Heart Attack (Myocardial Infarction)

A heart attack is a medical emergency because your heart isn’t receiving enough oxygen-rich blood. This is often due to a blockage in one of your heart’s arteries (coronary arteries). Without steady blood flow, areas of your heart muscle can begin to die. This keeps your heart from pumping normally and reduces blood flow to the rest of your body.

You may also hear a heart attack referred to as a myocardial infarction or MI.

Call 911 or your local emergency services number if you think you’re having a heart attack. While they send help, ask if you should take an aspirin. Don’t drive yourself to the hospital or let someone else drive you. First responders can start treating you as soon as they arrive. They can also send word to the nearest hospital that you’re on your way. This saves valuable time.

Types of heart attacks (myocardial infarctions)

The two main types of heart attacks are:

• STEMI (ST-segment elevation myocardial infarction): This is a severe heart attack. It happens when one of your coronary arteries is totally blocked. A “widowmaker” is a specific type of STEMI where the blockage affects your left anterior descending (LAD) artery.
• NSTEMI (non-ST-segment elevation myocardial infarction): With this type, you have a partial blockage in a coronary artery that significantly reduces blood flow through a coronary artery. This is still a serious condition.

You might also hear your provider use these terms:

• Reinfarction: This is a heart attack that happens within 28 days of another one. 
• Recurrent heart attack: This is a heart attack that occurs more than 28 days after another one.

Heart attack symptoms

A heart attack can feel like crushing chest pain, but not always. You might notice pressure, squeezing or heaviness in your chest. At times, it can be hard to diagnose because it may also feel like you’re having indigestion or heartburn. The chest discomfort usually lasts at least 10 minutes.

Symptoms may not hit you all at once. You may have early warning signs that start gradually. For example, you may notice mild chest discomfort with usual activities, such as climbing stairs or taking a brisk walk.

In general, the typical signs and symptoms of a myocardial infarction include:

• Chest pain or discomfort, which may spread to your jaw, neck, shoulder, arm or back
• Shortness of breath or trouble breathing
• Feeling very tired or weak for no clear reason
• Upset stomach, nausea or vomiting
• Anxiety or feeling like something bad is going to happen
• Sweating a lot
• Feeling dizzy or lightheaded
• Passing out

It’s possible to have a heart attack without feeling chest pain. Some people only have shortness of breath, nausea or sweating. You might hear this called a “silent heart attack.” That’s because it doesn’t have the traditional symptoms. But it’s still a heart attack. And you still need care right away.

What causes a heart attack?

The most common cause of a heart attack is plaque buildup in your coronary arteries — a condition known as coronary artery disease. The plaque is most dangerous when its surface wears away or breaks open. Blood clots are drawn to that area. The clots can partly or completely block blood flow, leading to a heart attack.

It’s also possible for the plaque to take up so much space that there’s very little room for blood to get through. This severe narrowing reduces blood flow to your heart and may lead to a heart attack.

Other heart attack causes include:

• Anomalous coronary arteries: This is when you’re born with coronary arteries that aren’t in the right spots.
• Coronary artery spasm: Your coronary arteries quickly tighten, reducing blood flow.
• Coronary embolism: A blood clot or air bubble from somewhere else in your body ends up in a coronary artery.
• Hypertensive crisis: Your blood pressure is dangerously high.
• Microvascular coronary disease: Small vessels that branch off from your coronary arteries don’t work as they should.
• Spontaneous coronary artery dissection: There’s a tear in a coronary artery that slows or stops blood flow to your heart.
• Tachyarrhythmia: Your heart is beating very fast and out of rhythm for too long.

Risk factors

Your risk of a heart attack goes up if you:

• Are over age 45 (if you’re male)
• Are over age 50 or past menopause, whichever comes first (if you’re female)
• Have a history of heart disease in your biological family
• Have diabetes, high blood pressure, high cholesterol or obesity
• Smoke or use other tobacco products
• Eat lots of foods high in salt, sugar or saturated fat
• Drink too much alcohol
• Don’t get enough physical activity
• Use addictive substances, especially amphetamines or cocaine

You can’t do much about certain things, like aging or family history. But there’s still a lot you can do to lower your risk. From eating heart-healthy foods to exercising regularly, it all adds up. A healthcare provider can also calculate your risk of heart problems and tailor advice to your needs.

Complications of this condition

A myocardial infarction can damage your heart, leading to complications like:

• Arrhythmias: These are abnormal heart rhythms. Ones that start in your lower heart chambers can lead to cardiac arrest. 
• Cardiogenic shock: This is a sudden emergency where your heart can’t send enough blood to your body.
• Heart failure: This is a long-term problem with your heart’s pumping ability.
• Left ventricular thrombus: This is a blood clot that forms in your lower left heart chamber. It can break free and travel through your arteries, leading to a stroke.

