Risk Factors for PAD Development

Manesh Patel, MD:One thing that you mentioned about risk factors is interesting, and I’m going to ask Larry, how do you usually think about comorbidities, including heart failure? I tell our fellows in clinic, if the patients don’t smoke and don’t have diabetes, those are overrepresented in PAD [peripheral artery disease]. This comes from data that are a bit older, but the PARTNERS study where they evaluated patients doing an ABI [ankle-brachial index] in primary care clinics, about 7000 patients, and they found that a quarter of them had PAD. If they were 50 years old and over, they tested whether they had diabetes and tobacco use, or over 70. Unrecognized PAD probably exists in about a quarter [of patients] in our primary care clinics, and it fits with these comorbidities. Larry, please discuss the comorbid patient with heart failure or these risk factors in vascular disease. How do you think about this biologic process? Is it one, is it different? Same thing comes through for heart failure.

Larry Allen, MD:Coming off your comment about vascular beds, atherosclerosis is caused by similar risk factors, but the lower-extremity vascular bed is more affected by tobacco and smoking, and somewhat diabetes, whereas the coronary vascular bed is less affected by tobacco. If you consider the cerebrovascular bed in strokes, it appears that the disease is overaffected by hypertension. When you’re talking to your patient, or you’re thinking about in primary care, they shouldn’t smoke, they should control their weight, their diabetes, and their blood pressure. Even though some patients may have one disease and not the other, when we think about the American Heart Association’s Life’s Simple 7 [risk factors], the benefits carry across these various diseases. Having good control of those risk factors will be a great benefit overall.

You mentioned heart failure, and I spend a lot more time dealing with that. You spend a lot more time thinking about vascular disease, but there’s a lot of overlap there as well. The ESC [European Society of Cardiology] PAD guidelines give a 2A recommendation that if you have somebody with PAD, you should consider screening them with an echocardiogram or BNP [brain natriuretic peptide test] to check if they have heart failure, because so much of these issues overlap. Patients with heart failure, often it’s due to ischemic heart disease. But increasingly we think about patients with HFpEF [heart failure with preserved ejection fraction], which is caused by hypertension, diabetes, obesity, and other metabolic risk factors. It gets a little complicated if you try to split it all up, but if you take a step back and consider, how do I help my patient have good health and avoid multiple comorbidities, it’s really emphasizing high-value care.

Manesh Patel, MD:That’s a great point. Chris, I know you care about patients with diabetes and the overrepresentation in PAD, but not only that, for them one of the biggest outcomes of having vascular disease broadly is what can happen to their limbs. The guidelines vary a bit from the American Diabetes Association versus others, how do you think about patients with diabetes in identifying PAD?

Christopher Granger, MD: Patients with PAD, it’s kind of like the pinnacle of vascular disease, these are complicated patients. They have advanced vascular disease, and many of them have polyvascular disease. We talk about what populations do we need to do a better job with, and this is clearly one of them. These patients need intense attention to modify risk for progression of all types of vascular disease once they have PAD; one of those is diabetes. We have so much opportunity to improve care of diabetes. One of the most important trials ever done was this Diabetes Prevention Program. It was an NIH [National Institutes of Health] trial. Patients with prediabetes were randomized to metformin control, which is basically the American Heart Association guideline, or a program of advice for weight loss, which wasn’t very effective.

What was effective was that these people consistently increased their exercise. They walked 30 minutes a day, 5 days a week, and it cut the chance of developing diabetes by 56%. It’s amazing. It’s a central part for managing peripheral arterial disease, for heart failure. And it’s hard, I don’t know, maybe I’m naive. But many people can get out and walk 30 minutes a day, 5 days a week. We also looked carefully at how patients with diabetes and atherosclerotic cardiovascular disease are being treated in the United States, and it’s the same theme, not very well. High-intensity statins are used by less than 50% of this population, and we can get back to that, because that’s a big opportunity. ACE [angiotensin-converting enzyme] or ARB [angiotensin receptor blocker], 50%, and then the new drugs that improve cardiovascular outcome, SGLT2 inhibitors or GLP-1 [glucagon-like peptide-1] receptor agonists, with some limitation due to cost. That’s a big issue for a lot of patients. Even in a commercially insured database, it’s still less than 20%. We have big opportunities to improve care, and this is even more important for patients with PAD and diabetes.

Manesh Patel, MD:I think you’re right. About PAD, I don’t know if it’s the end stage, pinnacle, or the extreme of vascular disease, but it seems to be overrepresented in our elderly patients, while it appears that those who are younger have diabetes, tobacco use, and a variety of risk factors. Unfortunately, it’s also a health equity issue. We see around the United States that patients with PAD have less access to care and resources, which leads to underdiagnosis and lack of awareness. Sreekanth Vemulapalli, [MD,] and others looked at Medicare, these data are about 8 years old. In Medicare, 30% of people who had an amputation for arterial reasons never had an arterial test prior to their amputation. Amputation was the first treatment strategy in 2014 for PAD in 30% of Medicare-age patients, and the mortality 1 year after having an amputation in Medicare is 20%. These are end-stage patients sometimes who aren’t getting evaluated. It depends where you live, if you look at our state map or other state maps, you’ll see that it’s a disease, as we’ve seen with all other diseases in cardiovascular health, where we’re losing life expectancy. That’s happening in the rural base and around those areas.

This transcript has been edited for clarity.