Can you have a heart attack and not know it?

Medically reviewed on February 24, 2023 by Karen L. Janson, MS, MD. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Table of contents

• What is a heart attack?
• The dangers of silent heart attacks
• What are the signs of a silent heart attack?
• What are the risk factors for silent heart attacks?
• How do you know if you've had a silent heart attack?
• How to treat a silent heart attack
• How to prevent a silent heart attack
• Everlywell: take your heart health into your own hands
• Related content

When you think of a heart attack, you may envision someone clutching their chest, gasping for air, and collapsing to the ground. While some heart attacks present this way, not all of them do. In fact, some heart attacks go almost entirely undetected.

So, can you have a heart attack and not know it? Yes, you can. Silent heart attacks, also known as silent myocardial infarctions (SMIs), may only have mild symptoms if any at all. It’s estimated that around 45% of all heart attacks fall into this category [1].

Below, we’ll highlight the potential symptoms of a silent heart attack. We’ll also explain how you can find out if you’ve experienced a silent heart attack in the past.

What is a heart attack?

A heart attack occurs when one or more of your coronary arteries becomes clogged and partially or completely cuts off blood flow to your heart. The portions of your heart that do not receive blood flow are starved of oxygen and begin to die, leaving your heart muscle damaged and scarred [2].

The longer your heart goes without adequate oxygen, the more heart muscle damage can occur. Irreversible damage can occur in as little as 30 minutes [3]. As a result, it’s crucial for anyone experiencing a heart attack to receive immediate medical attention. In many cases, it can make the difference between life and death.

Unfortunately, if you don’t realize you’re having a heart attack, you may not call 911 and receive the prompt medical attention and early heart attack care you require. That’s why understanding the subtle signs of silent heart attacks is so important.

The dangers of silent heart attacks

Since silent heart attacks may have a milder or shorter duration of symptoms, you may assume they’re less harmful to your health. However, this could not be further from the truth.

To deepen your understanding, let’s explore some statistics and research findings that display the prevalence and danger of silent heart attacks:

• Roughly 800,000 Americans have heart attacks each year [2]. An estimated 45% of these heart attacks are silent [1].
• Silent heart attacks can increase your risk of heart failure [4]. They may also be associated with an increased risk of having a stroke [5].
• According to a study in the Journal of the American Medical Association, 8% of participants who had no initial signs of cardiovascular disease had myocardial scars ten years later, indicating they had a heart attack. 80% of these heart attack survivors didn’t realize they had suffered a heart attack [1].

Since people who experience silent heart attacks aren’t aware of their health predicament, they may never seek medical treatment or make the necessary lifestyle changes to prevent more severe heart issues going forward.

See related: How are hypertension, heart disease, and stroke related?

What are the signs of a silent heart attack?

Silent heart attacks can be hard to detect because their symptoms are often milder than those of classic heart attacks. Some people may not have any obvious symptoms at all.

Classic heart attacks are often accompanied by [6]:

• Severe chest pain, pressure, fullness, or squeezing
• Sudden shortness of breath
• Stabbing pain in one or both arms, jaw, neck, or shoulders
• Intense sweating, dizziness or lightheadedness, or weakness
• Nausea or vomiting

Instead, silent heart attack symptoms may more closely resemble heartburn, indigestion, or acid reflux. Silent heart attack symptoms can include [1]:

• Mild tightness or pressure in the center or left side of the chest. Chest discomfort may appear only briefly, lasting several minutes, or come and go. Chest discomfort may even be absent.
• Breathing difficulties – A heart attack prevents the heart from pumping enough oxygen-rich blood throughout the body. If you experience a silent heart attack, you may find yourself feeling winded from daily activities or struggling to keep up with your normal exercise routine.
• Lightheadedness and fatigue – A lack of blood supply can also lead to lightheadedness, dizziness, or fatigue. These symptoms may be mistaken for dehydration or low blood sugar.

Note: Women are more likely than men to experience heart attack symptoms other than chest pain. These symptoms include arm, neck, or upper abdominal discomfort, shortness of breath, lightheadedness, fatigue, nausea, and/or sweating. In fact, these symptoms may be more noticeable than any chest discomfort making a silent heart attack more difficult to recognize [11].

Therefore, many people experiencing silent heart attacks simply ignore these symptoms and wait for them to go away. In turn, they may not get the immediate medical care they need to save their heart health. This is why silent heart attacks can be even more dangerous than obvious ones, despite their milder symptoms.

What are the risk factors for silent heart attacks?

The risk factors for regular heart attacks and silent heart attacks are the same. They include [3]:

• Smoking
• Eating a diet high in saturated fat
• Being overweight or obese
• Consuming too much alcohol
• Living a sedentary lifestyle
• Being under emotional stress
• Having high blood pressure
• Having high LDL cholesterol, high triglycerides, or low HDL cholesterol
• Being diabetic
• Aging
• Having a personal history of heart attacks
• Having a family history of heart disease

Since a history of heart attack is associated with an increased risk of having another one, it may be’s important to find out if you’ve had a silent heart attack in the past.

