A heart attack occurs when the flow of blood to the heart is blocked, most often by a build-up of fat, cholesterol and other substances, which form a plaque in the arteries that feed the heart (coronary arteries). The interrupted blood flow can damage or destroy part of the heart muscle.
A heart attack, also called a myocardial infarction, can be fatal, but treatment has improved dramatically over the years. It’s crucial to call 911 or emergency medical help if you think you might be having a heart attack.
A heart attack occurs when one or more of your coronary arteries become blocked. Over time, a coronary artery can narrow from the buildup of various substances, including cholesterol (atherosclerosis). This condition, known as coronary artery disease, causes most heart attacks.
During a heart attack, one of these plaques can rupture and spill cholesterol and other substances into the bloodstream. A blood clot forms at the site of the rupture. If large enough, the clot can completely block the flow of blood through the coronary artery.
Another cause of a heart attack is a spasm of a coronary artery that shuts down blood flow to part of the heart muscle. Use of tobacco and of illicit drugs, such as cocaine, can cause a life-threatening spasm. A heart attack can also occur due to a tear in the heart artery (spontaneous coronary artery dissection).
Common heart attack signs and symptoms include:
- Pressure, tightness, pain, or a squeezing or aching sensation in your chest or arms that may spread to your neck, jaw or back
- Nausea, indigestion, heartburn or abdominal pain
- Shortness of breath
- Cold sweat
- Lightheadedness or sudden dizziness
Heart attack symptoms vary
Not all people who have heart attacks have the same symptoms or have the same severity of symptoms. Some people have mild pain; others have more severe pain. Some people have no symptoms, while for others, the first sign may be sudden cardiac arrest. However, the more signs and symptoms you have, the greater the likelihood you’re having a heart attack.
Some heart attacks strike suddenly, but many people have warning signs and symptoms hours, days or weeks in advance. The earliest warning may be recurrent chest pain (angina) that’s triggered by exertion and relieved by rest. Angina is caused by a temporary decrease in blood flow to the heart.
A heart attack differs from a condition in which your heart suddenly stops (sudden cardiac arrest, which occurs when an electrical disturbance disrupts your heart’s pumping action and causes blood to stop flowing to the rest of your body). A heart attack can cause cardiac arrest, but it’s not the only cause.
When to see a doctor
Act immediately. Some people wait too long because they don’t recognize the important signs and symptoms. Take these steps:
Call for emergency medical help. If you suspect you’re having a heart attack, don’t hesitate. Immediately call 911 or your local emergency number. If you don’t have access to emergency medical services, have someone drive you to the nearest hospital.
Drive yourself only if there are no other options. Because your condition can worsen, driving yourself puts you and others at risk.
- Take nitroglycerin, if prescribed to you by a doctor. Take it as instructed while awaiting emergency help.
Take aspirin, if recommended. Taking aspirin during a heart attack could reduce heart damage by helping to keep your blood from clotting.
Aspirin can interact with other medications, however, so don’t take an aspirin unless your doctor or emergency medical personnel recommend it. Don’t delay calling 911 to take an aspirin. Call for emergency help first.
What to do if you see someone having a heart attack
If you encounter someone who is unconscious, first call for emergency medical help. Then begin CPR to keep blood flowing. Push hard and fast on the person’s chest — about 100 compressions a minute. It’s not necessary to check the person’s airway or deliver rescue breaths unless you’ve been trained in CPR.