Myocardial Infarction

A myocardial infarction, commonly known as a heart attack, is a serious medical emergency that occurs when blood flow to part of the heart muscle stops or becomes severely reduced, causing the heart tissue to die from lack of oxygen.

Table of contents

• What is a myocardial infarction?
• Symptoms and warning signs
• Causes and risk factors
• How it is diagnosed
• Treatment options
• Recovery and rehabilitation
• Prevention and lifestyle changes

What is a myocardial infarction?

A myocardial infarction is an extremely dangerous condition that happens when your heart muscle doesn’t receive enough blood flow^[1]. The term myocardial infarction comes from medical words meaning damage to the heart muscle. Most people call it a heart attack^[2].

Your heart is a muscle that works constantly and needs a continuous supply of oxygen-rich blood to function. When blood flow stops or is severely reduced to a section of your heart, that part of the muscle begins to die^[1]. If blood flow isn’t restored quickly, a heart attack can cause permanent damage to your heart or even death.

Every year, more than 800,000 people in the United States have a heart attack^[1][6]. This means a heart attack occurs every 39 seconds^[25]. Myocardial infarction may be “silent” and go undetected, or it could be a catastrophic event leading to sudden death^[2].

When a heart attack happens, a part of your heart can’t pump properly because it’s dying from lack of blood flow. This disrupts how your whole heart works and can reduce or stop blood flow to the rest of your body, which can be deadly if not corrected quickly^[1].

Symptoms and warning signs

The most common symptom of a heart attack is chest pain or discomfort^[3][6]. Many people describe feeling pain in their chest during a heart attack. It can feel like discomfort, squeezing, heaviness, pressure, tightness, or crushing pain^[1][8]. The chest pain usually lasts more than 15 minutes^[20].

The pain may start in your chest and spread to other areas. It can radiate to your left arm (or both arms), shoulder, neck, jaw, back, or down toward your waist^[1]. Some people experience pain in their upper belly^[3].

People often think they’re having indigestion or heartburn when they’re actually having a heart attack^[1][3].

Heart attack symptoms that people commonly describe include:

• Chest pain (angina)
• Shortness of breath or trouble breathing
• Nausea or stomach discomfort
• Feeling lightheaded, dizzy, or passing out
• Cold sweat
• Fatigue or feeling unusually tired
• Heart palpitations
• Anxiety or a feeling of “impending doom”
• Trouble sleeping (insomnia)^[1][3]

Women are less likely to have chest pain or discomfort that feels like indigestion. They’re more likely to have shortness of breath, fatigue, and insomnia that started before the heart attack. Women also more commonly have nausea and vomiting or pain in their back, shoulders, neck, arms, or abdomen^[1][6].

About 30% of people have symptoms that are not typical^[4]. Some people only experience shortness of breath, nausea, or sweating without significant chest pain^[1].

Many people have warning signs hours, days, or even weeks in advance of a heart attack^[20]. Some heart attacks happen suddenly, but it’s important to pay attention to any unusual symptoms.

If you think you or someone you’re with is having a heart attack, call 911 (or your local emergency services phone number) immediately^[1][6]. Time is critical in treating a heart attack. A delay of even a few minutes can result in permanent heart damage or death^[1].

Causes and risk factors

Most heart attacks happen because of a blockage in one of the blood vessels that supply your heart^[1]. These blood vessels are called coronary arteries. Most often, the blockage occurs because of plaque, a sticky substance that can build up on the insides of your arteries. Plaque is made of a mixture of fat, cholesterol, calcium, and waste materials from your cells^[1][3].

That buildup is called atherosclerosis^[1][3]. Think of it like pouring grease down your kitchen sink that can clog your home plumbing^[1]. When there’s a large amount of this buildup in the blood vessels to your heart, this is called coronary artery disease, which is the leading cause of death in the United States^[1][2].

Sometimes, plaque deposits inside the coronary arteries can rupture and form a blood clot. The clot can block the arteries, causing a heart attack^[3][8]. A less common cause is a severe spasm, or sudden contraction, of a coronary artery that can stop blood flow to the heart muscle^[6].

Several factors can increase your risk of developing coronary artery disease and having a heart attack. An international study identified the following major risk factors:

• Smoking
• Abnormal cholesterol levels in the blood
• High blood pressure (hypertension)
• Diabetes
• Abdominal obesity (a waist-to-hip ratio greater than 0.90 for males and greater than 0.85 for females)
• Psychosocial factors such as depression, stress, and life events including job loss and family conflict
• Lack of daily consumption of fruits or vegetables
• Lack of physical activity^[2]

About half of all Americans have at least one of these three key risk factors for heart disease: high blood pressure, high blood cholesterol, and smoking^[6].

Some risk factors cannot be controlled, such as your age or family history. But you can take steps to lower your risk by changing the factors you can control^[6].

How it is diagnosed

A heart attack is often diagnosed in an emergency setting^[11]. If you’ve had or are having a heart attack, healthcare providers will take immediate steps to diagnose and treat your condition.

Several tests are used to diagnose a heart attack:

Electrocardiogram (ECG or EKG) is usually the first test done. This test records electrical signals as they travel through your heart. Sticky patches called electrodes are attached to your chest and sometimes your arms and legs. The signals are shown as waves on a monitor or printed on paper. An ECG can show if you are having or have had a heart attack^[11].

Blood tests check for certain heart proteins that slowly leak into the blood after heart damage from a heart attack. These proteins are called cardiac markers or cardiac biomarkers. Blood tests can detect these substances to confirm a heart attack^[2][11].

Chest X-ray shows the condition and size of your heart and lungs^[11].

Echocardiogram uses sound waves (ultrasound) to create images of your moving heart. This test can show how blood moves through your heart and heart valves. It can help identify whether an area of your heart has been damaged^[11].

