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Background: Adopting artificial intelligence (AI) in medicine may improve speed and accuracy in patient diagnosis. We sought to develop an AI algorithm to interpret wide-complex tachycardia (WCT) electrocardiograms (ECGs) and compare its diagnostic accuracy with that of cardiologists., Methods: Using 3330 WCT ECGs (2906 supraventricular tachycardia [SVT] and 424 ventricular tachycardia [VT]), we created a training/validation (3131) and a test set (199 ECGs). A convolutional neural network structure using a modification of differentiable architecture search was developed to differentiate between SVT and VT., Results: The mean accuracy of electrophysiology (EP) cardiologists was 92.5% with sensitivity 91.7%, specificity 93.4%, positive predictive value 93.7%, and negative predictive value 91.7%. Non-EP cardiologists had an accuracy of 73.2 ± 14.4% with sensitivity, specificity, and positive and negative predictive values of 59.8 ± 18.2%, 93.8 ± 3.7%, 93.6 ± 2.3%, and 73.2 ± 14.4%, respectively. AI had superior sensitivity and accuracy (91.9% and 93.0%, respectively) than non-EP cardiologists and similar performance compared with EP cardiologists. Mean time to interpret each ECG varied from 10.1 to 13.8 seconds for EP cardiologists and from 3.1 to 16.6 seconds for non-EP cardiologists. AI required a mean of 0.0092 ± 0.0035 seconds for each ECG interpretation., Conclusions: AI appears to diagnose WCT with accuracy superior to non-EP cardiologists and similar to EP cardiologists. Using AI to assist with ECG interpretations may improve patient care., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Coronary CT angiography (CCTA) has been gradually adopted into clinical practice over the last two decades. CCTA has high diagnostic accuracy, prognostic value, and unique features such as assessment of plaque composition. CCTA-derived functional assessment techniques such as fractional flow reserve and CT perfusion are also available and can increase the diagnostic specificity of the modality. These properties propound CCTA as a competitor of functional testing in diagnosis of obstructive CAD, however, utilizing CCTA in a concomitant fashion to potentiate the performance of the latter can lead to better patient care and may provide more accurate prognostic information. Although multiple diagnostic challenges such as evaluation of calcified segments, stents, and small distal vessels still exist, the technologic developments in hardware as well as growing incorporation of artificial intelligence to daily practice are all set to augment the diagnostic and prognostic role of CCTA in cardiovascular disorders., (Copyright © 2024. Published by Elsevier Inc.)

Background: Across medical specialties, including nuclear cardiology, competency based medical education (CBME) changes the emphasis of learning from a time or experiential emphasis to a proficiency focused approached. Plotted on a learning-curve graph the emphasis on learning has shifted from the duration/ volume-based x-axis to the performance-based y-axis., Current Status: It has proven difficult to establish y-axis-based standards within nuclear cardiology to assess learning. As such there is a paucity of data to verify current experiential training targets and only recently is data emerging that seeks to find CBME targets by which proficiency (y-axis units) can be evaluated. Initial reports from such CBME-oriented studies indicate that in current nuclear cardiology practice, the number of studies required to achieve competency is dependent upon the chosen measure of competency that is assessed (summed stress score versus % LV ischemia), the case mix, and the modality being learnt (PET versus SPECT). Recent findings have also suggested that prior levels of experiential training may be an underestimation of the number of supervised studies learners need to interpret before they achieve competency., Summary: Nuclear cardiology training has adopted the concept of CBME and is progressing toward a more modern approach to trainee assessment. This brief review provides the background, current requirements and insights into new developments in nuclear cardiology training., Competing Interests: Declaration of Competing Interest Dr Small has received honoraria and research funding from Pfizer. Dr Chow receives research support from TD Bank, Siemens Healthineers, and Artrya. He has an equity interest in Artrya., (Copyright © 2024. Published by Elsevier Inc.)

