Understanding Your CT Coronary Angiogram Report

Your CT Coronary Angiogram Report, Decoded
What CAD-RADS, calcium scores and plaque descriptions really mean — and what usually happens next.
If you've just received a CTCA report filled with abbreviations like CAD-RADS, Agatston, stenosis, and LAD, this guide translates that language into plain English. Understand what the scan found, what it means for your heart, and what to ask your doctor.
Questions to Ask Your Doctor
The Bottom Line
What the Scan Actually Does — and Why It Matters
How CTCA Works
A CTCA is a non-invasive scan producing detailed 3D images of the arteries supplying your heart muscle. It uses an iodine contrast dye injected into a vein, and often a tablet or injection to slow your heart rate for sharper images.
Why It's Better Than a Stress Test
A treadmill or stress test only detects reduced blood flow — which usually appears once an artery is already significantly narrowed. A CTCA looks directly at the artery walls, finding early fatty build-up (plaque) years before it causes symptoms.
Guideline-Recommended
Both the 2021 US chest pain guideline and the 2024 ESC guideline recommend CTCA as a first-choice test for new chest pain in people not known to have heart disease.
The Scottish SCOT-HEART trial found that adding CTCA to standard care reduced coronary death or heart attack over five years — 2.3% vs 3.9% — mostly by finding plaque early and starting preventive treatment.
The Artery Map: Reading Your Report's Geography
Your report names the main coronary arteries and describes each in segments — proximal (near the start), mid, and distal (far end). Location matters: a narrowing near the start of the LAD affects far more heart muscle than the same narrowing in a small side branch.
"Right dominant" or "left dominant" describes which artery gives rise to the PDA — the branch supplying the underside of the heart. Most people are right dominant. Either pattern is a normal variation, not a disease.
Stenosis and CAD-RADS: Your Summary Score
Stenosis means narrowing of the artery channel by plaque. CAD-RADS (Coronary Artery Disease Reporting and Data System) condenses the whole scan into one standard category based on the worst narrowing found. The current version, CAD-RADS 2.0, was published in 2022.
1
CAD-RADS 0
No plaque. Very reassuring — chest pain is very unlikely to come from the coronary arteries.
2
CAD-RADS 1–2
1–49% narrowing. Early to mild atherosclerosis. Prevention with lifestyle and usually a statin.
3
CAD-RADS 3
50–69% narrowing. Moderate. Prevention, symptom treatment, and sometimes a blood-flow test.
4
CAD-RADS 4A–4B
Severe narrowing or left main ≥50%. Prompt cardiology review; invasive angiogram often considered.
5
CAD-RADS 5
100% blocked. Cardiology review; further tests may assess whether muscle beyond it is still alive.
A narrowing under 50% is non-obstructive — it doesn't limit blood flow, but it is still real atherosclerosis worth treating. Most heart attacks start from plaques that were not severely narrowed beforehand.
The Letters After the Number: CAD-RADS Modifiers
CAD-RADS 2.0 reports often add modifier letters — for example CAD-RADS 3/P3/HRP. These are often as important as the number itself.
P1–P4
Plaque burden — how much plaque overall, from mild (P1) to extensive (P4). Guides how intensive prevention should be.
HRP
High-risk plaque — features linked to a higher chance of rupture. Prompts more intensive prevention.
I
Ischaemia — results of a blood-flow test such as FFR-CT, shown as positive, negative or borderline.
N
Non-diagnostic — part of the scan could not be assessed reliably, often due to heart motion, irregular rhythm, or heavy calcium.
The CAD-RADS category tracks closely with long-term outcomes. People with CAD-RADS 0 have an excellent outlook; risk rises progressively with higher categories and higher plaque burden.
The Calcium Score (Agatston Score)
Many CTCAs include a calcium score — a quick scan without dye that measures how much calcified (hardened) plaque is in your coronary arteries, reported as an Agatston number.
Your report may also give a percentile — comparing you with people of the same age, sex and ethnicity. A high percentile means your arteries are ageing faster than expected.
Three Common Misunderstandings
1
Zero is reassuring, not a guarantee
In the CONFIRM registry, 3.5% of symptomatic patients with a zero calcium score still had ≥50% narrowing. The contrast CTCA still matters.
