(USA TODAY) -- The news that James Gandolfini, 51, star of The Sopranos, diedof heart troubles stunned his fans, but for medical experts, it was areminder of the thousands who remain at risk of a similar fate all thetime.

Claudio Modini, head of the emergency room at the PoliclinicUmberto I hospital in Rome, said Gandolfini suffered a cardiac arrestand was pronounced dead at 11 p.m. Wednesday after resuscitation effortsin the ambulance and hospital failed. CNN, quoting an "Italianofficial," reported Friday that an autopsy confirmed that Gandolfinidied of a heart attack.

A heart attack may cause cardiac arrestand sudden death. Heart attacks are caused by a blockage that stopsblood flow to the heart. Cardiac arrest is an abrupt loss of heartfunction caused when the heart's electrical system malfunctions. About360,000 cardiac arrests are assessed by emergency medical services inthe USA annually.

About 715,000 people in the USA will havea new or recurrent heart attack this year, according to the AmericanHeart Association. The average age of the first heart attack is 64.7years for men and 72.2 years for women.

USA TODAY talked to Donna Arnett, the president of the American HeartAssociation and the American Stroke Association, about the risk ofhaving a heart attack and ways to avoid it. Arnett is chairman of thedepartment of epidemiology in the School of Public Health at theUniversity of Alabama at Birmingham.

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The answers below are from both Arnett and the American Heart Association website:

Q: What is a cardiac arrest? Is it the same as a heart attack?

A:No. The term heart attack is often mistakenly used to describe cardiacarrest. Though a heart attack may cause cardiac arrest and sudden death,the terms don't mean the same thing. Heart attacks are caused by ablockage that stops blood flow to the heart. A heart attack refers todeath of heart muscle tissue due to the loss of blood supply, notnecessarily resulting in the death of the heart attack victim.

Cardiacarrest is caused when the heart's electrical system malfunctions. Incardiac arrest, death results when the heart suddenly stops workingproperly. This may be caused by abnormal, or irregular, heart rhythmscalled arrhythmias. A common arrhythmia in cardiac arrest is ventricularfibrillation. This is when the heart's lower chambers suddenly startbeating chaotically and don't pump blood. Death occurs within minutesafter the heart stops.

Cardiac arrest may be reversed if CPR(cardiopulmonary resuscitation) is performed and a defibrillator is usedto shock the heart and restore a normal heart rhythm within a fewminutes.

Q: How common is it for someone in their 50s to have a heart attack?

A:Though risk for heart attacks increases with age, it is not uncommonfor a heart attack to occur in the early 50s. Data from one study showthat for every 1,000 men, ages 45-54, three will have heart attacksevery year. This is why it is important for men and women to visittheir health professional to be screened for conditions that increaseheart disease risk, such as high blood pressure, high blood cholesteroland type 2 diabetes.

Q: Could Gandolfini's weight have contributed to heart troubles?

A:Obesity is a contributor to the risk of heart attack. We know thatexcess body weight raises blood cholesterol and blood pressure and caninduce type 2 diabetes.

Q: What is a heart attack?

A:A heart attack occurs when the blood flow that brings oxygen to theheart muscle is severely reduced or cut off completely. This happensbecause coronary arteries that supply the heart muscle with blood canslowly become narrow from a buildup of fat, cholesterol and othersubstances that together are called plaque. This slow process is knownas atherosclerosis.

When plaque in a heart artery breaks, ablood clot forms around the plaque. This blood clot can block the bloodflow through the heart muscle. When the heart muscle is starved foroxygen and nutrients, it is called ischemia. When damage or death ofpart of the heart muscle occurs as a result of ischemia, it is called aheart attack or myocardial infarction (MI). About every 34 seconds,someone in the USA has a myocardial infarction or heart attack.

Q: What are the major risk factors for a heart attack?

A:There are several major risk factors for heart disease that people haveno control over, including your genetics. People whose parents hadheart disease are more likely to develop it. Among the other riskfactors you can't change: getting older, being male (men are at agreater risk than women), heredity, including race. Heart disease riskis higher among Mexican Americans, American Indians, native Hawaiiansand some Asian Americans. This is partly because of higher rates ofobesity and type 2 diabetes.

There are factors you can changethat lower your risk including - getting up and moving more, notsmoking, maintaining a healthy weight and controlling your bloodpressure and cholesterol.

Q: Why is high blood pressure a risk factor for heart disease?

A:High blood pressure means the blood running through your arteries flowswith too much force and puts pressure on your arteries, stretching thempast their healthy limit and causing microscopic tears. Unfortunately,the scar tissue that forms to repair those tears traps plaque and whiteblood cells, which can lead to blockages, blood clots and hardened,weakened arteries.

One in three adults have high blood pressure,but many people don't even know they have it. The risk can be reduced byfollowing a healthful diet, including cutting back on salt; exercising;keeping a healthy weight; managing stress; limiting alcohol; andavoiding smoking. Some people who do those things may still needmedication.

Q: Why do men often develop and die from heart disease at a younger age than women?

A:Men tend to have higher blood pressure and higher cholesterol, and theyare more likely to be smokers than women. Men are less likely to betreated for high blood pressure than women. One big problem for men is alot of them don't manage their blood pressure as well as women do.

Contributing: The Associated Press

How to spot a heart attack

TheAmerican Heart Association says some heart attacks are sudden andintense - the "movie heart attack," where no one doubts what'shappening.

But most heart attacks start slowly, with mild pain ordiscomfort. Often people affected aren't sure what's wrong and wait toolong before getting help. Here are signs that can mean a heart attack ishappening:

•Chest discomfort. Most heart attacks involvediscomfort in the center of the chest that lasts more than a few minutesor that goes away and comes back. It can feel like uncomfortablepressure, squeezing, fullness or pain.

•Discomfort in other areasof the upper body. Symptoms can include pain or discomfort in one orboth arms, the back, neck, jaw or stomach.

•Shortness of breath with or without chest discomfort.

Othersigns may include breaking out in a cold sweat, nausea orlightheadedness. As with men, women's most common heart attack symptomis chest pain or discomfort. Women are somewhat more likely than men toexperience some of the other common symptoms, particularly shortness ofbreath, nausea/vomiting and back or jaw pain.

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