Lipid disorders

August 15, 2011

Perhaps the most well-established and well-studied risk factors for CHD are abnormalities in blood cholesterol and lipid levels. The typical diet consumed in Western societies contains between 50 and 100 g of fat and 0.5 g of cholesterol. These fats are not water soluble and are transported in the blood in association with lipoproteins. Abnormalities in the metabolism of these lipoproteins lead to elevated levels of cholesterol and triglycerides in the blood. While some individuals have genetic abnormalities that lead to impaired metabolism of lipids, the majority of cases of elevated levels of cholesterol result from lifestyle factors. These include sedentary lifestyle, obesity, and diets high in total and saturated fats.

The National Cholesterol Education Program Adult Treatment Panel III (NCEP III) recommends that adults 20 years of age and older should undergo fasting lipid profile evaluation once every 5 years. This blood test includes measurement of total cholesterol, LDL, HDL as well as triglycerides. The primary contributor to CHD risk is the LDL level. However, elevated triglyceride and decreased HDL are also significant risks and appear to be stronger predictors of risk for coronary artery disease in women than men.

Current NCEP guidelines apply the same cholesterol targets for women as men but recognize certain differences particularly with regard to HDL. Each 1% decrease in HDL level confers a 2-3% increase in risk of coronary artery disease. HDL cholesterol is generally higher in women than men. The most recent guidelines define a low HDL as less than 40 mg/dl for men but a level less than 50 mg/dl is considered a marginal risk factor for women and frequently is a marker of the metabolic syndrome.

Dietary modification by reducing fat intake and increasing fiber content is often the first step in therapy for those with elevated cholesterol levels and should be used in conjunction with drug therapy when this is needed. Highly effective and potent medications, namely, the “statin” class of drugs, are now available that have been demonstrated in large clinical trials to be very effective in lowering LDL as well as moderately raising HDL. These agents have been shown to significantly reduce the risk of CHD events in those with as well as those without known coronary disease. The Cholesterol and Recurrent Events (CARE) trial, for example, studied 576 postmenopausal women 3-20 months after myocardial infarction (MI, heart attack). These women had average cholesterol levels. Women in the study who were treated with pravastatin (a statin drug) had a 43% reduction in fatal coronary artery disease or recurrent MI. This result is similar to that from pooled data from other trials using statins, which showed an average reduction of 29% in coronary artery disease events as compared with 31% in men.

Most recently, the Heart Protection Study enrolled over 20,000 patients with history of cardiovascular disease or diabetes who were between the ages of 40 and 80. This study included over 5,000 women. Patients treated with simvastatin had a 27% reduction in major coronary events. This benefit was similar in both sexes and was, interestingly, irrespective of initial cholesterol level.

Treatment with this class of medication to aggressively lower cholesterol levels in high-risk female and male patients can significantly reduce cardiovascular complications.

SEE ALSO: Acute myocardial infarction, Cardiovascular disease, Cholesterol, Diabetes, Exercise, Hormone replacement therapy, Hypertension, Nutrition, Smoking

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Category: Coronary Risk Factor