2
Calcium ≠ narrowing
A high score can sit alongside open arteries. Heavy calcium can also blur images and make narrowings harder to measure.
3
A rising score on a statin isn't bad
Statins stabilise plaque by making it more calcified. A higher score after starting treatment does not mean the medicine has failed.
Plaque Types: What Your Report Is Describing
Calcified Plaque
Older, hardened build-up. Bright white on CT. Generally more stable and less likely to rupture suddenly.
Non-Calcified (Soft) Plaque
Younger, fattier build-up. Dark grey on CT. More active and more likely to cause trouble — even without significant narrowing.
High-Risk Plaque (HRP)
Labelled when a plaque shows ≥2 of: positive remodelling, low-attenuation core, spotty calcification, or napkin-ring sign. Prompts intensive prevention — not automatically a stent.
The total amount of plaque across all arteries is one of the strongest predictors of a future heart attack — often more telling than any single narrowing. People with widespread non-obstructive plaque had similar risk to those with a single obstructive narrowing in large studies.
A Worked Example: One Report, Translated
Here is a typical CTCA conclusion, followed by what it means in plain English.
"Right dominant circulation. Agatston score 186 (78th percentile). Mixed plaque in the proximal LAD causing 50–69% stenosis, with positive remodelling and low-attenuation plaque. Mild non-obstructive plaque in the mid RCA. LCx unremarkable. Impression: CAD-RADS 3/P2/HRP."
What usually happens next: Start or intensify a statin with a firm cholesterol target, consider low-dose aspirin, and treat blood pressure and other risk factors. If symptoms are present, a blood-flow test (FFR-CT, stress test, or pressure wire) would guide whether a stent could help.
What Happens Next — and Questions to Ask
Management by CAD-RADS
CAD-RADS 0
Reassurance. No heart-specific medication needed; look for other causes of symptoms.
CAD-RADS 1–2
Prevention: statin scaled to plaque burden, blood pressure, diabetes, smoking, diet and exercise.
CAD-RADS 3
Prevention plus often low-dose aspirin; blood-flow test if symptomatic.
CAD-RADS 4–5
Cardiology review; invasive angiogram often recommended — urgently for left main or three-artery disease.
In stable disease, the ISCHEMIA trial found that routinely adding stents to good medical treatment did not reduce heart attacks or deaths over ~4 years. Stents clearly help in heart attacks and for persistent symptoms despite medication.
7 Questions to Ask Your Doctor
What is my CAD-RADS category, and what does my plaque burden (P grade) mean for me?
1.Do I have any high-risk plaque features?
2.Should I be on a statin, and what LDL level should I aim for?
3.Do I need aspirin?
4.Does any narrowing need a blood-flow test such as FFR-CT or a stress test?
5.Were there any incidental findings needing follow-up?
6.Should my family be checked, given what my scan showed?
7.
The Bottom Line
A CTCA is valuable because it can find coronary disease early — often years before a heart attack. Whatever your report says, the most powerful levers remain the familiar ones: not smoking, controlling blood pressure and cholesterol, staying active, eating well, and taking prescribed medicines consistently.
Don't Ignore Plaque
Non-obstructive plaque still causes heart attacks. "Nothing is blocked" does not mean nothing needs treating.
Don't Stop Your Statin
A rising calcium score on a statin often means the plaque is stabilising — not that the medicine has failed.
Don't Ignore New Symptoms
A normal scan does not override new or changing symptoms. See your doctor again if anything changes.
Call 000 immediately if you have chest pain lasting more than 10 minutes, severe or worsening pain, or pain with sweating, breathlessness, nausea, or radiation to your arm, jaw, neck or back — regardless of what your report says.
Bring your report to your GP or cardiologist and ask them to walk you through your CAD-RADS category, calcium score, plaque findings, and what they recommend for you. Key references include CAD-RADS 2.0 (2022), the SCOT-HEART trial, and the ISCHEMIA trial.
© 2026 Dr Primero Ng. All rights reserved.
Consultant Interventional Cardiologist, Perth, Western Australia.
Information on this website is general in nature and does not replace individual medical advice.