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Medical Report: Preventing Coronary Artery Disease

Scott, Shelby M.D., FACSM

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Shelby Scott, M.D., FACSM, is a full-time faculty member at Natividad Family Medicine Residency Program in Salinas, California, and is assistant clinical professor at the University of California, San Francisco Department of Family and Community Medicine. She coordinates the orthopedic and sports medicine curricula at Natividad Medical Center where she has a sports medicine clinic. Dr. Rush completed a fellowship in sports medicine at The Orthopedic Specialty Hospital in Salt Lake City, Utah. She is board certified in Sports Medicine and Family Practice. Dr. Rush is a physician for the U.S. Ski & Snowboard Association and a team physician for Hartnell College and North Salinas High School. She was also a member of the medical team for skating events at the 2002 Olympic Games.

Despite awareness of the risks of heart disease, coronary artery disease (CAD) remains the leading cause of death in the United States (1). Numerous studies have demonstrated the efficacy of cholesterol reduction in both primary and secondary prevention of heart disease. Primary prevention is the deterrence of a first coronary event, and secondary prevention is the reduction of disease and mortality after a coronary event. However, every 33 seconds, another person in the United States dies of heart disease.

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Because of public awareness, many clients approach healthcare workers and exercise professionals to ask whether they should have their cholesterol tested. If they have already had it tested, they often ask what the "ideal" cholesterol levels are, what nonmedical interventions can lower their cholesterol, and when they should start taking medications. The U.S. Preventive Services Task Force and the American College of Physicians recommend routine screening of fasting lipid levels at 35 years of age in men and 45 in women. If there is no change in risk factors, screening is repeated every 5 years. Table 1 outlines risk factors for CAD. People with two or more risk factors, known CAD, diabetes, or a strong family history of CAD need routine screening earlier. National Education Program Guidelines recommend yearly or biannual screening in high-risk people beginning at 20 years old (2).

Table 1
Table 1
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Once the measurements are done, treatment depends upon total cholesterol (TC), high-density lipoprotein levels (HDL-C), low-density lipoprotein levels (VLDL-C), and triglyceride levels (TG). Most clients will be anxious to know what the perfect numbers are and how to achieve them. Ideally, this is a conversation to be held with their primary care professional, but when patients leave their physician's office with more questions than when they entered, they will seek information elsewhere. Because CAD is the leading cause of mortality in the United States, it is worth addressing the problem on multiple fronts. If a healthcare provider recommends medications to alter a client's cholesterol profile, it is because the client is at increased risk of a coronary event without treatment. For most people, a trial of diet and activity modification may be attempted for three to four months before starting a medication to lower lipids (3). The physician and exercise professionals need to educate clients on achievable ways to reduce coronary risk. The keys to lifestyle intervention are reduced saturated fat and cholesterol intake, increased physical activity, weight control, and smoking cessation. One of the biggest problems facing healthcare professionals is the poor compliance with lipid-lowering agents and lifestyle interventions (4).

Recent studies have shown that aggressive dietary changes can often lower the lipid profile by more than 30% (5). This can be achieved through the addition of certain unsaturated fats to the diet, in particular, those found in nuts and plant sterols/stanols. Stanols decrease the amount of cholesterol absorbed with meals. They are found in soy and pine tree oils. Current commercial preparations are Benecol and Take Control margarines. Eating 1 to 2 tablespoons per day can decrease LDL-C in a few weeks (6). The benefits of the plant sterols increase when combined with a low-fat diet. Stanol/sterol-fortified juices, yogurt, cereals, and breakfast bars are being marketed in other countries, and an orange juice preparation is soon to hit the U.S. market. Walnuts and almonds are readily available in the United States and can reduce LDL-C. However, the reduction is small (5%) at easily ingested levels-8 to16 walnuts per day (7). This benefit is similar to that seen with garlic therapy or oatmeal/oatbran ingestion. At higher walnut intake, there is some evidence to support a reduction in TC and LDL-C, but the treatment levels are too high to expect adherence.

Other effective dietary modifications include increased fiber intake and foods low in cholesterol and trans-fatty acids. The addition of 3 to 6 g of soluble fiber from oat or psyllium can lower LDL-C by more than 5%. Saturated fats should account for less than 7% of caloric intake, with cholesterol limited to less than 200 mg per day. Cholesterol is only found in animal products: egg yolks, dairy, meat, liver, and shellfish. The average American ingests 256 mg of cholesterol per day, requiring a greater than 20% reduction in intake. The recommended overall daily fat intake is very achievable, at 25% to 35% of total calories. Lower fat intake may be set as a goal for certain people, after discussion with a physician and nutritionist.

