Coronary Artery Disease - Reporting and Data System

The Coronary Artery Disease - Reporting and Data System (CAD-RADS)) is a standardized findings communicationstandardised method for reporting and clinical decision aid relevant tocommunicating coronary CT angiography findings and serves as a clinical decision support tool to guide subsequent patient management.

History and etymology

The system was created by a collaboration of the Society for Cardiovascular Computed Tomography (SCCT), the American College of Radiology (ACR), and the North American Society for Cardiovascular Imaging (NASCI) and was also endorsed by the American College of Cardiology (ACC). The CAD-RADS system was initially published in 2016 ¹.

A The system was then updated to CAD-RADS classification2.0 in 2022 and is applied per patient, representingan expert document intended to serve as a practice guideline ². The new version incorporates several methods for the most severely obstructivecategorisation including new descriptors of overall coronary arteryplaque burden and options to include CT fractional flow reserve or myocardial CT perfusion results for the assessment of lesion identified-specific ischaemia if obtained ². Each category describes an imaging interpretationIt also now includes the description of non-atherosclerotic coronary abnormalities as well as further management recommendationsa separate modifier “E” for exceptions ². This

Usage

The usage of the CAD-RADS 2.0 system is intended for patients withincludes the following ²:

• application on a per-patient basis in two different clinical presentationssettings

• description of the most clinically relevant and usually most severe coronary artery luminal stenosis (applies for vessels ≥1.5 mm in diameter)

• different methods for the estimation, quantification and description of the overall plaque burden

• option to include lesion-specific CT-based myocardial ischaemia testing results obtained by CT-FFR or CT perfusion

• guide to patient management based on the above findings

The different clinical settings in which CAD-RADS is used include ^1,2:

• patients presenting with stable chest pain

• patients presenting with acute chest pain, negative first troponin, negative or nondiagnostic electrocardiogram, and low to intermediate risk (Thrombolysis In Myocardial Infarction (TIMI) risk score <4) (emergency department or hospital setting)

InterpretationCAD-RADS categories

Stable chest pain

• CAD-RADS 0

  • interpretation: documented absence of coronary artery disease

• maximal stenosis: 0% maximal-no coronary luminal stenosis and no plaque

• management recommendations:

  • no further cardiac investigation

  • reassurance; consider nonatherosclerotic causes of chest pain 

CAD-RADS 1

• interpretation: minimal nonobstructive coronary artery disease

• maximal stenosis: 1-24% maximal coronary stenosis =- minimal stenosis, or

• plaque with no stenosis (positive remodeling(includes positive remodelling)

• management recommendations:

  • no further cardiac investigation

  • consider nonatherosclerotic causes of chest pain 

  • P1: consider preventive therapy and risk factor modification 

  • P2: preventive therapy and risk factor modification

  • P3 or P4: aggressive preventive therapy and risk factor modification

CAD-RADS 2

• interpretation: mild nonobstructive coronary artery disease

• maximal stenosis: 25-49% maximal coronary - mild stenosis = mild stenosis

• management recommendations:

  • no further cardiac investigation

  • consider nonatherosclerotic causes of chest pain 

  • P1 or P2: preventive therapy and risk factor modification 

  • P3 or P4: aggressive preventive therapy and risk factor modification

CAD-RADS 3

• interpretation: moderate stenosis

• maximal stenosis: 50-69% maximal - moderate stenosis

• management recommendations:

  • consider functional assessment

  • P1-P4: aggressive preventive therapy and risk factor modification

  • consider other treatments including anti-anginal therapy as per guideline

  • I+: consider invasive coronary stenosisangiography, in particular in the setting of persistent symptoms despite optimal medical therapy

CAD-RADS 4

• interpretation: severe stenosis

• maximal stenosis:

  • CAD-RADS 4a 4a:: 70-99% maximalsevere coronary stenosis

  • CAD-RADS 4b 4b: left main >50% stenosis or three-vessel obstructive (disease with ≥70% stenosis) disease

• management recommendations:

  • CAD-RADS 5 4a: totalconsider invasive coronary occlusionangiography or functional assessment

  •  4b:

    • 100% maximal invasive coronary stenosis = total occlusion
    angiography (recommended)    
  • CAD-RADS N: obstructive coronary artery disease cannot be excluded
    • nondiagnostic study

