There are some concerns, however, with this new risk calculator. The risk calculator has not been prospectively tested for accuracy in predicting cardiovascular risk, and when compared with observed event rates in three large-scale primary prevention cohorts, the new ACC/AHA risk-prediction algorithm overestimated observed risks.2 This may also be problematic because there are some instances where the risk-assessment algorithm may not be consistent with best medical practice. As more data become available, this risk calculator will likely be updated.
In the previously noted Basic Four patients, high-intensity statin therapy that is designed to reduce LDL cholesterol by more than 50% is recommended (see High-, moderate-, and low-intensity statin therapy). For patients who are unable to tolerate high-intensity statin, moderate-intensity statin therapy that aims for a reduction of 30% to 50% is recommended.1 Moderate-intensity statin therapy is also recommended for patients with diabetes and a 10-year risk of ASCVD of less than 7.5%.1 (See Examples of application of 2013 ACC/AHA guidelines.) Thus far, there is not sufficient evidence to support the addition of a nonstatin (such as niacin, fenofibrate, ezetimibe) to further lower the risk of ASCVD.
What about the patient who is not in one of the four statin-therapy groups where there is uncertainty in starting a statin? In this situation, additional factors may be considered to inform treatment decision making, which include1:
* Primary LDL-C 160 mg/dL or greater or other evidence of genetic hyperlipidemias
* Family history of premature ASCVD with onset younger than 55 years of age in a first-degree male relative or younger than 65 years of age in a first-degree female relative
* High-sensitivity C-reactive protein 2 mg/L or greater
* Coronary artery calcium score 300 Agatston units or greater, or 75 percentile or greater for age, sex, and ethnicity
* Ankle-brachial index less than 0.9
* Elevated lifetime risk of ASCVD.
Initiating and monitoring statin therapy
When starting a patient on a statin, as always, a thorough history and physical exam is first and foremost. Needed life-style modifications should be discussed, and goals should be set. As with any drug therapy, a discussion of potential benefits along with possible adverse reactions is needed. Recommended lab studies, in addition to a lipid profile, include baseline liver function studies. Further testing depends upon other risk factors and/or comorbidities along with other medications that might be prescribed. For instance, if a fenofibrate were to be prescribed for a patient with a triglyceride level over 500 mg/dL, then a renal panel to include a serum creatinine, blood urea nitrogen (BUN), and glomerular filtration rate (GFR) would be needed. Creatine kinase (CK) may be useful in patients who are at an increased risk for adverse muscle events, such as those patients with a personal or family history of statin intolerance, muscle disease, or concomitant drug therapy that can increase the likelihood of myopathy.1 CK may also be needed for patients on statins who complain of muscle symptoms. After statins are started, liver panel, including transaminases, alkaline phosphatase, and bilirubin, along with a fasting lipid profile, should be measured 4 to 12 weeks after initiation or dose adjustment, and every 3 to 12 months thereafter as clinically indicated. During statin therapy, if symptoms suggest hepatotoxicity such as unusual fatigue or weakness, loss of appetite, abdominal pain, dark-colored urine, or yellowing of the skin or sclera, then a liver panel should be measured. The guideline suggests that if the LDL cholesterol, on two subsequent readings, is less than 40 mg/dL, the statin dose can be decreased.1
In general, myalgia exists when a patient experiences muscle aches or weakness without associated CK elevation; myopathy occurs when the muscle pain or soreness is accompanied with a CK greater than 10× the upper limit of normal (ULN); myositis is defined as muscle symptoms and CK elevation; and rhabdomyolysis as muscle symptoms, significant CK elevations usually greater than 10× ULN with urinary myoglobin with possible evidence of organ damage, such as renal compromise.6,7 If any symptoms suggesting statin intolerance develop during therapy, discontinue the statin, obtain a CK, and evaluate the patient for other conditions that might increase the risk of muscle symptoms. Conditions that predispose patients to statin intolerance include, but are not limited to, hypothyroidism, vitamin D insufficiency, kidney or hepatic dysfunction, rheumatologic disorders such as polymyalgia rheumatica, corticosteroid myopathy, or primary muscle disease.1 These disorders need to be ruled out and treated prior to restarting the statin. When symptoms resolve, the patient should be started on a lower-dose statin. Although not noted in the guidelines, patients can often be started on a lower daily dose of a statin, given two to three times per week and gradually increased to the optimal dose.8
The new ACC/AHA guidelines are an attempt to define practices for the majority of patients. It is important to be mindful that guidelines are never a replacement for clinical judgment. The new ACC/AHA guidelines focus on treatments that have been shown to reduce ASCVD events. The guidelines are not, and were never intended to be, a comprehensive approach to lipid management.
1. Stone NJ, Robinson J, Lichtenstein AH, et al. 2013 ACC/AHA guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults: a report of the American College of Cardiology/American Heart Association task force on practice guidelines. J Am Coll Cardiol
. [e-pub Nov. 7, 2013] http://circ.ahajournals.org/content/early/2013/11/11/01.cir.0000437738.63853.7a
2. Ridker PM, Cook NR. Statins: new American guidelines for prevention of cardiovascular disease. Lancet
3. National Cholesterol Education Program, National Heart, Lung, and Blood Institute, National Institutes of Health. Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) Final Report. NIH Publication No. 02–5215. Bethesda, MD: National Cholesterol Education Program, National Heart, Lung, and Blood Institute, National Institutes of Health; 2002.
4. Miller M, Stone NJ, Ballantyne C, et al. Triglycerides and cardiovascular disease: a scientific statement from the American Heart Association. Circulation
5. Goff DC Jr, Lloyd-Jones DM, Bennett G, et al. 2013 ACC/AHA guideline on the assessment of cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol
. [e-pub Nov. 12, 2013]
6. McKenney JM, Davidson MH, Jacobson TA, Guyton JR National Lipid Association Statin Safety Assessment Task Force. Final conclusions and recommendations of the National Lipid Association Statin Safety Assessment Task Force. Am J Cardiol
7. Pasternak RC, Smith SC Jr, Bairey-Merz CN, et al. ACC/AHA/NHLBI clinical advisory on the use and safety of statins. J Am Coll Cardiol
8. Scordo K. Statin Intolerance: Management Strategies. The American Journal for Nurse Practitioners
Keywords:© 2014 Lippincott Williams & Wilkins
American College of Cardiology; American Heart Association; atherosclerotic cardiovascular disease; cholesterol treatment guidelines; lipids; statins