Heart Attack (Myocardial Infarction)

Overview

What is a heart attack?

A myocardial infarction (commonly called a heart attack) is an extremely dangerous condition caused by a lack of blood flow to your heart muscle. The lack of blood flow can occur because of many different factors but is usually related to a blockage in one or more of your heart’s arteries. Without blood flow, the affected heart muscle will begin to die. If blood flow isn’t restored quickly, a heart attack can cause permanent heart damage and death.

A heart attack is a life-threatening emergency. If you suspect you or someone you're with is having a heart attack, do not hesitate to call 911 (or your local emergency services phone number). Time is critical in treating a heart attack, and a delay of even a few minutes can result in permanent heart damage or death.

How common are heart attacks?

New heart attacks happen to about 635,000 people in the U.S. each year. About 300,000 people a year have a second heart attack. About one in seven deaths in the U.S. is due to coronary heart disease, which includes heart attacks.

What happens during a heart attack?

When a heart attack happens, blood flow to a part of your heart stops or is far below normal, which causes that part of your heart muscle to die. When a part of your heart can’t pump because it’s dying from lack of blood flow, it can disrupt the pumping sequence for the entire heart. That reduces or even stops blood flow to the rest of your body, which can be deadly if it isn’t corrected quickly.

Symptoms and Causes

What causes a heart attack?

The vast majority of heart attacks occur because of a blockage in one of the blood vessels that supply your heart. This most often happens because of plaque, a sticky substance that can build up on the insides of your arteries (similar to how pouring grease down your kitchen sink can clog your home plumbing). That buildup is called atherosclerosis.

Sometimes, plaque deposits inside the coronary (heart) arteries can break open or rupture, and a blood clot can get stuck where the rupture happened. If the clot blocks the artery, this can deprive the heart muscle of blood and cause a heart attack.

Heart attacks are possible without a blockage, but this is rare and only accounts for about 5% of all heart attacks. This kind of heart attack can occur for the following reasons:

  • Spasm of the artery: Your blood vessels have a muscle lining that allows them to become wider or narrower as needed. Those muscles can sometimes twitch or spasm, cutting off blood flow to heart muscle.
  • Rare medical conditions: An example of this would be any disease that causes unusual narrowing of blood vessels.
  • Trauma: This includes tears or ruptures in the coronary arteries.
  • Obstruction that came from elsewhere in the body: A blood clot or air bubble (embolism) that gets trapped in a coronary artery.
  • Electrolyte imbalances: Having too much or too little of key minerals like potassium in your blood can cause a heart attack.
  • Eating disorders: Over time, an eating disorder can cause damage to your heart and ultimately result in a heart attack.

Who is most at risk for a heart attack?

Several key factors affect your risk of having a heart attack. Unfortunately, some of these risk factors aren't things you can control.

  • Age and sex.
  • Family history of heart disease.
  • History of preeclampsia, a condition that can develop during pregnancy.
  • Lifestyle.
  • If you have certain health conditions or diseases.

Age and sex

Your risk of heart attack increases as you get older, and your sex also influences when your risk of a heart attack starts to increase:

  • Men: The risk of heart attack increases greatly at age 45.
  • Women: The risk of heart attack increases greatly at age 50 or after menopause.

Family history

If you have a parent or sibling with a history of heart disease or heart attack — especially at a younger age — your risk is even greater. That risk increases with the following:

  • Your father or a brother who was diagnosed with heart disease at age 55 or younger.
  • Your mother or a sister who was diagnosed with heart disease at age 65 or younger.

Lifestyle

The lifestyle choices you make can also affect your risk of having a heart attack. The following lifestyle factors increase your risk of heart attack:

  • Lack of physical activity.
  • A diet high in sodium, sugar and fat.
  • Smoking or tobacco use (including smokeless or chewing tobacco and vaping).
  • Drinking too much alcohol.
  • Drug abuse (especially in younger individuals).

Other diseases and health conditions

The following health conditions can increase your risk of heart attack:

  • Diabetes.
  • Obesity.
  • High blood pressure (hypertension).
  • High cholesterol (hyperlipidemia).
  • Eating disorders (especially in younger individuals).

What are the symptoms of a heart attack?

Heart attacks can have a number of symptoms, some of which are more common than others. The symptoms you have are also influenced by your sex, as with men and women being more likely to have different heart attack symptoms.

