Coronary Artery Stenosis on CT
Understand Coronary Artery Stenosis on CT in Heart Cardiac CT imaging, what it means, and next steps.
30-Second Overview
Coronary artery luminal narrowing on CT angiography. Stenosis graded: none (0%), mild (1-49%), moderate (50-69%), severe (70-99%), occluded (100%)
CCTA has high negative predictive value (98-99%) for ruling out significant CAD. Detects both calcified and non-calcified plaque. Positive findings may require functional testing for ischemia assessment.
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Imaging Appearance
Cardiac CT FindingCoronary artery luminal narrowing on CT angiography. Stenosis graded: none (0%), mild (1-49%), moderate (50-69%), severe (70-99%), occluded (100%)
Clinical Significance
CCTA has high negative predictive value (98-99%) for ruling out significant CAD. Detects both calcified and non-calcified plaque. Positive findings may require functional testing for ischemia assessment.
Understanding Coronary Artery Stenosis
Coronary artery stenosis refers to narrowing of the coronary arteries, typically caused by atherosclerotic plaque buildup. This narrowing can reduce blood flow to the heart muscle, leading to chest pain (angina) or heart attack.
Coronary artery luminal narrowing graded as mild (＜50%), moderate (50-69%), severe (70-99%), or occluded (100%)
Here's how accurate coronary CTA is at detecting stenosis:
Excellent NPV (98-99%) for ruling out significant CAD
Correctly rules out healthy patients
Annual new cases
Think of coronary arteries like pipes supplying water to your house—when plaque builds up inside, flow becomes restricted. Coronary CTA creates detailed 3D images showing exactly where and how much these arteries are narrowed.
What Is Coronary Artery Stenosis?
Coronary artery stenosis is the narrowing of coronary arteries due to atherosclerosis. The severity determines whether symptoms occur and what treatment is needed.
Stenosis Grading:
| Category | Percentage Narrowing | Clinical Significance | |----------|---------------------|----------------------| | None | 0% | Normal artery | | Mild | 1-49% | Usually asymptomatic, medical management | | Moderate | 50-69% | May cause symptoms with exertion, may need testing | | Severe | 70-99% | Likely causes ischemia, may need intervention | | Occluded | 100% | Complete blockage, no blood flow beyond |
Plaque Composition:
- Calcified plaque - dense, stable (bright white on CT)
- Non-calcified (soft) plaque - more vulnerable to rupture
- Mixed plaque - combination of both
Why coronary CTA is valuable:
- Non-invasive alternative to cardiac catheterization
- Excellent negative predictive value (rules out disease)
- Visualizes both lumen and vessel wall
- Detects plaque before severe narrowing develops
- Can assess stent patency and bypass grafts
How Coronary Stenosis Appears on CTA
Coronary CT angiography uses high-resolution CT with ECG gating to freeze cardiac motion and capture detailed images of the coronary arteries.
What Normal Coronary Arteries Look Like
Coronary arteries appear smooth and uniform in caliber. LAD, LCX, and RCA courses are normal. No luminal narrowing. No visible plaque. All branches opacified uniformly. Myocardial enhancement homogeneous. Vessels taper normally as they branch.
What Coronary Stenosis Looks Like
Coronary artery shows luminal narrowing at plaque location. Plaque visible as wall thickening: calcified (bright white ＞130 HU), soft (lower density ＜50 HU), or mixed. Stenosis percentage measured. High-risk features may include positive remodeling, low attenuation plaque, spotty calcification.
Key Findings Pattern
When evaluating coronary stenosis on CTA, radiologists assess:
Key Imaging Findings
Degree of stenosis
Percentage of luminal narrowing: mild (＜50%), moderate (50-69%), severe (70-99%), occluded (100%)
Plaque composition
Calcified (dense ＞130 HU), non-calcified (soft, ＜50 HU), or mixed plaque
High-risk plaque features
Positive remodeling, low attenuation plaque, spotty calcification, napkin-ring sign
Plaque location
Proximal, mid, or distal segment; which vessel (LAD, LCX, RCA)
Lesion length and morphology
Focal vs. diffuse disease; length of narrowed segment
Side branch involvement
Stenosis involving or near major side branches
When Your Doctor Orders This Test
Here's a typical scenario where coronary CTA is ordered:
Clinical Scenario
Common indications:
- Stable chest pain with intermediate pre-test probability
- Atypical cardiac symptoms
- Inconclusive stress test
- Preoperative assessment for non-cardiac surgery
- Evaluation of stent or bypass graft patency
- Emergency department chest pain evaluation
Differential Diagnosis
Several conditions can cause similar findings or symptoms:
What Else Could It Be?
