Atherosclerosis: Overview of CAD/PAD
DECEMBER 13, 2019
Deepak L. Bhatt, MD, MPH: Maybe we should move on now to talk a little bit coronary artery disease [CAD] and peripheral artery disease [PAD]. And these things sometimes coexist, sometimes they don’t. What’s the primary care physician to know about the basics of CAD and PAD? Maybe I’ll even throw cerebrovascular disease in there?
Manesh Patel, MD: It’s a great question. And I’ll say that I often with our Fellows and others will say it’s the big 3, right? It’s atherosclerosis. Atherosclerosis is obviously a systemic process. Atherothrombosis is occurring throughout all these vessels. If it’s in any blood vessel, it’s quite possible that it’s in other blood vessels. Now, that doesn’t mean we don’t see people in clinical practice where it seems to be predominantly in 1 vascular bed, and it’s one of those interesting clinical questions we often try to understand. But what we recognize is that clearly, coronary artery disease, peripheral artery disease, and cerebrovascular disease play a role in what is still unfortunately the largest cause of morbidity, mortality worldwide and is unfortunately growing. In fact, we thought for a long time it was down, and now we know it’s flat to potentially going the other direction.
Coronary artery disease gets a lot of education and knowledge. I don’t mean that we still don’t have places to improve things, but a lot of our doctors, primary care physicians, general practitioners, and cardiologists all spend a lot of time thinking about coronary disease because we, in the ’30s, ’40s, and ’50s, had presidents having heart attacks. We had a huge amount of work to try to reduce cardiovascular disease and did make an effect, right? But peripheral artery disease, obviously, we have spent less information and time on, and it is a disease of the elderly that has overlapped, we think probably 30% to 40%. But we don’t really know because we haven’t tested a group of people broadly. We know about 200 million people worldwide likely have peripheral artery disease, 8 to 10 million people in the United States likely have peripheral artery disease that we know of clinically.
It manifests itself with atherosclerosis and thrombosis in the lower extremities. We tend not to call carotid disease peripheral artery disease, although it is a peripheral artery and it’s a cardiologist’s viewpoint to the heart.
Deepak L. Bhatt, MD, MPH: And the Canadians lump it all together, right?
John Eikelboom, MBBS, MSc, FRCPC: True.
Deepak L. Bhatt, MD, MPH: We’ve got to be respectful to our Canadian colleagues.
Manesh Patel, MD: Absolutely. I don’t want to be disrespectful to any of our colleagues. It is a matter of definition, and it may be cerebrovascular or peripheral, but it is of course important. And I would say that the importance for primary care physicians or any clinician is to recognize the disease. The first step is to recognize the disease, shoes off, pulse examination, what are the things you do to recognize peripheral artery disease? Do you ask questions about ambulation and activity? I’d be interested in what you think.
Vamsi Krishna, MD: We’ve done something interesting where we will have surveys of just 3 questions. And there are a lot of data on these simple surveys that people do in waiting rooms that are not very complicated, yet they really do a great job of at least highlighting, and if needed, ABIs [ankle brachial indexes] or TBIs, which are toe brachial indexes, which are really useful in diabetic patients.
Deepak L. Bhatt, MD, MPH: Why don’t you say a word for the audience about ABI or ankle brachial index and toe brachial index?
Vamsi Krishna, MD: For ankle brachial index, we typically use a cutoff of 0.9 and less. However, in a lot of diabetics and diffuse disease, they get medial calcification so that we can’t really occlude the pressure accurately. But then we can do something called toe brachial index, and the cutoff for that is 0.7 or less to diagnose PAD.
Manesh Patel, MD: Just to make sure I’m thinking about it the right way, I tell people it’s the blood pressure in the arm, the blood pressure in the leg. And so if it’s 100 up here, it should be 100 down there, in fact even a little bit higher with gravity. So if it’s 100 up here and it’s less than 90—or 0.9, because we put that one above—then we think there’s a narrowing somewhere that’s going to lead to adverse events over time.
Vamsi Krishna, MD: Absolutely. And what I tell primary care physicians as well and even other practitioners is that we’re not necessarily looking to put stents in, or do atherectomy, or do a procedure on this patient. It’s identifying that this patient has an obstructive lesion that might not be symptomatic, and that there are other options that we can do—be a little bit more aggressive with their blood pressure control or lipid management, as we brought up, incorporate them into a supervised exercise therapy. Catching them early is the key, and I think since you and I do a lot of intravascular management, I now have become a big critical limb ischemia care provider.
And so what I’m really noticing is that the current model is a patient comes into the hospital with a wound, I get consulted, and then the patient has very abnormal flow, but now they have an open wound, the chance of healing is low, they have acute kidney injury. Really we’re down 4 touchdowns in the 4th quarter and we’re trying to win, and we know that you might be able to do it every once in a while, but it’s not a great overall plan. And so I think, especially in the PAD world, it’s growing because we’re diagnosing it more, but we’re catching it too late. I think catching it earlier and using some of these wonderful therapies would be really helpful.
Manesh Patel, MD: The first message we talked about was the calcium score, CRP [C-reactive protein], and these other things. But taking off the shoes and socks, doing the pulse exam and not finding pulses in the lower extremity might be your first example of atherosclerosis burden.
Vamsi Krishna, MD: But that requires people touching patients.
Manesh Patel, MD: Socks are not easy, I get it.
Deepak L. Bhatt, MD, MPH: That doesn’t happen so often.
John Eikelboom, MBBS, MSc, FRCPC: I think one of the problems is that—and this discussion is a great example—if you’re a peripheral artery disease physician, that’s what you do, and when you’re a cardiologist, you spend time with the heart, and everybody expects you to do that. But for the family practitioner out there, you give the impression that these are 2 diseases and the 2 shan’t meet. But we need to emphasize it’s the same pathophysiology. The reason that they manifest differently is because there are different manifestations and different vascular beds. And by the time PAD manifests, you’ve got such extensive disease in most cases that you often have disease elsewhere, but it’s still the same disease.
Transcript edited for clarity.