Common heart attack symptoms

Symptoms most often described by people having a heart attack:

  • Chest pain (angina). This symptom can be mild and feel like discomfort or heaviness, or it can be severe and feel like crushing pain. It may start in your chest and spread (or radiate) to other areas like your left arm (or both arms), shoulder, neck, jaw, back or down toward your waist.
  • Shortness of breath or trouble breathing.
  • Nausea or stomach discomfort. Heart attacks can often be mistaken for indigestion.
  • Heart palpitations.
  • Anxiety or a feeling of “impending doom.”
  • Sweating.
  • Feeling lightheaded, dizzy or passing out.

Heart attack symptoms in women

Medical research in recent years has shown that women may have the above symptoms, but also have a higher chance of experiencing symptoms different from those listed above.

Women are less likely to describe the following:

  • Chest pain, especially in the center of the chest.
  • Discomfort that feels like indigestion.

Women are more likely to describe the following:

  • Shortness of breath, fatigue and insomnia that started before the heart attack.
  • Pain in the back, shoulders, neck, arms or abdomen.
  • Nausea and vomiting.

Is acute coronary syndrome the same as a heart attack?

Acute coronary syndrome is a life-threatening condition that requires emergency medical care and can result in a heart attack. Acute coronary syndrome is a name given to three types of coronary artery disease associated with a sudden rupture of plaque inside the coronary artery:

  • Unstable angina.
  • ST-segment elevation myocardial infarction or heart attack (STEMI).*
  • Non-ST segment elevation myocardial infarction or heart attack (NSTEMI).*

The location of the blockage, the length of time that blood flow is blocked and the amount of damage that occurs determine the type of acute coronary syndrome.

*See the Electrocardiogram description in the Diagnosis & Tests section for an explanation of STEMI and non-STEMI heart attacks.

Diagnosis and Tests

How are heart attacks diagnosed?

Heart attacks are usually diagnosed in an emergency room setting. A healthcare provider will diagnose a heart attack using the following:

  • History and symptoms: The provider will ask you about the symptoms you experienced. If someone was with you, the provider might also ask them to describe what happened.
  • Lab testing: Heart attacks cause a specific chemical marker to show up in your blood.
  • Heart-specific diagnostic tests: This includes tests that detect and record the electrical activity in your heart.
  • Imaging tests: These tests give providers a way to “see” inside your heart. Many of these tests can also show the location of a blood flow blockage, which can guide treatment.

What tests will be done to diagnose this condition?

Anyone with heart attack symptoms should undergo a physical examination, including checking pulse, blood oxygen levels, blood pressure, and listening to heart and lung sounds.

Other tests used to diagnose heart attack include:

  • Electrocardiogram (abbreviated as EKG or ECG): This is one of the first tests done when someone comes to an ER with heart attack symptoms. This test uses sensors called electrodes that attach to the skin of your chest. The electrodes pick up electrical activity in the heart and show it as a wave on a display or printout. By looking at the wave, providers can see the strength and timing of the electrical signal as it travels through your heart. When the signal doesn’t travel like it should, the shape of the wave changes, which can indicate a heart attack or similar problems. EKG for a heart attack is usually continuous to monitor for changes in heart activity.

STEMI and non-STEMI heart attacks

The wave of your heart's electrical signal is divided into sections using letters of the alphabet starting at P and ending at U. One particular section of the wave, the ST segment, shows activity in the heart's lower two chambers. Those chambers are the left ventricle and right ventricle.

Normally, the ST segment is very flat, but a heart attack that affects the ventricles will often cause the ST segment to be much taller than normal. Healthcare professionals call this kind of heart attack an ST-Elevation Myocardial Infarction, or STEMI. Heart attacks, in general, are broadly split into STEMI and non-STEMI categories, with STEMI heart attacks typically being more severe.

  • Blood tests. During a heart attack, the damage to heart muscle cells almost always causes a chemical marker to appear in your bloodstream. Blood tests that look for that marker are among the most reliable methods to diagnose a heart attack.

Certain kinds of tests can provide pictures or computer-generated images of the heart. These include:

  • Echocardiogram: This test uses ultrasound (high-frequency sound waves), similar to how bats use ultrasound like a sonar to see obstacles. The ultrasonic waves will travel through and bounce off different parts of your heart at different speeds. An echocardiogram can use that information to generate a picture of the inside and outside of your heart.
  • Angiogram: This test involves taking an X-ray after injecting a dye-like substance easily seen on an X-ray into your blood. This allows doctors to see areas with little or no blood flow.
  • Heart computed tomography (CT) scan: This imaging test uses X-rays and computer processing to create a highly detailed scan of your heart.
  • Heart MRI: This test uses a powerful magnetic field and computer processing to create an image of your heart.
  • Nuclear heart scans: Similar to angiography, these scans use a radioactive dye injected into your blood. What sets them apart from an angiogram is that they use computer-enhanced methods like computed tomography (CT) or positron emission tomography (PET) scans.

