When Tim Russert, the NBC correspondent and moderator of Meet the Press, died suddenly at the network's Washington, DC, bureau, it was widely reported that a heart attack had caused his death.

Russert did have a heart attack, but the actual cause of death was sudden cardiac arrest (SCA), a usually fatal disruption of the heart's normal rhythm. Each year, more than 325,000 Americans die from SCA.

A heart attack can lead to SCA, but not all SCA cases result from a heart attack. The difference is significant because the conditions don't require all the same treatments or the same emergency care.

More than half of heart attack victims survive, and they often have symptoms--the classic ones include chest pain, shortness of breath and sweating, while the less well-known ones include dizziness, fatigue and even jaw pain.

In contrast, the survival rate for SCA is 10% or less, and the condition usually causes no symptoms. Patients typically collapse and die without warning.

What you need to know to protect yourself or a loved one…

An Electrical Problem

Most heart attacks are caused by a plumbing problem. Typically, a blood clot forms on top of a ruptured plaque (fatty buildup) in a coronary artery. The clot (or clots) prevent blood from reaching the heart, sometimes leading to death.

SCA is usually due to an electrical problem. The electrical impulses that regulate the heartbeat become too rapid (ventricular tachycardia), chaotic (ventricular fibrillation) or both.

Result: The heart can't pump blood. Without proper emergency care, SCA victims die within minutes of the event.

The Right Emergency Care

Immediate emergency care is crucial for a person who suffers SCA. For every minute of ventricular fibrillation, the chance of survival decreases by about 10%.

Best approaches…

  • Jumpstart the heart. An automated external defibrillator (AED), which is about the size of a laptop computer and costs about $1,500 when purchased online, can increase the odds of survival by twofold to fourfold-and even more if it's located and used within the first minute or two after an attack.

AEDs are easy to use. Once the device is turned on, a computerized voice tells bystanders exactly what to do, such as when (and where) to attach the electrodes to the victim's chest and when to push buttons. The machine analyzes the heart's rhythm. If a patient is experiencing SCA, the machine will instruct the operator to press a "shock" button to restart the heart. The heart rhythm will again be analyzed to determine if more shocks are needed.

Because about 80% of SCAs occur in the home, many adults and particularly those with SCA risk factors (such as a previous heart attack or a family history of heart disease)—should consider buying an AED. In some cases, insurance will cover the cost of the device.

  • Chest compressions. Bystanders without access to an automated defibrillator can at least double an SCA victim's odds of survival by giving continuous chest compressions as soon as he/she collapses.

What to do: Put the heel of one hand in the center of the chest, place your other hand on top of the first hand for strength, and push the breastbone down one to one-and-a-half inches, Try to give about 100 compressions a minute—and keep giving them until emergency help arrives or the patient revives. If the victim is not breathing and SCA is suspected, don't waste time checking for a pulse or giving mouth-to-mouth resuscitation. These steps slow down the administration of heart compressions.

Important: Most states have "Good Samaritan" laws that protect bystanders who administer emergency care from personal liability.

  • Hospital care. SCA patients who survive long enough to reach an emergency room undergo a series of treatments that can increase the odds of survival by a factor of four. After being given shocks and/or chest compressions to restart the heart and restore circulation to the heart and brain, SCA patients also may receive induced hypothermia (available in about 25% of US hospitals. With this procedure, the body temperature is rapidly lowered with a cooling blanket or with cooled intravenous fluids) to about 89.6°F. This improves the chances for neurological recovery.

Treating Survivors

Patients who survive SCA require ongoing treatment to prevent subsequent attacks.

Two main approaches…

  • Restore the heart's rhythm. An implantable cardioverter defibrillator (CD) is a surgically implanted device that continuously analyzes heart rhythms and administers electrical shocks, as needed, to prevent ventricular fibrillation. The device is about 98% effective in interrupting ventricular arrhythmias.
  • Radio-frequency ablation. With this nonsurgical procedure, the doctor uses a catheter to deliver a burst of radio-frequency energy (similar to microwave heat) to destroy clusters of damaged heart-muscle cells.

Success rate: Up to 90%.

Underlying Causes

SCA has several underlying causes. Among the most common…

  • Coronary artery disease. Most victims of SCA are later found to have significant atherosclerosis (accumulations of plaque) in two or more coronary arteries. Impaired circulation can damage the heart and disrupt its electrical activity.
  • Muscle abnormalities. Patients who have suffered a previous heart attack may have scarring or other types of damage that alter normal heart rhythms.
  • Too-rapid heartbeat. In some genetically predisposed patients, the release of the hormone adrenaline during exercise or from stress can speed up the heartbeat to the levels associated with ventricular tachycardia, leading to SCA.

Lifesaving Tests

If you have been diagnosed with heart disease or have had a prior heart attack, ask your doctor to refer you to an electrophysiologist, a cardiologist who specializes in heart-rhythm disturbances.

You probably will be advised to undergo a test that uses an ultrasound of the heart to measure your ejection fraction (a percentage measurement of blood that's pumped out of a filled ventricle with each heartbeat). Patients with readings below 30% to 35% have a significant risk for SCA and may be candidates for an ICD.

Also important: The presence of calcium within the coronary arteries means that a patient has atherosclerosis and needs to be vigilant about managing coronary risk factors. Coronary artery calcium screening is recommended for all men age 45 and older and women age 55 and older. The only exceptions are adults with no coronary risk factors and patients who already have been diagnosed with atherosclerosis.

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