• Ajay Yerramasu, Avijit Lahiri, Shreenidhi Venuraju, Alain Dumo, David Lipkin, S Richard Underwood, Roby D Rakhit, and Deven J Patel.
• Clinical Imaging and Research Centre, Wellington Hospital, London, UK.
• Eur Heart J Cardiovasc Imaging. 2014 Aug 1; 15 (8): 886-92.

BackgroundCoronary artery calcium (CAC) imaging by unenhanced computed X-ray tomography (CT) is recommended as an initial diagnostic test for patients with stable chest pain symptoms but a low likelihood (10-29%) of underlying obstructive coronary artery disease (CAD) after clinical assessment. The recommendation has not previously been tested prospectively in a rapid access chest pain clinic (RACPC).MethodsWe recruited 300 consecutive patients presenting with stable chest pain to the RACPC of three hospitals. All patients underwent CAC imaging, followed by invasive coronary angiography (ICA) in patients with CAC ≥ 1000 Agatston units (Au) and CT coronary angiography (CTCA) in those with CAC <1000. Patients with 50-70% stenosis on CTCA underwent myocardial perfusion scintigraphy (MPS) while those with ≥ 70% stenosis underwent ICA. Obstructive CAD was defined as ≥ 70% stenosis on ICA or the presence of inducible ischaemia on MPS. Patients were followed up clinically for a mean of 17 (SD 6) months.ResultsThe mean patient age was 60.6 (SD 9.6) years and 48% were males. Obstructive CAD was found in 56 (19%) patients, of whom 42 (14%) underwent revascularization. CAC was zero in 131 (44%) patients, of whom two (1.5%) had obstructive CAD and one (0.8%) underwent revascularization. The sensitivity, specificity, negative predictive value, and positive predictive value of CAC ≥ 1 for detection of obstructive CAD were 96, 53, 32, and 98%, respectively. None of the 57 patients with low pre-test probability of CAD and zero CAC had obstructive CAD or suffered a cardiovascular event during the follow-up.ConclusionPatients with stable chest pain symptoms but a low likelihood of CAD can safely be diagnosed as not having obstructive CAD in the absence of detectable coronary calcification by unenhanced CT. Patients with CAC >400 Au have a high prevalence of obstructive CAD and further investigation with ICA or functional imaging may be warranted rather than CTCA. These findings support NICE guidance for the investigation of stable chest pain. ClinicalTrials gov identifier: NCT01464203.Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

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