  Acute chest pain, negative first troponin, negative or non-diagnostic electrocardiogram, and low to intermediate risk

  • CAD-RADS 0

    P1-P4: acute coronary syndrome highly unlikely

    • 0% maximal coronary stenosis
  • CAD-RADS 1: acute coronary syndrome highly unlikely
    • 1-24% maximal coronary stenosis, or
    • plaque with no stenosis (positive remodeling)
  • CAD-RADS 2: acute coronary syndrome unlikely
    • 25-49% maximal coronary stenosis
  • CAD-RADS 3: acute coronary syndrome possible
    • 50-69% maximal coronary stenosis
  • CAD-RADS 4: acute coronary syndrome likely
    • CAD-RADS 4A: 70-99% maximal coronary stenosis
    • CAD-RADS 4B: left main >50% stenosis or three-vessel obstructive (≥70% stenosis) disease
  • CAD-RADS 5: acute coronary syndrome very likely
    • 100% maximal coronary stenosis = total occlusion
  • CAD-RADS N: acute coronary syndrome cannot be excluded
    • nondiagnostic study

  Management recommendations

  Recommendations for further cardiac investigation and therapeutic approach accompanies each CAD-RADS category and is different for these two groups of patients.

  Stable chest pain

  • CAD-RADS 0
    • no further cardiac investigation
    • reassurance; consider nonatherosclerotic causes of chest pain 
  • CAD-RADS 1
    • no further cardiac investigation
    • consider nonatherosclerotic causes of chest pain; consideraggressive preventive therapy and risk factor modification

    • consider other treatments including anti-anginal therapy and revascularisation options as per guideline

  CAD-RADS 25

  • no further cardiac investigation

    interpretation:  total or subtotal coronary occlusion

  • maximal stenosis: 100% - coronary occlusion

  • management recommendations:

    • consider non-atherosclerotic causes of chest pain; considerinvasive coronary angiography, functional and/or viability assessment

    • P1-P4: aggressive preventive therapy and risk factor modification, particularly for patients with nonobstructive plaque in multiple segments

    • consider other treatments including anti-anginal therapy and revascularisation options as per guideline

  • CAD-RADS 3
    • consider functional assessment
    • consider symptom-guided anti-ischaemic and preventive pharmacotherapy as well as risk factor modification per guideline-directed care; other treatments should be considered per guideline-directed care 
  • CAD-RADS 4
    • CAD-RADS 4a: consider invasive coronary angiography or functional assessment
    • CAD-RADS 4b: invasive coronary angiography is recommended
    • consider symptom-guided anti-ischaemic and preventive pharmacotherapy as well as risk factor modification per guideline-directed care; other treatments (including options of revascularization) should be considered per guideline-directed care 
  • CAD-RADS 5
    • consider invasive coronary angiography and/or viability assessment
    • consider symptom-guided anti-ischaemic and preventive pharmacotherapy as well as risk factors modification per guideline-directed care; other treatments (including options of revascularization) should be considered per guideline-directed care.

  • CAD-RADS N

    • interpretation:  exclusion of obstructive coronary artery disease not possible

    ​

    • maximal stenosis: nondiagnostic

    • management recommendations: additional or alternative evaluation may be needed

    assessment as necessary 

  Acute chest pain, negative first troponin, negative or non-diagnostic electrocardiogram, and low to intermediate risk

  • CAD-RADS 0

    • interpretation: acute coronary syndrome is highly unlikely

    • maximal stenosis: 0% - no coronary luminal stenosis and no plaque

    • management recommendations:

      • no further evaluation of acute coronary syndrome is required; considernecessary

      • Tn+: consider other etiologiescauses of increased troponin

      • reassurance

    CAD-RADS 1

    • consider

      interpretation:  acute coronary syndrome is unlikely

    • maximal stenosis: 1-24% - minimal stenosis or plaque with no stenosis (includes positive remodelling)

    • management recommendations:

      • no further evaluation of non-acuteacute coronary syndrome etiology, if normal troponin and no ECG changesnecessary

      • Tn+: consider other causes of increased troponin

      • P1 or P2: referral forto outpatient follow-up for preventive therapy and risk factor modification

      • P3 or P4: referral to outpatient follow-up for preventive therapy and aggressive risk factor modification

    CAD-RADS 2

    • consider

      interpretation:  acute coronary syndrome is less likely

    • maximal stenosis: 25-49% - mild stenosis

    • management recommendations:

