It is common to feel confused when a coronary artery calcium (CAC) scan reveals a high score, yet a healthcare provider states there is no significant arterial blockage. This apparent contradiction arises from the distinct nature of what a calcium score measures versus what constitutes an immediate obstruction to blood flow. Understanding this difference is important for interpreting the test results and making informed health decisions.
What a Calcium Score Measures
A coronary artery calcium (CAC) score quantifies calcified plaque in the heart’s artery walls. Obtained via a specialized, non-contrast computed tomography (CT) scan, it measures calcium deposits, a marker of atherosclerosis – a condition where plaque builds up in arteries.
The score, often reported as an Agatston score, ranges from zero to over 1,000; higher numbers indicate a greater burden of calcified plaque. A zero score suggests a very low risk of a heart attack, while any score above zero means some evidence of coronary artery disease. A CAC score directly measures calcification extent, not the degree of arterial narrowing or blockage that might impede blood flow.
Understanding Plaque Formation and Calcification
Atherosclerosis is a long-term process involving the buildup of fatty substances, cholesterol, and cellular waste, known as plaque, within artery walls. These plaques begin as fatty streaks and can calcify over time, accumulating calcium deposits.
Plaque can be broadly categorized into two types: soft (non-calcified) and hard (calcified). Soft plaque, rich in fatty deposits and inflammatory cells, is considered more unstable and prone to rupture, potentially leading to blood clots and heart attacks. In contrast, calcified plaque is generally more stable and less likely to rupture. The calcium score primarily detects this hard, stable calcified plaque. While its presence signifies long-standing atherosclerosis, it does not necessarily indicate an immediate, severe narrowing of the artery lumen.
Interpreting a High Calcium Score
A high calcium score indicates a greater burden of atherosclerosis within the coronary arteries. Even without a current significant blockage, this finding signals an elevated long-term risk of future cardiovascular events like heart attacks or strokes. The score serves as a powerful predictor of these events, providing prognostic value.
For instance, an Agatston score between 1 and 100 indicates mild coronary artery disease, while scores above 400 suggest extensive disease and higher heart attack risk. A score greater than 1000 is associated with a much higher risk of cardiovascular events and mortality. Thus, a high calcium score acts as an early warning sign, prompting a more proactive approach to cardiovascular health.
Next Steps and Management
Individuals with a high calcium score should consult a healthcare provider to discuss next steps. The primary focus of management is aggressive risk factor modification to slow plaque progression and reduce the likelihood of future cardiovascular events.
This includes adopting a heart-healthy lifestyle, such as managing blood pressure, cholesterol, and diabetes, quitting smoking, maintaining a healthy weight, and engaging in regular exercise. Medications like statins are often considered to lower cholesterol and stabilize existing plaque. While a calcium score itself cannot be lowered, these interventions aim to stabilize plaque and reduce heart attack risk.