A Coronary Artery Calcium Scoring (CACS) test is a non-invasive procedure that uses a specialized computed tomography (CT) scan to evaluate heart health. The primary purpose is to measure calcified plaque present within the walls of the coronary arteries. These calcium deposits are a direct indication of atherosclerosis, or coronary artery disease, helping providers estimate a person’s risk of a future heart attack or stroke. The result is the Agatston score, which quantifies the extent of this calcification.
Hydration and Dietary Restrictions
Most testing facilities generally allow and encourage the consumption of plain water up until the time of the scan to ensure adequate hydration. Water will not interfere with the imaging process itself.
A mandatory fasting period is required for food and non-water beverages, typically for at least four hours before the appointment. This ensures the digestive system is inactive, preventing interference with the imaging field around the heart. The fasting rule applies to anything containing calories or stimulants, including milk, juice, sodas, and solid food. The primary exceptions are plain water and necessary medications, which should be taken as usual unless specifically instructed otherwise by a physician.
Factors Affecting Test Quality
The accuracy of the calcium score depends on capturing clear, motion-free images of the heart. The CT scanner synchronizes rapid pictures with the patient’s heartbeat, making a low and stable heart rate necessary for a successful scan. A heart rate above 60 to 70 beats per minute introduces motion artifacts, blurring the images and leading to an inaccurate or non-diagnostic result.
Patients must strictly avoid all substances and activities that could elevate the heart rate in the hours leading up to the test. This includes abstaining from all sources of caffeine (coffee, tea, energy drinks, and certain sodas) for at least four hours prior to the scan. Nicotine, including cigarettes, cigars, or vaping products, must also be avoided for the same four-hour minimum period because it is a potent vasoconstrictor and stimulant.
Strenuous physical activity, such as heavy exercise or running, should also be avoided on the day of the test. If the heart rate remains high, medication like an oral beta-blocker may be administered at the facility to temporarily slow the heart and ensure a successful image capture.
Navigating the Scan Procedure
On the day of the test, the entire procedure is quick, often taking only about 10 to 15 minutes from check-in to completion. Patients are asked to change into a gown and remove all metal objects, as metal interferes with the CT imaging process. These objects include:
- Jewelry
- Hairpins
- Clothing with zippers
- Underwire
The technologist attaches small, sticky electrode patches to the patient’s chest, connecting them to an electrocardiogram (EKG) machine. This EKG monitors the heart’s electrical activity, allowing the CT scanner to precisely time the image acquisition to the resting phase of the heart cycle. The patient then lies flat on a table that slides into the CT scanner, which is a large, open ring.
The CACS scan does not involve any injection of contrast dye, unlike some other types of CT scans. The actual image acquisition takes only a few seconds. During this time, the patient will be asked to hold their breath for about 10 to 20 seconds. Remaining perfectly still and following the breath-hold instructions minimize motion and ensure image clarity.