Incidence and Clinical Manifestations of PAD

Manesh Patel, MD: Marc,you and Sonia have certainly been leaders in this around the world, maybe you could describe a little bit for us about what the atherosclerosis and atherothrombosis leads to clinically for our patients with PAD [peripheral arterial disease] when they become symptomatic. What are the types of things they present with, and what are the sort of morbidities this leads to for our patients?

Marc P. Bonaca, MD, MPH: It’s a great question, Manesh. As you said, I think it’s estimated there are over 230 million people with PAD globally. Just before I mention that, I was thinking of your example of you’re in the clinic, and your fellow diagnoses PAD without the risk factors. And the other side of that is also true, though. If you have a patient who is over 55 years old with diabetes and smoking, or of more advanced age, I think the FRIENDS registry showed like 1 in 3 have PAD. That’s the other question, have you checked for PAD in this patient with risk factors because they probably have it?

Manesh Patel, MD: Experience would even say it’s similar. Like you said, for a while we’ve known that up to a quarter to a third of those patients in primary care might have PAD. And we won’t get into the United States Preventive Services Task Force recommendations…but we know that there could be ways in which we could identify patients with peripheral disease sooner.

Marc P. Bonaca, MD, MPH: Yes. To get to the risk, why does it matter, is one question people have asked. If you know someone has coronary disease already, and you’re giving them an aspirin and a statin or whatever, why does it matter whether you identify lower extremity PAD? It matters I think that we’ve really begun to recognize that PAD isn’t just a subgroup of an atherosclerosis population to put in trials to enhance MACE [major adverse cardiac event] risk, or risk of MI [myocardial infarction] and stroke. They certainly do have risk of MI and stroke as high as those who’ve had an MI or stroke, or even higher, so they clearly have that risk.

But I think it’s really important to understand who has PAD because of what you asked about, Manesh, what are the manifestations? What’s the natural history? And the reality is that although we don’t often recognize typical claudication, the majority, if not all of these patients, have substantial functional impairments. Now, they may not recognize that it’s vascular disease. They might say, “I’m getting old, or my joints hurt, or my muscles are sore because I’m taking a statin.” Who knows, but there’s really vascular disease. And those functional impairments are actually really important. Many patients with PAD can’t even walk 2 blocks. And if you think of it, trying to go down the mailbox or play with the kids, these functional impairments are important, and they’re modifiable with things like exercise. If you have a patient with coronary disease and you don’t know they have PAD, how do you know to refer them for supervised exercise therapy?

The other issue, of course, is the downstream effects because it’s a progressive disease. Most studies have shown that over 3 to 4 years, about 1 in 4 patients will need at least 1 procedure to restore perfusion on their legs, either for debilitating symptoms or to prevent tissue loss. That’s an extremely high rate. We’ll talk a little bit about what happens after that first intervention, but that does set off sort of a course of disease then that accelerates. We also know that, although less traditionally recognized inmedical therapy trials, trials like COMPASS and others have recognized acute limb ischemia and amputation. For many people, they may say these things are rare. ALI [acute limb ischemia] doesn’t really happen much, amputation is rare, but the truth is in this population, it’s just as frequent or more frequent than an MI or a stroke, so it has to be on all of our minds.

Manesh Patel, MD: Yes, I know it’s critical to think about that we’ve started to learn what a burden there might be, and it’s a little bit like that quote from To Kill a Mockingbird, “You really don’t understand the world until you put your feet in somebody else’s shoes and walk around for a while.” If you think about the patient with PAD, they’re seeing specialists or clinicians all the time with significant functional limitation, but they’re not getting that changed. Sonia, you’ve been for a while talking to us about how we can be better at caring for our patients with PAD. Briefly for our groups, and I’m sure there are many people who are listening to this or paying attention to some of these things, what are some of the burdens, if you will, that patients with PAD will complain about, or the tools we have to capture their limitations? Marc told us a lot about certainly the events we think about, both the limb events and the heart events, but obviously there are functional limitations for a lot of our patients with PAD that are probably their first manifestations often.

Sonia Anand, MD, PhD: Yes. You’re right, Manesh, that patients will present typically with that pain in their legs, let’s say. A growing proportion is presenting with the acute limb ischemia. Then it takes a while for the patient with PAD patient, depending on your health system, to make their way through the system in terms of getting the diagnosis and getting to a specialist. That varies from place to place. Then the second approach involves the clinic foundational principles around smoking cessation, walking programs. We know there’s good evidence supporting both.

Then we have what I like to call the toolkit of many different medicines that we can use to apply to our patients. But it is challenge, and it goes beyond simply writing a prescription to a patient with PAD. And that’s where we often will be quick to point the finger at the individual patient, saying they didn’t take the medicines as prescribed, or there’s low adherence. But they face a lot of challenges in their own world. We know there’s an increased proportion of patients who have PAD who are of low socioeconomic status background, so they have other challenges, the cost of medication, not having health insurance in some settings.

And then we spend a relatively limited period of time with our patient with PAD. So I think some sort of health coaching, it could be a vascular nurse, it could be some other allied health care professional, is really important for the patient to understand why they need to take the drugs. Then after that, I think systems level barriers exist. Within our own hospitals, we have barriers to optimize in patient care, meaning we might not have a direct referral to cardiac rehab or PAD rehab, where we know walking programs and having allied health professionals involved is effective. We’re excited in the field because we have a huge number of therapeutic options at present, but there are still barriers, not only patient barriers, but physician barriers and health system barriers that we have to overcome in order to optimize patient treatment.

Manesh Patel, MD: That’s a great outline for what we’re going to tackle in a couple of areas we really need to discuss.

This transcript has been edited for clarity.