At the dawn of a new decade, what is the best way to assess a person’s risk for atherosclerosis (plaque in the heart arteries)? There are many different tools to choose from including several risk calculators, blood tests (for example C reactive protein) and imaging tests (such as stress tests or ultrasound of the neck arteries to determine if plaque is present). Of all of the approaches available, what is the optimal approach for someone who may have coronary artery disease?
The first step is to see a doctor, have a good physical examination and basic laboratory tests, including total cholesterol and LDL cholesterol (the “bad” cholesterol). If the total cholesterol is over 200 or the LDL is over 100, the next step is to enter the data into the American College of Cardiology risk calculator (cvriskcalculator.com). The calculator will give an estimate of the chance of a heart attack or stroke within the next 10 years. The estimate can be broken into four categories:
Low Risk: 0- 5%
Borderline Risk: 5-7.5%
Intermediate Risk: 7.5-20%
High Risk > 20%
Low risk patients need no further testing or medication, but should continue with a heart healthy lifestyle. High risk patients should be started on aspirin, blood pressure medication (if appropriate) and a statin to reduce cholesterol. For those in the borderline and intermediate categories, additional consideration is needed. The next step is to assess whether the patient has other risk enhancers. These include:
LDL > 160 mg/dl,
high-sensitivity C reactive protein level (a measure of inflammation) > 2.0 mg/L,
triglycerides > 175 mg/dl,
peripheral arterial disease,
chronic kidney disease,
chronic inflammatory disease (rheumatoid arthritis, psoriasis, or lupus),
metabolic syndrome (hypertension, diabetes, high triglycerides, obesity),
family history of premature heart disease, or
premature menopause
For the patient with borderline or intermediate risk and the presence of one or more risk enhancer, a statin should be initiated. If there is still uncertainty about starting medication or the patient is reluctant, the next step is to do a coronary calcium score. The coronary calcium score is obtained with a computed tomography (CT) scan. No contrast is used, so there is no preparation and no intravenous line is needed. The patient goes into the CT scanner, holds their breath and the scan is obtained. The whole process takes only a few minutes. The down side of the scan is that a small dose of radiation is used and in many cases insurance doesn’t cover the cost. Fortunately, locally, the cost for a coronary calcium score is just $99. The scan measures the plaque burden in the heart arteries. Plaque is formed by cholesterol deposition followed by inflammation and calcium build up. The scan can detect and quantify the amount of calcium seen in the heart arteries. The coronary calcium score is the sum of all of the calcium seen in all of the heart arteries. However, the scan does not show the amount of blockage in the arteries (plaque may be present only in the wall of the artery or it may be part of a plaque causing blockage to blood flow). A coronary calcium score of 0 means there is no plaque in the heart arteries and the patient is at very low risk for a future heart attack. No statin is recommended. A calcium score between 1 and 99 means there is plaque present and a statin should be considered, especially for patients older than 55. For patients with a coronary calcium score over 100, a statin is indicated and further testing, such as a nuclear stress test should be done to see if the plaque is causing significant blockage.
It is important to realize that this approach is only for patients who do not have heart artery disease (primary prevention). For those with a history of disease (a heart attack or stroke, heart bypass surgery or a heart stent) or those who have diabetes with an LDL over 70, this approach should not be used and those patients should be on a statin. In addition, this approach is only for adults between the ages of 40 and 75.
What about patients who are 75 years old or older? Should they be on a statin? The risk for cardiovascular disease increases with older age. Taking a statin may help reduce that risk. On the other hand, other diseases (such as cancer or dementia) also rise with advancing age and limit the benefit of statins. For patients with a history of heart attack, stroke or cardiac revascularization (secondary prevention), the data is clear: continue the statin, even in the very elderly. For primary prevention in those over age 75 the data is less clear. A recent trial of patients over 70 years old showed a lower risk of dying from any cause for those on statin versus those who were not on statin. In addition, the statin patients had fewer heart attacks and strokes. Another study looked at patients over 75 who had their statin stopped. The participants who came off their statin were at higher risk for hospitalization and cardiovascular events. One of the reasons for stopping a statin in older patients is the perception that statins increase the risk for dementia. However, there never has been an increased risk for dementia in all of the studies done on statins. A recent study of statin patients 70 to 90 years old confirmed that there was no increased risk for dementia. In fact the statin patients showed less cognitive decline, suggesting statins may be protective for brain function.