      • no further evaluation of non-acuteacute coronary syndrome etiology, if normal troponin and no ECG changesnecessary

      • in the setting of  high clinical suspicion, Tn+ or features of high-risk plague:

      • consider hospital admission with inpatient cardiology consultation

      • P1 or P2: referral forto outpatient follow-up for preventive therapy and risk factor modification

      • if clinical suspicion

        P3 or P4: referral to outpatient follow-up for preventive therapy and aggressive risk factor modification

    CAD-RADS 3

    • interpretation:  acute coronary syndrome possible

    • maximal stenosis: 50-69% - moderate stenosis

    • management recommendations:

      • consider hospital admission with inpatient cardiology consultation

      • consider functional assessment

      • I+: consider invasive coronary angiography

      • P1-P4: aggressive preventive therapy and risk factor modification

      • consider other treatments including anti-anginal therapy as per guideline

    CAD-RADS 4

    • interpretation:  acute coronary syndrome is likely

    • maximal stenosis:

      •  4a: 70-99% severe coronary stenosis

      •  4b: left main >50% stenosis or three-vessel obstructive disease with ≥70% stenosis

    • management recommendations:

      • hospital admission with inpatient cardiology consultation

      •  4a: consider invasive coronary angiography or functional assessment

      •  4b: invasive coronary angiography (recommended)    

      • P1-P4: aggressive preventive therapy and risk factor modification

      • consider other treatments including anti-anginal therapy and revascularisation options as per guideline

    CAD-RADS 5

    • interpretation:  acute coronary syndrome is very likely

    • maximal stenosis: 100% - coronary occlusion

    • management recommendations:

      • hospital admission with inpatient cardiology consultation

      • urgent invasive coronary angiography and revascularisation in the setting of suspected acute coronary occlusion

      • P1-P4: aggressive preventive therapy and risk factor modification

      • consider other treatments including anti-anginal therapy and revascularisation options as per guideline

    CAD-RADS N

    • interpretation:  exclusion of acute coronary syndrome is high or if high-risk plaque features are noted, consider hospital admission with cardiology consultation

    not possible
  • CAD-RADS 3
    • consider hospital admission with cardiology consultation, functional testing, and/or invasive coronary angiography for evaluation and management.

      maximal stenosis: nondiagnostic

    • recommendation for anti-ischemic and preventive

      management should be considered as well as risk factor modification; other treatments should be considered if presence of hemodynamically significant lesion.

  • CAD-RADS 4
    • consider hospital admission with cardiology consultation; further evaluation with invasive coronary angiography and revascularization as appropriate
    • recommendation for anti-ischaemic and preventive management should be considered as well as risk factor modification
  • CAD-RADS 5
    • consider expedited invasive coronary angiography on a timely basis and revascularization if appropriate if acute occlusion
    • recommendation for anti-ischaemic and preventive management should be considered as well as risk factor modifications. 
  • CAD-RADS N
    • recommendations: additional or alternative evaluation for acuterequired

    Plaque burden

    Coronary plaque burden has been included in the CAD-RADS system under the designation “P” and can be categorised or graded according to the severity or overall amount into the following ²:

    • P1: mild amount of plaque

    • P2: moderate amount of plaque

    • P3: severe amount of plaque

    • P4: extensive amount of plaque

    Since CAD-RADS 0 excludes the presence of plaques, the designation P0 is considered redundant ².

    Different methods to grade or categorise the overall amount of coronary syndromeplaque include the following:

    • coronary artery calcium (such as Agatston score, calcium volume score)

    • segment involvement score

    • overall visual assessment

    However, there is needed currently no recommendation for a single specific method but rather the advice to select the technique considered most appropriate for a particular institution ².

    Modifiers

    The CAD-RADS categories can be supplemented by various modifiers that convey additional information including the following ²:

    • modifier N: nondiagnostic study

  • modifier HRP: high-risk plaque (updated from V = vulnerable)

  • modifier I: ischaemia (new)

  • modifier S: stent

  • modifier G: graft

  • modifier E: exceptions (new)

  Modifiers

  If more than one modifierThe CAD-RADS coding is presentintended to follow the categories stenosis, plaque burden and finally modifiers with the symbol “/” (slash) should follow eachseparating categories and potentially modifiers. If several modifiers are present they are listed in the above order ².

