Computed tomography angiography for the interventional cardiologist

European Heart Journal – Cardiovascular Imaging (2014) 15, 842–854 doi:10.1093/ehjci/jeu053 REVIEW Computed tomography angiography for the interventional cardiologist Pedro de Araújo Gonçalves 1,2,3, Carlos A.M. Campos 4,5, Patrick W. Serruys4, and Hector M. Garcia-Garcia 4* Received 7 January 2014; accepted after revision 3 March 2014; online publish-ahead-of-print 7 April 2014 In recent years, coronary CT angiography (CCTA) has become a widely adopted technique, not only due to its high diagnostic accuracy, but also to the fact that CCTA provides a comprehensive evaluation of the total (obstructive and non-obstructive) coronary atherosclerotic burden. More recently, this technique has become mature, with a large body of evidence addressing its prognostic validation. In addition, CT angiography has moved from the field of ‘imagers’ and clinicians and entered the interventional cardiology arena, aiding in the planning of both coronary and structural heart interventions, being transcatheter aortic valve implantation one of its most successful examples. It is therefore of utmost importance that interventional cardiologists become familiar with image interpretation and up-to-date regarding several CTA features, taking advantage of this information in planning the procedure, ultimately leading to improvement in patient outcomes. On the other hand, the increasing use of CCTA as a gatekeeper for invasive coronary angiography is expected to lead to an increase in the ratio of interventional to diagnostic procedures and significant changes in the daily cath-lab routine. In a foreseeable future, cath-labs will probably offer an invasive procedure only to patients expected to undergo an intervention, perhaps becoming in this change true interventional-labs. ----------------------------------------------------------------------------------------------------------------------------------------------------------Keywords CT angiography † Coronary artery disease † Structural heart interventions Come gather ‘round people, wherever you roam And admit that the waters, around you have grown... ...Then you better start swimmin’, or you’ll sink like a stone For the times they are a-changin’. Bob Dylan Introduction Advances in the field of computed tomography (CT) have made possible the non-invasive evaluation of coronary artery disease (CAD) and in recent years coronary CT angiography (CCTA) has become a widely adopted technique. This was due not only to its high diagnostic accuracy, but also to the fact that CCTA provides a comprehensive evaluation of both obstructive and non-obstructive CAD and, more recently, its prognostic information has been validated. The initial studies of CCTA addressed mainly its diagnostic accuracy. This was done both by comparison with the gold standard invasive coronary angiography (ICA) and with intravascular ultrasound (IVUS). As the technique became more robust and widely adopted in clinical practice, data were gathered regarding cardiovascular outcomes and this opened a second phase of studies addressing its prognostic value. The latest technological advances have significantly improved CCTA temporal resolution and volume coverage, leading to a decrease in radiation and contrast dose, and improvements in image quality, that will further reinforce the role of CCTA for the evaluation of patients with possible CAD and potentially for making clinical decisions based on these findings (e.g. CT-based coronary atherosclerotic burden scores and functional assessment of coronary lesions). Correlation with ICA: cardiac CT diagnostic accuracy Many studies have been published evaluating the diagnostic accuracy of CCTA, by comparing with the gold standard ICA. These were initially done with four-detector row,1 – 4 followed by 16-detector row scanners,5 – 9 but by that time significant limitations existed related to the dose of contrast, long breath-hold times, and high percentage of * Corresponding author. Tel: +31 10 2062828; fax: +31 10 2062847, Email: Published on behalf of the European Society of Cardiology. All rights reserved. & The Author 2014. For permissions please email: 1 Hospital de Santa Cruz, CHLO, Lisbon, Portugal; 2Hospital da Luz, Lisbon, Portugal; 3CEDOC, Chronic Diseases Research Center, FCM-NOVA, Lisbon, Portugal; 4Thoraxcenter, Erasmus Medical Center, Room z120, ’s Gravendijkwal 230, Rotterdam, CE 3015, The Netherlands; and 5Heart Institute (InCor), University of São Paulo Medical School, Sao Paulo, Brazil 843 segments excluded from analysis due to insufficient image quality. In a meta-analysis of 27 studies comparing CCTA (with scanners of at least 16-detector row) with ICA, the per-patient sensitivity was very high (96%), but the specificity was only modest (74%), leading to a positive predictive value (PPV) of 68%.10 The 64-detector row scanners are now considered to be the minimum requirement for CCTA.11 In a more recent meta-analysis, including only studies with 64-detector row scanners, the reported per-patient sensitivity was 99%, specificity 89%; PPV was 93% and negative predictive value (NPV) was 100%.12 Nevertheless, even with 64-detector row scanners, some multicentre trials, have reported low specificity and PPV when evaluating consecutive non-selected patients. In the assessment by coronary computed tomographic angiography of individuals undergoing invasive coronary angiography (ACCURACY) trial, a prospective multicentre evaluating stable patients without known CAD who underwent CCTA before clinically indicated ICA, CCTA had a diagnostic sensitivity, specificity, PPV, and NPV of 94, 83, 48, and 99%, respectively.13 The low specificity and PPV reported in this trial could be related to the fact that patients were consecutively included irrespective of the baseline coronary calcium score, body mass index, or heart rate, variables that are well known to influence image quality. In another multicentre study, Meijboom et al. 14 evaluated the diagnostic performance of CCTA in a population including both stable and acute chest pain patients without known CAD referred for ICA. No patients or segments were excluded because of impaired image quality attributable to either coronary motion or calcifications and the prevalence of obstructive CAD was 68%, factors that could explain the low per-patient specificity of 64% for CCTA found in this study, leading to a PPV of 86%. Once again, the per-patient sensitivity was 99% and the NPV was 97%. With the development of dual source scanners, there was a significant increase in temporal resolution, leading to a less dependence on heart rate control.15 The introduction of new acquisition protocols with prospective ECG –triggering16 lead to a significant reduction in radiation dose, which was further reduced to ,1 mSv doses with high-pitch spiral acquisitions, without compromising diagnostic accuracy17,18 (Figure 1). Likewise, 320-detector row scanners also lead to significant improv (...truncated)