Cardiovascular disease — including coronary atherosclerosis and cerebrovascular disease — remains the number one cause of mortality in the United States. One out of three people in this country will die of cardiovascular causes. Although I can’t say that the other top causes of mortality are particularly attractive — cancer, chronic lung disease, accidents and dementia — premature cardiovascular death can certainly be very devastating and it makes sense to do our best to prevent it.
In November 2013, updated guidelines for the treatment of high cholesterol were released by the American College of Cardiology-American Heart Association. These guidelines were the subject of significant controversy. In contrast to the previous guidelines from 2002, the current guidelines do not suggest treatment based primarily on numerical cholesterol targets. Rather, the guidelines stratify people according to determined cardiovascular risk and recommend either high intensity statin treatment, moderate intensity statin treatment, or no statin treatment. The guidelines do not support using other types of cholesterol-lowering drugs because at this point there is not good data to suggest that using other types of treatments is beneficial in terms of preventing actual cardiovascular outcomes (heart attack, stroke or cardiovascular death). This is despite the fact that there are treatments out there that do lower one’s cholesterol numbers.
How is cardiovascular risk determined?
With the new guidelines, a new risk calculator was proposed. In my clinical practice in the past I’ve used the Framingham Risk Calculatorand the Reynolds Risk Calculator.
The new risk calculator released with the 2013 guidelines is a bit different. Some experts have suggested that it overestimates risk. With the new risk calculator, if one’s ten year risk of a cardiovascular event exceeds 7.5% then treatment with a statin is recommended.
The new guidelines divide people into the following groups of patients between ages 40 and 75 years who are in need of treatment with statins, or so called “statin benefit groups.”
- Those with LDL over 190mg/dL (high intensity statin treatment is recommended)
- Those with a ten year risk of >7.5% (moderate intensity statin treatment is recommended)
- Those with established cardiovascular disease (high intensity statin treatment is recommended)
- Those with diabetes, in which 10 year risk is >7.5% (high intensity statin treatment is recommended)
- Those with diabetes, in which 10 year risk is <7.5% (moderate intensity statin treatment is recommended)
What qualifies as high intensity statin treatment? LDL lowering of 50% or greater. What is moderate intensity statin treatment? LDL lowering of 30-50%.
The guidelines suggest that particular statins may be better than others at achieving these goals and good outcomes: atorvastatin, simvastatin, and rosuvastatin. Other statins are typically used when patients experience unwanted side effects, like muscle pain.
How are things different with the new guidelines?
Let’s take an example.
A 71-year-old white female, non-smoker, non-diabetic, with a history of hypertension, asked me whether or not she should be treated for high cholesterol. She is concerned about her risk of heart disease, as her mother had a stroke in her 60s and then sudden death, presumed cardiovascular, at age 83.
My patient’s most recent total cholesterol level was 204 mg/dL with an LDL level of 121 mg/dL and an HDL level of 64 mg/dL. A couple of years ago I calculated her Framingham Risk score, which is 6% with these risk factors. This represents low to intermediate risk.
To get further information I also ordered a coronary calcium score, which was found to be zero. Last year, based on these numbers and the older guidelines, I recommended against treatment with a statin. However, now, based on the new risk assessment tool, the same patient has a ten year risk of 16%. With the new guidelines she would unequivocally qualify for moderate dose statin.
At this point, I am not exactly sure what to do with the coronary calcium score, which probably projects that her risk is lower than the 16% that the new equation came up with. Nonetheless, I am not sure that coronary calcium scoring entirely predicts all cardiovascular risk — for example risk related to small vessel disease and stroke, so perhaps she should receive treatment. Low dose, statin treatment might be a good compromise here.
Interestingly, based on this new risk calculator virtually every 71-year-old, even with optimal risk factors, would qualify for treatment with a statin. Herein lies the controversy with this tool.
Nonetheless, my own view of the new guidelines is mostly favorable. To me it simplifies things based on what we know from numerous well designed studies. Treatment, with an emphasis on statins, is based on risk projection and less attention is paid to absolute numbers. I hope that the next decade will continue to bring more a nuanced understanding of risk.
Juliet K. Mavromatis is an internal medicine physician who blogs at Dr Dialogue.