For every heart attack that strikes with chest pain, shortness of breath and nausea, almost two more slide in under the radar among older adults, a new study found.
The imaging study of 936 elderly men and women in Iceland found 17 percent had signs of an unrecognized heart attack: a blood vessel blockage that scarred the heart, according to MRI images, without sparking the symptoms that land patients in the hospital. Less than 10 percent of study participants had a heart attack with recognizable symptoms.
"The fact that there were more people with unrecognized heart attacks than recognized heart attacks suggests it's a big problem," said study author Dr. Andrew Arai of the Bethesda Md.-based National Blood, Heart and Lung Institute, a division of the National Institutes of Health.
But the problem gets bigger. Unrecognized heart attacks are almost as deadly as "full-blown" symptomatic ones, Arai said. Of the 157 people whose heart attacks went unnoticed, 44 died within eight years of follow-up.
"I think doctors need to be looking more carefully for this," said Arai, whose study was published today in the Journal of the American Medical Association. "And maybe we should be treating these people a little more aggressively. In someone we know had a heart attack, we work twice as hard to lower their cholesterol."
Arai said about half of patients who had evidence of an unrecognized heart attack recalled having symptoms they chalked up to the flu or indigestion at the time.
"But the other half had no idea," he said, adding that patients are often surprised to hear their hearts have been damaged. "Maybe it happened in their sleep. Or in people with diabetes, maybe they just didn't feel it."
Roughly 28 percent of the study participants had diabetes, which can cause nerve damage that blocks the warning signs of a heart attack, said Dr. Martha Grogan, a cardiologist at the Mayo Clinic in Rochester, Minn., who was not involved in the study.
"Diabetics often have atypical symptoms or none at all," Grogan said, stressing that the elderly and largely diabetic Icelandic study population -- 60 percent of whom smoked -- are not representative of the greater population.
But even in the greater population, Grogan added, "heart attack symptoms are often vague and start out slowly."
"It's not like the Hollywood heart attack, where someone grabs their chest as they fall to the ground," she said. "Some people think they have a bad case of the flu, they feel achy and run-down. Some people think they have heart burn."
Because damage from unrecognized heart attacks can only be detected by pricy MRI scans and can't be undone, preventing the damage is key, according to Grogan.
"If you think you might be having a heart attack, err on the side of getting checked out," Grogan said, adding that blood tests can quickly detect the signs of a heart attack, and medications can restore blood blow and prevent irreversible harm.
"Don't feel silly or feel like you're imposing. If you go to the emergency room and it's not a heart attack, trust me, everyone will be happy."