Last November, the 2018 Guideline on the Management of Blood Cholesterol was released by the American Heart Association and the American College of Cardiology. It replaced the 2013 Guideline. Lipid-lowering strategies are designed to lower the risk of Arteriosclerotic Cardiovascular Disease, or ASCVD, which includes heart disease, strokes, and peripheral arterial disease. In the 2018 Guideline, strategies to lower not just total cholesterol but also “bad” cholesterol, or LDL, were revised. It is becoming increasingly apparent that it is LDL that is responsible for ASCVD. While HDL, or “good” cholesterol, has a protective effect on ASCVD, the focus is primarily on lowering LDL.
The Guideline suggests that for a screening lipid profile, fasting is not necessary. However, that does not take into consideration the fact that triglycerides are very sensitive to food intake and may be artificially elevated in a non-fasting sample. Since the triglyceride level is used to calculate LDL, a non-fasting sample may be accurate only for total cholesterol and HDL. That is why I recommend that all lipid profiles I perform should be fasting ones. Recommendations to lower LDL in the Guideline include primary prevention of ASCVD, or preventing it in those who do not have ASCVD, and secondary prevention, which is preventing worsening disease in those who do have ASCVD. The new guidelines are much more aggressive than the 2013 ones. For example, the recommended strategy for anyone, beginning at 20 years of age or older, with an LDL of 190 or greater who does not have ASCVD should be high intensity statin use, the aim being to get the LDL below 100. High intensity statin use refers to dosage—40mg or more of atorvastatin (Lipitor) or 20mg or more of rosuvastatin (Crestor).
Recommendations for primary prevention for diabetics and those at high and intermediate risk for ASCVD is to lower the LDL to 70. For those with ASCVD, the recommendation is to get the LDL below 50. While separate studies have confirmed that statins have a protective effect on ASCVD, stains alone may be insufficient to reach the recommended goal. Ezetimibe (Zetia) may be added to reach goal, however it does not have the protective effects that have been seen with statins. Recently, the FDA approved two new drugs of a new class to lower LDL levels. They are proprotein convertase subtilisin/kexin type 9, or PCSK9, inhibitors. The two new drugs are evolocumab (Repatha) and alirocumab (Praluent). Liver cells have receptors that attach to and remove lipids, especially LDL, from the blood. These receptors are destroyed by the protein PCSK9. The new drugs block PCSK9 from destroying the receptors, thereby lowering LDL. These new drugs also have shown protective effects, like statins, against ASCVD.
Side effects from statins are rare but include myalgias, or muscle pains, that primarily affect the larger muscles on both sides of the body. They may also raise liver enzyme levels, although this too is not seen very often. Ezetimibe, which is not absorbed by the gut, may cause an upset stomach or diarrhea. Side effects with PCSK9 inhibitors are rare, but studies are still being done and, because they are new, they are not yet in widespread use. So, get to your doctor to assess your lipid levels and discuss your risk of developing ASCVD or having it get worse.
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