Signs of approaching "sudden" cardiac arrest, an electrical malfunction that stops the heart, usually appear at least a month ahead of time, according to a study of middle-age men in Portland, Oregon.
"We're looking at how to identify the Tim Russerts and Jim Gandolfinis - middle aged men in their 50s who drop dead and we don't have enough information why," said Sumeet Chugh, senior author of the study and associate director for genomic cardiology at the Cedars-Sinai Heart Institute in Los Angeles.
Some 360,000 out-of-hospital cardiac arrests occur each year in the United States, largely involving middle-aged men, with only 9.5 percent surviving, according to the American Heart Association.
Patients can survive if they are given cardiopulmonary resuscitation (CPR) immediately and their hearts are jolted back into normal rhythm with a defibrillator.
Earlier clinical trials have focused only on symptoms or warnings signs within an hour of such attacks. But Chugh's study set out to determine whether signs and symptoms occurred as much as a month before sudden cardiac arrests.
Researchers went back and examined medical records of men 35 to 65 years old after they had out-of-hospital attacks. In addition, paramedics reaching the scene of fatal attacks asked family members what signs and symptoms the patient may have had in preceding weeks.
Among 567 men who had "sudden" arrests, researchers determined 53 percent had symptoms beforehand. Among those with symptoms, 56 had chest pain, 13 percent had shortness of breath and 4 percent had dizziness, fainting or palpitations.
About 80 percent of symptoms happened between four weeks and one hour before the cardiac arrest, researchers said. And although most men had coronary artery disease, just half had been tested for it before their attacks.
"The findings were entirely unexpected," Chugh said. "We never thought more than half of these middle-aged men would have had warning signs so long before their cardiac arrests. Previously we thought most people don't have symptoms so we can't do anything about it."
Chugh said most people who have the same kinds of symptoms don't go on to have cardiac arrests.
"Even so, they should seek medical care," he said. "The message here is, if you have these signs or symptoms, please don't ignore them: seek healthcare."
Chugh said he and his colleagues are also attempting to identify people at risk by comparing biologies of those that have had sudden cardiac arrests with sample populations in Portland that have never had cardiac arrests.
The new findings, from the 11-year-old "Oregon Sudden Unexpected Death Study," were presented on Tuesday at the annual scientific sessions of the American Heart Association being held in Dallas.
The researchers are conducting similar studies among women. The ongoing study is being funded by the U.S. Centers for Disease Control and Prevention, AHA and the Doris Duke Charitable Foundation.