Coronary Calcium Scoring

As a cardiologist, the most common question I am asked by those who do not have a heart problem is, “What is my risk for a heart attack?” Often the question comes from a person who knows someone who has either survived a heart attack or who has died suddenly of heart disease.

Determining one’s risk for a heart attack begins with identifying common risk factors for heart disease and then calculating an individual’s ten-year risk of heart attacks using “risk calculators.” One problem with this approach is that many heart attacks happen in people who are considered “low risk.” Because of this paradox, many blood and imaging tests are available to further define heart attack risk.

The most accurate of these tests is a coronary calcium score. The purpose of the test is to help a medical provider determine how aggressively to treat someone to prevent heart problems. A calcium score “sees” calcium within the blood vessels around the heart. Calcium in blood vessels is a sign of atherosclerosis, or hardening of the arteries. An abnormal calcium score is associated with an increased risk of heart attack and death.

The calcium score, however, is far from perfect.  Individuals with normal scores can have heart attacks, and those with abnormal scores can be free of heart attacks for life. Current recommendations from national cardiology groups recognize these limitations and recommend that the test preferably be performed on individuals with an intermediate heart attack risk (10-20 percent chance of a heart attack over ten years). 

As with most medical testing advertised to the general public, the purpose of the test is often misunderstood, even among medical professionals. Calcium scores do not identify blockages. This misunderstanding may lead to inappropriate testing and/or high risk procedures such as coronary angiograms (heart caths) for questionable benefit. Our current understanding of stents or heart bypass surgery is that, in most instances, they are no better than medications in people with normal hearts who have no symptoms with exercise.  Most people who undergo this test fit the above description, thus…buyer beware.

Calcium scoring has other drawbacks. In someone who is unlikely to have a heart attack, an abnormal score will bring about needless mental anxiety. Conversely, in an individual who is a ticking time bomb for a heart attack, a normal score may give a false sense of reassurance. Also, calcium scoring uses radiation, putting a small number of people at future risk of developing cancer from the test itself.

Abnormal scores in the right patient will appropriately lead to the initiation of healthy lifestyle changes and medications that lower cholesterol (statins) and thin the blood (aspirin). These therapies do work and will give a high-risk individual the best chance to delay or avoid a heart attack. Only with certain high scores should further testing (i.e. stress testing) be considered, albeit selectively. 

In my practice, I will generally obtain a calcium score for two types of patients. The first group is those at intermediate risk of heart disease who are unsure about cholesterol lowering therapy; second, patients with a low risk of heart disease but with an extreme risk factor (i.e. significant, early heart disease in the family). In the end, the best way to prevent a first heart attack is not with a calcium score, a cardiac stent or bypass surgery. The good news is that there are nine modifiable risk factors for heart disease that if corrected will absolutely prevent or delay a heart attack. A worldwide study identified these risk factors as:  high cholesterol, high blood pressure, smoking, diabetes, belly fat, high stress, lack of fruits and vegetables and sedentary lifestyle.

Dr. Matthew Nelson is an invasive cardiologist at St. Alexius Heart & Lung Clinic. He is board-certified in cardiology and echocardiography. He has a special interest in preventative cardiology.