Objectives To estimate the prevalence of non-calcified coronary artery disease (CAD) in patients with suspected stable angina and a zero coronary artery calcification (CAC) score, and to assess the prognostic significance of a zero CAC in these symptomatic patients.
Methods In this prospective cohort study, consecutive patients with stable chest pain underwent CAC scoring ± CT coronary angiography (CTCA) as part of routine clinical care at a single tertiary centre over 7 years. Major adverse cardiac event (MACE) was defined as cardiac death, non-fatal myocardial infarction and/or non-elective revascularisation.
Results A total of 915 of 1753 (52.2%) patients (mean age 56.8 ± 12.0 years; 46.2% male) had a zero CAC score. Of the 751 (82.1%) patients with a zero CAC in whom CTCA was performed, 674 (89.7%) had normal coronary arteries, 63 (8.4%) had non-calcified CAD with < 50% stenosis and 14 (1.9%) had ≥ 50% stenosis in at least one coronary artery. The negative predictive value of a zero CAC for excluding a ≥ 50% CTCA stenosis was 98.1%. Over a median follow-up period of 2.2 years (range 1.0–7.0 years), the absolute annualised rates of MACE were as follows: zero CAC 1.9 per 1000 person-years and non-zero CAC 7.4 per 1000 person-years (HR 3.8, p = 0.009). However, after adjusting for age, gender and cardiovascular risk factors using a multivariable Cox proportional hazards model, there was no statistically significant difference in the risk of MACE between the two patient cohorts (p = 0.19). After adjusting for age, gender and cardiovascular risk factors, the HR for all-cause mortality among the zero CAC cohort vers non-zero CAC was 2.1 (p = 0.27).
Conclusion A zero CAC score in patients undergoing CT scanning for suspected stable angina has a high negative predictive value for the exclusion of obstructive CAD and is associated with a good medium-term prognosis.
- coronary artery disease
- chest pain clinic
- CT scanning
- risk stratification
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Contributors Contributors XW and EPVL contributed equally to the data collection, the statistical analysis and drafted the initial manuscript. JMT, NJHP and NKR contributed to the data collection. HP advised on the statistical analysis. JHFR, JB, MW, JMT and DG planned the study and JHFR is the study guarantor.
Funding JHFR is part-supported by the National Institute of Health Research (NIHR) Cambridge Biomedical Research Centre, the Higher Education Funding Council for England, the British Heart Foundation, the EPSRC and the Wellcome Trust. EPVL is funded by the Frank Edward Elmore Fund and the Medical Research Council’s Doctoral Training Partnership. JMT is supported by the Wellcome Trust.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The study was a planned clinical service evaluation and was carried out after favourable review by the hospital’s audit board.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No additional data are available.
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