Besides its effects on your body, a heart attack also raises your risk for depression. This can make it hard for you to keep up with your daily routine, including rehab and other health check-ups.

How doctors diagnose this condition

A heart attack diagnosis needs to happen fast. It usually starts when first responders reach you and continues in the ambulance and emergency room. Healthcare providers use two key tests to see if you’re having a heart attack, and if so, what type:

• Electrocardiogram (ECG/EKG): An EKG makes a graph of your heart’s electrical signals. This can show if heart muscle injury is occurring and whether you’re having a STEMI or NSTEMI. It can also show rhythm problems.
• Troponin test: This blood test checks for a protein called cardiac troponin (cTn). During a heart attack, the damage to your heart muscle makes cTn appear in your blood.

Providers in the ER will talk to you about your symptoms, if you’re able to speak. They might also ask someone who was with you to describe what happened.

You may need more tests to check your heart function, rule out other causes of chest pain and check for complications. Possible tests include:

• Echocardiogram to see how well your heart is squeezing and how well your heart walls are moving
• Coronary angiogram to show the blood vessels to your heart and look for blockages
• Heart CT scan to show if there’s any significant narrowing or hardening of your heart’s arteries
• Heart MRI to look for blood flow problems in your heart’s arteries
• SPECT scans or PET scans to find areas of your heart that aren’t receiving as much blood or are injured

How is a heart attack treated?

Treatment focuses on getting blood flowing to your heart again as soon as possible. Usually, this means you have a procedure to clear the blockage from your coronary artery. The sooner this happens after your symptoms start, the more it can help you. You’ll likely also need several medicines to help your heart work better and lower your risk of more problems.

There are three main ways healthcare providers can restore blood flow to your heart:

• Percutaneous coronary intervention (PCI): This procedure opens your coronary artery. Providers use a thin tube (catheter) and a tiny balloon to clear the blockage. They usually also place a stent to keep your artery open. You may hear this called angioplasty and stenting.
• Coronary artery bypass grafting (CABG): This surgery creates a new blood vessel that goes around the blockage. It can help if you have severe blockages that PCI can’t manage.
• Fibrinolytic therapy: If PCI or CABG isn’t possible, healthcare providers use medicine to break up blood clots in your coronary artery. They give it through an IV line or a catheter.

Medicines

Medicines you may need as part of your heart attack treatment include:

• ACE inhibitors or ARBs to lower your blood pressure and help your heart recover
• Antiarrhythmics to stop or prevent dangerous heart rhythms, which heart attacks can cause
• Anticoagulants if you have atrial fibrillation or blood clots
• Aspirin and a P2Y12 inhibitor (dual antiplatelet therapy) to lower the risk of blood clots in your heart’s arteries and on your stent after PCI
• Beta-blockers to slow down your heart rate so your heart can recover from the injury of a heart attack
• Nitroglycerin to relieve chest pain
• Statins to help stabilize the plaque in your heart’s arteries (so it’s less likely to break open) and reduce your blood cholesterol levels

Recovery time

Your heart attack symptoms should start to go away as you receive treatment. You’ll likely feel tired and weak during your hospital stay and for several days after.

Your healthcare provider will tell you how long you can expect to stay in the hospital, usually anywhere from a few days to a couple of weeks. It depends on the treatments you receive and how your body responds. In general, PCI has a shorter hospital stay than CABG.

Heart attack recovery takes anywhere from two weeks to three months. Your provider will advise you on how to take care of yourself during this time. They’ll also say when it’s safe to go back to work, drive and do other things.

Cardiac rehab is a key part of recovery. This 12-week program includes supervised exercise, nutrition advice and more. It helps you feel better faster and lowers your risk of future heart problems.

When should I see my healthcare provider?

Follow-up visits are vital after a heart attack. After you finish cardiac rehab, you’ll see your provider every three months for the first year. Then, you’ll get down to every six months and eventually, once a year. At these visits, your provider will:

• Do tests to check your heart function
• Make sure you’re taking the right doses of your medicines
• Talk with you about daily habits and changes you want to make
• Answer your questions

Call your provider if you have:

• New or changing symptoms
• Side effects from medicines
• Sadness, worries or anxiety that won’t go away
• Questions about which activities are safe for you to do

What can I expect if I have a heart attack?

The treatment you receive for a heart attack doesn’t end when you leave the hospital. Once you have a heart attack, your risk for having another goes up. This means you’ll need to take prescribed medicines and make changes to your daily habits.

Today, many people survive a heart attack. But lots of things affect your outlook, including how much heart damage occurred, your age and underlying conditions. That’s why it’s so important to work closely with your provider. They’ll do everything possible to protect your heart and help you live a long life.