A silent heart attack is a heart attack that occurs without symptoms or with unrecognized symptoms. A person may not know they had a heart attack until they receive a diagnosis after weeks or months have passed.

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 refers to a lack of blood flow to the heart that occurs without pain often associated with blocked arteries. As a result, the heart attack often goes unnoticed, and a person may not have sought help.

An individual may dismiss symptoms that do occur as simple fatigue, a strained muscle, or indigestion. They may only learn of having 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.

The authors of a 2018 study found that people who have had a silent heart attack have the same long-term survival as those with ordinary heart attacks.

They note 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 other survivors of 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 a 2018 study, a person who has had a silent heart attack has an estimated 35% increased risk of heart failure. People in their early 50s or younger have an even greater risk increase.

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

Learn about the risks of an untreated heart attack here.

According to the AHA, some studies indicate that females living with diabetes have an increased risk of having a silent heart attack.

However, research from 2021 suggests that the number of incidents of silent heart attack is higher among males than females. The researchers go on to note that females may be at a higher risk of complications than males.

Other risk factors for a silent heart attack include:

Some people may not experience any symptoms or signs of a silent heart attack, which doctors may later detect through tests, such as an electrocardiogram, or ECG, and echocardiogram.

Other individuals may experience nonspecific symptoms that they do not recognize as a sign of a heart attack. These can include:

  • excessive, prolonged fatigue
  • indigestion
  • a feeling of a strained muscle in the back or chest

Other symptoms may include:

Learn more about the signs of a heart attack here.

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

When blood flow to the heart stops for around 15 minutes, the heart can become damaged. After about 30 minutes, the damage is irreversible. However, these time scales can vary.

When the symptoms manifest, a person should immediately seek treatment to restore blood flow and prevent critical tissue in the heart from dying or becoming damaged.

Learn about the different stages of a heart attack here.

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

An individual should contact a doctor as soon as possible if they or someone else experiences:

  • unexplained shortness of breath
  • excessive fatigue
  • a feeling of a strained chest muscle or back

Although these may be signs of a silent heart attack, a doctor can help rule out other conditions that may explain them.

Learn about stopping a heart attack here.

A lack of oxygen-rich blood to all or part of the heart leads to a heart attack. The majority of heart attacks occur due to ischemic heart disease. This condition develops when there is a buildup of plaque in the coronary arteries.

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

Although 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

If a person recognizes the symptoms and seeks medical attention right away, an emergency room doctor will likely use one or more of the following treatments:

  • nitroglycerin, which improves blood flow and reduces burden on the heart
  • aspirin, which prevents clotting
  • oxygen therapy

If symptoms go unnoticed, as is often the case in silent heart attacks, a doctor may take steps to ensure that blood continues to flow to the heart. The primary treatment options include medications that break up clots and percutaneous coronary intervention, which is a surgical procedure to help open up the arteries.

Other treatments may include:

  • use of beta-blockers
  • therapy to help reduce stress on the heart
  • blood thinners

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

Some tests that can help a doctor diagnose a silent heart attack include:

The AHA also suggests that females should make sure to advocate for themselves or bring a person along to help advocate for them. It warns that doctors can often dismiss the symptoms as related to anxiety.

Learn about blood tests and heart attack diagnoses here.

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

Others may experience increased exercise intolerance or an increased heart rate following a heart attack.

It is advisable for a person to seek guidance from a doctor about the steps they should take following a silent heart attack.

The outlook for a person who had a silent heart attack is similar to that for people who have noticeable symptoms of a heart attack. They have an increased risk of:

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

Improving the outlook

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

Some actionable steps an individual can take to improve their outlook include:

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

A silent heart attack occurs with no or unrecognized symptoms. A person may only discover they had a silent heart attack months or years later.

When symptoms do occur, they may include fatigue, a feeling of a muscle spasm in the back or chest, or nausea.

Treatment will depend on when a person discovers they had a heart attack. Doctors will likely recommend preventive medication as well as lifestyle changes following a heart attack. Taking these steps can help a person prevent future heart attacks and other potential complications.