A blockage in the heart’s arteries may reduce or completely cut off the blood supply to a portion of the heart. This can cause a blood clot to form and totally stop blood flow in a coronary artery, resulting in a Heart attack (also called an acute Myocardial Infarction or MI).

Irreversible injury to the heart muscle usually occurs if medical help is not received promptly. Unfortunately, it is common for people to dismiss heart attack symptoms.

The American Heart Association and other medical experts say the body likely will send one or more of these warning signals of a heart attack:

 
• Uncomfortable pressure, fullness, squeezing or pain in the center of the chest lasting more than a few minutes.  
• Pain spreading to the shoulders, neck or arms. The pain may be mild to intense. It may feel like pressure, tightness, burning, or heavy weight. It may be located in the chest, upper abdomen, neck, jaw, or inside the arms or shoulders.  
• Chest discomfort with lightheadedness, fainting, sweating, nausea or shortness of breath.  
• Anxiety, nervousness and/or cold, sweaty skin.  
• Paleness or pallor.  
• Increased or irregular heart rate.  
• Feeling of impending doom.

Not all of these signs occur in every attack. Sometimes they go away and return. If some occur, get help fast. IF YOU NOTICE ONE OR MORE OF THESE SIGNS IN YOURSELF OR OTHERS, DON’t WAIT. CALL EMERGENCY MEDICAL SERVICES (9-1-1) RIGHT AWAY! In the event of cardiopulmonary arrest (no breathing or pulse), call 9-1-1 and begin Cardiopulmonary resuscitation (CPR) immediately.

Myocardial infarction: Causes, incidence, and risk factors

Most heart attacks are caused by a clot that blocks one of the coronary arteries (the blood vessels that bring blood and oxygen to the heart muscle). The clot usually forms in a coronary artery that has been previously narrowed from changes related to atherosclerosis. The atherosclerotic plaque (buildup) inside the arterial wall sometimes cracks, and this triggers the formation of a clot, also called a thrombus.

A clot in the coronary artery interrupts the flow of blood and oxygen to the heart muscle, leading to the death of heart cells in that area. The damaged heart muscle loses its ability to contract, and the remaining heart muscle needs to compensate for that weakened area.

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.

The risk factors for coronary artery disease and heart attack include:

 
• Smoking  
• High blood pressure  
• Too much fat in your diet  
• Poor blood cholesterol levels, especially high LDL (“bad”) cholesterol and low HDL (“good”) cholesterol  
• Diabetes  
• Male gender  
• Age  
• Heredity

The actual diagnosis of a heart attack must be made by a doctor who has studied the results of several tests. The doctor may:

 
• Review the patient’s complete medical history.  
• Give a physical examination.  
• Use an electrocardiogram (or EKG) to discover any abnormalities caused by damage to the heart.  
• Use a blood test to detect abnormal levels of certain enzymes in the bloodstream.

What does heart-related chest pain feel like?

If you suffer chest pain, particularly while exercising, you will almost certainly wonder whether it might be heart-related - and well you should. Heart muscle pain - angina - is likely to be the first warning of blocked coronary arteries, the cause of most heart attacks.

While there are no infallible guidelines about whether a chest pain is heart-related, it generally takes a particular form. Heart discomfort is rarely a sharp, stabbing pain. The textbook description of angina is a feeling of heaviness, pressure, tightness or aching in the chest, usually accompanied by shortness of breath. The pain generally goes away when you stop exerting yourself, and it frequently isn’t especially severe, which is, perhaps, unfortunate.

Even a Heart attack may not be unbearably painful at first, permitting its victim to delay seeking treatment for as much as four to six hours after its onset. By then, the heart may have suffered irreversible damage. It is not unknown for patients to drive themselves to emergency rooms with what proved to be very serious and even fatal heart attacks.

Angina is a protest from the heart muscle that it isn’t getting enough oxygen because of diminished blood supply. A heart attack is simply the most extreme state of oxygen deprivation, in which whole regions of heart muscle cells begin to die for lack of oxygen. If the blockage in the arteries serving the heart muscle can be cleared quickly enough - within the first few hours of the onset of the attack - the permanent damage can be held to a minimum.

That’s why it is so vital to seek medical attention quickly if you feel the sort of pressing pain or heaviness described above. There is a 90 percent probability that pain of this type is angina. And even if it goes away, the artery blockages that caused it are still there and will grow progressively worse.

Ignoring this sort of pain because it is not unbearable or because it goes away is the worst thing you can do. It is the only warning you are likely to get of a potentially lethal condition. Heed it! Consult a cardiologist immediately.

You can have a heart attack without knowing it

The nation’s longest-running heart study suggests that about one heart attack in four produces no symptoms - or at least none that the victim associates with a heart problem.

These so-called “silent heart attacks,” however, are only the most extreme case of a still more prevalent condition called “silent ischemia” - a chronic shortage of oxygen - and nutrient-bearing blood to a portion of the heart. Both conditions put their victims at significant risk.

The cause of ischemia, silent or otherwise, is almost always Atherosclerosis - the progressive narrowing of the heart’s arteries from accumulations of cholesterol plaque. In most instances, this reduction in blood supply generates a protest from the heart - the crushing pain called angina. But in perhaps 25 to 30 percent of heart attack victims, there were no previous symptoms of these gradually developing blockages. The Framingham Heart Study, which followed 4,000 Massachusetts men for more than 40 years, found that 25 percent of their subjects’ heart attacks go unnoticed until their annual EKGs detect their after-effects.

The absence of pain, however, doesn’t mean an absence of damage. The heart has a built-in reserve capacity, allowing it to suffer a certain amount of scarring and weakening from a heart attack and continue to meet the body’s needs. But further ischemia or another heart attack, even a mild to moderate one, may prove fatal because that reserve capacity is no longer there. Even those who survive another heart attack are at increased risk of becoming cardiac cripples, disabled by congestive heart failure or arrhythmias heartbeat irregularities.

There is no way of predicting absolutely who is a candidate for silent ischemia, but statistically, the greater the number of risk factors for coronary artery disease that you have, the more likely you are to be a candidate. Those risk factors include some you can’t control - your age, sex and genetic predisposition to atherosclerosis - and those you can influence, like diabetes, high blood pressure, high blood cholesterol, smoking, lack of exercise and obesity.

As a rule of thumb, I would urge you to undergo a screening for silent ischemia if you have any three of these factors working against you - a man over age 50 who smokes, or a post-menopausal woman with a ten-year history of diabetes and chronic unfavorable blood cholesterol levels, for instance.

The screening for undetected ischemia is a medical history and physical examination and a cardiac stress test - a workout on a treadmill while your heart function is monitored.

It’s a simple, painless and inexpensive way to learn whether the beating of your heart is accompanied by the inaudible ticking of an atherosclerosis time bomb that could kill you.