Overview of PAD: Epidemiology and Pathophysiology

Transcript: Deepak L. Bhatt, MD, MPH: Let’s move on to discuss and provide an overview of peripheral artery disease [PAD]. I’ll start with you, Marc. If you would, give us a quick recap of the epidemiology of peripheral artery disease: in the United States, worldwide, and whatever else you want to cover.

Marc P. Bonaca, MD, MPH: Thank you, Deepak. The term peripheral artery disease is interpreted differently in different places. The most general concept is atherosclerosis outside the coronary arteries, whether it’s in the carotids, the lower extremities, and so on. Many of us in practice think of it as lower-extremity atherosclerosis, which afflicts more than 200 million people worldwide. It’s important from an epidemiology perspective to recognize that in general, it’s underdiagnosed. The manifestations are atypical in a lot of patients. They may walk slower or have some leg symptoms, but it’s not always recognized as vascular disease. It’s much more prevalent than we understand, just based on diagnosis codes. It’s associated with all the problems that atherosclerosis brings, such as heart attacks or stroke. Importantly, very specific to this population are lower-extremity complications, such as functional limitation, critical limb ischemia, amputation, and acute limb ischemia. It’s an important problem. It’s a growing problem as the population ages and we see more obesity and diabetes.

Deepak L. Bhatt, MD, MPH: Mike, why is it that cardiologists don’t really pay a lot of attention to peripheral artery disease? Some of them do, obviously. But as a general principle, it doesn’t seem as though it’s front and center. There are a lot of publications showing that PAD is bad, with high rates of ischemic events, cardiovascular events, and mortality. But in general, I don’t know if cardiologists still pay a lot of attention to it. Why is that?

C. Michael Gibson, MD, MS: I don’t know, Deepak. It’s bad. If you can’t walk around and take care of yourself, this can be a very devastating disease. The prognosis, as we’re going to get into, is horrible for people with multiple, impactful diseases. This is why we’re doing the program, in part. Cardiologists need to take much more care and pay much more attention to PAD than they’re doing currently. It’s sad.

Deepak L. Bhatt, MD, MPH: I agree. Matt, it seems that repeat revascularization is much more frequent in patients with PAD than patients with coronary artery disease. What is the reason for that?

Matthew T. Menard, MD: That’s a great question, Deepak. Anyone who intervenes in the lower-extremity disease, at some point in their careers, has thought that, “Oh, the fibula vessels are a mirror image of the heart, and we can learn a lot from our cardiology colleagues and cardiac surgeons.” It doesn’t really seem to translate all that well, and it’s really divided into 3 separate anatomic segments that all behave differently. The SFA, the superficial femoral artery, has its own unique challenges. It’s the center point of a lot of torque and angulation and compression when you move and bend the knee. The popliteal artery is a particularly tough segment, and the biggest challenge we face is probably how to keep things open across that segment, at least for endovascular therapy. And then, the tibial arteries are their own unique anatomic bed and have their own challenges.

We’re also seeing more challenges with diabetic patients that we didn’t see 20 years ago, when very frequently the pedal vessels were spared. Now it’s very common to see really diffuse, severe disease across the ankle into the foot. The options are different. As you said, it is a very challenging territory, and the things that we do don’t work as well as we’d like them to. We’re faced with a lot of reinterventions, both from the surgical side of things and the vascular side of things.

Deepak L. Bhatt, MD, MPH: Absolutely. One of the things we learned from vascular surgeons is that the patients with PAD often have a lot of coronary artery disease, if you think back to the classic studies such as those done by a vascular surgeon, Dr Norman Hertzer, from the Cleveland Clinic. He’d done that initial work showing that 90% or more of patients undergoing vascular surgery had concomitant coronary disease, which at the time was a really striking finding. I actually had the privilege of scrubbing in with Dr Hertzer a number of times when he was active as a surgeon. Matt, have you ever met Dr Hertzer?

Matthew T. Menard, MD: I met him once. I don’t know him well, but he’s certainly a legend.

Deepak L. Bhatt, MD, MPH: He used to smoke quite a bit too. That’s neither here nor there. But there’s a lot we can learn from vascular surgeons, either as vascular medicine or cardiology specialists.

Transcript Edited for Clarity