Medically reviewed by Nachiket J. Patel, MD, FACC, FSCAI. Last reviewed July 2026.
The phrase heart CT can refer to different tests. A coronary calcium score is a quick, noncontrast scan that measures calcified plaque. Coronary CT angiography, or CCTA, uses contrast to examine the coronary arteries in greater detail.
Choosing the correct test matters. A calcium score is mainly a prevention tool; it does not show every narrowing. CCTA can evaluate symptoms and anatomy but requires more preparation and is not ideal for every patient.
Flow Heart & Vascular orders and interprets heart CT results in the context of symptoms, prior testing, kidney function, heart rate, and the decision the scan is meant to inform.
What does a coronary calcium score show?
A calcium score detects calcified atherosclerotic plaque and reports an Agatston score. A higher score generally means a greater burden of coronary plaque and a higher future cardiovascular risk.
A score of zero can be reassuring in the right prevention setting, but it does not exclude noncalcified plaque, coronary spasm, microvascular disease, or an acute heart problem. Age, diabetes, tobacco use, family history, and symptoms still matter.
The result can help a patient and clinician decide how intensively to address cholesterol and other risk factors when the best prevention approach is uncertain.
How are calcium scores commonly grouped?
The score is interpreted with age, sex, symptoms, and the rest of the risk profile. These broad groups describe plaque burden; they do not choose a medication or procedure by themselves.
- 0: no calcified plaque detected; this can lower estimated near-term risk in the right setting but does not exclude noncalcified plaque
- 1–99: calcified plaque is present and the burden is often described as mild
- 100–399: a more substantial calcified-plaque burden, often described as moderate
- 400 or higher: extensive calcified plaque associated with higher cardiovascular risk
Who may benefit from a calcium score?
A calcium score is most useful when a person has no known coronary disease and the result could change a prevention decision, such as whether to begin or intensify cholesterol-lowering treatment. Current risk estimates, diabetes, tobacco use, family history, and other risk enhancers all shape that decision.
The test often adds little after coronary disease or a prior stent is already established. Chest pain or exertional breathlessness may call for a test aimed at the symptom rather than a screening calcium score, so the question should be clarified before scanning.
What does coronary CT angiography show?
CCTA uses an intravenous contrast agent and ECG-gated imaging to show the coronary artery lumen and wall. It can identify calcified and noncalcified plaque and estimate the severity of narrowing.
The test may be useful for selected patients with stable chest discomfort, an uncertain prior test, or a need to clarify coronary anatomy without starting with catheter angiography.
Heavy calcium, a very irregular rhythm, inability to control the heart rate, or certain kidney and contrast concerns can reduce image quality or change the test choice.
How do I prepare for a cardiac CT?
Follow the exact instructions from the imaging center and the prescription you receive. For CCTA, a medication such as metoprolol is sometimes prescribed to slow the heart rate and improve image quality. Take it only as written on the pharmacy label.
You may be asked to avoid caffeine, nicotine, food, or certain medicines for a defined period. Do not hold a prescription unless the ordering team or imaging center specifically instructs you to do so.
Tell the team about kidney disease, a previous contrast reaction, asthma, pregnancy possibility, erectile-dysfunction medication, and your current heart rate and blood pressure.
What happens during the scan?
Electrodes are placed on the chest so images can be timed to the heartbeat. The scanner is open at both ends, and the scan itself is brief.
For CCTA, contrast is injected through an IV and often causes a temporary warm sensation. Nitroglycerin may be given when appropriate to improve visualization of the coronary arteries.
A calcium score does not require IV contrast. Both tests use radiation, but the protocol is designed to obtain the needed information with an appropriate dose.
What do the results mean?
A calcium score should be translated into an age- and risk-appropriate prevention plan. A high score does not automatically mean that a stent is needed.
A CCTA report may describe plaque type and degree of narrowing. Borderline findings may require functional testing or, in selected cases, invasive angiography. The images should be matched to symptoms before a treatment decision is made.
Incidental findings outside the heart can also appear and may require follow-up with the appropriate clinician.
Frequently asked questions
Does a calcium score of zero mean I cannot have a heart attack?
No test reduces risk to zero. A zero score can lower estimated risk in selected patients, but it does not exclude every type of plaque or acute disease.
Is CCTA the same as a catheter angiogram?
No. CCTA is noninvasive imaging. Catheter angiography places a small tube in an artery and can allow treatment during the same procedure.
Why might my heart rate need to be slower?
A slower, steadier rate reduces motion and helps the CT scanner obtain sharper coronary images.
Related heart and vascular information
Schedule an appointment
If you have a stable heart or circulation concern, request an appointment with Flow Heart & Vascular in Mesa, Arizona. Call 911 for emergency symptoms.
This page provides general education and does not replace individualized medical advice.
