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Understanding New Cholesterol Treatment Guidelines: A Q&A with Karen Aspry, MD

11/22/2013
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Karen Aspry, MD, Director of the Lipid and Prevention Program

New guidelines for cholesterol treatment and cardiovascular risk assessment, which differ significantly from the old guidelines last updated in 2004, were released jointly by the American College of Cardiology and American Heart Association (ACC/AHA) on November 12, 2013. We asked cardiologist and lipid specialist Karen Aspry, MD, director of the Cardiovascular Institute’s Lipid and Prevention Program, key questions about the new guideline.

1. For patients without cardiovascular disease the new guidelines recommend providers use a new risk calculator, which has generated some controversy because some investigators believe it overestimates risk. Is the calculator wrong?  

The new ACC/AHA risk calculator was derived from four community-based population studies that directly measured risk factors in blacks and whites free of known cardiovascular disease at entry, and then recorded heart attack and stroke rates over at least 10 years. The guideline authors admit that risk estimates using this score are higher than observed in patients enrolled in clinical trials (for example, the Women’s Health Initiative and the Women’s Health Study), or certain cohorts (for example, the Physicians’ Health Study and Nurses’ Health Study) because these subjects were far healthier than those in community-based cohorts or in the U.S population as a whole. Also, some of these healthier cohorts did not directly measure risk factors and relied on subject reports only. The guideline authors do admit that the risk calculator probably overestimates risk in Hispanics and East Asians. On the other hand, it doesn't estimate risk of stents, angioplasty or hospitalization for unstable angina or TIA, so it underestimates global cardiovascular risk to some degree. The bottom line: The new risk estimator is based on actual observations from contemporary U.S. community-based cohorts, and reflects the high long-term risk of cardiovascular disease among black and white Americans, due principally to our high burden of risk factors.

2. The new guidelines recommend statins be considered for patients with risk > 7.5% in 10 years, whereas previously the threshold was > 10% risk in 10 years. Why has this changed, and isn’t this risk low?  

The guideline authors chose a risk of 7.5% or higher as the threshold to be considered for lifestyle and statin therapy because recent meta-analyses of clinical trials showed statins reduced heart events and strokes in individuals with a risk as low as >5 to <10%, and this benefit was as robust as in those with higher absolute risk. Also, while a >7.5% chance of a heart attack or stroke in 10 years doesn't seem high enough to warrant drug treatment, it’s important to recognize that this translates to a cumulative risk of fatal or non-fatal heart attack or stroke of about 22% over 30 years (7.5% for each of 3 decades). This is aligned with recent survey data that show more than 1/2 of Americans with a low 10-year risk estimate actually have a high lifetime risk of cardiovascular disease.

3. Should my provider rely on the risk calculator alone?  

The guideline authors say no. As noted above, the risk calculator probably overestimates risk in Hispanics and East Asians, so ethnicity should be considered when using it for decision-making. On the other hand, if a patient and provider believe lifetime risk may be higher than the 10-year calculator estimates, family history and other tests can be used to guide decision-making. A family history of early heart attack, an LDL level consistently > 160mg/dl, elevation of hsCRP (or Cardio CRP) > 2mg/L, an elevated Coronary Calcium Score (CAC) > 75th percentile, or an abnormal screening test for PAD called the Ankle-Brachial Index (or ABI) can be used to modify the decision to start statin treatment since all have been shown to 'add value' to the risk score. Finally, it’s important to recognize that the guideline requires providers to include patients in the discussion of risk and the decision to start statin therapy, to keep treatment not only ‘evidence-based’ but ‘patient-centered.’

4. The guidelines recommend statins be considered in 3 other high risk groups, without using a risk estimator. Is this new?  

The guidelines recommend lifestyle and statin treatment in those with: known atherosclerotic vascular disease (based on prior heart attack, stent, bypass, angina, abnormal stress test, stroke, or peripheral artery disease), diabetes mellitus and age 40-79, or very elevated LDL-cholesterol > 190mg/dl without a secondary cause, because individuals in these groups have the highest risk of future fatal or non-fatal heart attack and stroke. These indications are similar to the previous guidelines, except for the recommendation for statin therapy in all with an LDL-C >190mg/dl, due to the high likelihood of a familial cholesterol disorder.  

5. Are statins the best treatment option for lowering risk? Yes, after a healthy diet and lifestyle. There have been more than 25 large placebo-controlled statin trials worldwide in > 170,000 individuals at high, intermediate and lower risk, which have shown that statins reduce the relative risk of cardiovascular events like heart attack, stroke, stents and bypass, by 25% when moderate intensity doses are used, and by an additional 15% (for a total of ~ 40%) when high intensity doses are used. In the latter case, this means that if 10 patients are destined to have a heart attack or stroke, an estimated 4 will avoid an event. The individual outcomes data for women are not as strong as for men simply because their numbers in clinical trials have been lower, making it difficult to collect the numbers of ‘events’ needed to generate precision and statistical significance. However, new ‘meta analyses’ which combine study data show statins reduce combinations of cardiovascular endpoints similarly in women and men.

6. The new guidelines call for clinicians to choose statins over other cholesterol drugs, and higher doses in those under age 75. Why?  

Because early statin trials showed that the lower the LDL cholesterol, the lower the rate of heart attacks and strokes, the older guideline interpreted this to mean ‘lower LDL is better,’ giving clinicians the freedom to use any lipid drug and dose that lowered LDL cholesterol. However, because moderate dose statins have now been shown to reduce heart attacks and strokes even when cholesterol levels are ‘normal,’ and higher dose statins reduce risk more, the new guideline interprets this to mean only that ‘a moderate statin is better than none, and a higher dose statin is even better.’ So high risk individuals are now recommended to take a high intensity statin dose, and intermediate risk persons to take a moderate dose, as long as they are under age 75 and tolerating the drug. For those 75 or older, the dose should be modified. For those with side effects from statins, other cholesterol lowering medications can be substituted.

7. What are the latest data on the safety of statins?  

When dosed appropriately, statins are taken up by the liver and have little systemic exposure. In the liver, they reduce cholesterol synthesis, causing liver cells to take in more cholesterol from the blood. This reduces blood levels of LDL particles so fewer diffuse into artery walls to cause cholesterol build-up and heart attacks. The risk of a statin causing serious liver disease is about 1 in a million, no higher than in the general population, so the FDA no longer requires routine monitoring of liver function tests. The risk of a statin causing a life-threatening effect on muscles is < 2 in 100,000. The risk of diabetes while taking a statin is about 15% higher than in non-statin users, occurs almost exclusively in those with ‘pre-diabetes,’ and doesn’t change short term outcomes—this group of individuals still benefits from the drug. Finally, the risk of cognitive impairment from statins is based primarily on individual reports to the FDA. However, a recently published meta-analysis showed no short term effects of statins on cognition, and a possible long term protective effect against dementia.

Learn more about the Cardiovascular Institute’s Lipid and Prevention Program