Cardiac Syndrome X and Microvascular Angina - Doctablet®

Cardiac Syndrome X and Microvascular Angina


Angina is the name for the type of chest pain people feel when poor circulation starves their heart of blood.  When describing what causes angina, doctors often compare the arteries of the heart to blocked pipes. We can think of “unclogging pipes” or “releasing a blockage” when we consider the treatment procedure: a stent. Sometimes people have angina, but their coronary arteries are not blocked. The analogy of a blocked pipe then stops making sense. This is not surprising, because the heart’s circulation is much more complicated than rigid metal pipes. Now the problem is somewhere else: in the tiny capillaries that dig into the heart muscle to feed it with blood. 

This condition has many names, but it is commonly called
“Cardiac Syndrome X” or CSX for short

What is Cardiac Syndrome X?

Cardiac Syndrome X is also known as microvascular angina, microvascular disease or microvascular dysfunction. The symptoms of Cardiac Syndrome X are the same as those that result from a blocked artery in your heart. They include chest pressure or burning when a person walks and limiting shortness of breath with activity. Recent studies have recognized that people who suffer from CSX are at a much higher risk of having heart attacks, strokes and heart failure. Microvascular disease is different than classic coronary artery disease. It is less well understood and its treatment challenging.


Cardiac Syndrome X and Microvascular Angina: causes and treatments.
Where does the name “Cardiac Syndrome X” come from?

The name Cardiac Syndrome X was first presented in an editorial commentary published in 1976. It described a group of patients labeled as “X,” who all had signs of a heart attack while their hearts were being exercised but had normal coronaries. It is important to avoid confusing Cardiac Syndrome X with what some doctors call “Metabolic Syndrome X,” which is something else altogether.

What causes Cardiac Syndrome X?

To understand how Cardiac Syndrome X occurs, we need to take a short tour inside the heart muscle and peek at how its circulation works in broad terms. The arteries that feed blood to the heart are much more than rigid metal pipes. Arteries operate much like large organs in the body do: reacting to the environment and modifying their function as needed. When we exercise, the body’s demand for energy and oxygen goes up, so the heart starts pumping faster and stronger. When blood begins to rush through the arteries that feed blood to the heart, the walls of these arteries stretch. This stretching causes the release of substances that travel downstream, directing the small capillaries that penetrate the muscle to plump so they receive and deliver more blood. More blood being injected into the heart muscle allows it to squeeze stronger and faster. Microvascular dysfunction is a problem caused by a breakdown of this process. When a person suffering from Cardiac Syndrome X exercises, the capillaries that feed blood to the muscle do not work like they are supposed to. They do not plump to deliver more blood, so the heart muscle struggles without the blood supply it needs. This causes angina and shortness of breath. The mechanisms that cause the tiny blood vessels in the heart to plump when necessary are complex and incompletely understood. Still, several different things are well recognized to be related to the problem:

  • Inflammation

    This is caused by the damage to the blood vessels and capillaries from things like unhealthy diets and smoking

  • Low levels of the good type of cholesterol: HDL

    High levels of HDL are believed to protect the vasculature, and are seen in people who exercise regularly and avoid the trans-fat found in fried foods.

  • Insulin resistance, diabetes and pre-diabetes

    High levels of insulin in the blood are well known to be present in patients suffering from Cardiac Syndrome X.

How is Cardiac Syndrome X diagnosed?

Diagnosing CSX is very challenging. Today, it is usually diagnosed by exclusion. When someone presents with angina symptoms, he or she usually undergoes stress testing first. If a stress test shows the heart muscle is, in fact, starving of blood, a coronary angiogram follows to look for a blockage. If symptoms are typical for Cardiac Syndrome X and the coronaries are not blocked, a presumptive diagnosis of Cardiac Syndrome X can be made.Today there are tests available to diagnose microvascular dysfunction objectively. These tests are actually seldom used in practice. They involve injecting medications into the heart’s circulation that causes the normal plumping of the microvessels and measuring the amount of blood that is able to enter into the heart muscle.

How is Cardiac Syndrome X treated?

Treatment for Cardiac Syndrome X should be directed by an experienced doctor. Since there are no specific guidelines for its treatment, the approach is multifaceted. It is often necessary to try different strategies when treating the microvessels. Different medications that can be used in Cardiac Syndrome X.

Different medications that can be used in Cardiac Syndrome X :
  • Calcium channel blockers like Amlodipine and Nifedipine produce dilatation of the arteries of the body.
  • Nitrates like nitroglycerine and Isosorbide also cause the dilatation of arteries and veins in the body.
  • Antianginals like Ranolazine, the mechanism by which this agent reduces angina, is not well understood. It involves the regulation of the electrical conduction across the heart cells.

When treating Cardiac Syndrome X, it is important to pay attention to your metabolic health. This is measured by the following:

The amount of exercise you do
How much you weigh
Your measure of insulin resistance by way of HgbAIC or fasting glucose, HDL and triglyceride levels

Improving metabolic health and getting rid of the metabolic syndrome may improve the function of the body’s microcirculation and improve microvascular angina. Finally, there is some evidence that plant-based diets may help improve microvascular function by improving metabolic health and reducing the intake of substances present in animal-based diets that provoke microvascular dysfunction.

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Last Modified: Jul 28, 2018 @ 7:20 pm
About the Author

Jose Taveras M.D. F.A.C.C.


Dr Taveras works as a cardiologist caring for spanish speaking communities in the Bronx. He completed a dual residency in Internal Medicine and Pediatrics and then served as chief resident of internal medicine at the St. Vincent’s Catholic Medical Center of New York. He went on to specialize in cardiovascular disease at NYU Winthrop Hospital , under the mentorship of Dr. Kevin Marzo, chief of Cardiology at Winthrop. He is board certified in both internal medicine and cardiovascular diseases, and sub specializes in echocardiography, nuclear cardiology and computed tomography of the heart. Apart from his work in community outreach, Dr. Taveras' career focuses on innovation and technology. Dr. Taveras is a fellow of the American College of Cardiology. 

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