Table 1 shows that both her total cholesterol and LDL-cholesterol (the “bad’ cholesterol) are abnormally high. And although her HDL-cholesterol (the “good” cholesterol is within the desirable range, the relationship (or ratio) between the total cholesterol blood concentration and HDL-cholesterol is also too high.

Table 1. Lipid profile for Ann with desirable and high values

Ann is willing to start treatment, but now that she has had time to think about it, she has lots of questions. As she lights another cigarette she asks, “Why am I at risk for coronary artery disease? What is a risk factor, anyway? What do the cholesterol results really mean? Why didn’t my doctor just change my diet? I could try going off fat for about 6 months and then be tested again. Isn’t there any complementary or alternative treatment that might be safer and still get my cholesterol into the normal range?

Ann’s risk factors

The fact is that her lipid levels are significantly abnormal. Ann is among more than 60 million Americans at risk of coronary heart disease. All heart attacks, with rare exceptions, are caused by atherosclerosis, which is a narrowing and “hardening” of the blood vessels that bring oxygen-carrying blood to the heart. The narrowing occurs because of an imbalance between LDL-cholesterol, which deposits fatty plaque on the vessel walls and HDL-cholesterol, which removes the fatty deposits and brings them to the liver for metabolism.

Furthermore, Ann is a smoker, with high blood pressure (systolic blood pressure = 130 mmHg): two more risk factors for heart disease. The roundtrip commute to her Manhattan office takes at least 3 hours each day. Yes, her career is exciting and she loves it, but it is stressful and consumes most of her waking hours. Consequently, she has little time and energy when she finally gets back to her condo in New Jersey at the end of the day. She spends little time exercising and the “power” lunches and dinners with clients have lead to weight gain. She has gained about 25 pounds since college. Constant stress, lack of exercise and obesity are additional risk factors for Ann.

Who decides what is a risk factor?

Ann has lots of risk factors. But what, exactly, is a risk factor, and how do laboratory values or physical characteristics become recognized as a “risk factor” for coronary heart disease?

The term “risk factor” was originally coined by Dr. William Kannel, the first director of the famous Framingham study. In 1948, researchers in the Boston suburb of Framingham, Massachusetts enrolled more than 5,000 local residents and monitored them and their offspring for decades. It became clear that certain factors predisposed a person to the development of atherosclerosis (hardening of the arteries). The work from Framingham, as well as from other studies, resulted in the creation of a list of risk factors.

This list is not static. The consensus over what is a risk factor changes as more information becomes available. Risk factors are also not absolute predictors of coronary artery disease. Heart attacks occur in people without risk factors, while many people with risk factors never experience heart disease. However, the likelihood of heart disease is higher among those with risk factors. And the risk increases with each additional risk factor a person has. Table 2 lists factors generally thought to increase the risk of cardiovascular disease.

Table 2. Cardiovascular risk factors

Criteria for a risk factor

A laboratory value or physical characteristic becomes a risk factor for coronary heart disease, when it meets certain criteria. These include the following.

·        A strong statistical association between the factor and cardiovascular disease

·        A consistent association that the risk factor produces disease regardless of sex, age or race

·        The association must make biological sense

·        Treatment should favorably change the risk factor

·        The factor should make an independent contribution to increasing the person’s risk of developing disease.

It is also desirable, but not essential, that the impact of the risk factor be demonstrated in the laboratory studies.

Calculating risk

It is possible to compare Ann’s risk of developing heart disease over the next decade to the others in her community by using Tables 3 and 4, which are based on the Framingham Heart Study.

The formula is simple: age + HDL-cholesterol + total cholesterol + systolic blood pressure + smoking + diabetes + EKG evidence of an enlarged left ventricle in the heart provide a point score. This value is compared to others in another table (Table 3) to determine the comparative risk of having coronary artery disease.

Table 3. Coronary heart disease risk factor prediction chart: Framingham Heart Study

Cigarette smoker: add 4 points (Pts)
Diabetic male: add 3 points
Diabetic female: add 6 points
EKG evidence of left ventricular hypertrophy: add 9 points
Source: Black, 1992.Table 4. Probability of coronary heart disease and comparative 10-year risk

Source: Black, 1992.
Ann gets 4 points for her age, 46 years. Her HDL-cholesterol is in the desirable range (subtract 2 points = 2 points). However, total cholesterol is high, primarily due to her elevated LDL-cholesterol (add 5 points = 7). With a systolic blood pressure of 130 mmHg she adds another 2 points plus 4 more for being a smoker (add 6 points = 13).

Her total is 13, which translates in Table 4 to a 3% risk for coronary heart disease in the next 5 years and 8% in the next 10 years. By comparison, the average 10-year risk for women her age is 5%. Therefore, Ann’s current physical condition and lifestyle include factors that increase by 3% her risk of being diagnosed with coronary heart disease by the time she is 56 years old.

A complementary strategy for controlling risk

The key to reducing risk is to control the factors that predispose to heart disease. The first step is to stop smoking. According to the Framingham tables, this change alone in her lifestyle will lower her risk to within the average range for women her age.

Next comes diet. For many people with borderline high cholesterol, dietary changes may be sufficient to lower cholesterol into the desirable range. Unfortunately for Ann, her LDL-cholesterol and total cholesterol are so high, she will probably have to combine diet with drug therapy.

It’s worth the effort

Stopping smoking could add 7 years to her life, according to the Centers for Disease Control and Prevention. Lowering cholesterol will also reduce her chances of developing coronary heart disease and suffering the other complications associated with heart disease, such as myocardial infarction and coronary artery bypass grafting.

Acting now could make the difference in being here to see her daughter graduate from college, or hold her first grandchild, or enjoy a few years of quality retirement after 2 or 3 decades of 3-hour roundtrip commutes to work. It’s worth the effort.

Dr. Russo is vice president of medical communications at Vicus.com. He is a pharmacist and medical writer, with more than 20 years of experience in medical education.

References

Holme I. Effects of lipid-lowering therapy on total and coronary mortality. Curr Opin Lipidol, 1995; 6(6):374-8.

Le Fur C. Influence of mental stress and circadian cycle on postprandial lipemia. Am J Clin Nutrition, 1999; 70:213-20.

Black, HR. Cardiovascular risk factors. Chapter 3. In, Yale University School of Medicine Heart Book. Zaret BL, Moser M, Cohen LS [eds]. New York, Hearst Books, 1992.

Centers for Disease Control and Prevention. Smoking-attributable mortality and years of potential life lost—United States, 1990. Morbidity and Mortality Weekly Report 1993; 42(33):645-8.

Centers for Disease Control and Prevention. Office on Smoking and Health, unpublished data, 1994.