Warning signs seen in failure of hearts

WASHINGTON — New research shows sudden cardiac arrest is not always so sudden, with a lot of people ignoring potentially lifesaving warning signs hours, days or even a few weeks before they collapse.

Cardiac arrest kills about 350,000 in the U.S. every year. It’s not a heart attack, but worse: The heart abruptly stops beating, its electrical activity knocked out of rhythm. CPR can buy critical time, but so few patients survive that it’s been hard to tell whether the longtime medical belief is correct that it’s a strike with little or no advance warning.

A study that has closely tracked sudden cardiac arrest in Portland, Ore., for more than a decade got around that roadblock, using interviews with witnesses, family and friends after patients collapse and tracking down the patients’ medical records.

About half of middle-aged patients for whom symptom information could be found had experienced warning signs, mostly chest pain or shortness of breath, in the month before suffering a cardiac arrest, researchers reported Monday. The research offers the possibility of one day preventing some cardiac arrests if doctors could figure out how to find and treat the people most at risk.

“By the time the 911 call is made, it’s much too late for at least 90 percent of people,” said Dr. Sumeet Chugh of the Cedars-Sinai Heart Institute in Los Angeles, who led the study reported in Annals of Internal Medicine. “There’s this window of opportunity that we really didn’t know existed.”

A fraction of patients considered their symptoms bad enough to call 911 before they collapsed, but they were the ones who were most likely to survive.

That’s a reminder to the public not to ignore possible signs of heart trouble in hopes that they’re just indigestion, said University of Pittsburgh emergency medicine specialist Dr. Clifton Callaway, who wasn’t involved in Monday’s study.

“Chest pain, shortness of breath — those are things you should come in the middle of the night to the emergency department and get checked out,” said Callaway, who chairs the American Heart Association’s emergency care committee. “We strongly recommend you don’t try to ride it out at home.”

Previous heart attacks, coronary heart disease, and certain inherited disorders that affect heartbeat all can increase the risk of sudden cardiac arrest. People known to be at high risk may receive an implanted defibrillator to shock the heart back into rhythm.

Monday’s data from the Oregon Sudden Unexpected Death Study examined records for nearly 1,100 people ages 35 to 65 who suffered cardiac arrest between 2002 and 2012.

For about a quarter of patients, researchers could find no information about whether they experienced symptoms — making it impossible to say how common the warning signs are.

But of the remaining 839 patients, half had evidence of at least one symptom in the previous month, the study found. For most, the symptoms began within 24 hours of their collapse, although some came a week before and a few up to a month before. Chest pain was most common in men, while women were more likely to experience shortness of breath. Other symptoms included fainting and heart palpitations.

Chugh had no way to determine symptom severity. But only 19 percent of patients called 911 about symptoms, mostly people with already diagnosed heart disease or those who were having recurrent symptoms. Their survival rate was 32 percent, compared with 6 percent for other patients. Partly that’s because a fifth of those 911 callers had their cardiac arrest in the ambulance on the way to the hospital.

The study is just the start of research to better predict who is at highest risk for cardiac arrest, and to determine how to target them without panicking people who would do fine with general heart disease treatment, Chugh said.