Did You Have a Heart Attack—And Not Know It?

April 1, 2012
Bottom Line Health
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When you have a heart attack, you know it because the main symptom—crushing chest pain—is overwhelmingly obvious. That’s what most of us believe about heart attacks. But it’s not always true.

What few people realize: Studies show that 20% to 60% of all heart attacks in people over age 45 are unrecognized or “silent.” And the older you are, the more likely it is that you’ve already had a silent heart attack. In a study of 110 people with a mean age of 82, an astounding 68% had suffered a silent heart attack.

What happens during a silent heart attack? You may have no symptoms at all. Or you may have symptoms that are so mild—for example, a bout of breathlessness, digestive upset or neurological symptoms such as fainting—that neither you nor your doctor connects them with a heart attack.

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Scientists don’t know why some people have unrecognized heart attacks. But they do know that a silent heart attack is a real heart attack and can cause as much damage to heart muscle as a nonsilent heart attack. And just like a person with a known heart attack, anyone who has had a silent heart attack is at higher risk for another heart attack, heart failure, stroke…or sudden death from an irregular heartbeat.

Recent scientific evidence: In a six-year study by cardiologists from the University of California in San Diego and San Francisco—published in Clinical Research in Cardiology in April 2011—people who were diagnosed with a silent heart attack at the beginning of the study were 80% more likely to have another “cardiovascular event,” such as a heart attack or stroke, by the end of the study period.

In a five-year study by cardiologists at the Mayo Clinic, people with an unrecognized heart attack were seven times more likely to die of heart disease than people who didn’t have an unrecognized heart attack.

If you have risk factors for heart disease, it is vitally important to your health that you find out if you have had a silent heart attack. Here’s how…


If you’re at high risk for heart disease, your primary care physician should perform an electrocardiogram (EKG)—a test that checks for problems with the electrical activity of your heart—every year during your regular checkup. If the EKG reveals significant “Q-waves”—markers of damaged heart tissue—you have had a silent heart attack.

“High risk” means that you have two or more risk factors for heart disease. These risk factors include a family history of heart disease (in a first-degree relative such as a sibling or parent)…high blood pressure…smoking…inactivity…obesity…high LDL “bad” cholesterol…low HDL “good” cholesterol…high triglycerides…and type 2 diabetes.

The groups at highest risk for having an unrecognized heart attack are adults over age 65…women…and people of any age with type 2 diabetes.


If your EKG reveals a previously unrecognized heart attack, it’s wise to see a cardiologist and receive the exact same treatment that you would get if you had a recognized heart attack. Elements of that treatment should include…

Treadmill stress test. The cardiologist will check for and interpret many variables, such as your symptoms (if any), the electrical patterns of your heart rhythms and your blood pressure while you are on a treadmill. Important: Be sure to get your cardiologist’s advice on special steps to take to ensure accurate results. For example, you should have no caffeine within 24 hours of the test.

If the results of the stress test indicate “severe myocardial ischemia”—poor blood flow to the heart muscle—it may be necessary to have a coronary angiogram (X-rays of the heart’s arteries) to accurately diagnose the degree of blockage and decide whether you should pursue such options as angioplasty (in which a balloon is inserted into the coronary artery and inflated to restore normal blood flow) or coronary bypass surgery (in which a blood vessel is grafted from another part of the body to give blood a new pathway to the heart).

However, in most cases, heart disease that is associated with a silent heart attack can be managed with such as not smoking…losing weight if you’re overweight…and getting regular exercise. In addition, medications may include…

Aspirin. A daily dose of 81 mg of aspirin is the best choice for an antiplatelet drug to reduce the risk for blood clots. Very important: A higher dose does not increase the cardiovascular benefit—but does increase the risk for gastrointestinal bleeding.

Beta-blocker. This class of drugs slows the heart rate, relaxing the heart and helping to manage high blood pressure.

Angiotensin-converting enzyme (ACE) inhibitor. These drugs expand blood vessels, improving blood flow and lowering blood pressure—thus allowing the heart to work less.

Statin. If you have heart disease, this cholesterol-lowering medication reduces your risk for another heart attack or dying from heart disease—regardless of whether your levels of LDL “bad” cholesterol are high or low.

In addition, statin use should be accompanied by a diet that is low in cholesterol (less than 200 mg per day) and low in saturated fat (less than 7% of total calories).

Also important: It’s crucial that people with diabetes maintain tight control of their HbA1C levels. This measure of long-term blood sugar control should be less than 7%.

However, HbA1C levels should not be aggressively lowered below 6.5% in diabetes patients with cardiovascular disease, according to the Action to Control Cardiovascular Risk in Diabetes study—that increases the risk for death because it would indicate that blood glucose is at times too low.

In general, the best way for people with diabetes to protect against heart attacks and strokes is to give up cigarettes if they smoke…lose weight if necessary…reduce blood pressure to 130–139/80–89 mmHg…and reduce LDL cholesterol to less than 70 mg/dL.

If these lifestyle measures do not also sufficiently lower the person’s HbA1C level, standard antidiabetes medication can be used.