  Non-diagnostic (N)

  “N” can be used as a CAD-RADS category or as a modifier concerning the respective context of a non-diagnostic study. It has been recommended to be used as a category as a replacement for the numerical stenosis assessment in the setting of a non-diagnostic coronary segment and no other segment with at least moderate coronary stenosis (>50%) ². On the other hand, in the setting of significant coronary stenosis (>50%), it has been recommended to be used as a modifier following the category “P” for plaque burden.

  High-risk plaque (HRP)

  The term high-risk plaque features has been recommended to replace the previous term vulnerable plaque and is the second modifier in the list ². High-risk features have been associated with a higher risk or likelihood of the following order²:

  • modifier N: nondiagnostic

    acute coronary syndrome irrespective of the degree of stenosis

  • modifier S: stent

    major adverse cardiovascular events in the setting of stable chest pain

  • modifier G: graft
  • modifier V: vulnerability​

    lesion-specific ischaemia

  For exampleAs a result, patients might require hospital admission or observation in the setting of acute chest pain and require more aggressive preventive management ².

  Ischaemia (I)

  The modifier “I” demonstrates that a CT-specific ischaemia test has been performed either CT-FFR or stress CT perfusion, which might be used in the setting of moderate to severe stenosis or in proximal lesions ≥40% including high-risk plaque features to further evaluate the stenosis and to define whether it is haemodynamically relevant. The modifier can be categorised as the following ²:

  • positive (I+): in the setting of concordant lesion-specific abnormal CT-FFR (≤0.75), myocardial ischaemia or peri-infarction ischaemia in the defined coronary territory

  • negative (I-): in the background of concordant lesion-specific normal CT-FFR (>0.80) or absence of ischaemic changes in a defined coronary territory on stress CT perfusion

  • borderline (I+/-): in the setting of borderline CT-FFR (0.76-0.80)

  Stent (S)

  The modifier “S” marks the presence of a coronary stent; coronary in-stent restenosis and stent occlusion are classified like the native coronary arteries.

  Graft (G)

  The modifier “G” designates the presence of at least one coronary artery bypass graft. In this setting lesions of the graft, the distal anastomosis and the run-off vessel as well as the non-bypassed are considered in the classification whereas stenosis bypassed by a patent graft is not. However, the overall plaque burden is assessed for both native coronary arteries and bypass grafts ².

  Exceptions (E)

  The modifier “E” indicates the presence of non-atherosclerotic coronary abnormalities also as a potential cause for coronary narrowing or stenosis such as coronary artery dissection or congenital coronary artery anomalies².

  Examples

  • mild stenosis due to plaque with high-risk features: CAD-RADS 2/V/HRP

  • non-interpretable coronary stent with a mild amount of plaque burden without evidence of other obstructive coronary disease: modifier S = CAD-RADS N/P1/S

  • presence of stent and a new moderate stenosis showing a plaque with high-risk features: modifiers S and V=CADCAD-RADS 3/HRP/S/V

  • presence of a stent, grafts extensive amount of plaque and non-evaluable segments due to metal artifacts: modifiers S and G=CADcircumferential plaques: CAD-RADS N/P4/S/G

  • severe amount of plaque, presence of patent left internal mammary artery (LIMA) to the left anterior descending artery (LAD) and expected occluded proximal LAD, mild non-obstructive stenosis in the right coronary artery (RCA) and left circumflex artery (LCx): CAD-RADS 2/P3/G

  • severe amount of plaque, patent left internal mammary artery (LIMA) to the left anterior descending artery (LAD) and expected occluded proximal LAD. Mild non-obstructivesaphenous vein graft to the circumflex artery (Cx) and moderate stenosis in the right coronary artery (RCA) and left circumflex artery (LCx. modifier G =: CAD-RADS 25/P3/G

  • for

    a patient withmoderate amount of plaque, severe stenosis (70-99%) in one segment with abnormal lesion-specific CT-FFR ≤0.75 and a non-diagnostic area in another segment, the study should be graded as: CAD-RADS 4/P2/N/I+

  • no plaque, moderate stenosis due to coronary dissection: CAD-RADS 3/E

  See also

  • ACC/AHA classification of coronary lesions

  • CAC-DRS: Coronary Artery Calcium Data and Reporting System

  • RADS (Reporting and Data Systems)