The mainstay, however, of lipid-lowering treatment is a class of medications called statins. The statins reduce the amount of cholesterol made in the body and reduce the CAD risk associated with elevated lipid levels (8, 9). They stabilize plaques in arteries and inhibit clot formation. Statins are given at bedtime and are fairly well tolerated. One side effect for exercise specialists to watch for is myopathy, or muscle damage (Table 2). It occurs in 1% to 5% of people taking statins. People taking multiple medications or those with complex medical conditions are at the greatest risk. The risk of myopathy also increases as the dose of the medication increases. Myopathy may present as nonspecific muscle aches. The clinician can diagnose the problem by using a blood test called creatine kinase muscle fraction (CK-MM) and checking for medication interactions. However, the muscle and joint aches may occur without an elevation of muscle enzyme. Any client who is on astatin and experiences undue muscle aching or dark urine needs to be evaluated by a healthcare professional. It also is prudent to advise the client to stop the statin medication (but not other medications) until this evaluation.

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Table 2
Table 2
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Statins are extremely effective at lowering cholesterol, but many people require a second agent. Other commonly prescribed agents are fibrates and niacin. The fibrates increase the risk of myopathy when given in combination with a statin. With more clients on both agents, myopathy will become an increasing problem. Fibrates are used to lower triglycerides (TG) in the serum. Elevated TG is common in people with diabetes or metabolic syndrome. Niacin is a B vitamin and can be purchased without a prescription. When taken at high doses, it has the most favorable effect upon the cholesterol profile, but it is poorly tolerated. Niacin is known to cause flushing of the skin, gas and bloating, upset stomach, conjunctivitis (or pink eye), vomiting, and diarrhea. It also can increase blood glucose levels and trigger gout. Despite these problems, niacin is efficacious when added with a statin at reaching treatment targets. There is a sustained-release formula of niacin that has fewer gastrointestinal and flushing side effects. Other treatment agents include cholesterol absorption inhibitors (ezitimibe) and bile acid sequestrants. These agents are typically added to a treatment plan with a statin. They do not seem to increase the incidence of myopathy.

In summary, as the population both ages and increases in girth, the number of clients on lipid-lowering agents will increase. Because many of these medications may cause muscle damage, it is important for all exercise professionals to recognize this as a potential problem. Additionally, a little information about the efficacy of lifestyle interventions may decrease the number of clients prescribed statins. A healthy lifestyle with 200 kcal/day spent in exercise and a low cholesterol, low saturated fat, balanced diet can prevent heart disease as well as the statins. Reinforcement of dietary changes, recommended physical activity, and medication adherence on multiple fronts can increase compliance with treatment recommendations and help prevent stroke, CAD, and other cardiovascular disorders.

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References

1. American Heart Association. Heart Disease and Stroke Statistics-2003 Update. www.americanheart.org/downloadable/heart/10590179711482003HDSStataBookREV-03.pdf. Accessed October 5, 2005.

2. National Cholesterol Education Program. http://www.nhlbi.nih.gov/chd/. Accessed October 5, 2005.

3. Chong, P.S., and B.S. Bachenheimer. Current, new and future treatments in dyslipidemia and atherosclerosis. Drugs 60:55-93, 2000.

4. McBride, P., H. Schrott, M.B. Plane, et al. Primary care practice adherence to National Education Program guidelines for patients with coronary artery disease. Archives of Internal Medicine 158:1238-1244, 1998.

5. Jenkins, D.J., C.W. Kendall, A. Marchie, et al. Effects of a dietary portfolio of cholesterol-lowering foods vs lovastatin on serum lipids and C-reactive protein. Journal of the American Medical Association 290:502-510, 2003.

6. Westrate, J.A., and G.W. Meijer. Plant sterol-enriched margarines and reduction of plasma total- and LDL-cholesterol concentrations in normocholesterolaemic and mildly hypercholesterolaemic subjects. European Journal of Clinical Nutrition 52:334-343, 1998.

7. Zambon, D., J. Sabate, S. Munoz, et al. Substituting walnuts for monounsaturated fat improves serum lipid profile of hypercholesterolemic men and women. A randomized crossover trial. Annals of Internal Medicine 132:538-546, 2000.

8. Colhoun, H.M., D.J. Betteridge, P.N. Durrington, et al. Primary prevention of cardiovascular disease with atorvastatin in type 2 diabetes in the Collaborative Atorvastatin Diabetes Study (CARDS): Multi-center randomized placebo-controlled trial. Lancet 364:685-696, 2004.

9. Grundy, S.M., J.I. Cleeman, N.M. Bairney, et al. Implications of recent clinical trials for the National Cholesterol Education Program Adult Treatment Panel III guidelines. Circulation 109:3112-3121, 2004.

© 2005 American College of Sports Medicine

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