The Cardiac Wellness Clinic in Seattle will sometimes use advanced testing to determine a person's risk of having a heart attack or stroke. This list includes definitions of some of the most commonly used tests. All of these tests are available at Virginia Mason.
ABI - Ankle brachial index
Ankle brachial index or ABI is used to diagnose peripheral arterial disease. Peripheral arterial disease, or PAD, refers to the clogging and hardening of peripheral (non-heart, as in the arms or legs) arteries by the accumulation of plaque.
The test is done by comparing the blood pressure in the ankle with that in the arm. Lower blood pressure in the lower part of the leg compared with the pressure in the arm may indicate PAD.
The carotid intima media thickness (CIMT) is an easy and painless test that can help show your risk of heart attack or stroke. It is done by looking at the carotid arteries in your neck with ultrasound.
The CIMT measures the thickness of the inner two layers of the wall (the intima and the media) of the carotid artery. In the early stages of atherosclerosis (hardening of the arteries) these two layers thicken. This test can be used to find these early changes - before you have symptoms or an abnormal stress test.
Studies have shown that if there is early atherosclerosis in the carotid arteries, then there is probably atherosclerosis of other arteries, such as the heart, as well.
Computed Tomography Coronary Artery Calcium Score or CT CACS
A Coronary Artery Calcium Score is a painless test done by a CT scanner. This is similar to having a limited version of a chest CT, and does not require any IV or contrast.
Plaque, which is composed of cholesterol and fats, forms in the walls of arteries. This plaque gradually becomes calcified (hardened). A CT CACS exam can measure these calcium deposits in the coronary arteries. The amount of calcium seen on CT is related to the amount of underlying coronary atherosclerosis (hardening of the arteries of the heart).
A high coronary artery calcium score from a CT scan can help to predict fatal and nonfatal heart attacks or the need for coronary bypass surgery or coronary (balloon) angioplasty in the next one to two years. A low calcium score suggests a very low risk for blocked coronary arteries and heart attack or stroke.
How much better a CT scan predicts heart disease compared to other risk factor assessment isn’t entirely known. CT CACS is not a substitute for cardiac catheterization. CT measurement of coronary calcium isn’t helpful for patients who’ve already had a heart attack or undergone coronary bypass surgery or coronary angioplasty.
The test may be less useful for younger people (men under 40; women under 50) because it takes time for the plaque to calcify before it is seen on CT. In other words, soft plaque may be in the arteries, but because it has not calcified, it will not been detected on CT.
Exercise Stress Test
Exercise stress tests are used to find heart disease that is apparent only during physical activity. These tests can also be used to help a patient choose the best physical activity program. Also called a treadmill test, a stress test uses an EKG to measure how the heart performs during activity, such as walking on a moving treadmill. A medication stress test uses medication instead of exercise to increase the heart rate in individuals who cannot exercise long enough to do a useful test.
Advanced Lipid testing
The VAP® (Vertical Auto Profile) Test, NMR Lipoprofile® Test and the Berkeley HeartLab® profile are all commercially available expanded cholesterol tests that can help determine a person’s risk of developing heart disease. These tests can be useful in assessing people who are at intermediate or unknown risk (someone with no information on family history), including those with inherited risk factors who often develop early heart disease.
Like routine tests, the Advanced Lipid Tests measure total cholesterol, HDL ("good" cholesterol), LDL ("bad" cholesterol), and triglycerides. The tests also measure cholesterol subclasses that play important roles in the development of heart disease. This additional information allows your healthcare provider to improve the detection of heart disease risk, and will often help in developing a specific treatment plan.
C-reactive protein (CRP) is a blood component, which rises in the bloodstream with disease of inflammation. “High-sensitivity” or “cardio” CRP is a more specialized blood test which has been used as a long-term predictor of heart attack. The results of this test may be used with more basic measures to help you and your doctor estimate your heart disease risk.
Lipoprotein (a), also known as lp(a) is another cholesterol protein subclass. This cholesterol particle is like a “sticky” LDL (bad cholesterol), which may be measured with specialized testing. A very high level of this particle significantly increases a person’s risk for heart attack and stroke. Also, the “statin” cholesterol-lowering drugs don’t lower lp(a), so measuring lp(a) can help you and your doctor understand your treatment options.
Homocysteine is a normal-circulating amino acid (protein building block). When this blood component increases to a high level in the bloodstream, it can contribute to the build up of plaque in the blood vessels. Sometimes the homocysteine excess is inherited, but Vitamin B deficiency, smoking, kidney disease, and some drugs can raise the homocysteine, as well.