How do you know if you've had a silent heart attack?

Silent heart attacks don’t always have clear symptoms. An electrocardiogram (abbreviated ECG or EKG) or an exercise stress test can help determine if your heart muscle has been injured.

ECG

ECGs are tests that record your heart’s electrical signals. ECGs can show if your heart has any muscle damage. Abnormal test results may indicate that you’ve had a silent heart attack in the past [7]. Your healthcare provider may order an ECG if you report:

• Chest pain
• Heart palpitations
• Rapid pulse
• Shortness of breath
• Dizziness or lightheadedness
• Weakness
• Fatigue
• Difficulty exercising

Since the symptoms of heart disease can come and go, your healthcare provider may even recommend that you use a continuous ECG monitor. These wearable devices can record your heart’s electrical activity continuously or exclusively during a symptomatic event.

Exercise stress test

Stress tests evaluate how the heart functions during exercise. During a stress test, monitors track your heart rate, heart rhythm, breathing, and blood pressure as you ride a stationary bike or walk on a treadmill. These tests can uncover issues with your heart’s blood flow or rhythm that may be due to a silent heart attack [8].

If you suspect you may have had a silent heart attack, you may want to ask your healthcare provider about these tests. When it comes to your heart health, it's much better to be safe than sorry.

How to treat a silent heart attack

The treatment protocol for a silent heart attack may include [9]:

• Undergoing balloon or laser angioplasty to open a blocked vessel in the heart
• Stent surgery
• Cardiac artery bypass (CABG) surgery
• Taking medication to dissolve a clot or improve heart function
• Taking statins which can lower your cholesterol levels

Additionally, your healthcare provider may recommend you make changes to your diet, such as reducing your intake of processed foods and saturated fats. Your provider may also encourage you to incorporate exercise to lower cholesterol, and quit smoking. These heart-healthy habits could help protect you from future health problems.

How to prevent a silent heart attack

If you get checked out and discover you haven’t experienced a silent heart attack, that’s fantastic news. To take a proactive posture, you can reduce your chances of ever having one by [10]:

• Understanding your personal risk factors
• Checking your blood pressure and cholesterol levels regularly
• Exercising often
• Eating a healthy diet
• Limiting your alcohol consumption
• Cutting out smoking
• Managing your stress levels
• Getting enough sleep

These preventative practices can also protect you from a host of other health issues.

Everlywell: take your heart health into your own hands

In addition to taking steps to prevent heart attacks, you can monitor your heart health with a Heart Health Test from Everlywell. This at-home lab test measures the following heart health markers:

• Total Cholesterol
• HDL
• Calculated LDL
• Triglycerides
• hs-CRP
• HbA1c

After sending in your finger-prick blood sample, we’ll have it tested at a CLIA-certified laboratory and reviewed by an independent board-certified physician in your state. We’ll then send your results with easy-to-understand explanations of what they mean. These test results can shed light on your current risks for heart disease and diabetes.

Related content

How are hypertension, heart disease, and stroke related?

Is heart disease curable?

8 different types of heart disease

References

1. The danger of "silent" heart attacks. Harvard Health. URL. Published November 3, 2020. Accessed February 10, 2023.
2. What is a heart attack? National Heart, Lung, and Blood Institute. URL. Updated March 24, 2022. Accessed February 10, 2023.
3. Heart attack. Johns Hopkins Medicine. URL. Accessed February 10, 2023.
4. Qureshi WT, Zhang Z-M, Chang PP, et al. Silent myocardial infarction and long-term risk of heart failure: The ARIC Study. Journal of the American College of Cardiology. URL. Published January 2018. Accessed February 10, 2023.
5. Merkler AE, Bartz T, Kamel H, et al. Abstract 58: Silent myocardial infarction and subsequent ischemic stroke in the cardiovascular health study. URL. Published March 11, 2021. Accessed February 11, 2023.
6. Heart attack symptoms, risk, and recovery. Centers for Disease Control and Prevention. URL. Published July 12, 2022. Accessed February 10, 2023.
7. Electrocardiogram - StatPearls - NCBI Bookshelf. URL. Updated June 13, 2022. Accessed February 11, 2023.
8. Stress test. Mayo Clinic. URL. Published December 16, 2022. Accessed February 10, 2023.
9. Treatment of a heart attack. American Heart Association. URL. Updated March 31, 2017. Accessed February 10, 2023.
10. Understand your risks to prevent a heart attack. American Heart Association. URL. Updated December 6, 2022. Accessed February 10, 2023.
11. How heart disease is different for women. Mayo Clinic. URL. Published January 20, 2022. Accessed February 10, 2023.