The Deadly Threat of Silent Heart Attacks
For more than six months, Harriett Cooke had been uncommonly tired, panting when she walked her sixth grade science class to the cafeteria and struggling to keep her eyes open when she drove home at night.
One day, during a class trip outside the school, she just couldn't go on. "I sat there on the side, I put my head down on the table, and I knew I shouldn't be feeling like this," said Ms. Cooke, 67, who lives in Durham, N.C.
Making excuses, she left and stopped at her doctor's office, where staff ordered an electrocardiogram (EKG). The test showed that Ms. Cooke had suffered a so-called "silent heart attack" at some indeterminate point, perhaps months earlier.
Few people know about this type of heart attack, characterized by a lack of recognizable symptoms. Yet silent heart attacks are even more common in older adults than heart attacks that immediately come to the attention of doctors and patients, according to a recent study in The Journal of the American Medical Association.
What's more, they're equally deadly.
The research underscores the importance of paying attention to lingering, hard-to-pin-down symptoms in older adults, experts say. Many elderly men and women tend to dismiss these; caregivers shouldn't let that happen.
The JAMA report is based on data from 936 men and women ages 67 to 93 from Iceland who agreed to undergo EKGs and magnetic resonance imaging exams to detect whether heart attacks had occurred. EKGs assess the heart's electrical activity, while M.R.I.'s look at its mechanical pumping activity.
So-called "recognized" heart attacks were identified when signs of heart damage were evident, and the patient's medical record indicated that medical attention had been sought and a diagnosis rendered. "Silent" heart attacks were also signified by heart damage, but in those cases evidence from medical records was lacking.
When results were tallied, silent heart attacks were twice as common (22 percent) among older patients as recognized heart attacks (10 percent). Five years after tests were administered, death rates for patients with both recognized and silent heart attacks were 23 percent, almost double the 12 percent death rate for older adults who'd never experienced a myocardial infarction, the technical name for this medical event.
Recognized heart attacks may be more serious in the short run, but silent heart attacks are equally dangerous in the long run because they don't receive medical attention, said Dr. Andrew E. Arai, the lead author and chief of the cardiovascular and pulmonary branch of division of intramural research at the U.S. National Heart, Lung and Blood Institute.
Indeed, seniors who had the silent version were less likely to get treatments for coronary artery disease — aspirin, beta blockers, and cholesterol-lowering statins. Yet tests documented they had higher-than-average risk factors: elevated blood pressure, high cholesterol, hardening of the arteries, and evidence of plaque buildup in blood vessels.
Results from Iceland may not be fully generalizable to the United States since more people smoke in Iceland, and there's greater diversity in the population here. But a key takeaway message is that heart attacks aren't always easy to detect, especially in older people.
"Not everyone has classic symptoms — chest pain, maybe radiating to the arm, nausea, sweating, shortness of breath," Dr. Arai said.
"In reality, many patients, have much less clear cut symptoms," he continued. "They may think it's a bad case of indigestion or the flu, or this may even occur during their sleep and they won't realize that anything happened."
If you're an older person and you've been feeling seriously unwell for a while, "go see your doctor, don't blow it off," Dr. Arai said.
That's not an invitation for people to run out and demand M.R.I.'s of the heart if they've been feeling flulike for several weeks. Although M.R.I.'s identified more silent heart attacks than EKGs in the JAMA report, these tests are expensive, not widely available, and stress echocardiograms, nuclear stress tests, and computerized tomography (CT) coronary angiograms are good alternatives, said Dr. Michael Shen, section head of cardiac imaging at the Cleveland Clinic in Florida.
Tests should be based on the patient's family history, personal history, symptoms like shortness of breath or tightness in the chest, and risk factors like cholesterol levels, high blood pressure, smoking and diabetes, Dr. Shen said.
In the JAMA study, 26 percent of patients with diabetes (266 altogether) had silent heart attacks, compared with 11 percent who had clinically recognized heart attacks.
"We don't really understand what causes one person to have chest pain and another person not to have chest pain," said Dr. LeRoy E. Rabbani, director of cardiac intensive care and the cardiac inpatient service at NewYork-Presbyterian Hospital/Columbia University Medical Center in New York. But diabetics, who are prone to nerve damage known as neuropathy, "may have impaired sensation that extends to chest wall."
To illustrate the point, Dr. Rabbani tells of an elderly patient who had undergone coronary artery bypass surgery and had stents implanted in his arteries to prop them open. Each time his heart gave him trouble over a period of a dozen years, he had felt chest pain.
But one day, after developing diabetes in his 80s, this patient felt a little dizzy, noticed a nose bleed and fainted after arriving at his ear nose and throat doctor's office. In the emergency room, tests showed that he had had a heart attack, with no symptoms this time, six hours before. "Even in a given individual, things can change," Dr. Rabbani said.
There's no opportunity to restore heart muscle damaged in a silent heart attack, but there is opportunity to intervene to prevent a second heart attack or heart failure.
"One has to look at (a silent heart attack) as a potential marker for coronary atherosclerosis and take a more detailed look to see if risk factors are being treated adequately," said Dr. Christopher O'Connor, chief of cardiology at Duke University School of Medicine.
If damage is relatively mild, "there are a whole host of medications we can use to prevent the occurrence of a second event," he said. If damage is more significant, bypass surgery, stents, and even devices like implantable defibrillators may be warranted.
Afterward, doctors monitor patients more frequently and "pay much more attention to ambiguous symptoms like prolonged fatigue, confusion or shortness of breath," Dr. O'Connor continued. "Before, we thought these silent events were less important. Now, we realize they're equally important as symptomatic heart attacks and deserving of careful follow-up."
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