodegradable scaffolds—the ones that are designed to “disappear” over time, but which are certainly in place for a while? Do you think there’s much interest in providing bioresorbable scaffolds in the SFA or other areas?

Dr. White: At this point, I get the sense that the price point for these newer scaffolds is pretty high. A certain number of these procedures are going to be balloon-only with the drug-eluting balloon being used occasionally, but clearly there will be a need for bail-out devices. Then the question will be: What will be the pricing of a bare-metal stent, a drug-eluting metal stent, or one of these novel scaffolding technologies? Typically, the use of these devices in the lower extremities is at a discount compared to coronary devices, but we’d need a proper cost-benefit analysis, which may take a few years.

Dr. King: Another condition that cardiologists are managing all the time—where interventionists can certainly play a role—is hypertension. I’m thinking, in particular, about the approach of renal denervation. All the specialties involved in the interventional arena will be interested as that becomes more widely used. Chris, what’s your view of the role of the interventional cardiologist with renal denervation?

Dr. White: I’ve been absolutely dumbfounded by the lack of complications that have been reported with this nascent technology over the last 5 years. Many people were impressed with its efficacy, but had serious doubts about the safety of being able to apply these selective thermal injuries to renal arteries without some downstream problem. But these problems simply have not emerged.

This appears to be an extremely safe procedure to perform, particularly by a skilled interventionalist. It is a renal procedure that requires peripheral skill to perform; it’s not strictly peripheral angioplasty, but it’s clearly something on the rise and a skill that I think cardiologists are going to want to have in their own armamentarium.

When you compare the burden of taking hypertensive medications—possibly taking multiple drugs every day for 40 or 50 years—with undergoing a 25 or 30-minute procedure with smaller, more manageable risks, it’s astounding. I think we’re going to look back on the first decade of this century as big a turning point; similar to what we saw in the 1970s with coronary intervention. Interventional therapy for hypertension is going to become dominant for this prevalent disease.

It’s important to mention that you cannot be a successful interventional cardiologist in the vascular arena without paying attention to the medical management and risk factor modification of PAD. Just as in the coronaries, we are responsible for an LDL target of 70 in a patient with secondary prevention; and my interventional colleagues hit those targets very well.

In my opinion, there is no better provider for continuity of care and risk factor management for patients with vascular disease than the cardiologist. Once you engage an interventional cardiologist, you engage him or her for the long haul. Few specialties can do that.

Dr. King: One area where maybe all interventional cardiologists should not be venturing into is intracerebral interventions. You’ve certainly been a leader in making sure that we have training requirements to ensure operators are only working in the areas where they have adequate experience and training edge. What do you think about kind of moving above the carotid artery and into the cerebral arteries?

Dr. White: I’m glad you brought this up because this is key. Patients who have significant cerebrovascular disease and have failed best medical therapy with recurrent symptoms have terrible prognoses. The problem is that it is such a delicate area to work in, so the risk of complications, particularly for “casual” interventionalists—and I include neurologists, neurovascular operators, and radiologists in this—simply cannot navigate this area safely. We’ve seen several negative trials in the last year that have woken us up to the fact that the current complication rate doesn’t really justify the therapy.

But what I really think we’re finding is that we really need to have a focused referral base. These are elective cases, they’re not strokes, and patients should be referred to centers of excellence, with highly experienced operators who then can manage these patients.

Dr. King: I’m sure, in addition to the carotid artery, there are other areas, perhaps in all areas, where the idea of adequate experience is important.

Dr. White: True, and, to that point, it is multidisciplinary care, and with that team approach, you can make up for the gaps in experience. For instance, who better to drive a steerable guidewire and balloon in the brain than a cardiologist who’s done 1,000 coronary interventions in his life? But this is done with a radiologist or a neuroradiologist present, who understands every congenital anomaly and every other natural variation in the cerebral circulation. So, we stand there together, at the cath table managing these patients as a team.

You know, at Ochsner, I participate in what we call a men’s health clinic, in conjunction with the endocrinology and urology departments, where patients who are having erectile dysfunction problems, who have failed medical therapy and have hemodynamic compromise, with pelvic blood flow measured with ultrasound. Those patients respond quite well to endovascular procedures, and these are procedures that cardiologists do quite well. So, with reasonable, noninvasive screening, we’re able to identify patients who will likely respond to treatment.

Dr. King: I am impressed with the greater interest in diagnostic work in peripheral vascular disease, including the ankle brachial index studies and some of the venous assessment that cardiologists are now involved in.

Dr. White: And I’d also say, Spencer, that many cardiologists are using noninvasive, cross-sectional CTA imaging, which really lends itself to use in the periphery as well.

Dr. King: Well, certainly the technology for intervention beyond the heart and coronary arteries has grown tremendously, perhaps to the point that the misconception that cardiologists are only “heart doctors” has started to fade away in the 15 or so years from when we started the interventional cardiology boards.

Initially, we were not encouraged to force training in peripheral vascular and structural heart disease when the interventional cardiovascular boards first started. That has changed dramatically over the last 15 years, as all programs now do require peripheral vascular and structural heart disease training.

Members of the future generation of interventionalists are clearly going to be very prominent players, and not always in isolation as you pointed out, but in collaboration with other specialists that are equally engaged in the noncoronary interventions.

Dr. White: In my opinion, if you want succeed, you check your ego at the door. You combine your strengths to do whatever needs to be done. We’re seeing this in other elements of cardiovascular disease, like TAVR, where we just do our best for the patients, and we do it as a team.

Clinical Topics: Diabetes and Cardiometabolic Disease, Invasive Cardiovascular Angiography and Intervention, Prevention, Vascular Medicine, Interventions and Vascular Medicine, Hypertension

Keywords: Denervation, Referral and Consultation, Coronary Disease, Carotid Arteries, Risk Factors, Iliac Artery, Hypertension, Renovascular, Renal Dialysis, Cerebral Arteries, Renal Artery, Cerebrovascular Disorders, Medicare, United States, Cooperative Behavior, Cost-Benefit Analysis, Stroke, Endovascular Procedures, Atherosclerosis, Continuity of Patient Care, Drug-Eluting Stents, Ankle Brachial Index, Femoral Artery, Angioplasty, Peripheral Vascular Diseases, Hemodynamics, Subclavian Vein, Prognosis, Secondary Prevention, Erectile Dysfunction, Coronary Vessels

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