Bob Underwood, MD: The most common type of heart disease is caused by a buildup of plaque in the arteries that supply blood to the heart. We all know this as atherosclerosis. This narrowing can cause the familiar symptoms like chest pain, fatigue, and shortness of breath. But up to 50 percent of people who experience these symptoms don't actually have any large vessel blockage. And sometimes this presentation, without coronary artery disease, is simply called chest pain syndrome X. But now with advances in specialized testing, cardiologists can provide a more specific diagnosis for these patients; coronary microvascular dysfunction.

I'm Dr. Bob Underwood, and welcome to HeartSpeak Consult, brought to you by Baylor, Scott & White, Heart & Vascular Hospital, Dallas Fort Worth, and Waxahachie. To discuss and learn more about CMD, today we are joined by Dr. Darren Kumar, an Interventional Cardiologist on the medical staff at Baylor Scott & White Heart & Vascular Hospital, Fort Worth. Dr. Kumar is a Board Certified Cardiologist specializing in a wide range of cardiovascular conditions, including preventive care and complex interventional procedures.

He holds multiple certifications in nuclear cardiology and vascular interpretation. Dr. Kumar, welcome to HeartSpeak.

Yuvaraj "Darren" Kumar, MD, FACC, FSCAI, RPVI: Thank you very much. Glad to be here.

Host: Yeah, so this is kind of a new area in terms of diagnosis. So can you help us understand exactly what is coronary microvascular disease and can you explain the difference between CMD and coronary artery disease or CAD?

Yuvaraj "Darren" Kumar, MD, FACC, FSCAI, RPVI: Sure. Coronary microvascular disease, as you mentioned, used to be called cardiac syndrome X or non obstructive coronary artery disease. It's also called small coronary artery vessel disease. So when we do a typical angiogram, we look at the major epicardial vessels, and that only accounts for about 5 percent of the entire blood supply of the coronary anatomy.

So 95 percent of it, we don't even see. And so we miss a lot of potential areas of heart disease that we may not see on the traditional angiogram. So with newer techniques and modalities, we are able now to inquire more about the disease structure of these small vessels and are looking for treatment strategies to help patients when they don't have the major obstructive coronary artery disease that we think of, which is disease in the major epicardial vessels at least 50 percent or greater.

Host: So how does the coronary microvascular disease relate to anginal symptoms? And how is that different between CMD and CAD?

Yuvaraj "Darren" Kumar, MD, FACC, FSCAI, RPVI: The angina symptoms are pretty much the same. You know, we get chest discomfort of some type, whether it's heaviness, tightness, pressure; just like we do have in major epicardial vessel disease. But as you mentioned, nearly half the patients who undergo a coronary angiogram will have normal coronary arteries, but continue to have symptoms.

So we need to investigate this further, and now we have tools to do so by looking for different modalities, and that could include coronary artery spasm that we don't see when we do a typical angiogram, and we have to induce that. We can also look for microvessel spasm. And we can look and assess microvessel tone, with different technologies and modalities.

Host: Wow. So, for the patients coming in, you know, we want to assess them, kind of what are their risk factors? Are they the same between CMD and CAD? You know, such as high cholesterol or something like that?

Yuvaraj "Darren" Kumar, MD, FACC, FSCAI, RPVI: Yes, actually the risk factors are pretty much the traditional cardiovascular risk factors, but we tend to see a higher preponderance of coronary microvascular disease in women in a ratio of about three to one. So where we typically do not do a good job of diagnosing women's angina symptoms, we are also potentially missing a big window of opportunity of looking at coronary microvascular disease as part of their symptom presentation.

Host: That's impressive. So, you talked about testing. What are some of the tests that you can do to investigate these?

Yuvaraj "Darren" Kumar, MD, FACC, FSCAI, RPVI: Well, there are three major categories. There's cardiac MRI, and there's cardiac PET scanning that we can look into. And we're looking at tissue perfusion by flow on these scans. And this requires a great amount of expertise by cardiologists who are involved in imaging and can do this. And as we already know, PET is not widespread available yet. MRI is getting there. The more widespread and probably tried and true method is going to be the invasive coronary angiogram, and putting a pressure wire down into the coronary artery to do these testing and pressure measurements.

Host: Got it. Okay, so that helps us actually see the blood flow into that microvascular system.

Yuvaraj "Darren" Kumar, MD, FACC, FSCAI, RPVI: So, a couple of things. There's two parts to testing in the cath lab. First, after we've ruled out major epicardial vessel, we can give acetylcholine intracoronary and look for spasm. So we'll see that, and if we don't see it, but the patient has their typical symptoms of angina or EKG changes, but the vessels look the same, then we can probably say they have micro vessel spasm.

But once we've excluded spasm, whether epicardial or microvessel, that we then put a specialized wire down the coronary artery and typically the LAD since it's the biggest, and we can measure flows, by similar to what we do when we do cardiac outputs with a Swan-Ganz catheter.

And by measuring these flows, we can get a good assessment of the microvessel flow. This is very similar to what interventional cardiologists do when they do fractional flow reserve or IFR measurements to measure the severity of a stenosis in the epicardial vessel.

Host: So, now that we are coming through diagnosis, what type of management is there for these patients? So, once we've diagnosed this as CMD, not CAD, what do we do to help manage the patient?

