title: Prevalence of obstructive coronary artery disease and prognosis in patients with stable symptoms and a zero-coronary calcium score.
abstract: OBJECTIVE
  CT calcium scoring (CTCS) and CT cardiac angiography (CTCA) are widely used in patients with stable chest pain to exclude significant coronary artery disease (CAD). We aimed to resolve uncertainty about the prevalence of obstructive coronary artery disease and long-term outcomes in patients with a zero-calcium score (ZCS).
  
  
  RESULTS
  Consecutive patients with stable cardiac symptoms referred for CTCS or CTCS and CTCA from chest pain clinics to a tertiary cardiothoracic centre were prospectively enrolled. In those with a ZCS, the prevalence of obstructive CAD on CTCA was determined. A follow-up for all-cause mortality was obtained from the NHS tracer service. A total of 3914 patients underwent CTCS of whom 2730 (69.7%) also had a CTCA. Half of the patients were men (50.3%) with a mean age of 56.9 years. Among patients who had both procedures, a ZCS was present in 52.2%, with a negative predictive value of 99.5% for excluding ≥70% stenosis on CTCA. During a mean follow-up of 5.2 years, the annual event rate was 0.3% for those with ZCS compared with 1.2% for CS ≥1. The presence of non-calcified atheroma on CTCA in patients with ZCS did not affect the prognostic value (P = 0.98).
  
  
  CONCLUSIONS
  In patients with stable symptoms and a ZCS, obstructive CAD is rare, and prognosis over the long-term is excellent, regardless of whether non-calcified atheroma is identified. A ZCS could reliably be used as a 'gatekeeper' in this patient cohort, obviating the need for further more expensive tests.
authors.affiliation: Department of Cardiology and Imaging, Royal Brompton and Harefield NHS Foundation Trust, London UB9 6JH, UK.|Imperial College London, National Heart and Lung Institute, London SW7 2AZ, UK.
authors.forename: Tarun K
authors.initials: TK
authors.lastname: Mittal
authors.affiliation: Department of Cardiology and Imaging, Royal Brompton and Harefield NHS Foundation Trust, London UB9 6JH, UK.
authors.forename: Alison
authors.initials: A
authors.lastname: Pottle
authors.affiliation: Department of Cardiology and Imaging, Royal Brompton and Harefield NHS Foundation Trust, London UB9 6JH, UK.|Imperial College London, National Heart and Lung Institute, London SW7 2AZ, UK.
authors.forename: Ed
authors.initials: E
authors.lastname: Nicol
authors.affiliation: Department of Cardiology and Imaging, Royal Brompton and Harefield NHS Foundation Trust, London UB9 6JH, UK.|Imperial College London, National Heart and Lung Institute, London SW7 2AZ, UK.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Barbir
authors.affiliation: Imperial College London, National Heart and Lung Institute, London SW7 2AZ, UK.|Imperial College NHS Healthcare Trust, London W2 1NY, UK.
authors.forename: Ben
authors.initials: B
authors.lastname: Ariff
authors.affiliation: Department of Cardiology and Imaging, Royal Brompton and Harefield NHS Foundation Trust, London UB9 6JH, UK.|Imperial College London, National Heart and Lung Institute, London SW7 2AZ, UK.
authors.forename: Saeed
authors.initials: S
authors.lastname: Mirsadraee
authors.affiliation: Department of Cardiology, East and North Hertfordshire NHS Trust, Stevenage SG1 4AB, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Dubowitz
authors.affiliation: Imperial College London, National Heart and Lung Institute, London SW7 2AZ, UK.|Department of Cardiology, East and North Hertfordshire NHS Trust, Stevenage SG1 4AB, UK.
authors.forename: Diana A
authors.initials: DA
authors.lastname: Gorog
authors.affiliation: Department of Cardiology, Buckinghamshire Healthcare NHS Trust, Amersham HP7 0JD, UK.
authors.forename: Piers
authors.initials: P
authors.lastname: Clifford
authors.affiliation: Department of Cardiology, Buckinghamshire Healthcare NHS Trust, Amersham HP7 0JD, UK.
authors.forename: Soroosh
authors.initials: S
authors.lastname: Firoozan
authors.affiliation: Department of Cardiology and Imaging, Royal Brompton and Harefield NHS Foundation Trust, London UB9 6JH, UK.|Department of Cardiology, The Hillingdon Hospitals NHS Foundation Trust, Uxbridge UB8 3NN, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Smith
authors.affiliation: Department of Cardiology, The Hillingdon Hospitals NHS Foundation Trust, Uxbridge UB8 3NN, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Dubrey
authors.affiliation: Department of Cardiology, London North West Healthcare NHS Trust, Harrow HA1 3UJ, UK.
authors.forename: Harmeet
authors.initials: H
authors.lastname: Chana
authors.affiliation: Department of Cardiology, London North West Healthcare NHS Trust, Harrow HA1 3UJ, UK.
authors.forename: Jaymin
authors.initials: J
authors.lastname: Shah
authors.affiliation: Department of Cardiology, London North West Healthcare NHS Trust, Harrow HA1 3UJ, UK.
authors.forename: Nigel
authors.initials: N
authors.lastname: Stephens
authors.affiliation: Department of Cardiology, Luton and Dunstable University Hospital, Luton LU4 0DZ, UK.
authors.forename: Christopher
authors.initials: C
authors.lastname: Travill
authors.affiliation: Department of Cardiology, John Radcliffe Hospital, Oxford, OX3 9DU, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Kelion
authors.affiliation: Joint Department of Medical Imaging, University Hospital Network, Toronto, Canada.
authors.forename: Mini
authors.initials: M
authors.lastname: Pakkal
authors.affiliation: NIHR Cardiovascular Biomedical Research Unit, Bart's Heart Centre, London EC1A 7BE, UK.
authors.forename: Adam
authors.initials: A
authors.lastname: Timmis
mesh_terms: D000368:Aged; D060050:Angina, Stable / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D002114:Calcinosis / Q000000981:diagnostic imaging* / Q000453:epidemiology; D000072226:Computed Tomography Angiography; D017023:Coronary Angiography / Q000379:methods; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011379:Prognosis; D018570:Risk Assessment; D012720:Severity of Illness Index; D015996:Survival Rate
keywords: coronary CT angiography ; coronary artery calcification ; coronary artery disease ; prognosis; stable angina 