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Purpose and principlesIndications, selection and cautionsMethod and interpretationClinical next stepsRisks, monitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Coronary CT angiography and calcium scoring

Cardiology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Time-critical presentation

CTCA for stable chest pain is not a substitute for the acute STEMI or high-risk NSTE-ACS pathway. New rest pain, dynamic ECG change or instability requires emergency assessment.

Purpose and principles

Use CT coronary angiography as the UK first-line anatomical test for appropriate stable chest pain and interpret stenosis, plaque and calcium without false reassurance.

CTCA has high rule-out value in an appropriate low-to-moderate likelihood population and also identifies non-obstructive plaque that should prompt prevention assessment. It does not directly prove ischaemia.

Acquisition may include heart-rate control and sublingual nitrate under a department protocol. These improve image quality but require blood-pressure, conduction and medicine checks.

Report coronary dominance, origin and course, plaque distribution, stenosis category, image limitations, significant extracardiac findings and the recommended next decision.

Key points

  • NICE CG95 recommends 64-slice-or-above CTCA first-line when assessment indicates typical or atypical angina.
  • CTCA visualises lumen and plaque; a calcium score quantifies calcified plaque but does not show stenosis or non-calcified plaque.
  • NICE no longer uses stand-alone coronary calcium scoring to diagnose stable angina.
  • A zero calcium score does not exclude non-calcified coronary atherosclerosis or an acute coronary syndrome.
  • Rate regularity, breath-hold, obesity and heavy calcification affect image quality; calcium blooming can overestimate stenosis.
  • Intermediate CT stenosis may need functional imaging or validated CT-derived fractional flow reserve before invasive decisions.
  • Check pregnancy possibility, renal function where indicated, previous contrast reaction and interacting drugs before iodinated contrast and rate-control medication.

Indications, selection and cautions

Obstructive or high-risk anatomy

Left main, proximal multivessel or severe stenosis requires prompt specialist correlation and often invasive assessment, particularly with symptoms.

Non-obstructive plaque

Plaque below an obstructive threshold is not a normal result; address cardiovascular prevention and symptom mechanism.

Indeterminate segment

Motion, blooming or poor opacification can make a key segment non-diagnostic; it must not be silently counted as normal.

Anomalous coronary course

An interarterial or intramural course can be clinically important, especially with exertional symptoms, and needs specialist anatomical review.

Contrast reactionRed flag

Bronchospasm, facial or laryngeal swelling, hypotension or collapse after contrast requires an immediate emergency response.

Method and interpretation

  1. 01
    CT coronary angiographyFirst step
    Why
    Exclude or define anatomical coronary disease in stable suspected angina.
    Interpretation and limitations
    A diagnostic study can identify normal arteries, non-obstructive plaque or stenosis; correlate severity and symptoms rather than treating anatomy alone.
  2. 02
    Coronary artery calcium score
    Why
    Quantify calcified plaque burden for selected preventive-risk questions.
    Interpretation and limitations
    Agatston score reflects calcified burden, not stenosis; zero does not exclude soft plaque and is not the NICE diagnostic test for stable angina.
  3. 03
    CT-derived fractional flow reserve
    Why
    Estimate functional significance of selected intermediate CT stenoses.
    Interpretation and limitations
    Use only validated technology and adequate source images; it complements rather than rescues a non-diagnostic scan.
  4. 04
    Functional imaging
    Why
    Assess inducible ischaemia when CTCA shows uncertain functional significance or is non-diagnostic.
    Interpretation and limitations
    Match the perfusion or wall-motion territory to the CT lesion before revascularisation decisions.
  5. 05
    Renal function assessment
    Why

Clinical next steps

01Preferred routeStable suspected anginaFirst stepPreferredTypical or atypical angina without acute features+
  1. 1Complete clinical assessment, resting ECG and baseline safety checks.
  2. 2Offer 64-slice-or-above CTCA under NICE CG95.
  3. 3If arteries are normal, reconsider non-coronary and vasomotor causes; if plaque is present, address prevention.
  4. 4For severe disease, uncertain significance or non-diagnostic key segments, proceed to functional imaging or invasive assessment according to risk.
02AlternativeOptimising acquisitionAlternativeHeart rate, rhythm or patient factors may impair CTCA+
  1. 1Review rhythm, pulse, blood pressure, conduction disease, asthma, ventricular function and current medicines.

Risks, monitoring and follow-up

  • Record heart rate, rhythm and blood pressure before rate-control or nitrate administration.
  • Observe for immediate contrast reaction and follow the emergency protocol if it occurs.
  • Review renal function after contrast only when clinical risk or local contrast policy indicates.
  • Document radiation dose and whether every important segment was diagnostic.
  • Track preventive treatment and follow-on investigation after plaque or indeterminate stenosis is reported.

Special situations

CTCA is anatomical

A 50% stenosis may or may not cause ischaemia; functional correlation can prevent unnecessary intervention.

Calcium blooming

Dense calcium spreads across pixels and can make the residual lumen appear smaller than it is.

Zero is not no disease

Younger patients and acute plaque events can involve non-calcified plaque despite an Agatston score of zero.

Normal coronaries redirect the question

Persistent angina with non-obstructive arteries should raise vasospastic or microvascular mechanisms rather than diagnostic closure.

Incidental findings need ownership

Clinically important extracardiac findings require a named follow-up route, not a buried sentence.

Common pitfalls

  1. 01

    Using stand-alone calcium scoring to diagnose stable angina.

  2. 02

    Calling a zero calcium score a lifetime guarantee against coronary disease.

  3. 03

    Sending an unstable ACS presentation to an outpatient CTCA pathway.

  4. 04

    Treating a heavily calcified non-diagnostic segment as unobstructed.

  5. 05

    Proceeding to PCI from CT anatomy alone when an intermediate lesion's functional significance is uncertain.

Practice

Two practice questions

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Question 1 of 2
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CardiologyOriginal SBA

Meaning of zero calcium

A 44-year-old with exertional chest discomfort has a coronary calcium score of zero. Which statement is correct?

Choose one answer, then submit
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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE CG95: Recent-onset chest pain
  • NICE HTG429: HeartFlow FFRCT
  • ESC 2024 Guidelines for chronic coronary syndromes
  • ESC/EACVI cardiovascular CT consensus collection

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
Identify patients at increased risk from iodinated contrast and plan exposure safely.
Interpretation and limitations
Use current departmental and contrast-agent guidance; risk depends on kidney function, acute illness, hydration and contrast burden.
2
Use authorised beta-blocker and nitrate protocols only when safe; formulation and IV dosing are department-specific.
  • 3Optimise breath-hold and contrast timing while minimising radiation and contrast dose.
  • 4If adequate images remain unlikely, choose a suitable functional modality rather than force a poor CTCA.
    • 03EscalationHigh-risk CT resultEscalationLeft main, severe proximal disease or extensive obstructive CAD+
    1. 1Contact the responsible clinician promptly and review current symptoms for instability.
    2. 2Start or optimise guideline-directed antianginal and preventive therapy as clinically appropriate.
    3. 3Arrange invasive angiography with functional lesion assessment where it will guide revascularisation.
    4. 4Use multidisciplinary and shared decision-making for PCI versus CABG when anatomy is complex.