The coronary arteries are an important part of the circulatory system, allowing oxygenated blood to flow into the heart. Coronary artery fistulas are irregular connections between coronary arteries and other parts of the circulatory system, such as the heart.

They occur in less than 1% of the general population, but they can cause health complications.

Most of coronary artery fistulas are present at birth. Although largely asymptomatic, meaning they cause no symptoms, they can sometimes lead to serious conditions, such as heart attack or heart failure. However, there are some effective means of treating this type of fistula.

In this article, we discuss coronary artery fistulas, including symptoms, causes, diagnosis, treatment, and prognosis.

The majority of coronary artery fistulas do not cause any symptoms. On average, coronary artery fistulas will remain asymptomatic for around 20 years.

However, some coronary artery fistulas can cause noticeable changes within a person’s body, including:

Many of these symptoms arise because coronary artery fistulas may prevent the heart from receiving enough blood. The coronary arteries work to direct blood into the heart.

Blood is important for the heart, because the heart needs the oxygen and nutrients present in the blood. Without these, the heart becomes unable to pump blood around the body. This can lead to heart attack and heart failure, causing symptoms such as chest pain and shortness of breath.

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A diagram of the heart and its arteries showing a coronary artery fistula. Infographic by Jason Hoffman.

There are several causes of coronary artery fistulas.

Around 90% of coronary artery fistulas are congenital, meaning they are present from birth.

Congenital coronary fistulas may also arise when certain temporary embryonic connections between coronary arteries and the circulatory system do not degrade properly.

The remaining coronary artery fistulas, which doctors call acquired, can also arise for several reasons. For instance, they can result from cardiac trauma to the circulatory system, such as gunshot wounds or stab injuries.

Interventional cardiac procedures can also lead to coronary artery fistulas. These procedures include:

Likewise, cardiac conditions, such as heart attack, can result in coronary artery fistulas.

Most coronary artery fistulas are small, do not cause complications, and resolve spontaneously.

However, when fistulas are larger, with more blood flowing where it should not, they may cause symptoms and complications that require treatment.

The most common and effective treatment for coronary artery fistulas is catheterized closure.

During this procedure, a healthcare professional will place a very narrow tube, or catheter, into the affected coronary artery. A doctor can use the catheter to place tiny balloons or micro-coils into the coronary artery.

Doctors can block the irregular connection by placing these micro-coils or balloons around the fistulas.

There are several methods to diagnose coronary artery fistulas, including:

  • Electrocardiogram: This test can help detect changes in heart function by measuring the electricity in a person’s heart.
  • Chest X-ray: This can help detect more serious complications of coronary artery fistulas, such as pleural effusion from heart failure.
  • MRI scan: This test can help more definitively confirm the presence or absence of fistulas.
  • Coronary angiography: Doctors use this test to look at the coronary arteries. A traditional angiogram uses X-rays and a dye to look at a person’s blood vessels, with a catheter inserted into the arteries to disperse the dye. A coronary CT angiogram is a noninvasive scan that provides a more detailed X-ray. It involves injecting the dye in a person’s wrist instead of using a catheter.

A healthcare professional will assess the coronary artery fistulas they detect, along with any health complications these may be causing.

According to a recent study, many people with coronary artery fistulas do not experience any symptoms, which is why doctors often do not detect the condition early.

This makes it difficult to accurately estimate life expectancy of people with the condition. The outlook for people with coronary artery fistulas depends on many factors.

Some individuals with coronary artery fistulas never experience any symptoms. However, for those who develop complications, the outlook varies depending on the associated condition.

For instance, coronary artery fistulas can lead to heart attacks. When acute, heart attacks have a mortality rate of 5–30%.

Coronary artery fistulas can also lead to congestive heart failure. According to research, a person hospitalized with congestive heart failure has a 10% risk of dying within 30 days. This mortality rate rises to 22% within 1 year and to 42% within 5 years.

Although these figures are high, coronary artery fistulas are benign for many people.

Coronary artery fistulas are uncommon, irregular connections between the coronary arteries and other parts of the circulatory system.

The vast majority of this type of fistula are asymptomatic for many years and can remain so during a person’s lifetime.

In some cases, however, coronary artery fistulas can lead to serious health issues, such as heart attack and congestive heart failure.

A person who experiences shortness of breath and swollen legs should contact a healthcare professional about assessment.

Anyone who experiences chest pain should seek immediate medical attention.