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The doctor of NBC's Tim Russert has said that the veteran journailst died at age 58 Friday after plaque ruptured an artery, causing a sudden coronary thrombosis.

Russert suffered what is called sudden cardiac death or the unexpected natural death from a cardiac cause which occurs within a short time period, usually less than an hour from the onset of symptoms.

Heart disease is the No. 1 killer of both men and women in the United States. The U.S. Centers for Disease Control and Prevention estimate that 770,000 Americans will have a new coronary attack in 2008, and about 430,000 will have a recurrent attack.

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About every 26 seconds, an American will have a coronary event, and about one every minute will die from one, the CDC's Web site reports. In a nutshell, more than half a million people will die this year from heart disease.

A number of factors can influence a person’s risk for heart disease, including heredity and lifestyle choices such as smoking, excessive drinking, history of diabetes and consuming a high fat diet.

Perhaps the first defense against a fatal heart attack is recognizing the risk factors. There are different ways a heart attack can prevent itself. In addition to sudden cardiac death, there are two other types of heart attacks.

Number one is the silent heart attack. Here you don’t have major chest pain, you don’t have shoulder pains, you may have a little palpitation, but you’re not tired, you’re not fatigued, and you’re not dizzy. However, when you go in for a physical, the doctor finds that you have had a silent heart attack.

Number two is typical angina or chest pain. This is chest pain with chest pressure that doesn’t go away, and it is quite important for individuals with these symptoms to get themselves to hospital within 30 minutes.

I've presented three types of heart attacks, but the underlying theme is the same—they all involve chronic or acute coronary artery disease.

In other words, you don’t go around with a normal coronary artery one day and the next day develop a major clot. The heart attack may present itself differently in different people, but the cause is the same no matter how we experience the critical moment.

Assessing Your Risk

Researchers have long noted the importance of body shape in determining a person’s risk factors for heart disease. They talk about the apples versus the pears. The apples tend to store their access fat in their stomach and chest. The pears store it below the hips, in their thighs and buttocks.

A recent study found that a person’s waist-to-hip ratio is an even better predictor of cardiovascular risk than their body mass index, or BMI, the commonly used ratio of weight to height. It appears that a large waist size, which generally indicates large amounts of abdominal fat, is more harmful than a larger hip size.

Determine your body shape and risk for cardiovascular disease by calculating your waist-to-hip ratio. First, measure your waist at its smallest circumference; then, measure your hips at their widest. Next, divide your waist measurement by your hip measurement. For example, a person with a thirty-six-inch waist and forty-inch hips would have a waist-to-hip ratio of 0.9. Waist-to-hip ratios over 0.85 in women and over 0.9 in men are strongly associated with an increased risk for heart disease.

Know the Signs

Most heart attacks do not come on swiftly and cause immediate death. And the best chance for surval is getting medical attention immediately at the first sign of a heart attack. The American Heart Association lists the following as the symptoms of a possible heart attack:

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

Dr. Manny Alvarez is the managing editor of health news at FOXNews.com, and is a regular medical contributor on the FOX News Channel. He is chairman of the Department of Obstetrics and Gynecology and Reproductive Science at Hackensack University Medical Center in New Jersey. Additionally, Alvarez is Adjunct Professor of Obstetrics and Gynecology at New York University School of Medicine in New York City.