Cardiac Risk Assessment

About the Test

How is the lipid panel used?

The lipid panel is used to help determine your risk of heart disease and to help make decisions about what treatment may be best if there is borderline or high risk. The results of the lipid panel are considered along with other known risk factors for heart disease to develop a plan for treatment and follow-up. Depending on the results and other risk factors, treatment options may involve lifestyle changes such as diet and exercise or lipid-lowering medications such as statins.

The lipid panel measures cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C, “good” cholesterol) as well as calculates low density lipoprotein cholesterol (LDL-C, “bad” cholesterol). Triglycerides are a form of fat and a major source of energy for the body.

According to 2002 guidelines from the NCEP Adult Treatment Panel III, the desirable ranges for the components of the lipid panel are:

• Cholesterol <200 mg/dL (5.18 mmol/L)
• HDL-cholesterol > 40 mg/dL (1.04 mmol/L)
• LDL-cholesterol <100 mg/dL (2.59 mmol/L) — this is considered optimal; levels will depend on the number and type of risk factors present and reason for testing.
• Triglycerides <150 mg/dL (1.70 mmol/L)

Some other information may be reported as part of the lipid panel. These parameters are calculated from the results of the tests identified above.

• Non-HDL-C — calculated by subtracting the HDL-C result from the total cholesterol result; this is considered to be the portion of cholesterol that is most likely to lead to hardening of the arteries (atherosclerosis).
• Very low-density lipoprotein cholesterol (VLDL-C) — calculated by dividing the triglyceride value by 5 (if in mg/dL, or by 2.2 if in mmol/L); this formula is based on the typical composition of VLDL particles; there is growing evidence that VLDL-C plays an important role in the process that leads to the formation of plaques in arteries.
• Cholesterol/HDL ratio — calculated by dividing the HDL-C result into the total cholesterol result; a higher ratio indicates a higher risk of heart disease while a lower ratio indicates a lower risk.

What other tests may be used to assess cardiac risk?

Some other tests that may be used to assess cardiac risk include:

• High-sensitivity C-reactive protein (hs-CRP): Studies have shown that measuring CRP with a high sensitivity test can help identify risk of CVD. This test is different from the regular CRP test, which detects elevated levels of CRP in people with infections and inflammatory diseases. The hs-CRP test measures CRP that is in the normal range for healthy people. It can be used to distinguish people with low normal levels from people with high normal levels. High normal levels of hs-CRP in otherwise healthy individuals have been found to be predictive of the future risk of heart attack, stroke, sudden cardiac death, and peripheral arterial disease, even when lipid levels are within acceptable ranges. Several groups have recommended that this test be used for people with moderate risk of heart attack over the next 10 years. However, there is not a consensus on how the test should be used otherwise, nor on how frequently the test should be repeated.
• Lipoprotein A (Lp(a)): Lp(a) is a lipoprotein consisting of an LDL molecule with another protein (Apolipoprotein (a)) attached to it. Lp(a) is similar to LDL-C but does not respond to typical strategies to lower LDL-C such as diet, exercise, or most lipid-lowering drugs. Since the level of Lp(a) appears to be genetically determined and not easily altered, the presence of a high level of Lp(a) may be used to identify individuals who might benefit from more aggressive treatment of other risk factors.

Several other tests are being studied for their usefulness in determining cardiac risk. Currently, there is no consensus or formal recommendations for them. A healthcare practitioner may order one or more of these tests to help assess cardiac risk.

Some of these include:

• LDL particle testing (LDL-P) (number and size)
• Lp-PLA₂
• Homocysteine
• GGT
• Urine albumin (microalbumin)
• Cystatin C
• Fibrinogen
• Apo A-I
• Apo B
• APOE Genotyping (CVD)
• MTHFR Mutation

How is treatment determined?

Health organizations have different recommendations for treatment based on your predicted CVD risk.

