Heart attack (Myocardial Infarction)

Overview

A heart attack occurs when the flow of blood to the heart is blocked. The blockage is most often a buildup of fat, cholesterol and other substances, which form a plaque in the arteries that feed the heart (coronary arteries).

Sometimes, a plaque can rupture and form a clot that blocks blood flow. 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.

Symptoms

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
• Fatigue
• 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. For others, the first sign may be sudden cardiac arrest. However, the more signs and symptoms you have, the greater the chance 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 might be recurrent chest pain or pressure (angina) that's triggered by activity and relieved by rest. Angina is caused by a temporary decrease in blood flow to the heart.

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 who might be having a heart attack

If you see someone who's unconscious and you believe is having a heart attack, first call for emergency medical help. Then check if the person is breathing and has a pulse. If the person isn't breathing or you don't find a pulse, only then should you begin CPR.

Push hard and fast on the person's chest in a fairly rapid rhythm — about 100 to 120 compressions a minute.

If you haven't been trained in CPR, doctors recommend performing only chest compressions. If you have been trained in CPR, you can go on to opening the airway and rescue breathing.

Causes

A heart attack occurs when one or more of your coronary arteries becomes blocked. Over time, a buildup of fatty deposits, including cholesterol, form substances called plaques, which can narrow the arteries (atherosclerosis). This condition, called coronary artery disease, causes most heart attacks.

During a heart attack, a plaque can rupture and spill cholesterol and other substances into the bloodstream. A blood clot forms at the site of the rupture. If the clot is large, it can block blood flow through the coronary artery, starving the heart of oxygen and nutrients (ischemia).

You might have a complete or partial blockage of the coronary artery.

• A complete blockage means you've had an ST elevation myocardial infarction (STEMI).
• A partial blockage means you've had a non-ST elevation myocardial infarction (NSTEMI).

Diagnosis and treatment might be different depending on which type you've had.

Another cause of a heart attack is a spasm of a coronary artery that shuts down blood flow to part of the heart muscle. Using tobacco and illicit drugs, such as cocaine, can cause a life-threatening spasm.

Infection with COVID-19 also may damage your heart in ways that result in a heart attack.

Risk factors

Certain factors contribute to the unwanted buildup of fatty deposits (atherosclerosis) that narrows arteries throughout your body. You can improve or eliminate many of these risk factors to reduce your chances of having a first or another heart attack.

Heart attack risk factors include:

• Age. Men age 45 or older and women age 55 or older are more likely to have a heart attack than are younger men and women.
• Tobacco. This includes smoking and long-term exposure to secondhand smoke.
• High blood pressure. Over time, high blood pressure can damage arteries that lead to your heart. High blood pressure that occurs with other conditions, such as obesity, high cholesterol or diabetes, increases your risk even more.
• High blood cholesterol or triglyceride levels. A high level of low-density lipoprotein (LDL) cholesterol ("bad" cholesterol) is most likely to narrow arteries. A high level of triglycerides, a type of blood fat related to your diet, also increases your risk of a heart attack. However, a high level of high-density lipoprotein (HDL) cholesterol ("good" cholesterol) may lower your risk.
• Obesity. Obesity is linked with high blood cholesterol levels, high triglyceride levels, high blood pressure and diabetes. Losing just 10% of your body weight can lower this risk.
• Diabetes. Not producing enough of a hormone secreted by your pancreas (insulin) or not responding to insulin properly causes your body's blood sugar levels to rise, increasing your risk of a heart attack.
• Metabolic syndrome. This syndrome occurs when you have obesity, high blood pressure and high blood sugar. Having metabolic syndrome makes you twice as likely to develop heart disease than if you don't have it.
• Family history of heart attacks. If your siblings, parents or grandparents have had early heart attacks (by age 55 for males and by age 65 for females), you might be at increased risk.
• Lack of physical activity. Being inactive contributes to high blood cholesterol levels and obesity. People who exercise regularly have better heart health, including lower blood pressure.
• Stress. You might respond to stress in ways that can increase your risk of a heart attack.
• Illicit drug use. Using stimulant drugs, such as cocaine or amphetamines, can trigger a spasm of your coronary arteries that can cause a heart attack.
• A history of preeclampsia. This condition causes high blood pressure during pregnancy and increases the lifetime risk of heart disease.
• An autoimmune condition. Having a condition such as rheumatoid arthritis or lupus can increase your risk of a heart attack.

Complications

Complications are often related to the damage done to your heart during a heart attack, which can lead to:

• Abnormal heart rhythms (arrhythmias). Electrical "short circuits" can develop, resulting in abnormal heart rhythms, some of which can be serious, and may lead to death.
• Heart failure. A heart attack might damage so much heart tissue that the remaining heart muscle can't pump enough blood out of your heart. Heart failure can be temporary, or it can be a chronic condition resulting from extensive and permanent damage to your heart.
• Sudden cardiac arrest. Without warning, your heart stops due to an electrical disturbance that causes an abnormal heart rhythm (arrhythmia). Heart attacks increase the risk of sudden cardiac arrest, which can cause death without immediate treatment.

Prevention

It's never too late to take steps to prevent a heart attack — even if you've already had one. Here are ways to prevent a heart attack.

• Medications. Taking medications can reduce your risk of a subsequent heart attack and help your damaged heart function better. Continue to take what your doctor prescribes, and ask your doctor how often you need to be monitored.
• Lifestyle factors. You know the drill: Maintain a healthy weight with a heart-healthy diet, don't smoke, exercise regularly, manage stress and control conditions that can lead to a heart attack, such as high blood pressure, high cholesterol and diabetes.