Coronary Artery Calcium Scans Help Refine Treatment Decisions
Landmark research demonstrates the benefits of using CAC tests when appropriate.
An early marker of coronary artery disease is the amount of calcium in the arteries. Normally, our arteries should not contain any calcium, but as we age, calcium tends to deposit in the walls of our arteries.
Coronary artery calcium refers to the amount of calcium in the coronary arteries. As calcium deposits itself in the coronary arteries or in the plaques that are formed on the walls of arteries, the arteries become stiffer, increasing the chance of a heart attack.
Traditionally, your doctor will obtain a detailed history, physical examination and cholesterol panel to assess your risk of having a heart attack. The cholesterol panel is comprised of total cholesterol, high-density lipoprotein cholesterol (known as HDL or “good cholesterol”), low-density lipoprotein cholesterol (known as LDL or “bad cholesterol”) and triglyceride levels.
High cholesterol contributes to heart attacks by blocking the coronary arteries (arteries that supply blood to the heart). High cholesterol can also block arteries in other parts of the body. These blockages are what physicians call “atherosclerotic cardiovascular disease.”
If the risk of having a heart attack is elevated, your physician will prescribe a cholesterol-lowering medication, such as a statin. The American Heart Association (AHA)/American College of Cardiology (ACC) guidelines recommend starting treatment with a statin (such as Crestor or Lipitor) in high risk patient groups. However, in patients for whom the decision to start treatment is unclear with the physical examination and cholesterol panel, a coronary artery calcium score can assist in guiding the decision.
Estimating the 10-year heart disease risk can be misleading in women and young to middle-aged adults with metabolic syndrome traits and a family history of premature cardiovascular disease. On the other hand, patients with no other risk factors may have a falsely elevated risk simply because of their age, since age is the predominant factor considered when calculating risk. All of the patients described above are those who might benefit from getting a coronary artery calcium score.
The AHA/ACC guidelines have established criteria outlining when coronary artery calcium testing should be utilized and are also encouraging future research. Recent studies have shown that coronary artery calcium testing can more appropriately assess the actual risk of patients whose traditional atherosclerotic cardiovascular disease risk is between 5–20%.
The Multi-Ethnic Study of Atherosclerosis (MESA) showed that patients with elevated coronary artery calcium scores and no risk factors for heart disease had elevated rates of heart disease when compared to patients with zero coronary artery calcium levels and multiple risk factors. Furthermore, this study demonstrated that about half of individuals with a risk estimate of 5–15% have zero coronary artery calcium levels and many more have minimal levels of coronary artery calcium.
Obtaining a coronary artery calcium score is a fast and safe procedure. There have been some concerns regarding the risk of radiation exposure associated with coronary artery calcium scans. However, many medical societies have advised that the benefits of coronary artery calcium testing far outweigh the risks of minimal radiation exposure. On average, the amount of radiation exposure in obtaining a coronary artery calcium scan is equivalent to obtaining roughly 30 chest X-rays. It is also worth noting that repeating coronary artery calcium scores is not recommended compared to other tests, such as blood cholesterol panels.
This recent research on coronary artery calcium should encourage discussion and shared-decision making between health care providers and patients who are unsure if they want to take statins, especially when the patient has healthy cholesterol levels or has experienced a side effect with statin therapy in the past. A coronary artery calcium scan can provide greater insight into an individual’s risk, which can then guide a refined treatment decision.
Authors: Chanukya Dahagam, MD, PharmD and Konstantinos Aronis, MD