What Is a Heart Attack?

Note: Call 911 immediately if you think you're having a heart attack.

A heart attack, also called a myocardial infarction, happens when blood flow to part of the heart is severely reduced or blocked. The most common cause of a heart attack is coronary artery disease (CAD).

CAD develops as fatty deposits called plaques build up along the walls of the blood vessels of the heart. This buildup narrows or blocks blood flow to the heart.

A heart attack occurs when a blood clot suddenly forms in the narrow area, cutting off blood to the heart. When this happens, there is a chance that the heart muscle will be significantly damaged. The severity of a heart attack depends on the amount of the heart muscle involved and how long blood flow to the heart is stopped.

People at risk for heart disease and those who have had previous attacks should have regular checkups and try to improve their blood pressure, cholesterol, weight, and physical activity.


Factors such as age, family history, cholesterol level, blood pressure, and tobacco use all affect your risk of having a heart attack.

For many people, the first sign of CAD is a heart attack. The symptoms of a heart attack can vary depending on where and how bad the block is. Watch for these warning signs:

  • Uncomfortable pressure, fullness, squeezing, or pain in the center of the chest that lasts more than a few minutes or goes away and returns.
  • Pain that spreads to the shoulder, neck or arm, or sometimes the jaws or teeth.
  • Chest discomfort with lightheadedness, fainting, sweating, nausea, or shortness of breath.
  • Chest pain (angina) without other symptoms.
  • Shortness of breath, especially during or after stress or exercise.
  • Severe indigestion or heartburn that doesn't go away with antacids or comes with weakness, nausea, or sweating.

For some people, more frequent angina can be a predictor of a heart attack. Angina is caused by temporary loss of blood flow to the heart and often is brought on by exertion or strong emotion.

Treating a Heart Attack

If you have any of the warning signs listed above, call 911 right away. Don't wait or try to drive yourself to the hospital. Treating symptoms within 1 to 2 hours after they start can greatly reduce damage to the heart.

The goal of emergency care for a heart attack is to reduce work done by the heart and to prevent further damage to the heart muscle.

Clinical review by Art Resnick, MD
Kaiser Permanente
Reviewed 03/01/2014
Aspirin: More Than Just Headache Relief

There is some evidence that chewing one adult-strength uncoated aspirin (325 milligrams) can reduce the damage from a heart attack if taken shortly after a heart attack starts.