Guidelines from the American College of Cardiology (ACC) and the American Heart Association (AHA) recommend that a risk calculator be used to determine your 10-year risk of CVD if you are age 40 to 75 and do not have heart disease. Many factors are considered in the calculation, including total cholesterol, LDL-C, HDL-C, age, gender, race, blood pressure, presence of diabetes, and smoking habit. An initial (baseline) risk should be calculated and then your risk can be tracked over time with each subsequent risk calculation. Ten-year risk is categorized below:

ACC and AHA recommend treatment with statins if you:

• Have heart disease (diagnosed by medical history, physical exam, imaging scans, etc.)
• Have LDL-C greater than 190 mg/dL (4.90 mmol/L)
• Are age 40 to 75 years with diabetes and LDL-C 70-189 mg/dL (1.81-4.90 mmol/L) but do not have heart disease
• Are age 40 to 75 years old and do not have diabetes or heart disease but have LDL-C level between 70-189 mg/dL (1.81-4.90 mmol/L) and 10-year risk of developing heart disease of greater than 7%

The U.S. Preventive Services Task Force (USPSTF) makes recommendations on the use of statins for treatment in adults ages 40 to 75 with no history of heart disease (i.e., no symptoms of coronary artery disease or stroke), based on risk factors (i.e., LDL-C greater than 130 mg/dL(3.37 mmol/L), HDL-C level less than 40 mg/dL(1.0 mmol/L), diabetes, high blood pressure, smoking) and the use of the risk calculator.

• If you have one or more risk factors and a calculated 10-year CVD event risk of 10% or greater, then the USPSTF recommends the use of a low-to-moderate dose statin.
• If you have one or more risk factors and your calculated 10-year CVD event risk is 7.5% to 10%, then the Task Force says your healthcare practitioner may choose to offer a low-to-moderate dose statin. This is because the probability that you will have a CVD event is lower, so the benefit of a statin is likely to be smaller.

Use of the risk calculator and ACC/AHA guidelines remains controversial and is evolving as more data become available. Some say that the current risk calculator can overestimate risk. Many still use older guidelines (2002) from the NCEP Adult Treatment Panel III to evaluate lipid levels and CVD risk. (See above for the target values listed in “How is the lipid panel used?”) According to NCEP Adult Treatment Panel III guidelines, if you have LDL-C above the target values and risk factors (e.g., family history, cigarette smoking, diabetes, high blood pressure), you require treatment.

Are some people more at risk for a heart attack than others?

Yes. The following factors can increase your risk of heart attack:

• High LDL-C
• Cigarette smoking
• Being overweight or obese
• Unhealthy diet
• Being physically inactive—not getting enough exercise
• Age (if you are a male 45 years or older or a female 50-55 years or older)
• Hypertension (blood pressure of 140/90 or higher or taking high blood pressure medications)
• Family history of premature heart disease (heart disease in a first-degree male relative under age 55 or a first-degree female relative under age 65)
• Pre-existing heart disease or already having had a heart attack
• Diabetes or prediabetes

Are there home test kits for determining if I am at risk for a heart attack?

No. Your overall cardiac risk is based on a number of factors, including your personal health history as well as the results of any or all of the tests mentioned previously. An assessment requires interpretation by a trained medical professional. However, there are resources available to help you better understand your risk. Using results of the lipid panel and a physical exam, you can calculate your 10-year risk of heart disease or stroke using the Heart Risk calculator from AHA and American College of Cardiology if you are age 40 to 75 and do not have heart disease. And there are home tests available to measure your cholesterol.

Is there anything else I should know?

A healthy diet and exercising are important in reducing blood pressure, cholesterol, and triglycerides. Sometimes these lifestyle changes are not sufficient to reach desirable levels. There are also drugs (statins) that are effective in lipid management. Some conditions involving elevated lipids levels are hereditary. High lipid levels in these conditions cannot always be lowered sufficiently by diet and exercise. This type of elevation usually requires treatment with lipid-lowering drugs.