Plaque causing luminal narrowing on CTA. Management based on severity: medical therapy for mild/moderate, PCI (stent) or CABG for severe symptomatic. Functional testing guides revascularization decisions.
Transient narrowing not visible on static CTA. Diagnosis requires clinical suspicion, may be provoked during angiography. Treated with calcium channel blockers, nitrates. CTA may appear normal.
Abnormal coronary artery origin or course. May cause ischemia if course between great vessels. Management varies by anomaly type. Surgical correction if high-risk course.
Segment of coronary artery tunneled within myocardium. Systolic compression visible on CTA. Usually benign but can cause ischemia in some cases. Beta-blockers may help.
Normal coronaries on CTA. Consider GERD, musculoskeletal, pulmonary, or anxiety causes. No cardiac intervention needed. Further workup directed by clinical presentation.
How Accurate Is Coronary CTA for Stenosis?
Coronary CTA has excellent diagnostic performance:
Coronary CTA detects most significant stenoses. Recent advances in scanner technology and image reconstruction have improved accuracy, especially for smaller vessels and calcified plaque. Calcified lesions may still be overestimated.
Landmark trial showed coronary CTA is safe and effective for evaluating stable chest pain, with similar outcomes to functional testing. CTA led to more catheterizations and revascularizations but also more preventive therapy.
What Happens Next?
Management depends on stenosis severity and symptoms:
What Happens Next?
Result interpretation and risk assessment
Normal CTA: CAD effectively ruled out. Non-obstructive CAD: risk factor modification. Obstructive CAD: cardiology consultation. Ischemia testing if moderate stenosis with symptoms.
Medical therapy (all CAD patients)
Aspirin or alternative antiplatelet. Statin therapy (high-intensity). Beta-blocker if indicated. ACE inhibitor if diabetes or LV dysfunction. Lifestyle modifications essential.
Functional testing if needed
Moderate stenosis with symptoms: stress test or FFR-CT to determine if stenosis causes ischemia. Ischemia-guided revascularization improves outcomes. Treat ischemia, not just anatomy.
Revascularization assessment
Severe proximal stenosis with symptoms: consider PCI (stent) or CABG. Multi-vessel disease: may need surgical consultation. Left main disease: usually surgical (CABG). Shared decision-making.
Surveillance and prevention
Lipid monitoring, blood pressure control. Repeat imaging if symptoms change. Vaccination (flu, pneumonia, COVID). Cardiac rehabilitation if revascularization performed. Stress management.
When to Seek Immediate Care
Call 911 immediately for:
- Chest pain or pressure that doesn't go away
- Shortness of breath
- Pain radiating to arm, neck, jaw, or back
- Cold sweat, nausea, or lightheadedness
- Severe weakness or anxiety
Frequently Asked Questions
How does coronary CTA compare to cardiac catheterization?
Coronary CTA is non-invasive (no catheter inserted into the heart), while cardiac catheterization is invasive. CTA is excellent for ruling out CAD and assessing plaque burden. Cardiac catheterization allows immediate treatment (stent placement) if blockage is found and provides pressure measurements to assess stenosis significance.
Does a normal CTA mean I'm totally safe?
A normal coronary CTA effectively rules out significant CAD for the next 2-5 years. However, plaque can still progress. Continue heart-healthy habits: don't smoke, exercise regularly, eat a healthy diet, and maintain healthy weight, blood pressure, and cholesterol.
What if they find blockage?
Treatment depends on severity and symptoms. Options include: medications (aspirin, statins, beta-blockers), lifestyle changes, angioplasty with stent placement, or bypass surgery. Your cardiologist will discuss the best option based on your specific situation, symptoms, and test results.
Can I have CTA if I have stents?
Yes, CTA can evaluate stent patency. However, artifacts from the metal stent can sometimes limit assessment, especially in smaller stents (＜3 mm). Newer scanners are better at evaluating through stents. Your doctor will determine if CTA is appropriate or if other testing is needed.
How should I prepare for coronary CTA?
Preparation includes: no caffeine for 12-24 hours, possible beta-blocker to slow heart rate, no food for 4-6 hours before the scan, bring medication list, avoid erectile dysfunction medications for 48 hours before the test. Good hydration before and after helps flush contrast from kidneys.
References
Medical References
This content is referenced from authoritative medical organizations:
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Medical Disclaimer: This information is for educational purposes. CAD requires management by a cardiologist. Always seek emergency care for chest pain.
Correlate with Lab Results
When Coronary Artery Stenosis on CT appears on imaging, doctors often check these lab tests:
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