Purpose: Coronary computed tomography angiography (CCTA) is an important non-invasive tool for the assessment of coronary artery disease and the delivery of information incremental to coronary anatomy. CCTA measured left ventricular (LV) mid-diastolic volume (LV MDV ) and LV mass (LV Mass ) have important prognostic information but the utility of prospectively ECG-triggered CCTA to predict reduced left ventricular ejection fraction (LVEF) is unknown. The objective of this study was to determine if indexed LV MDV (LV MDVi ) and the LV MDV :LV Mass ratio on CCTA can identify patients with reduced LVEF., Materials/methods: 8179 patients with prospectively ECG-triggered CCTA between November 2014 and December 2019 were reviewed. A subset derivation cohort of 4352 healthy patients was used to define normal LV MDVi and LV MDV :LV Mass . Sex-specific thresholds were tested in a validation cohort of 1783 patients, excluded from the derivation cohort, with cardiac disease and known LVEF. The operating characteristics for 1 SD above the mean were tested for the identification of abnormal LVEF, LVEF≤35 ​% and ≤30 ​%., Results: The derivation cohort had a mean LV MDVi of 61.0 ​± ​13.7 ​mL/m 2 and LV MDV :LV Mass of 1.11 ​± ​0.24 ​mL/g. LV MDVi and LV MDV :LV Mass were both higher in patients with reduced LVEF than those with normal LVEF (98.8 ​± ​40.8 ​mL/m 2 vs. 63.3 ​± ​19.7 ​mL/m 2 , p ​< ​0.001, and 1.32 ​± ​0.44 ​mL/g vs. 1.05 ​± ​0.28 ​mL/g, p ​< ​0.001). Both mean LV MDVi and LV MDV :LV Mass increased with the severity of LVEF reduction. Sex-specific LV MDVi thresholds were 79 ​% and 80 ​% specific for identifying abnormal LVEF in females (LV MDVi  ​≥ ​69.9 ​mL/m 2 ) and males (LV MDVi  ​≥ ​78.8 ​mL/m 2 ), respectively. LV MDV :LV Mass thresholds had high specificity (87 ​%) in both females (LV MDVi :LV Mass  ​≥ ​1.39 ​mL/g) and males (LV MDVi :LV Mass  ​≥ ​1.30 ​mL/g)., Conclusion: Our study provides reference thresholds for LV MDVi and LV MDV :LV Mass on prospectively ECG-triggered CCTA, which may identify patients who require further LV function assessment., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Benjamin Chow reports a relationship with TD Bank that includes: funding grants. Benjamin Chow reports a relationship with SIEMENS that includes: funding grants. Benjamin Chow reports a relationship with Artrya that includes: equity or stocks and funding grants. Daniel Juneau reports a relationship with Advanced Accelerator Applications that includes: consulting or advisory. Daniel Juneau reports a relationship with Pfizer Inc that includes: consulting or advisory. Daniel Juneau reports a relationship with AbbVie Inc that includes: consulting or advisory., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Coronary computed tomography angiography (CCTA) is vital for diagnosing coronary artery disease; however, prospective ECG-triggered acquisition, minimizing radiation exposure, limits left ventricular (LV) ejection fraction (EF) evaluation. We aimed to assess the feasibility and utility of LVEF 100msec , a new index for estimating LV function using volumetric changes during 100 msec within systole., Methods: This retrospective study analyzed patients who underwent prospective ECG-triggered CCTA with systolic acquisition between January 2015 and June 2022. The LVEF 100msec was calculated using the maximum and minimum LV volumes among the three phases (300, 350, and 400 msec post-QRS) and expressed as a percentage. Patients were classified into normal, mild-moderately reduced, or severely reduced LV function categories based on the reference test. The LVEF 100msec was compared among groups, and the optimal cutoff value of LVEF 100msec for predicting severe LV dysfunction was investigated., Results: The study included 271 patients (median age ​= ​58 years, 52% male). LVEF was normal in 188 (69.4%), mild-moderately reduced in 57 (21.0%), and severely reduced in 26 (9.6%) patients. Median LVEF 100msec value was 9.0 (6.7-12.6) for normal LV function, 4.7 (3.1-8.8) for mild-moderately reduced, and 2.9 (1.5-3.8) for severely reduced LV function. LVEF 100msec values significantly differed among categories (p ​< ​0.001). The optimal LVEF 100msec cutoff for severe LV dysfunction was 4.3%, with an AUC of 0.924, sensitivity of 88%, and specificity of 89%., Conclusion: The LVEF 100msec may serve as a valuable indicator of severe LV dysfunction., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Gary S. Small receives grant funding from Pfizer for amyloid research. Benjamin J.W. Chow receives research support from TD Bank, Siemens Healthineers, and Artrya. He is a consultant for and has equity interest in Artrya., (Copyright © 2023 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.)

