What is a Heart Attack?

Definition:

A heart attack is when low blood flow causes the heart to starve for oxygen. Heart muscle dies or becomes permanently damaged. Your doctor calls this a myocardial infarction.

Alternative Names
Myocardial infarction; MI; Acute MI

Causes, incidence, and risk factors
Most heart attacks are caused by a blood clot that blocks one of the coronary arteries. The coronary arteries bring blood and oxygen to the heart. If the blood flow is blocked, the heart starves for oxygen and heart cells die.


A clot most often forms in a coronary artery that has become narrow because of the build-up of a substance called plaque along the artery walls. (See: atherosclerosis) Sometimes, the plaque cracks and triggers a blood clot to form.

Occasionally, sudden overwhelming stress can trigger a heart attack.

It is difficult to estimate exactly how common heart attacks are because as many as 200,000 to 300,000 people in the United States die each year before medical help is sought. It is estimated that approximately 1 million patients visit the hospital each year with a heart attack. About 1 out of every 5 deaths are due to a heart attack.

Risk factors for heart attack and coronary artery disease include:

• Bad genes (hereditary factors) 
• Being male 
• Diabetes 
• Getting older 
• High blood pressure 
• Smoking 
• Too much fat in your diet 
• Unhealthy cholesterol levels, especially high LDL ("bad") cholesterol and low HDL ("good") cholesterol. 

Higher-than-normal levels of homocysteine, C-reactive protein, and fibrinogen may also increase your risk for a heart attack. Homocysteine is an amino acid. C-reactive protein and fibrinogen are linked to inflammation. Fibrinogen is also involved in blood clotting.

Symptoms 
Chest pain is a major symptom of heart attack. However, some people may have little or no chest pain, especially the elderly and those with diabetes. This is called a silent heart attack.

The pain may be felt in only one part of the body or move from your chest to your arms, shoulder, neck, teeth, jaw, belly area, or back.

The pain can be severe or mild. It can feel like:

• Squeezing or heavy pressure 
• A tight band around the chest 
• Something heavy sitting on your chest 
• Bad indigestion 

Pain usually lasts longer than 20 minutes. Rest and a medicine called nitroglycerine do not completely relieve the pain of a heart attack.

Other symptoms of a heart attack include:

• Shortness of breath 
• Nausea or vomiting 
• Anxiety 
• Cough 
• Fainting 
• Lightheadedness - dizziness 
• Palpitations (feeling like your heart is beating too fast) 
• Sweating, which may be extreme 

Prevention

To prevent a heart attack:

• Keep your blood pressure, blood sugar, and cholesterol under control. 
• Don't smoke. 
• Consider drinking 1 to 2 glasses of alcohol or wine each day. Moderate amounts of alcohol may reduce your risk of cardiovascular problems. However, drinking larger amounts does more harm than good. 
• Eat a low fat diet rich in fruits and vegetables and low in animal fat. 
• Eat fish twice a week. Baked or grilled fish is better than fried fish. Frying can destroy some of the benefits. Exercise daily or several times a week. Walking is a good form of exercise. Talk to your doctor before starting an exercise routine. 
• Lose weight if you are overweight. 

If you have one or more risk factors for heart disease, talk to your doctor about possibly taking aspirin to help prevent a heart attack. Aspirin therapy (dose 75 mg to 325 mg a day) or a drug called clopidogrel may be prescribed for women at high risk for heart disease. Aspirin therapy is recommended for women over age 65 to prevent heart attack and stroke as long as blood pressure is controlled and the benefit is likely to outweigh the risk of gastrointestinal side effects. Regular use of aspirin is not recommended for healthy women under age 65 to prevent heart attacks.

New guidelines no longer recommend hormone replacement therapy, vitamins E or C, antioxidants, or folic acid to prevent heart disease.

After a heart attack, you will need regular follow-up care to reduce the risk of having a second heart attack. Often, a cardiac rehabilitation program is recommended to help you gradually return to a normal lifestyle. Always follow the exercise, diet, and medication plan prescribed by your doctor.

References 
Mosca L, Banka CL, Benjamin EJ, et al. Evidence-Based Guidelines for Cardiovascular Disease Prevention in Women: 2007 Update. Circulation. 2007; Published online before print February 19, 2007. Pollack CV Jr. 2004 American College of Cardiology/American Heart Association guidelines for the management of patients with ST-elevation myocardial infarction: implications for emergency department practice. Ann Emerg Med. 2005; 45(4): 363-76. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Clinical Guidelines/Evidence Reports. 2003 May; 3(5233); 1. Boden WE, O'rourke RA, Teo KK, et al. Optimal Medical Therapy with or without PCI for Stable Coronary Disease. N Engl J Med. 2007 Mar 26; [Epub ahead of print].