A heart attack—also called myocardial infarction or MI—occurs when an area of heart muscle is completely deprived of blood, and the heart muscle cells die.

A heart attack may result when plaque inside the heart arteries breaks open or ruptures, forming a clot that significantly blocks blood flow through the artery.

A plaque is made up of cholesterol, white blood cells, calcium, and other components, and it is surrounded by a fibrous cap. This fibrous cap may tear or rupture if blood suddenly flows faster, or the artery suddenly narrows. A tear or rupture signals the body to repair the injured artery lining, much as it might heal a cut on the skin, by forming a blood clot to seal the area. A blood clot that forms in an artery can completely block blood flow to the heart muscle and cause a heart attack.

The pain of a heart attack often occurs with other symptoms, including:

• Chest discomfort or pain that may be crushing or squeezing or may feel like a heavy weight on the chest.
• Chest discomfort or pain that occurs with:
  • Sweating.
  • Shortness of breath.
  • Nausea or vomiting.
  • Pain that spreads from the chest to the neck, the jaw, or one or both shoulders or arms.
  • Dizziness or lightheadedness.
  • A fast or irregular heartbeat.
  • Loss of consciousness.

The pain of a heart attack usually will not go away with rest.

It is important to recognize the early stages of a heart attack and to seek emergency care. Medical treatment is needed to prevent death. Sometimes medicines can be given to reduce the damage to the heart muscle caused by a heart attack.