Background: Elevated coronary artery calcium (CAC) scores in subjects without prior atherosclerotic cardiovascular disease (ASCVD) have been shown to be associated with increased cardiovascular risk., Objectives: The authors sought to determine at what level individuals with elevated CAC scores who have not had an ASCVD event should be treated as aggressively for cardiovascular risk factors as patients who have already survived an ASCVD event., Methods: The authors performed a cohort study comparing event rates of patients with established ASVCD to event rates in persons with no history of ASCVD and known calcium scores to ascertain at what level elevated CAC scores equate to risk associated with existing ASCVD. In the multinational CONFIRM (Coronary CT Angiography Evaluation for Clinical Outcomes: An International Multicenter) registry, the authors compared ASCVD event rates in persons without a history of myocardial infarction (MI) or revascularization (as categorized on CAC scores) to event rates in those with established ASCVD. They identified 4,511 individuals without known coronary artery disease (CAC) who were compared to 438 individuals with established ASCVD. CAC was categorized as 0, 1 to 100, 101 to 300, and >300. Cumulative major adverse cardiovascular events (MACE), MACE plus late revascularization, MI, and all-cause mortality incidence was assessed using the Kaplan-Meier method for persons with no ASCVD history by CAC level and persons with established ASCVD. Cox proportional hazards regression analysis was used to calculate HRs with 95% CIs, which were adjusted for traditional cardiovascular risk factors., Results: The mean age was 57.6 ± 12.4 years (56% male). In total, 442 of 4,949 (9%) patients experienced MACEs over a median follow-up of 4 years (IQR: 1.7-5.7 years). Incident MACEs increased with higher CAC scores, with the highest rates observed with CAC score >300 and in those with prior ASCVD. All-cause mortality, MACEs, MACE + late revascularization, and MI event rates were not statistically significantly different in those with CAC >300 compared with established ASCVD (all P > 0.05). Persons with a CAC score <300 had substantially lower event rates., Conclusions: Patients with CAC scores >300 are at an equivalent risk of MACE and its components as those treated for established ASCVD. This observation, that those with CAC >300 have event rates comparable to those with established ASCVD, supplies important background for further study related to secondary prevention treatment targets in subjects without prior ASCVD with elevated CAC. Understanding the CAC scores that are associated with ASCVD risk equivalent to stable secondary prevention populations may be important for guiding the intensity of preventive approaches more broadly., Competing Interests: Funding Support and Author Disclosures Dr Budoff has received grant support from the National Institute of Health and General Electric. Dr Al-Mallah has received support from the American Heart Association, BCBS Foundation of Michigan, and Astellas. Dr Cademartiri has received grant support from GE Healthcare; and has served on the Speakers Bureau of Bracco and as a consultant for Servier. Dr Chow holds the Saul and Edna Goldfarb Chair in Cardiac Imaging Research; and has received research support from TD Bank, AusculSciences, Siemens Healthineers, and Artrya. Dr Hausleiter has received a research grant from Siemens Medical Systems. Dr Kaufmann has received institutional research support from GE Healthcare; and has received grant support from Swiss National Science Foundation. Dr Berman has a consultant agreement with General Electric. Dr Min has served as an employee and retains equity from Cleerly, Inc; has served on the medical advisory board for Arineta; and has received grant support from the National Institutes of Health. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Ischemia with nonobstructive coronary arteries (INOCA) is common clinically, particularly among women, but its prevalence among patients with at least moderate ischemia and the relationship between ischemia severity and non-obstructive atherosclerosis severity are unknown., Objectives: The authors investigated predictors of INOCA in enrolled, nonrandomized participants in ISCHEMIA (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches), sex differences, and the relationship between ischemia and atherosclerosis in patients with INOCA., Methods: Core laboratories independently reviewed screening noninvasive stress test results (nuclear imaging, echocardiography, magnetic resonance imaging or nonimaging exercise tolerance testing), and coronary computed tomography angiography (CCTA), blinded to results of the screening test. INOCA was defined as all stenoses <50% on CCTA in a patient with moderate or severe ischemia on stress testing. INOCA patients, who were excluded from randomization, were compared with randomized participants with ≥50% stenosis in ≥1 vessel and moderate or severe ischemia., Results: Among 3,612 participants with core laboratory-confirmed moderate or severe ischemia and interpretable CCTA, 476 (13%) had INOCA. Patients with INOCA were younger, were predominantly female, and had fewer atherosclerosis risk factors. For each stress testing modality, the extent of ischemia tended to be less among patients with INOCA, particularly with nuclear imaging. There was no significant relationship between severity of ischemia and extent or severity of nonobstructive atherosclerosis on CCTA. On multivariable analysis, female sex was independently associated with INOCA (odds ratio: 4.2 [95% CI: 3.4-5.2])., Conclusions: Among participants enrolled in ISCHEMIA with core laboratory-confirmed moderate or severe ischemia, the prevalence of INOCA was 13%. Severity of ischemia was not associated with severity of nonobstructive atherosclerosis. (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches [ISCHEMIA]; NCT01471522)., Competing Interests: Funding Support and Author Disclosures This project was supported by National Institutes of Health grants (U01HL105907, U01HL105462, U01HL105561, and U01HL105565) and supported in part by Clinical Translational Science Award (11UL1 TR001445 and UL1 TR002243) from the National Center for Advancing Translational Sciences and by grants from Arbor Pharmaceuticals LLC and AstraZeneca Pharmaceuticals LP. The manuscript contents are solely the responsibility of the authors and do not necessarily represent official views of the National Center for Advancing Translational Sciences, the National Heart, Lung, and Blood Institute, the National Institutes of Health, or the Department of Health and Human Services. Devices or medications were provided by Abbott Vascular (previously St. Jude Medical, Inc); Medtronic, Inc; Phillips (previously Volcano Corporation); and Omron Healthcare, Inc; medications were provided by Amgen Inc; Arbor Pharmaceuticals, LLC; AstraZeneca Pharmaceuticals, LP; Espero Pharmaceuticals; Merck, Sharp & Dohme Corp; and Sunovion Pharmaceuticals. All authors have received funding from the National Heart, Lung and Blood Institute for the study. Dr Reynolds has received nonfinancial support from Abbott Vascular, Siemens, BioTelemetry, and Leipsic; is a consultant and holder of stock options from Circle CVI and HeartFlow; is the recipient of research grants from GE Healthcare and Edwards; and serves on speakers bureaus for Philips and GE Healthcare. Dr Budoff has received grant support from General Electric; has been on the Medical Advisory Board of Arineta; and has received salary from and has ownership interest in Cleerly, Inc. Dr Berman has received software royalties from Cedars-Sinai Medical Center. Dr Lopes has received grants and other support from Bayer, Boehringer Ingleheim, Bristol-Myers Squibb, Daiichi Sankyo, and Glaxo Smith Kline; and has received grants from Medtronic, Merck, Pfizer, Portola, and Sanofi. Dr Chow holds the Saul and Edna Goldfarb Chair in Cardiac Imaging Research; has received research support from TD Bank, CV Diagnostix and AusculSciences, and Siemens Healthineers; and has equity interest in General Electric. Dr Stone has received personal fees from