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A silent heart attack is a heart attack that occurs without symptoms or with unrecognized symptoms. A person might have a heart attack and not know it until they receive a diagnosis weeks or months later.

This article discusses the signs of a silent heart attack. It also outlines risk factors, recovery, and outlook for people who have had a silent heart attack.

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A silent heart attack is a lack of blood flow to the heart, often resulting from blocked arteries, that occurs without pain. Because there is no pain, a person may not know they have had a heart attack and may not seek medical attention.

An individual may dismiss any symptoms that occur as simple fatigue, a strained muscle, or indigestion. They may only learn they have had a heart attack if they undergo testing for other symptoms.

According to the American Heart Association (AHA), silent heart attacks account for around 170,000 of the estimated 805,000 annual heart attacks.

Learn more about cardiovascular health in our dedicated hub.

A 2018 study found that people who have had a silent heart attack have the same long-term survival as those who have had ordinary heart attacks. The authors found that about half of all survivors of a silent heart attack died within 10 years of the incident, which is the same rate as for survivors of other heart attacks.

However, people who have had a silent heart attack may be at risk of other complications, such as heart failure and stroke.

According to another 2018 study, a person who has had a silent heart attack has an estimated 35% higher risk of heart failure than a person without a history of heart attacks. People in their early 50s or younger have an even greater risk increase.

Moreover, a 2021 study suggests that people who have experienced a silent heart attack may have an increased risk of stroke later in life.

Learn about the risks of an untreated heart attack.

According to the AHA, silent or unrecognized heart attacks may occur more often in females than in males.

Risk factors for a silent heart attack, which are the same as for a recognized heart attack, include:

Some people may not experience any symptoms or signs of a silent heart attack, while others may experience nonspecific symptoms that they do not connect to a heart attack. These can include:

Learn more about the signs of a heart attack.

The duration of a silent heart attack can vary. If a person experiences symptoms, they should seek medical attention immediately.

When blood flow to the heart stops for around 20 minutes, the heart can sustain irreversible damage. However, this time frame can vary.

Learn about the different stages of a heart attack.

An individual who suspects they have symptoms of a heart attack should seek emergency medical attention immediately. They should call 911 and get an ambulance to take them to the hospital.

Learn about stopping a heart attack.

A lack of oxygen-rich blood to all or part of the heart leads to a heart attack. Most heart attacks are due to atherosclerotic heart disease. This condition develops when plaque builds up in the coronary arteries.

In some cases, a portion of plaque can break free and form a blood clot. If the clot grows, it can cause a blockage that prevents blood from reaching the heart.

Although this is less common, a severe spasm or tightening of a coronary artery can also lead to a heart attack. The spasm stops blood from reaching the heart. Health experts do not know the exact cause, but several factors may play a role, including:

  • exposure to extreme cold
  • stress or pain
  • smoking
  • use of certain drugs

Since a person will likely not notice symptoms or associate them with a silent heart attack, they may receive a diagnosis after the heart attack has occurred. A doctor may not diagnose a silent heart attack until they check for other conditions.

The following tests can help a doctor diagnose a silent heart attack:

Because of disparities in the way healthcare professionals recognize and treat heart attack symptoms in women, the AHA recommends that women be suspicious of any symptoms of a possible heart attack and advocate for themselves to ensure appropriate testing and treatment.

People should avoid using the term “anxiety attack” when describing their symptoms to reduce possible bias that could lead healthcare professionals to an incorrect diagnosis.

Learn about blood tests and heart attack diagnoses.

When a person presents with heart attack symptoms, an emergency room doctor will begin medical therapy immediately and call a cardiologist to assess whether the person needs emergency stent placement.

Immediate medical therapies include:

  • aspirin, which prevents clotting
  • other anticoagulants, such as heparin
  • nitroglycerin, which improves blood flow and reduces the burden on the heart
  • beta-blockers
  • oxygen therapy

If doctors diagnose a previous silent heart attack, they may recommend that a person take medications such as the following to help lower the risk of a future heart attack:

  • aspirin
  • statins
  • beta-blockers
  • blood pressure-lowering medications such as ACE inhibitors or angiotensin receptor blockers

A person may not know for several years that they have had a silent heart attack. They may only discover it when they visit a doctor for a routine exam or other health issues.

Some people may experience decreased exercise tolerance, fatigue, or an increased heart rate after a heart attack.

It is advisable for a person to seek guidance from a doctor about steps to take after a silent heart attack.

The outlook for a person who has had a silent heart attack is similar to the outlook for people who have noticeable symptoms of a heart attack. A person will have an increased risk of:

  • another heart attack
  • heart failure
  • stroke
  • sudden death

Making small lifestyle changes may help improve a person’s outlook.

Actionable steps an individual can take to improve their outlook include:

  • regularly monitoring their blood pressure and cholesterol
  • exercising regularly
  • informing a doctor about any unusual symptoms
  • avoiding smoking
  • eating a balanced diet with plenty of fruits, vegetables, lean meats, and whole grains

A silent heart attack occurs without recognizable symptoms. People may not learn that they have had a silent heart attack until months or years later.

Possible symptoms include fatigue, a feeling of a muscle spasm in the back or chest, and nausea.

Treatment will depend on when a person discovers they have had a heart attack.