Coronary artery aneurysm (CAA) is when a section of the coronary artery widens to more than 1.5 times the size of nearby sections. It can lead to a heart attack, rupture of the affected artery, and even sudden death.

The coronary artery that supplies oxygenated blood to the heart.

CAA often does not cause any symptoms until complications develop. As such, it is important that people are aware of the causes of and the risk factors for the condition.

This article describes what CAA is, including its symptoms, diagnosis, treatment, possible complications, and outlook.

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Coronary arteries are major arteries that deliver oxygenated blood to the heart.

There are two main coronary arteries: the right coronary artery and the left coronary artery. The left coronary artery branches into two further arteries: the left anterior descending artery and the circumflex artery. Together, the coronary arteries supply blood to the entire heart muscle.

Each of the coronary arteries consists of different sections, or segments. CAA is a rare condition in which a segment of a coronary artery enlarges, or dilates, more than 1.5 times the diameter of adjacent segments.

According to the American Heart Association (AHA), an aneurysm occurs when a portion of an artery wall weakens, allowing that part to bulge or balloon outward. The ballooned section is at risk of rupturing and may put pressure on nearby structures.

Researchers are still unsure as to the exact cause of CAA. However, it likely develops similarly to other types of aneurysms that impact large blood vessels. This process involves the following:

  • damage to and thinning of the inner wall of the artery
  • increased pressure or stress on weakened artery walls
  • increasing dilation of the affected section of the artery

Below, we discuss some conditions that can cause CAA.


Atherosclerosis is a condition in which the inner walls of the arteries become lined with a substance experts call arterial plaque. This substance consists of fat, cholesterol, calcium, waste products, and a clotting material called fibrin.

In atherosclerosis, arterial plaque causes the arteries to narrow and harden, impeding their ability to carry oxygenated blood.

Atherosclerosis accounts for more than 90% of cases of CAA.


Most people with atherosclerosis do not experience any symptoms until an artery becomes completely blocked. At this stage, the most common symptoms of atherosclerosis include:

  • chest pain
  • difficulty breathing
  • pain in a limb, which may indicate a blocked artery in that area
  • muscle weakness
  • fatigue
  • confusion, due to impaired blood flow to the brain

Kawasaki disease

Kawasaki disease (KD) is a condition of unknown cause that presents with fever primarily in children under the age of 5 years.

Children with KD may develop acquired heart disease, which refers to types of heart disease that occur after birth.

KD is the leading cause of CAA in children.


KD may cause the following symptoms:

Takayasu arteritis

Takayasu arteritis (TA) is a condition that causes inflammation of the aorta, which is the main artery that carries blood away from the heart to the rest of the body. The condition can restrict blood flow, resulting in damage to the body’s vital organs and tissues.


TA may cause the following symptoms:

Percutaneous coronary intervention

Percutaneous coronary intervention (PCI) is a nonsurgical procedure that involves inserting a stent into a blood vessel that has become narrowed by atherosclerosis.

A stent is a small device that helps dilate a blood vessel, thus easing blood flow.


People who undergo PCI may experience symptoms health experts associate with atherosclerosis, such as:

  • chest pain
  • difficulty breathing
  • muscle weakness
  • fatigue

Congenital heart defects

Congenital heart defects are conditions in which the heart or the blood vessels surrounding the heart do not develop properly before birth.

Congenital CAA accounts for around 20–30% of CAA cases.


Symptoms of congenital heart conditions vary depending on the type of the condition a person has.

Some congenital heart conditions are very mild and do not cause any symptoms or health complications. Others can be severe and may require treatment with medication or surgery.

Connective tissue disorders

Some genetic disorders that impact the connective tissues can cause CAA. Examples include Marfan syndrome and Ehlers-Danlos syndromes (EDS).


Symptoms of Marfan syndrome include:

  • slim body and taller than average height
  • long limbs
  • excessive curvature of the spine
  • crooked teeth
  • eye conditions
  • collapsed lungs

Symptoms of EDS include:

  • extreme joint flexibility
  • joint instability
  • frequent dislocations
  • joint deformities
  • scoliosis, which is a sideways curvature of the spine
  • skin that can stretch more than usual
  • unusual scarring

Other causes

Some other conditions that may weaken or damage arteries and contribute to the development of CAA include:

  • infections
  • noninflammatory and non-atherosclerotic vascular disease
  • fibromuscular dysplasia, a rare blood vessel condition in which the body replaces flexible cells within the arteries with cells that are more fibrous
  • drug use, including the use of cocaine, amphetamine, or protease inhibitors

To diagnose CAA, a doctor will ask a person about their symptoms and their personal and family medical history.

Also, the doctor may use several imaging tools, including:

However, the most common method for confirming a CAA diagnosis is coronary angiography with intravascular ultrasound.

Coronary angiography is a special type of invasive test that uses X-ray technology and a contrast dye to help determine the shape, location, and size of aneurysms. It can also help establish the degree of atherosclerosis in the arteries.

Intravascular ultrasound is an ultrasound of the arteries. It provides information about the structure of artery walls and the inner composition of the arteries. The procedure can help detect the type of aneurysm a person has.

There is no consensus on the best treatment or management options for CAA. The optimal approach depends on several factors, including:

  • a person’s signs and symptoms
  • the cause of the aneurysm
  • the aneurysm’s size, location, and progression
  • the presence of coexisting atherosclerosis

Below are some potential treatment and management options for CAA.

Medical treatment

Medications and therapies are available to help treat CAA, manage contributing factors, and prevent the progression of the condition.

Examples include:


PCI involves inserting a stent or small coil in the affected blood vessel to keep the blood flowing. The procedure can help prevent complications resulting from impaired blood flow.


A doctor may recommend surgery in cases of CAA that are not treatable using more conservative methods, such as medication and PCI.

Surgery may involve procedures to:

  • repair the weakened section of the artery
  • remove, or resect, the aneurysm
  • tie off, or ligate, a part of the artery to reduce blood flow to the aneurysm
  • remove blood clots
  • bypass the aneurysm

People with CAA may experience several complications, some of which can be life threatening.

Examples include:

The outlook for a person living with CAA depends mostly on the size of the aneurysm.

In many cases, small aneurysms have a low risk of severe complications. By contrast, large aneurysms have a high risk of causing severe complications and death.

Around 50% of large aneurysms that health experts associate with CAA result in obstruction of the artery, which may cause:

  • heart arrhythmias
  • heart attack
  • sudden death

It is important to contact a doctor for a medical evaluation if a person is experiencing symptoms of CAA. They should also get regular checkups if they have a personal or family history of conditions that may increase their risk of CAA.

Appropriate treatment and management of CAA will help prevent possible complications of the condition.

CAA is a rare condition in which a section of the coronary artery significantly dilates and thins out. This can lead to severe, potentially life threatening complications, such as heart arrhythmia, heart attack, and rupture of the affected artery.

A person with CAA may be unaware that they have the condition, as symptoms typically do not appear until an artery becomes entirely blocked.

It is therefore important that people receive regular checkups if they have a personal history of conditions that can increase their risk of CAA, such as atherosclerosis, congenital heart defects, or connective tissue disorders.

The outlook for CAA is typically more favorable for smaller aneurysms, with health experts generally associating larger aneurysms with a greater risk of complications.

However, timely treatments in the form of medications, a PCI, or a surgery can help manage the condition and prevent complications from occurring.