Management and Treatment

How are heart attacks treated?

Treating a heart attack means restoring blood flow to the affected heart muscle as soon as possible. This can happen in a variety of ways, ranging from medication to surgery. It's extremely likely that treatment will use several of the following methods.

Supplementary oxygen

People having trouble breathing or with low blood oxygen levels will often receive supplementary oxygen along with other heart attack treatments. You can breathe the oxygen either through a tube that sits just below your nose or a mask that fits over your nose and mouth. This increases the amount of oxygen circulating in the blood and reduces the strain on your heart.

Medications

  • Anti-clotting medications: This includes aspirin and other blood-thinning medicines.
  • Nitroglycerin: This medicine is used to relieve chest pain. It also is a powerful vasodilator, meaning it causes blood vessels to widen so blood can pass through more easily.
  • Thrombolytic (clot-busting) medications: These intravenous (IV) medications cause blood clots to break down and dissolve. These medications are usually used only within the first 12 hours after a heart attack.
  • Anti-arrhythmia medications: Heart attacks can often cause malfunctions in your heart’s normal beating rhythm called arrhythmias. Some arrhythmias can be life-threatening. Anti-arrhythmia medications can stop or prevent these malfunctions.
  • Pain medications: The most common pain medication given during heart attack care is morphine. This can help alleviate chest pain.

Percutaneous coronary intervention

Restoring circulation to the affected heart muscle is usually done with a procedure called percutaneous coronary intervention. Often called PCI for short, this procedure uses a catheter-based device inserted into a major blood vessel (usually one near your upper thigh).

Once the catheter is inserted into the blood vessel through a small incision, the provider threads it up to the blocked artery on your heart. Once it reaches the location of the blockage, the provider will inflate a small balloon on the end of the device to widen the blood vessel and clear the blockage.

PCI is a critical tool in restoring blood flow, and the sooner that happens, the better the chance of a good outcome. Hospitals use a metric called “door-to-balloon time” to measure their ability to treat a heart attack. This is the average time it takes for patients to undergo PCI after they first come into the Emergency Room.

PCI often includes the placement of a stent at the site of the blockage. Stents are made of metallic mesh and look like tube-shaped scaffolds. They help hold the artery open so another blockage doesn’t happen in the same spot. Some stents are coated with a medication that prevents clotting or tissue growth on the stent itself (either of which could cause another blockage).

Coronary artery bypass grafting

Patients who have severe blockages of their coronary arteries may undergo coronary artery bypass grafting. This surgery is often called open-heart surgery, bypass surgery or CABG (the acronym is pronounced the same as “cabbage”).

CABG involves taking a blood vessel from elsewhere in the body (usually your chest, arm or leg) and using it to construct a detour for blood to use. This reroutes blood around the blocked artery section (or more than one artery; a double bypass goes around two arteries, three is a triple, and so on).

Prevention

Can I prevent having a heart attack?

In general, there are many things that you can do that may prevent a heart attack. However, some factors beyond your control — especially your family history — can still lead to a heart attack despite your best efforts. Still, reducing your risk can postpone when you have a heart attack and reduce the severity if you have one.

How can I reduce my risk of having a heart attack?

Although there are several risk factors that you can’t control, there are many ways you can help yourself and reduce your risk of a heart attack. These include:

  • Schedule a checkup: Find a primary care provider and see them at least once a year for a checkup or wellness visit. An annual checkup can catch many of the early warning signs of heart disease, including signs that you can't feel. These include your blood pressure, blood sugar levels, cholesterol levels and more.
  • Quit tobacco products: This includes smokeless tobacco and all vaping products.
  • Exercise regularly: Aim for 20 to 30 minutes of moderately intense physical activity a week.
  • Eat a healthy diet: Examples include the Mediterranean or Dash diets. A plant-based diet approach is an excellent alternative.
  • Maintain a healthy weight: Your primary care provider can advise you on a healthy goal weight and provide you resources and guidance to help you reach that goal.
  • Manage your existing health conditions: This includes high cholesterol levels, high blood pressure and diabetes.
  • Reduce your stress: Consider techniques such as yoga, deep breathing and meditation.
  • Take your medications: Don’t just take medications when you remember to or when you have a doctor’s appointment coming up.
  • Keep all your medical appointments: Seeing your healthcare providers regularly can help uncover heart-related issues or other medical problems you didn't know you had. This can also help treat problems sooner rather than later.

Being an active contributor to your health doesn't mean you have to make lifestyle changes all on your own. Ask your primary care provider and other providers on your healthcare team for help. They can provide the information and resources you need, and point you to services from which you might benefit.