Coronary catheterization (angiogram) involves inserting a long, thin tube called a catheter into an artery, usually in the leg, and guiding it to your heart. Dye flows through the catheter to help the arteries show up more clearly on images. This test can show blockages in your coronary arteries^[11].

Cardiac CT scan or MRI creates images of your heart and chest to assess damage and check for complications^[11].

Treatment options

The first goal in treating a heart attack is to restore blood flow as quickly as possible to salvage as much of the heart muscle as possible^[13]. Time is critical because the more time that passes without treatment to restore blood flow, the greater the damage to the heart muscle^[6].

Even before reaching the hospital, emergency personnel may begin treatment with aspirin, medications to prevent blood clots, oxygen, nitroglycerin to widen coronary vessels, and drugs to decrease the heart’s workload and regulate heart rhythm^[16].

At the hospital, healthcare professionals can run tests to find out if a heart attack is happening and decide the best treatment. In some cases, a heart attack requires cardiopulmonary resuscitation (CPR) or an electrical shock (defibrillation) to get the heart pumping again^[6].

The main treatments used to restore blood flow include:

Primary percutaneous coronary intervention (primary PCI), also called coronary angioplasty, is an emergency procedure to widen blocked coronary arteries. A thin tube with a small balloon at the end (called a catheter) is inserted into a blood vessel in your groin or arm. The catheter is passed through your blood vessels up to your heart. When the catheter reaches the narrowed section of your coronary artery, the balloon is inflated to open it. A flexible metal mesh tube called a stent is usually inserted into the artery to help keep it open^[15][16].

Thrombolytic or fibrinolytic medicines are drugs that break down blood clots. These are usually given by injection if you cannot be treated urgently with PCI^[15].

Coronary artery bypass graft (CABG) surgery may be needed if angioplasty is not technically possible. This operation involves taking a blood vessel from another part of your body (usually your chest, leg, or arm) and attaching it to your coronary artery above and below the blockage. This creates a new route for blood to flow around the blocked area^[15].

After initial treatment, you will likely need to take medications. Common medications include aspirin and other antiplatelet medicines to prevent blood clots, beta blockers to lower the heart’s workload, and medicines to lower cholesterol and blood pressure^[13][15].

Recovery and rehabilitation

Recovering from a heart attack can take anywhere from two weeks to three months^[19]. How long your recovery takes depends on many factors, including the severity of your heart attack, how quickly you received treatment, the type of treatment you received, and your overall health^[19].

During the first week you return home from the hospital, you may feel tired or weak. This is normal because the heart attack damaged your heart muscle, and your heart needs time to recover^[19]. It’s important to find balance between resting and being active^[19].

You should be able to return to light activities like getting dressed, bathing, and light household chores. Pace yourself and spread your activities throughout the day. If you feel tired, stop and rest^[19].

Cardiac rehabilitation is an important part of your recovery. This is a medically supervised program that helps you recover and get back to living your life after a heart attack^[8][24]. Cardiac rehabilitation programs usually include exercise training, education about heart-healthy living, and counseling to reduce stress^[24].

Research has found that people who attend cardiac rehabilitation have a lower risk of having another heart attack and being admitted to the hospital. It also has a positive impact on their wellbeing and quality of life^[23].

Most cardiac rehabilitation programs are available locally, often in weekly sessions that last 6 to 12 weeks^[23]. Your cardiac rehabilitation team will design a program to suit your age, fitness level, and any other medical issues^[23].

Most people can return to work after having a heart attack, but how quickly will depend on your health, the state of your heart, and the kind of work you do^[23].

After you’ve had a heart attack, your heart may be damaged. This could affect your heart’s rhythm and its ability to pump blood to the rest of your body. You may also be at risk for another heart attack or other conditions^[6].

Prevention and lifestyle changes

You can lower your chances of having another heart attack by making important lifestyle changes and following your doctor’s recommendations^[6].

Important steps to reduce your risk include:

Quit smoking. Smoking accounts for 20% of deaths from heart disease. If you smoke, quitting is one of the most important things you can do for your heart health^[2][8].

Eat a heart-healthy diet. One of the most recommended eating patterns for heart health is the Mediterranean diet. This diet emphasizes fruits, vegetables, whole grains, lean proteins, and healthy fats. It can significantly reduce the risk of heart disease^[21]. Aim for at least five servings of fruits and vegetables each day. Choose whole grains like oatmeal, brown rice, and whole-wheat bread. Include fish, especially fatty fish like salmon, which are high in omega-3 fatty acids that help reduce inflammation^[21].

Exercise regularly. Adults should do at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic exercise each week, unless advised otherwise by your doctor^[8]. Talk with your healthcare team about a safe exercise plan for you^[6].

Lose weight if you’re overweight or obese. Obesity is linked to several factors that increase the chances of heart attacks, including high blood pressure, diabetes, and unhealthy cholesterol levels^[2][8].

Manage stress. Psychosocial factors such as depression and stress can increase your risk of heart disease^[2]. Your cardiac rehabilitation program can provide relaxation techniques and support for managing anxiety^[23].

Moderate your alcohol consumption. Excessive alcohol use can weaken and thin the heart muscle^[21].

Take your medications as prescribed. Your doctor may prescribe medicines to lower your cholesterol, control your blood pressure, prevent blood clots, or manage diabetes. Taking these medicines exactly as directed is essential^[6][25].

Attend all follow-up appointments. Regular checkups allow your healthcare provider to monitor your recovery and adjust your treatment plan as needed^[6].

Making these lifestyle changes can greatly improve your life expectancy and quality of life after a heart attack^[21]. Although recovering from a heart attack can feel scary or intimidating, with proper treatment, lifestyle changes, and support, most people can return to active, full lives^[24].