Heart Attack (Myocardial Infarction)

Overview

What is a heart attack?

A heart attack, or myocardial infarction (MI), is permanent damage to the heart muscle. "Myo" means muscle, "cardial" refers to the heart, and "infarction" means death of tissue due to lack of blood supply.

What happens during a heart attack?

A heart attack happens when one or more of your coronary arteries suddenly becomes blocked, stopping the flow of blood to the heart muscle and damaging it – causing a heart attack. Let’s back up and learn more about your coronary arteries.

Your coronary arteries are a network of blood vessels that surround your heart muscle and supply it with blood that is rich in oxygen and nutrients. Your heart muscle needs this continuous supply of oxygen and nutrients to function. Over time, sometimes one or more of your coronary arteries narrow because of a buildup of cholesterol and fatty deposits (called plaque) on the inner walls. This is called atherosclerosis. Sometimes this plaque ruptures and forms a clot within the artery, which restricts blood flow to your heart. Blocked blood flow cuts off the needed supply of oxygen and nutrients, damaging or destroying that area of heart muscle.

Symptoms and Causes

What are the symptoms of a heart attack?

Symptoms of a heart attack include:

  • Angina: Chest pain or discomfort in the center of the chest; also described as a heaviness, tightness, pressure, aching, burning, numbness, fullness or squeezing feeling that lasts for more than a few minutes or goes away and comes back. It is sometimes mistakenly thought to be indigestion or heartburn.
  • Pain or discomfort in other areas of the upper body including the arms, left shoulder, back, neck, jaw, or stomach.
  • Trouble breathing or feeling shortness of breath.
  • Sweating or "cold sweat."
  • Fullness, indigestion, or choking feeling (may feel like "heartburn").
  • Nausea or vomiting.
  • Light-headedness, dizziness, extreme weakness or anxiety.
  • Rapid or irregular heart beats.

If you are having any of these symptoms and they last for more than 5 minutes, SEEK EMERGENCY TREATMENT (CALL 911) WITHOUT DELAY. These symptoms could be the signs of a heart attack and you need to get treatment as soon as possible.

Are heart attack symptoms in women different?

Although most women and men report symptoms of chest pain with a heart attack, women are slightly more likely than men to report unusual symptoms. More vague or less typical "heart" symptoms reported in women include:

  • Upper back or shoulder pain.
  • Jaw pain or pain spreading to the jaw.
  • Pressure or pain in the center of the chest.
  • Light headedness.
  • Pain that spreads to the arm.
  • Unusual fatigue for several days.

If you experience any of these symptoms of a heart attack, call for emergency assistance (911). Don't wait for your symptoms to "go away." Early recognition and treatment of a heart attack can reduce the risk of heart damage. Even if you're not sure your symptoms are a heart attack, get it checked.

The best time to treat a heart attack is within one hour of the onset of the first symptoms. Waiting just a couple hours for medical help may change your treatment options, increase the amount of damage to your heart muscle and reduce your chance of survival.

Diagnosis and Tests

How is a heart attack diagnosed?

Several tests may be ordered to determine if you've experienced a heart attack. These include:

12-lead ECG

The 12-lead ECG (also known as EKG or electrocardiogram) can help to tell what type of heart attack you've had and where it has occurred. This is one of the first tests done. Frequently paramedics will do this test where you had the potential heart attack or on the way to the hospital.

In addition, your heart rate and rhythm can be watched. You'll also be connected with leads (wires) to a monitor for continuous monitoring of your heart rate and rhythm.

Blood studies

Blood may be drawn to measure levels of biochemical markers. These markers are found inside your body's cells and are needed for their function. When your heart muscle cells are injured, their contents --including the markers -- are released into your bloodstream. By measuring the levels of these markers, your doctors can determine the size of the heart attack and approximately when the heart attack started. Other blood tests may also be performed.

Echocardiogram (echo)

An echo can be performed during and after a heart attack to learn about how your heart is pumping and identify areas of your heart that are not pumping normally. The echo is also valuable to see if any structures of the heart (valves, septum, etc.) have been injured during the heart attack.

Cardiac catheterization (cath)

Cardiac catheterization (cath) may be performed during the first hours of a heart attack if medications are not relieving the ischemia or symptoms. The cardiac cath can directly see the blocked artery and guide the choice for which procedure (such as angioplasty, stent placement or coronary artery bypass surgery) may follow.

Management and Treatment

How is a heart attack treated?

Heart attack treatment begins immediately. The goal of treatment is to treat you quickly and limit heart muscle damage.

Medications

The goals of medication therapy are to break up or prevent blood clots, prevent platelets from gathering and sticking to the plaque, stabilize the plaque, and prevent further ischemia. These medications must be given as soon as possible (within 30 minutes from the start of heart attack symptoms) to decrease the amount of damage to the heart muscle. The longer the delay in starting these drugs, the more damage that occurs and the less benefit they can provide.

Heart Attack: Thrombolytic medications are used to break up clots blocking the artery

Thrombolytic medications are used to break up clots blocking the artery

Medications given right after the start of a heart attack may include:

  • Aspirin
  • Thrombolytic Therapy ("clot busters")
  • Heparin
  • Other antiplatelet drugs
  • Any combination of the above

Other drugs, given during or after a heart attack lessen your heart's work, improve the functioning of the heart, widen or dilate your blood vessels, decrease your pain, and guard against any life-threatening heart rhythms. Your doctor will prescribe the appropriate medications for you.

Interventional Procedures

During or shortly after a heart attack, you may go to the cardiac catheterization laboratory to directly evaluate the status of your heart, arteries and the amount of heart damage. In some cases, procedures (such as angioplasty or stents) are used to open up your narrowed or blocked arteries. These procedures may be combined with thrombolytic therapy to open up the narrowed arteries, as well as to break up any clots that are blocking them.

Coronary artery bypass surgery

If necessary, bypass surgery may be performed to restore the heart muscle's supply of blood.

Prevention

Can a heart attack be prevented?

There are many actions you can take to reduce your risk of a heart attack:

You don't have to make lifestyle changes all on your own. Ask your healthcare team for help. They are there to help you and can provide the information you need and point you to services that can help.

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