If you've already had a heart attack, your healthcare provider will recommend a cardiac rehabilitation program. This program's goals are to reduce your chance of a second heart attack. These medically supervised programs provide counseling and focus on the same healthy living goals listed above.

Outlook / Prognosis

What can I expect if I have this condition?

After you've had a heart attack, you're at a higher risk of a similar occurrence. Your healthcare provider will likely recommend follow-up monitoring, testing and care to avoid future heart attacks. Some of these include:

  • Heart scans: Similar to the methods used to diagnose a heart attack, these can assess the effects of your heart attack and determine if you have permanent heart damage. They can also look for signs of heart and circulatory problems that increase the chance of future heart attacks.
  • Stress test: Your provider may also recommend that you undergo a stress test. These are heart tests and scans that take place while you’re exercising. Stress tests can show potential problems that stand out only when your heart is working harder.
  • Cardiac rehabilitation: Your healthcare provider may recommend that you go through a cardiac rehabilitation program during your recovery from a heart attack. These programs are medically supervised and focus on helping you improve your overall health and lifestyle, which can prevent another heart attack. Cardiac rehabilitation generally involves a team of providers and experts, including doctors, physical therapists, nurses, exercise specialists/trainers, dietitians, health educators, counselors and more.

How soon after treatment will I feel better?

In general, your heart attack symptoms should decrease as you receive treatment. You will likely have some lingering weakness and fatigue during your hospital stay and for several days after. Your healthcare provider will give you guidance on rest, medications to take, etc.

Recovery from the treatments also varies, depending on the method of treatment. The average hospital stay for a heart attack is between four and five days. In general, expect to stay in the hospital for the following length of time:

  • Medication only: Patients treated with medication only have an average hospital stay of approximately six days.
  • PCI: Recovering from PCI is easier than surgery because it's a less invasive method for treating a heart attack. The average length of stay for PCI is about four days.
  • CABG: Recovery from heart bypass surgery takes longer because it is a major surgery. The average length of stay for CABG is about seven days.

When can I resume my usual activities?

Recovery from a heart attack after you’re released from the hospital depends on the severity of the heart attack, how soon treatment began, methods used and the health conditions you had — if any — before your heart attack. Your healthcare provider can explain the next steps for your recovery and what you can expect. In general, most people can return to work or resume their usual activities anywhere between two weeks to three months after their heart attack.

Living With

What are the complications of a heart attack?

Complications associated with heart attacks include:

  • Arrhythmias (abnormal heart rhythms): Management options include medication, pacemaker placement, implantable cardioverter defibrillator placement and other options.
  • Heart failure: If enough heart tissue has died, your heart is now weakened and can’t pump blood effectively, which can lead to heart failure.
  • Heart valve problems: Depending on the area of heart damage, your heart valves may be affected. Catheter-based procedures or surgery are treatment options for heart valve problems.
  • Sudden cardiac arrest: This sudden stoppage of your heart can be caused by arrhythmia.
  • Depression and anxiety: Talk to your healthcare provider. Management includes medication and counseling. Joining a support group can help.

Do women fare better or worse than men after a heart attack?

Younger women (pre-menopause) under age 45 have a better outcome than men of a similar age. Scientists believe this is because of estrogen's heart-protective effects. However, after menopause ends the protective benefits of estrogen, women fare worse than men. More specifically:

  • Women between the ages of 45 and 65 who've had a heart attack are more likely to die within a year of the event compared with men of this same age.
  • Women over age 65 are more likely to die within weeks of their heart attack than men over age 65.

Frequently Asked Questions

Why should I call 911 if I can drive myself to the hospital (or have someone drive me)?

If you have any symptoms of a heart attack, it’s best to call 911 for multiple reasons:

  • First responders can do some of the early testing and treatment for a heart attack on the way to the hospital. This can speed up the overall diagnosis and treatment process.
  • If you come into the hospital by ambulance, you usually have more immediate access to care. When you’re having a heart attack, every second matters.
  • Heart attacks can cause your heart to beat irregularly or stop entirely, either of which could cause you to pass out. If you’re in an ambulance when that happens, first responders can react immediately to stabilize you. You also won’t have to worry about passing out behind the wheel and causing a crash that could have devastating consequences for yourself or others.

A note from Cleveland Clinic

A blocked artery needs immediate care to prevent permanent heart damage. You may think that if your symptoms are not intense and severe, you’re not having a heart attack. However, it’s best to get your symptoms checked. Calling 911, rather than driving yourself or having someone else drive you, can be even more life-saving than you think. Time saved is heart muscle saved, and that means you have a better chance of a good outcome.

Last reviewed by a Cleveland Clinic medical professional on 08/11/2021.

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