A Coronary Artery Calcium (CAC) score test is a non-invasive medical imaging procedure using a specialized computed tomography (CT) scan to assess heart disease risk. This examination focuses on the coronary arteries, the vessels supplying blood to the heart muscle. The test detects and quantifies calcified plaque buildup within the artery walls, providing a measure of atherosclerosis. This score helps a healthcare provider predict an individual’s future risk for a cardiac event.
Preparing for the Test: Food and Drink Guidelines
Strict fasting is usually not required for a CAC scan unless the test is combined with blood work. However, specific dietary and stimulant restrictions are recommended to ensure the highest possible image quality.
You must avoid consuming any food, caffeinated beverages, and tobacco products for approximately four hours before the appointment. This time frame helps regulate your heart rate, which is essential for image clarity. Stimulants like caffeine and nicotine accelerate the heart rate, causing motion blur and making accurate calcium detection difficult.
The CT scanner captures clear images synchronized with your heart’s rhythm, which is optimized when the heart is beating slowly and steadily. A heavy meal can also increase the heart rate or cause gastrointestinal movement that may interfere with scan quality. It is permissible to drink water or clear, non-caffeinated liquids during this preparation window to maintain hydration.
Non-Dietary Preparation Requirements
Several preparatory steps are necessary for a successful cardiac CT scan. Patients should wear comfortable, loose-fitting clothing, as they may be asked to change into a hospital gown for the procedure. This helps facilitate the placement of monitoring equipment and ensures no objects interfere with the imaging.
All metal objects must be removed from the chest area, as metal can severely distort the CT images. This includes necklaces, body piercings, and clothing items with metal snaps, zippers, or underwire. Patients should also avoid applying lotions or powders to the chest area on the day of the test, as these substances can cause artifacts on the resulting images.
It is recommended to avoid any strenuous exercise in the hours leading up to the scan. Physical activity temporarily elevates the heart rate, which compromises the clarity of the CT pictures. Patients should continue to take routine medications as usual unless specifically instructed otherwise by their prescribing physician.
What to Expect During the Scan (Procedure)
The actual CAC scan is a quick procedure, generally taking about 10 to 15 minutes. When you enter the imaging room, you will lie on your back on a movable table that slides into the CT scanner, which resembles a large, open ring.
A technologist will attach small electrode patches to your chest, connecting them to an electrocardiogram (ECG) machine. The ECG monitors your heart’s electrical activity, ensuring the equipment captures images when the heart is at the most optimal point in its cycle. The table will then move you into the center of the scanner.
During the image acquisition, which lasts only a few seconds, the technologist will instruct you to hold your breath briefly. This momentary breath-holding, typically lasting 10 to 20 seconds, prevents chest movement and guarantees the sharpest images of the coronary arteries. The procedure is non-invasive and painless, allowing you to resume normal activities immediately afterward.