Cardiac CT for calcium scoring, also medically called the coronary calcium scan or coronary artery calcium (CAC) scoring is a type of test which measures the calcium-containing plaque in the arteries. The test uses special X-ray tests to get detailed pictures of the inside of the heart.
Most calcium is the body is found in the bones and teeth, which helps them stay strong and healthy. However, calcium accumulation in the arteries is not a healthy sign. Calcium accumulated plaque in the arteries can grow and then restrict the blood flow to the muscles of the heart. Measuring the level of calcified plaque via a cardiac CT can help the doctor to identify potential coronary artery disease, even before the person experiences any signs and symptoms.
The results of the CT scan help the doctor to determine the cause, intensity of the problem and then accordingly initiate treatment.
Need for the test
The doctor may ask the patient for cardiac CT to get a better understanding of the heart disease or when the treatment course is yet to be decided. A cardiac CT scan uses specialized X-ray technology, known as multidetector-row or multislice computerized tomography (CT) to obtain images of the plaque deposits in the blood vessels of the heart.
Plaque is a fatty composition of cholesterol, calcium and other materials found in the blood. It accumulated over time and sticks to the walls of the arteries, causing narrowing or blockages and further heart problems. Plaque restricts the flow of oxygen-rich blood to the muscles of the heart. It can also burst, thereby leading to the formation of blood clots that travel through the bloodstream and cause a heart attack.
Use of the test
A cardiac CT scan is used to detect the intensity of the situation, assess the presence of calcium in the plaque and accordingly frame the further course of action in terms of the treatment plan. The cardiac CT scan is most helpful in cases where the patient has a moderate risk of heart disease or the exact cause of the heart problem is not clear. This scan can also help people to make important lifestyle modifications and follow treatment.
However, the heart scan requires the person to be exposed to radiation. Even though the exposure is considered safe, yet the scan is not recommended if the risk of radiation is more than the benefit. That said, a heart scan is not recommended for the below types of patients:
- Men under the age of 40 and women under the age of 50 years since it is very unlikely to detect calcium at a younger age
- People with a very low risk of heart problem because detecting calcium with such patients is not easy unless they have a family history of heart problems
- People who have a high risk since the scan will provide no details than already known. This is very applicable for heavy smokers or people with diabetes and high cholesterol levels
- Patients that have symptoms or existing diagnosis of coronary artery disease, since the scan does not provide any information on the progression of the problem or risk
- People who recently got a coronary calcium heart scan
Preparation for the cardiac CT scan
Before making the appointment for the cardiac CT scan, the patient must ask the doctor about any special instructions or other important things including the time of arrival, identification, paperwork, etc.
The doctor might advise the patient to avoid caffeine and smoking for at least four hours before the scan. Once, the patient is in the examination room, he/she will be asked to change into a medical gown. All jewellery in the neck or the chest will need to be removed.
Procedure for the cardiac CT scan
Before starting the procedure, the doctor will attach sensors known as electrodes to the chest. These electrodes are connected to an electrocardiogram (ECG or EKG), which records the patient’s heart activity during the exam. This also coordinates the timing of the X-ray images between the heartbeats, when the muscles relax.
During the scan, the patient is asked to lie on their back on a table which slides into a tube-like structure known as a CT scanner. The head of the patient is outside the scanner at all times. During this time, the patient can be given an injection or a medication to slow the heartbeat and get clear images of the heart and the arteries. The medication can help calm the patient.
The patient will need to lie still and hold their breath for a few seconds until told to release. During this time, the X-rays pictures are taken and the procedure only takes about 10-15 minutes.
After the procedure, the patient does not need to follow any special instructions and can go home the same day by driving on own. Normal activities and everyday schedule can be followed without any hassle or precaution.
Results of the cardiac CT scan
The results of the tests are expressed as Agatston score, which is a number that reflects the total area of calcium deposits and the density of these deposits. The results can be read as:
- Zero indicates that there is no trace of calcium in the heart and there is a low chance of heart attack in the future
- A score between 100-300 implies that there is a moderate level of calcium in the heart, which is relatively associated with a high risk of heart attack and other heart diseases over the coming five -6 years
- Any score greater than 300 implies an urgent need for treatment since it represents high to severe disease or heart attack risk
Overall, a higher score implies higher risk. Moreover, a percentile score also represents the persons’ risk in comparison to others of the same age or sex.