FAMILY MEDICINE® COLUMN
By John C. Wolf, D.O.
Associate Professor of Family Medicine®
Ohio University College of Osteopathic Medicine

"SILENT" HEART ATTACKS CAN DO GREAT DAMAGE

Question: My sister, who is only 53, recently had a heart attack. She didn't have the "heavy" chest pain that I've heard is typical with heart attacks. Instead, she just didn't feel well. The doctor called this a "silent heart attack." How often are heart attacks silent?

Answer: You are right that heart attacks, the number one killer of Americans, are usually accompanied by telltale symptoms. However, in a significant number of cases the victim has little or no evidence of the onslaught that is taking place within. This is the type of heart attack that your sister had.

All heart attacks, whether or not they have noticeable symptoms, result from an insufficient amount of blood reaching the heart muscles. As you probably know, these heart muscles are supplied by their own set of arteries, the coronary arteries, instead of being nourished by the blood that is within the pumping chambers of the heart. There are many possible causes of blockage in coronary arteries, but most often hardening of the arteries (atherosclerosis) is the culprit.

Over the years the accumulation of cholesterol plaque narrows the arteries until so little blood gets through that the heart muscles become starved for oxygen. This precipitates a heart attack in which the muscle fibers supplied by the blocked coronary artery die because of the lack of oxygen and accumulation of waste products.

This unfortunate series of events happens to 1.5 million United States citizens each year. Of this group, about 800,000 seek immediate hospital care and an additional 500,000 die before reaching the hospital. The remaining 200,000, the "silent" heart attack victims, seek no medical care. About half of them have some sense of being ill, experiencing symptoms such as mild nausea or weakness. The other half don't feel ill at all.

Typically, silent heart attacks are only diagnosed at a later date when an electrocardiogram is done. In one well-respected research effort (Framingham study), routine electrocardiograms were performed on those who had no known history of heart attack. A surprising number of these tests showed evidence of a prior "silent" heart attack. In fact, when these figures were compared with general heart attack data, it was discovered that the statistics I just quoted might seriously underestimate the actual number of silent heart attacks. The "silent" variety may account for up to one-fourth the total heart attacks.

It might seem logical to assume that those who have a silent heart attack have suffered less heart damage than those who have pain. Unfortunately, this is not true. Those who have silent heart attacks probably have an abnormality in the part of the nervous system that carries sensation from the internal organs to the brain. The right nerve signals just aren't sent to the brain to register that a life-threatening event is taking place. Those individuals who are diabetic or who are over 70 are more likely to have this problem.

Another interesting feature of your question is that your sister is only 53. Women in their reproductive years have significantly reduced risk of heart attack when compared to men of the same age. After menopause, however, a woman's risk increases rapidly until at age 75 it is about the same as for a man. This difference is thought to be due to the protective benefits of estrogen.

There are a number of risk factors for heart attack. Heredity, age, gender, tobacco use, alcohol use, diabetes, level of physical fitness, cholesterol level and homocysteine level are a few of these. It is prudent for each of us to work to reduce as many of these risk factors as possible. One crucial thing to remember is that statistics are just numbers. An individual with low-risk factors for a heart attack can still have one.

Family Medicine® is a weekly column. To submit questions, write to John C. Wolf, D.O., Ohio University College of Osteopathic Medicine, Grosvenor Hall, Athens, Ohio 45701.