SYMPTOMS — The “typical” complaint of a person having an MI is persistent chest discomfort, resulting from ischemia involving an area of heart muscle. But there is wide variability in the symptoms a person can have when an MI is occurring. Some patients have no symptoms at all. Others, particularly women, older adults, diabetics, and individuals with a prior diagnosis of heart failure, may have other symptoms but not report chest discomfort. Still others have a combination of chest discomfort and other complaints. Some people having an MI will experience sudden death, also known as cardiac arrest.

Ischemic chest pain in angina and MI — Recall that the obstruction in blood flow that occurs in patients with CHD can cause an imbalance between the supply of oxygen-rich blood to an area of heart muscle and the demand for oxygen that exists at a point in time. This causes a relative lack of oxygen to the muscle, or ischemia, and may be felt by the patient as chest discomfort or angina pectoris. When the imbalance is eventually corrected during the anginal episode—for example, the person may rest, thereby decreasing the heart’s oxygen demand—the discomfort slowly goes away and no damage has occurred.

The chest discomfort that occurs in the setting of an MI, caused by a blood clot that more seriously obstructs blood flow, can be similar to an episode of angina, because it also arises from ischemia to the heart. It may last longer (an episode of angina usually lasts more than two but less than 20 minutes), and may not be relieved by the measures that often relieve angina, such as rest or the use of nitroglycerin under the tongue.

Many different conditions can cause pain in the chest. The ischemic chest discomfort of an MI can range from mild to severe, and typically has the following characteristics:

• Felt as a pressure, constriction, tightness, or squeezing, versus a sharp or stabbing pain
• Is not limited to a small area, but rather spreads through the chest
• May radiate to other areas of the body, including the upper abdomen, shoulders, arms, neck and throat, or lower jaw and teeth
• Comes on gradually and lasts more than a few seconds
• Is usually not made worse by pressing on the area of the chest that is affected, by taking a deep breath or by a particular position; however, lying down may make it worse, while sitting up may produce some reduction in intensity
• Is not relieved by antacids or food

Other symptoms of MI — A number of other symptoms can occur in the setting of an MI. They may occur in a patient with or without chest discomfort. These include:

• Shortness of breath
• Nausea, vomiting, or belching
• Sweating
• Palpitations
• Lightheadedness
• Fatigue
• Fainting
• Cardiac arrest (sudden cardiac death)

Source: http://www.uptodate.com/patients/content/topic.do?topicKey=hrt_dis/9329&title=Heart+attack+(Myocardial+infarction)#5

What Are the Signs and Symptoms of a Heart Attack?

Not all heart attacks begin with a sudden, crushing pain that is often shown on TV or in the movies. The warning signs and symptoms of a heart attack aren’t the same for everyone. Many heart attacks start slowly as mild pain or discomfort. Some people don’t have symptoms at all (this is called a silent heart attack).

Chest Pain or Discomfort

The most common symptom of heart attack is chest pain or discomfort. Most heart attacks involve discomfort in the center of the chest that lasts for more than a few minutes or goes away and comes back. The discomfort can feel like uncomfortable pressure, squeezing, fullness, or pain. It can be mild or severe. Heart attack pain can sometimes feel like indigestion or heartburn.

The symptoms of angina can be similar to the symptoms of a heart attack. Angina is pain in the chest that occurs in people with coronary artery disease, usually when they’re active. Angina pain usually lasts for only a few minutes and goes away with rest. Angina that doesn’t go away or that changes from its usual pattern (occurs more frequently or occurs at rest) can be a sign of the beginning of a heart attack and should be checked by a doctor right away.

Other Common Signs and Symptoms

Other common signs and symptoms that a person can have during a heart attack include:

• Upper body discomfort in one or both arms, the back, neck, jaw, or stomach
• Shortness of breath may often occur with or before chest discomfort
• Nausea (feeling sick to your stomach), vomiting, lightheadedness or fainting, or breaking out in a cold sweat

Not everyone having a heart attack experiences the typical symptoms. If you’ve already had a heart attack, your symptoms may not be the same for another one. The more signs and symptoms you have, the more likely it is that you’re having a heart attack.

Act Fast

Sometimes the signs and symptoms of a heart attack happen suddenly, but they can also develop slowly, over hours, days, and even weeks before a heart attack occurs.

Know the warning signs of a heart attack so you can act fast to get treatment for yourself or someone else. The sooner you get emergency help, the less damage there will be to your heart.

Call 9–1–1 for help within 5 minutes if you think you may be having a heart attack or if your chest pain doesn’t go away as it usually does when you take prescribed medicine.

Don’t drive yourself or anyone else to the hospital. Call an ambulance so that medical personnel can begin life-saving treatment on the way to the emergency room.

Some heart attacks are sudden and intense — the “movie heart attack,” where no one doubts what’s happening. But most heart attacks start slowly, with mild pain or discomfort. Often people affected aren’t sure what’s wrong and wait too long before getting help. Here are signs that can mean a heart attack is happening:

• Chest discomfort. Most heart attacks involve discomfort in the center of the chest that lasts more than a few minutes, or that goes away and comes back. It can feel like uncomfortable pressure, squeezing, fullness or pain.
• Discomfort in other areas of the upper body. Symptoms can include pain or discomfort in one or both arms, the back, neck, jaw or stomach.
• Shortness of breath. May occur with or without chest discomfort.
• Other signs: These may include breaking out in a cold sweat, nausea or lightheadedness

As with men, women’s most common heart attack symptom is chest pain or discomfort. But women are somewhat more likely than men to experience some of the other common symptoms, particularly shortness of breath, nausea/vomiting, and back or jaw pain.

If you or someone you’re with has chest discomfort, especially with one or more of the other signs, don’t wait longer than a few minutes (no more than 5) before calling for help. Call 9-1-1… Get to a hospital right away.

Calling 9-1-1 is almost always the fastest way to get lifesaving treatment. Emergency medical services staff can begin treatment when they arrive — up to an hour sooner than if someone gets to the hospital by car. The staff are also trained to revive someone whose heart has stopped. You’ll also get treated faster in the hospital if you come by ambulance.

If you can’t access the emergency medical services (EMS), have someone drive you to the hospital right away. If you’re the one having symptoms, don’t drive yourself, unless you have absolutely no other option.

How do I know if a heart attack has occurred?

A doctor who’s studied the results of several tests must diagnose a heart attack. The doctor will

• review the patient’s complete medical history.
• give a physical examination.
• use an electrocardiogram (e-lek”tro-KAR’de-o-gram) (ECG or EKG) to discover any abnormalities caused by damage to the heart. An ECG is a medical device that makes a graphical record of the heart’s electrical activity.
• sometimes use a blood test to detect abnormal levels of certain enzymes in the bloodstream.

Blood tests confirm (or refute) suspicions raised in the early stages of evaluation that may occur in an emergency room, intensive care unit or urgent care setting. These tests are sometimes called heart damage markers or cardiac enzymes.

Source: http://www.americanheart.org/presenter.jhtml?identifier=4595