Sudden cardiac death may not be so sudden after all.

A new study suggests people often develop symptoms of cardiac arrest, like chest pain or breathlessness, around two hours beforehand. In addition, up to two-thirds of sudden cardiac death victims have a history of heart disease that puts them at risk for cardiac arrest.

Researchers say learning to recognize these warning signs of cardiac arrest may offer a window of opportunity to prevent sudden cardiac death.

"Our study suggests that shifting the focus to educating high-risk patients and families may lead to earlier recognition, a quicker call to the emergency medical system (EMS), a higher percentage of bystander CPR [cardio pulmonary resuscitation], and thus to a higher probability of survival in patients with sudden cardiac death,” says researcher Dirk Muller, MD, PhD, of the University of Berlin, in a news release.

How Is Sudden Cardiac Arrest Different from a Heart Attack?

Recognizing Cardiac Arrest

Cardiac arrest occurs when the heart abruptly stops pumping.

According to the American Heart Association, more than 330,000 people die each year from heart disease before reaching a hospital, or in an emergency room. Most of these deaths are caused by sudden cardiac arrest.

In the study, researchers examined 406 cases of cardiac arrest out of the more than 5,000 rescue missions performed by doctors at a mobile intensive care unit in Berlin.

The results showed 72 percent of the cardiac arrests occurred at home and 67 percent were witnessed by a bystander.

Researchers collected information on symptoms preceding cardiac arrest on 323 of the 406 cases.

The most common warning symptom was chest pain lasting from 20 minutes to 10 hours and 30 minutes before the cardiac arrest, or a median of two hours. Chest pain occurred in 25 percent of the cardiac arrests witnessed by others.

Breathlessness for 10 minutes was reported in 17 percent of witnessed cardiac arrests; nausea or vomiting for 90 minutes before the arrest in 7 percent.

Other common symptoms were dizziness or fainting.

Background history was available in 352 of the patients. Researchers found that 106 of these cardiac arrest patients had a history of coronary artery disease that put them at increased risk for cardiac arrest, and 16 had experienced a previous cardiac arrest.

Heart Rate Reveals Risk of Sudden Death

Quick Treatment Crucial

The study showed bystanders performed CPR on 57 patients, and 13 of those patients (23 percent) survived to hospital discharge. Only 4 percent of cardiac arrest patients who did not receive bystander CPR survived.

Researchers found CPR attempts occurred more often in public locations (26 percent) than at home (11 percent).

They say the results suggest family members and caregivers of people with heart disease and at increased risk should be trained to recognize symptoms and perform CPR to reduce the likelihood of death from cardiac arrest.

“Training and prevention efforts should be focused on how to recognize the emergency, CPR training, and automated external defibrillator (AED) use," says Muller.

New CPR Rules: Push Hard, Push Fast

By Jennifer Warner, reviewed by Louise Chang, MD

SOURCES: Muller, D. Circulation: Journal of the American Heart Association, Sept. 5, 2006, online advance edition; vol 114. News release, American Heart Association.