What is a cardiac risk assessment?
This is a group of tests and health factors that have been proven to indicate a person's chance of having a cardiovascular event such as a heart attack or stroke. They have been refined to indicate the degree of risk: slight, moderate, or high.
What is included in a routine cardiac risk assessment?
Perhaps the most important indicators for cardiac risk are those of a person's personal health history. These include:
- Family history
- Cigarette smoking
- Blood pressure
- Exercise, physical activity
There are some imaging tests that may be used in cardiac risk assessment. Non-invasive tests may include, for example, an electrocardiogram (ECG, EKG) or a stress test, also called ECG stress test or metabolic stress test. Invasive tests may also be used to evaluate for the presence of cardiovascular disease (CVD), but they are usually used for diagnostic purposes in people with signs and symptoms and not for risk assessment. Examples include an angiography/arteriography and cardiac catheterization. (For more on these, see the Mayo Clinic's webpage on Coronary artery disease: Tests and diagnosis.)
The lipid profile is the most important blood test for cardiac risk assessment.
How is the lipid profile used?
The lipid profile is used to help determine an individual's 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 profile 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 profile 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. Below are the desirable ranges for the components of the lipid profile:
- 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)
- Triglycerides <150 mg/dL (1.70 mmol/L)
* optimal; levels will depend on the number and type of risk factors present and why testing is being done
Some other information may be reported as part of the lipid profile. 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 health practitioner may order one or more of these tests to help assess someone's risk.
Some of these include:
- LDL particle testing (LDL-P) (number and size)
- Urine albumin (microalbumin)
- Cystatin C
- Apo A-I
- Apo B
- APOE Genotyping (CVD)
- MTHFR Mutation
How is treatment determined?
Treatment is based on many factors, including the results of the lipid profile and a person's family and personal medical and lifestyle history.
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.