Coronary Microvascular Dysfunction: Treating an Underdetected Disease

Your heart is your engine — you count on it to keep you going every day. So, it’s only natural to worry that something is wrong if you have chest pain or shortness of breath. And while it’s easy to make the leap to wonder if a heart attack or major narrowing in the heart vessels are to blame, that isn’t always the case. Sometimes, the problem lies in the smaller blood vessels of your heart that are not visible on routine coronary angiography (cardiac catheterization). An often-overlooked condition called coronary microvascular dysfunction may be to blame.[MN1] [MS2]

What Is Coronary Microvascular Dysfunction?

Coronary microvascular dysfunction (CMD) also called small vessel disease — is a heart condition that affects the smallest arteries that deliver oxygen-rich blood to your heart. These tiny vessels are so small, in fact, they don’t show up on standard angiograms (heart X-rays that let your doctor get a clear view of your heart and its blood vessels).

“If you have coronary microvascular dysfunction, your larger blood vessels can appear normal on the images we collect during a coronary angiogram. Instead, it’s your small vessels that are diseased. These cannot be visualized on a conventional angiogram and require other forms of testing,” says Diana Revenco, MD, a board-certified interventional cardiologist at AdventHealth Carrollwood.

The dysfunction of these small caliber vessels may cause microvascular angina, abnormal stress test and even heart attack.

Who Is at Risk for Coronary Microvascular Dysfunction?

According to the American Heart Association, CMD affects more women than men[NM3] . Women with low estrogen levels — especially women going through menopause — are particularly vulnerable.

However, although women are at higher risk, anyone can develop the condition. Other risk factors for CMD include:

• Autoimmune disease (lupus, rheumatoid arthritics, vasculitis)
• Cardiomyopathy (hypertrophic, ischemic and nonischemic)
• Chronic kidney disease
• Diabetes
• High cholesterol
• Hypertension (high blood pressure)
• Low activity level
• Metabolic syndrome
• Smoking

How Do We Diagnose Coronary Microvascular Dysfunction?

Standard cardiac tests like CT scans, MRIs or stress tests aren’t sensitive enough to detect CMD. Your exam results could come back normal even if you’re experiencing symptoms. That’s why the interventional cardiologists at AdventHealth Carrollwood use a specialized test to detect and diagnose this condition.

“We offer specialized coronary microvascular testing to diagnose you. Using a minimally invasive procedure, we can analyze how well the small vessels of your heart work,” Dr. Revenco says. “This test is a valuable tool because it does what coronary angiograms and stress tests can’t. It can search for and reveal any underlying small vessel disease.”

Who Needs Coronary Microvascular Testing?

We may recommend coronary microvascular testing if you have:

• Abnormal stress test results with a normal coronary angiogram (A condition called INOCA - ischemia with normal coronary arteries)
• Chest pain without noticeable artery narrowing on heart imaging ( a condition called ANOCA - angina with normal coronary arteries)
• History of heart attack with normal heart imaging (a condition called MINOCA — myocardial infarction with normal coronary arteries)
• Shortness of breath with no obvious cause

The test typically lasts between 30 and 60 minutes. It’s a safe procedure that only carries minor risks of complications like allergic reactions or bleeding. And in most cases, you can go home the same day.

How Do We Perform Coronary Microvascular Testing?

The coronary microvascular test is a straightforward process. We typically perform it during a cardiac catheterization — a procedure that lets us examine your heart and blood vessels. For this test, we:

• Insert a flexible, thin tube called a catheter into a blood vessel in your wrist or groin
• Thread a special wire with a sensor attached through the catheter
• Introduce medications that cause your blood vessels to expand and or constrict to test their function

What Coronary Microvascular Testing Measures

We measure several values during the procedure to be sure we have an accurate assessment of your blood vessels:

• Coronary flow reserve (CFR): This value measures how much blood flow to your coronary arteries increases when you’re under stress or when you’re exerting energy. It tells us how effective your heart is at boosting blood flow when it needs more oxygen. When your CFR is lower, so is your risk of experiencing a negative heart event.
• Microcirculatory resistance: This value reflects the blood flow and blood pressure inside your coronary arteries. We use a sensor-enabled wire to measure it. Higher IMR scores can diagnose microvascular angina.
• Vasodilator and or vasoconstrictor medication response: We test how your blood vessels respond to medications like acetylcholine, adenosine and methylergonovine. These medications trigger expansion in healthy blood vessels. Unhealthy or damaged blood vessels stay narrow or spasm more.

Overall, Dr. Revenco says CMD testing can play a critical role in diagnosis, tailoring therapy for chest pain symptoms and prognosis.

“It may be easy or tempting to dismiss your chest pain when imaging shows the major arteries in your heart appear healthy on routine testing,” she says. “But a problem may still exist. Coronary microvascular testing gives us an opportunity to identify your condition and intervene early, decrease your symptoms and reduce your chances of having a cardiovascular event.

Support When and Where You Need It

If you or someone you love is concerned about chest pain or other lingering symptoms, it’s important to seek medical care. Our cardiovascular specialists are ready to help you get back to feeling your best and to safeguard your overall health. Schedule an appointment today.

About Dr. Revenco

Dr. Revenco is a fellowship trained interventional cardiologist with board certifications in cardiovascular disease, echocardiography, nuclear cardiology, vascular ultrasound interpretation and internal medicine. With 11 years of experience in cardiovascular disease treatment and management, Dr. Revenco is dedicated to working with patients to help them understand their specific cardiac disease processes and reasons for therapies to help them excel and live their best lives.