Calcium deposits in the coronary arteries are a sign of atherosclerotic plaque. A computed tomography (CT) calcium score (CACS) is a non-invasive imaging test that is used to determine your risk of heart attack based on the presence and extent of calcified plaque in the walls of your heart arteries. It uses CT imaging to construct images of your heart arteries that assess and measure the presence or absence of calcium-containing plaque within them. An increase in plaque inside your heart arteries can restrict blood flow to the heart muscle. A CT calcium score may identify the presence of coronary artery disease before you have any symptoms, emphasising the importance of monitoring calcified plaque early. This test is only suitable for individuals with no cardiac symptoms as the test cannot determine whether any heart artery narrowing is present to determine the cause of such symptoms.
Unlike CT coronary angiography, CT calcium scoring does not require intravenous contrast, heart rate lowering or any specific preparation. Like CT coronary angiography, coronary artery calcium scoring is also a non-invasive test. It measures the amount of coronary artery plaque by examining the extent of coronary artery calcification with a high-resolution CT.
A CT calcium score helps to accurately stratify your risk of heart attack and subsequently guide treatment if you are deemed by traditional risk calculators to be at moderate risk of heart attack, or if your heart attack risk is felt to be elevated based on your family history. The results of this test may help motivate people at moderate risk to make important lifestyle changes and follow treatment plans. A calcium score of zero does not necessarily rule out the chances of arterial disease, however, in such cases the chances of coronary blockages are low.
On the other hand, having a very high calcium score can indicate a higher chance of a coronary event or heart attack within five years. Thus, CACS test can be used to screen asymptomatic patients to assess their coronary artery disease risk, especially patients with related risk factors like hypertension, high cholesterol and others with history of heart disease in the family.
While the scan itself is a one minute procedure, patients are asked to lie down for around 15-20 minutes post scan. Within this time, complex data sets are processed and presented in the form of 3D images.
The result of the test is given as a number called an Agatston score which reflects the total area of calcium deposits and density of the calcium in the heart arteries. When calcium is present, the higher the score, the higher your risk of heart attack.
A score of zero means no calcium is seen in the heart and suggests a very low chance of developing a heart attack in the next 5-10 years.
A score of 1 to 100 means mild plaque deposits and corresponds to a low to moderate risk of heart attack in the next 5-10 years.
A score above 100 to 400 means moderate plaque deposits and is associated with a moderate to high risk of heart attack in the next 5-10 years.
A score above 400 is a sign of severe coronary disease and high heart attack risk in the next 5-10 years.
You will also receive a percentile score, which indicates your amount of calcium compared to people of the same age and sex. Under normal circumstances, test results are not available instantly. The process of processing and reporting images may take up to 2 hours.
Depending on the result of your CT calcium score, Dr Nasis may recommend additional tests, initiation or escalation of medical therapy, or lifestyle changes to reduce your risk of heart attack.