Contents lists available at ScienceDirect Journal of Cardiovascular Computed Tomography journal homepage: www.elsevier.com/locate/jcct Research paper Systematic assessment of procedural parameters, influence on downstream testing and 12-month outcomes of a CT-myocardial perfusion service Kheng-Thye Ho a,* , Hean-Yee Ong b , Sharon Ong c a Mount Alvernia Hospital, Heart Consultants Pte Ltd, Singapore b Mount Elizabeth Novena Specialist Centre, Cardiac Solutions Medical Centre, Singapore c Siemens Healthineers, Singapore ARTICLE INFO Keywords: CT myocardial perfusion Procedural parameters Downstream testing Outcomes Appropriateness ABSTRACT Aims: This study describes the real-world referral pattern of patients to a CT myocardial perfusion service, the technical issues associated with providing the service, the results of the studies, and the subsequent downstream utilization of other investigations, and patient outcomes. Methods and results: 115 consecutive patients underwent CTA, dynamic rest and dipyridamole-stress perfusion scanning. There were 29 (25%) and 14 (12%) patients who had reversible defects and fixed defects respectively, indicating abnormal flow reserve and previous infarction respectively. In the patients with fixed defects, delayed hyperenhancement was noted in all, indicative of prior infarction, scarring and non-viability. With the existing CTA Appropriateness Criteria, the categorization of “Appropriate,”“Of Uncertain Appropriateness”, and “Inappropriate” would have been applied to 25%, 25% and 50% of the present studies respectively. Up to 72% could have been referred for ischemia evaluation with other modalities of functional imaging after the non- diagnostic CT angiogram. Follow up was complete in 113 subjects (98%) over a period of 14 ± 8 months. In the 29 patients with abnormal flow reserve and CAD, 62% underwent invasive angiography and 94%, angioplasty within a 90-day period. In the patients who underwent angioplasty, all remained free of myocardial infarction or death and 88% remained free of myocardial infarction, death or readmission over a mean of 14 ± 8 months. Conclusion: A CT-myocardial perfusion service provided measures of ischemia and infarct detection over that of CTA alone. The information was utilized clinically by doctors to support a strategy of referral to revascular- ization versus conservative medical management. 1. Introduction Coronary CT angiography (CTA) has a high sensitivity and positive predictive value for the detection of coronary artery disease (CAD). These qualities have been leveraged upon for the exclusion of CAD in patients with low to intermediate pretest probability of CAD presenting with chest pain1. However, its utility in the assessment of disease in individuals with existing CAD and high pretest probability has been hindered by the lower specificity and positive predictive value in this group. This is partly due to issues specific to the technique such as partial volume averaging effects in the presence of calcified lesions or previous stent implantation. 2,3 There is also an imprecise correlation between the anatomical appearance of an atherosclerotic lesion and its functional significance in causing ischemia. 4 The limitations of a purely anatomical assessment have been reflected in Appropriate Use Guide- lines with CTA being given an Inappropriate or Uncertain classification in the evaluation of chest pain in patient with known CAD, or in pa- tients with previous stenting. 3 In these clinical scenarios, the utility of downstream testing, therapeutic decision-making and patient outcomes are largely influenced by the availability of functional information, which up to this point in time, CTA has not been able to provide. It is in such situations that techniques such as SPECT & PET imaging, stress- echo, stress MRI and invasive fractional flow reserve (FFR) studies are well-established and widely used. These techniques provide functional information regarding the presence or absence of myocardial ischemia, and have extensive literature documenting the correlation of test results with patient outcomes. 4–10 The last 8 years have seen an emergence of functional evaluation of atherosclerotic disease by CT techniques such as CT myocardial stress perfusion imaging (CTP) imaging, FFR-CT and TAG (transluminal at- tenuation gradient). 11–15 This has facilitated the incremental detection of abnormal flow reserve, and allowed the assessment of ischemia and https://doi.org/10.1016/j.jcct.2019.04.006 Received 8 December 2018; Received in revised form 13 March 2019; Accepted 15 April 2019 * Corresponding author. Mount Alvernia Hospital, 820 Thomson Road, Medical Centre D, #06-55, 574623, Singapore. E-mail address: DrHoKT@me.com (K.-T. Ho). Journal of Cardiovascular Computed Tomography xxx (xxxx) xxx–xxx 1934-5925/ © 2019 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved. Please cite this article as: Kheng-Thye Ho, Hean-Yee Ong and Sharon Ong, Journal of Cardiovascular Computed Tomography, https://doi.org/10.1016/j.jcct.2019.04.006