Yuvaraj "Darren" Kumar, MD, FACC, FSCAI, RPVI: This is where we kind of run into some trouble. This is kind of similar to heart failure with preserved ejection fraction, where we just don't have as many treatment options as we do for heart failure with reduced ejection fraction. So for spasm, we can think about using calcium channel blockers, but now we have a definitive diagnosis where we may be having these patients on beta blockers, we could switch them to calcium channel blockers and see. For microvessel disease due to abnormal tone, we can look into beta blockers or long acting nitrates. Or we can think about ranolazine as an alternative agent. This is a field where we're getting better at making the diagnosis, but unfortunately, treatment options are still not quite available, and hopefully, as we get more people and centers involved, we can get more databases and look into treatment strategies and see what could be more beneficial for our patients to keep them angina free and hopefully from presenting to the ER with continued chest pain.

Host: Yeah, because I can see this as a recurrent symptom. And, you know, it would be confusing even, me as an emergency physician, you're coming in with anginal type symptoms, but I'm looking at your cath report saying that your vessels are clean. So, yeah, that's huge. So what type of heart specialist would usually help manage this kind of patient? And how would you approach it kind of in a, in a multidisciplinary fashion?

Yuvaraj "Darren" Kumar, MD, FACC, FSCAI, RPVI: It requires, probably a collaborative effort from both general cardiologists, interventional cardiologists as well. And there's a big role with the primary care provider, as well, and including emergency room physicians to be more familiar with this terminology and what's going on and understanding what coronary microvascular disease is.

So I see it across the spectrum from the front lines all the way to the physician in the cath lab and in working together. I just don't see it as we're going to send you to a microvascular disease specialist. I think it's going to be a team based approach and working together on different fronts of looking at all sorts of things, to optimize patients' risk factors and educating them on what is going on as far as microvascular disease diagnosis and management.

Host: How about lifestyle changes? Would that impact how one might manage CMD?

Yuvaraj "Darren" Kumar, MD, FACC, FSCAI, RPVI: Absolutely. As just with about every other disease out there, especially heart disease, lifestyle is probably the first and foremost thing. And obviously, no smoking and most importantly, exercise because that's going to improve vasomotor tone.

 That's going to be key as to really emphasizing lifestyle with exercise and good habits of no smoking and weight loss and those measures that we do traditionally.

Host: Sure. So, any new research insights, treatment for CMD that you are finding particularly promising for what's upcoming?

Yuvaraj "Darren" Kumar, MD, FACC, FSCAI, RPVI: That's unfortunately one of the shortcomings of CMD. It's relatively new. There are multiple centers getting more and more involved. NYU, Cleveland Clinic, Stanford, are all major centers that have cardiologists who are very involved in starting up trials, to start looking into more standardized methods of doing these procedures in the cath lab, so we're more universal in diagnosing these patients and being more consistent.

 There's a big center of big studies coming out of NYU that are enrolling patients that hopefully will give us more insight into what treatment options we can offer patients. But unfortunately, this is a field that needs more attention and more participation in research and we're hoping to do this here in our institution in collaboration with other institutions in the Metroplex.

Host: Yeah, that's fascinating. I love seeing things on the frontier and, you know, we're advancing medicine every day and it's great to talk to folks who are actually in the middle of doing that. So what advice would you give to a primary care physician if they're managing patients who may be presenting with symptoms of CMD?

Yuvaraj "Darren" Kumar, MD, FACC, FSCAI, RPVI: The first thing I would say is let's optimize their risk factors. Do we have their blood pressure under control? Are they not smoking? Can we get them to exercise more? Get their diabetes under better control. And if they've undergone extensive cardiac evaluation and you're like, you know, you already had a normal angiogram or you've already had a normal stress test or a coronary CT angiogram and the patient is continuing to have symptoms; I think this is the patient you want to kind of have this idea in the back of your head to present this to the patient and discuss it with them and their family and have a good relationship with a cardiologist who will be willing to see these patients and discuss it further.

In my experience, I've had several patients where we've done a normal angiogram and just giving the patient the diagnosis that you do actually have some microvascular dysfunction gave them a sense of relief that they actually do have a disease process and actually made them somewhat feel better. They weren't thinking they were crazy and this was all made up and that sometimes is worth its weight in gold.

Host: It absolutely is. And having, you know, as like I said, as an emergency physician, taking care of patients with chest pain, and sometimes you don't have a clear diagnosis. This is great, kind of cutting edge stuff. I really love it. Anything else that you'd like to, to end with before we kind of close out today?

Yuvaraj "Darren" Kumar, MD, FACC, FSCAI, RPVI: Sure, I think this is hopefully going to continue to grow, and as we build public education and awareness of this, we can hopefully help more patients out. I think there are a lot of patients who are undiagnosed, underdiagnosed, and are frustrated that they don't have an answer to the problem that may be, that we may now have tools to help them better understand what's going on.

We have to again, emphasize that we don't have specific treatments, but as with anything new in medicine, we have to start somewhere and hopefully with more research, understanding trials, and patient participation, we will find treatment options just like we have for other disease processes to hopefully help improve quality of lives of our patients.

And, it is a low risk procedure compared to many other things that we do in the cardiac cath lab. So that's another advantage for patients, to uh not be scared of, this procedure to investigate things further.

Host: Yeah, you bet. Dr. Kumar, thanks so much. I have learned a ton today by talking with you.

Yuvaraj "Darren" Kumar, MD, FACC, FSCAI, RPVI: Well, thank you so much, Bob. Enjoyed talking to you.

Host: And thank you to our audience for joining us today on HeartSpeak Consult. If you'd like more information or to make a referral regarding coronary microvascular disease or dysfunction, please reach out to a program nurse navigator at Baylor Scott & White Heart & Vascular Hospital, Fort Worth at 817-922-7132, 817-922-7132. If you found this podcast helpful, please share it on your social channels and be sure to check out the entire podcast library for topics of interest to you. Baylor, Scott & White, Heart & Vascular Hospital, Dallas Fort Worth and Waxahachie, Joint Ownership with Physicians.