A heart scan for coronary calcium (CAC) is a non-invasive test used to assess future cardiovascular risk. It determines the presence and extent of calcified plaque buildup (atherosclerosis) within the heart’s arteries. The CAC score provides personalized data that refines standard risk assessment tools. This objective measurement of plaque burden allows for informed decisions regarding preventative treatment strategies.
How the Heart Scan Procedure Works
The heart scan uses specialized computed tomography (CT) imaging. This quick, non-invasive procedure requires the patient to lie on a table that slides into a large scanner. The technology captures multiple cross-sectional X-ray images of the heart as it beats. The machine synchronizes the X-ray exposure with the patient’s electrocardiogram (EKG) to ensure clear pictures and minimize motion blur.
Unlike other cardiac imaging tests, this scan does not require intravenous contrast dye. The CT scanner detects and measures the density and area of calcium deposits within the coronary arteries. The presence of calcium is a direct marker of established atherosclerotic disease, as plaque hardens and calcifies over time.
The scan measures only calcified plaque, not soft plaque or the degree of potential blockages. The total amount of calcification detected is translated into the Agatston score, which quantifies the overall plaque burden.
Determining Eligibility for the Scan
The coronary calcium scan is intended for asymptomatic individuals where the results can significantly influence preventative care decisions. Guidelines suggest the test is most beneficial for adults between 40 and 75 years of age who have an intermediate risk (5% to 20%) of developing atherosclerotic cardiovascular disease (ASCVD) over ten years. For people in this range, the CAC score acts as a tie-breaker, confirming or lowering the need for aggressive preventative therapy.
Individuals with specific risk factors fall into this target group, even if their calculated risk is slightly lower. These factors include a strong family history of premature coronary heart disease, defined as a first-degree male relative experiencing a cardiac event before age 55 or a female relative before age 65. Other factors include high blood pressure, elevated cholesterol levels, diabetes, and a history of smoking.
The scan is generally not recommended for two main groups. The first is those with a very low calculated risk. The second includes individuals who are already considered high-risk or who are experiencing symptoms. For symptomatic patients, the presence of disease is assumed, and more comprehensive diagnostic tests, such as a stress test or coronary computed tomography angiography (CCTA), are usually more appropriate.
Understanding Your Coronary Artery Calcium Score
The result of the scan is the Agatston score, calculated based on the number, size, and density of the calcium deposits found across the coronary arteries. This score quantifies the total burden of calcified plaque, and higher scores correlate to a greater risk of a future cardiovascular event.
A CAC score of zero is the best possible result, indicating the absence of detectable calcified plaque. This signifies a very low risk of a cardiac event and may lead to deferring preventative medications. A score in the range of 1 to 99 indicates minimal plaque buildup, suggesting a low to intermediate risk level and serving as an early warning sign.
Scores between 100 and 300 represent a moderate amount of calcified plaque, placing the individual in an intermediate to high-risk category compared to peers. A score greater than 300 is considered very high, indicating extensive plaque and a severely increased risk of heart disease. In this high range, aggressive intervention is often warranted.
The score is often reported alongside a percentile rank, which compares the patient’s calcium score to others in the same age, sex, and ethnic group. A high percentile rank means the patient has more calcified plaque than most of their peers.
Treatment and Follow-Up Based on Results
The CAC score guides specific, personalized treatment and follow-up plans. For an individual who receives a score of zero, the focus remains on maintaining a heart-healthy lifestyle. A score of zero can provide reassurance and may lead to deferring the initiation of statins, especially if other risk factors are mildly elevated. Repeat screening is generally not recommended for at least five to seven years.
If the score is greater than zero, even in the mild range (1 to 99), the result prompts a discussion about aggressive risk factor modification. For scores in the moderate-to-high range (100 or greater), an intensive management plan is adopted. The presence of plaque serves as a strong indicator to begin cholesterol-lowering medication, most commonly a statin, to stabilize existing plaque.
A score over 300 requires the most significant attention. This result necessitates aggressive treatment of all modifiable risk factors, including high-intensity statin therapy, blood pressure control, and potentially low-dose aspirin. A very high score may also prompt the healthcare provider to recommend additional diagnostic testing, such as a stress test, to determine if the extensive plaque is causing functional blockages.