Updated July 24, 2006

Heart Attack
Fast Action Needed

by Wayne L. Clark

The message is clear: People with diabetes need to recognize their increased risk of heart disease, and they need to ask their physicians about prevention and about what to do in an emergency.

“There are many reasons people delay seeking treatment,” says Costas T. Lambrew, M.D., retired director of the Division of Cardiology at Maine Medical Center in Portland, Maine. Dr. Lambrew served on the National Heart Attack Alert Program committee of the NHLBI, charged with investigating delay both before and after arrival at the hospital. “They don’t recognize the symptoms, or they say ‘it can’t be’ a heart attack,” he says. “Many people also don’t want to cause a fuss by having an ambulance pull into their neighborhood in the middle of the night, or they don’t want to inconvenience the paramedics. People who have had a heart attack often delay until the symptoms are as bad as they were the first time, which of course is the wrong thing to do.”

Emotional and social barriers also play a major role in the delay of treatment. “Women delay more than men,” Dr. Lambrew says, “perhaps because they have a higher pain threshold, and also because they frequently experience more subtle symptoms than men.” Ignoring nonclassic symptoms or having a mistaken perception of risk can cost precious time. In one survey of women (with and without diabetes), many mistakenly believed that cancer was the leading cause of death for women when, in fact, heart disease and stroke kill more than twice as many women as all cancers combined. Heart disease was long portrayed as a disease that mainly affected men, so women, especially women with diabetes, need to be aware of their actual level of risk.

What’s happening to the heart?
The classic heart attack symptom is described as a crushing pain in the chest, but it’s not necessarily the only symptom. A heart attack can manifest itself as chest discomfort or as pain in the arms, back, neck, jaw, and even the stomach. There may be a vague shortness of breath even before other symptoms appear. A person having a heart attack may break out in a cold sweat and be nauseous and light-headed. Many people report a feeling of doom. Symptoms can come on gradually and be intermittent and subtle.

People with diabetes often have atypical heart attack symptoms, and sometimes they have no symptoms at all. This may be another reason why people with diabetes are more likely to delay seeking treatment. The incidence of silent myocardial ischemia, or symptomless heart attacks, is as much as 30% higher in people with diabetes than in people without diabetes.

The causes of silent ischemia are not fully understood, but there appears to be an association with cardiac autonomic neuropathy (CAN). CAN is similar to the sensory neuropathy that can cause numbness, tingling, or pain in the feet and legs of people with diabetes, in that it is caused by damage to the nerve fibers around the heart. CAN also may increase the risk of cardiovascular events by itself, although the mechanism has not been completely explained.

All these symptoms, silent or not, are caused by a physically tiny problem. The heart’s blood supply comes from three major coronary arteries. (See this illustration.) These arteries divide and subdivide, with the branches feeding all of the heart muscle. A heart attack occurs when there is a blockage in one of the coronary arteries, usually caused by a clot. The clot often starts with the rupture of a plaque, or fatty deposit, that has built up in an artery wall. (These deposits are the results of the disease process known as atherosclerosis.) The body’s natural healing response is to cause clotting at the site of injury, but clotting in a vessel already narrowed by atherosclerosis can cut off the supply of oxygen-laden blood to parts of the heart muscle. The muscle tissue begins to die after even a short time without oxygen.

Wayne Clark is a freelance medical and science writer who has written extensively on diabetes. He lives in Maine.

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