The Coronary Artery Calcium (CAC) score test is a non-invasive procedure that uses specialized computed tomography (CT) imaging to quantify calcium deposits in the walls of the coronary arteries. The presence of calcium is a direct marker for atherosclerosis, the long-term buildup and hardening of plaque inside the arteries. A high CAC score indicates a significant burden of this established disease, prompting a thorough reassessment of heart health and preventive strategies. By identifying this subclinical disease before symptoms appear, the score helps determine the need for more aggressive risk management.
Understanding the Coronary Artery Calcium Score
The CAC score is derived from a specialized, non-contrast CT scan of the chest. The test measures the amount of calcified plaque, which is an old, stable form of plaque within the artery walls. The score does not measure soft, non-calcified plaque or the degree of artery narrowing, but it confirms the presence of long-standing coronary artery disease.
The quantitative result is calculated using the Agatston method, which assigns a score based on both the area and the density of the detected calcium deposits. Denser spots receive a higher weighted factor in the final tally. The total score in Agatston units is the sum of all calcified spots found across the four main coronary arteries. The presence of any calcification signifies that the process of atherosclerosis is active and has been progressing over time.
Interpreting Specific Score Ranges
The numerical CAC score provides a direct measure of plaque burden, which is used to stratify a person’s risk into distinct categories. A score of zero indicates no detectable calcified plaque and correlates with a very low likelihood of a cardiac event over the next decade. This finding can often lead to a de-escalation of preventive medication, such as statins, in certain patients.
A score between 1 and 100 indicates a minimal to mild plaque burden and a low risk for a cardiac event, confirming the presence of initial coronary artery disease. This range often serves as a warning sign, prompting patients and clinicians to intensify lifestyle-based prevention efforts. A score in the 101 to 400 range signifies a moderate plaque burden and a high risk of a cardiac event within the next three to five years.
Scores greater than 400 represent an extensive plaque burden and place the individual into a high-risk category, often demanding immediate medical intervention. A score exceeding 1,000 indicates a severe level of coronary artery disease, with a risk level comparable to individuals who have already suffered a heart attack. The absolute score is often presented alongside a percentile, which compares the result to other people of the same age, sex, and ethnicity, providing important context.
The Predictive Power for Future Cardiac Events
The CAC score is a powerful prognostic indicator, offering insight into the likelihood of Major Adverse Cardiovascular Events (MACE), which include heart attack, stroke, and cardiovascular death. The score provides predictive information that goes beyond traditional risk factor calculations, like cholesterol levels or blood pressure. For instance, an individual with high cholesterol but a CAC score of zero has a significantly lower actual risk than a person with seemingly normal cholesterol but a high CAC score.
A score of zero is associated with a favorable prognosis, with the rate of MACE being very low. This near-zero risk can provide reassurance and may prevent the unnecessary prescription of preventive medications. The risk of future events increases exponentially as the CAC score rises, demonstrating a clear dose-response relationship.
Individuals with a score greater than 400 face a risk that is more than three times higher compared to those with a score of zero. This level of risk is comparable to that of a person with established coronary artery disease, regardless of symptoms. The score is a powerful tool for risk stratification, helping to identify asymptomatic individuals at high risk. By pinpointing this severe subclinical disease, the CAC score enables targeted and more aggressive primary prevention.
Lifestyle Modifications and Medical Management
Receiving a high CAC score should prompt consultation with a healthcare provider, typically a cardiologist, to develop an aggressive management plan. The primary goal is to stabilize existing plaque and prevent the development of new calcification or the rupture of non-calcified plaque. This requires the intensified management of all traditional cardiovascular risk factors.
Lifestyle modifications form the foundation of the treatment strategy, starting with a heart-healthy diet that limits saturated and trans fats. Structured physical activity, such as 150 minutes of moderate-intensity exercise weekly, is recommended to improve cardiovascular function. Smoking cessation is also essential, as tobacco use significantly accelerates plaque progression and destabilization.
Medication often becomes a necessity, particularly the initiation or intensification of statin therapy to aggressively lower low-density lipoprotein (LDL) cholesterol and exert plaque-stabilizing effects. For patients with very high scores, such as those over 400, an extremely low LDL goal, potentially under 50 mg/dL, may be targeted. Low-dose aspirin therapy may also be considered in certain high-risk patients to reduce the risk of blood clot formation on existing plaque, mitigating the possibility of a heart attack or stroke.