Alcohol types

MINOCA heart attack: definition and types

A heart attack occurs due to a loss of blood supply to part of the heart. It often results from a blockage in a nearby artery. However, when a person suffers a heart attack that is not due to a blockage in an artery, experts may call it MINOCA.

A heart attack or myocardial infarction can be life-threatening and requires immediate medical attention. It is crucial to recognize warning signs, such as chest pain and difficulty breathing, as soon as possible and seek prompt treatment.

In this article, we will discuss what a MINOCA is, the difference in its symptoms, and possible causes.

MINOCA stands for “myocardial infarction with non-obstructive coronary arteries”. This is a heart attack that occurs without any blockage in the arteries.

Clinicians define a MINOCA as an acute myocardial infarction without obstructive coronary artery disease and no obvious cause. Research suggests that 6–14% heart attacks occur without blockage in the arteries.

Most heart attacks result from blocked arteries due to plaque buildup, known as atherosclerosis. Plaque is made up of cholesterol, deposits and other substances. When it builds up in the arteries, it can narrow or block them, which can slow the flow of oxygenated blood to the heart, increasing the risk of a heart attack.

Non-obstructive coronary artery disease occurs when there is an interruption in the blood supply to the heart, but a person does not have a blockage in their arteries. To diagnose this condition, the plaque in the blood vessel must block less than 50% arteries.

MINOCA and heart attacks resulting from blocked arteries tend to be similar. However, their underlying causes and the people they affect may differ.

Different types of MINOCA may include:

Spontaneous coronary artery dissection (SCAD)

SCAD occurs when the wall of an artery suddenly tears. Arterial walls have layers. When a tear occurs, blood can pool between these layers and create a bulge that can disrupt blood flow. Evidence suggests that 90% of SCAD cases occur in women, accounting for around a quarter of heart attacks in women under 60.

Doctors aren’t sure what causes such a sudden tear in an artery, but they think it may be a combination of factors, including:

  • genetic
  • hormones
  • systemic inflammatory diseases
  • fibromuscular dysplasia

Coronary artery vasospasm

A coronary artery vasospasm describes the spontaneous narrowing of a heart artery. This can happen if a person takes certain medications or stimulants that can cause blood vessels to constrict. When this happens, it can disrupt blood circulation. Also known as vasospastic angina, it is a common cause from MINOCA.

Microvascular disease

Microvascular disease refers to a condition that affects the walls and inner lining of the small blood vessels that branch off from the arteries of the heart. Damage to these walls and linings can restrict blood flow to the heart and cause blood vessels to spasm. A study 2022 found that about half of people with MINOCA had microvascular disease.

Stress cardiomyopathy

Stress cardiomyopathy, also known as broken heart syndrome or takotsubo syndrome, occurs when a person experiences sudden stress that can weaken the left ventricle of the heart, making it less able to pump blood efficiently.

Although the exact mechanism is not known, doctors believe it may be due to a sudden increase in stress hormones that affect the muscles and blood vessels connected to the left ventricle. However, research has shown that 1 out of 5 people report no stressful events before their symptoms, and it can also occur after positive life events.

muscle problems

Another potential cause of myocardial infarction is a problem with the muscles of the heart. For example, when heart tissue becomes inflamed, called myocarditis, it can damage muscles and prevent the heart from pumping blood. Myocarditis can occur due to infections, medications, and autoimmune diseases. Evidence suggests that myocarditis is present in 33% of MINOCA cases.

A study 2018 suggests that MINOCA occurs more frequently in younger people and people assigned female at birth, with women being 5 times more likely to experience MINOCA than men.

Some evidence also suggests that people with MINOCA are less likely to have traditional cardiovascular risk factors, such as a history of smoking, diabetes and obesity, and a family history of coronary heart disease.

However, some potential risk factors may include:

  • an increased risk of blood clotting problems
  • anxiety and depression
  • cancer
  • autoimmune conditions
  • infectious diseases, such as pneumonia, sepsis, and respiratory infections
  • hormones related to pregnancy, contraception and hormone replacement therapy

MINOCA tends to have symptoms similar to heart attacks that occur due to other causes. Some possible symptoms of a heart attack to understand chest pain, pain radiating elsewhere, shortness of breath and nausea. It should also be noted that MINOCA is more common in women, who may experience slightly different symptoms, such as fatigue and a general feeling of being unwell.

If a person thinks they may be showing symptoms of a heart attack, it is important that they see a doctor immediately. The earlier a person receives help, the more likely they are to recover.

A doctor can diagnose MINOCA when a person has signs of a heart attack without a blockage in their arteries. They will perform other tests to help them rule out other possible causes for the symptoms a person is experiencing.

For example, to look for blockages in arteries, a doctor may use a special type of x-ray called coronary angiography. This is a diagnostic test that uses x-rays and contrast dye to help detect blockages in a person’s arteries. Other diagnostic tests that can help determine the underlying cause of MINOCA may include:

MINOCA can occur for several reasons, so a doctor will manage each case individually by treating the underlying cause. Depending on the exact cause, a doctor may use one or a combination of the following treatments:

If a person is concerned about their heart health, they may wish to see a doctor to discuss their concerns and ways to minimize their risk of cardiovascular disease. If a person suspects the symptoms of a heart attack, it is vital that they seek emergency help immediately, because faster medical intervention can reduce the amount of damage to the heart.

Heart attacks that occur without plaque blockage in the arteries are known as MINOCA. This term means “myocardial infarction with non-obstructive coronary arteries”.

The symptoms of MINOCA are largely similar to the signs of a heart attack that occurs due to an obstruction. However, they have different risk factors and occur more often in younger women.

There are many different types and causes of MINOCA, which may require specific diagnostic tests for a doctor to find. A medical professional may prescribe various treatments depending on the underlying cause.