Terumo, Amaranth, Shockwave, Valfix, TherOx, Reva, Vascular Dynamics, Robocath, HeartFlow, Gore, Ablative Solutions, Matrizyme, Miracor, Neovasc, V-wave, SpectreWave, MAIA Pharmaceuticals, Orchestra Biomed, Vectorious Abiomed, Claret, Sirtex, Ancora, and Qool Therapeutics; other considerations from Cagent, Applied Therapeutics, Biostar family of funds; support from MedFocus family of funds, Aria; and personal fees from Cardiac Success work. Dr Boden has received support from Abbvie and Amarin; grants from Amgen; and personal fees from Amgen, Cleveland Clinic Clinical Coordinating Center, and Janssen. Dr Bangalore has received grants and personal fees from Abbott Vascular; and personal fees from Biotronik, Pfizer, and Amgen. Dr Hochman is principal investigator for the ISCHEMIA trial, for which grant, devices, and medications were provided by Abbott Vascular; Medtronic, Inc; St. Jude Medical, Inc; Volcano Corporation; Arbor Pharmaceuticals, LLC; AstraZeneca Pharmaceuticals, LP; Merck Sharp & Dohme Corp; Omron Healthcare, Inc; and financial donations from Arbor Pharmaceuticals LLC and AstraZeneca Pharmaceuticals LP., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: We examined age differences in whole-heart volumes of non-calcified and calcified atherosclerosis by coronary computed tomography angiography (CCTA) of patients with future ACS., Methods: A total of 234 patients with core-lab adjudicated ACS after baseline CCTA were enrolled. Atherosclerotic plaque was quantified and characterized from the main epicardial vessels and side branches on a 0.5 ​mm cross-sectional basis. Calcified plaque and non-calcified plaque were defined by above or below 350 Hounsfield units. Patients were categorized according to their age by deciles. Also, coronary artery calcium scores (CACS) were evaluated when available., Results: Patients were on average 62.2 ​± ​11.5 years old. On the pre-ACS CCTA, patients showed diffuse, multi-site, predominantly non-obstructive atherosclerosis across all age categories, with plaque being detected in 93.5% of all ACS cases. The proportion calcified plaque from the total plaque burden increased significantly with older presentation (10% calcification in those <50 years, and 50% calcification in those >80 years old). Patients with ACS <50 years had remarkably lower atherosclerotic burden compared with older patients, but a high proportion of high risk markers such as low-attenuation plaque. CACS was >0 in 85% of the patients older than 50 years, and in 57% of patients younger than 50 years., Conclusion: The proportion of calcified plaque varied depending on patient age at the time of ACS. Only a small proportion of plaque was calcified when ACS occurred at <50 years old, while this increased gradually with older age. Purely non-calcified atherosclerotic plaque was not uncommon in patients <50 years., Competing Interests: Declaration of competing interest Dr. Chinnaiyan is a non-compensated medical advisory board member of Heartflow Inc. Dr. Chow holds the Saul and Edna Goldfarb Chair in Cardiac Imaging Research, receives support from CV Diagnostix and Ausculsciences, receives educational support from TeraRecon Inc., and has equity interest in General Electric. Dr. Min is an employee of Cleerly, Inc. Dr. Samady serves on the scientific advisory board of Philips, has equity interest in Covanos Inc., and has a research grant from Medtronic, Abbott Vascular, and Philips. Dr. Shaw is on the scientific advisory board for Covanos, Inc. The remaining authors have no relevant conflicts to disclose., (Copyright © 2022. Published by Elsevier Inc.)

Research in artificial intelligence (AI) has progressed over the past decade. The field of cardiac imaging has seen significant developments using newly developed deep learning methods for automated image analysis and AI tools for disease detection and prognostication. This review is aimed at those without special background in AI. We review AI concepts and survey the growing contemporary applications of AI for image analysis in echocardiography, nuclear cardiology, cardiac computed tomography, cardiac magnetic resonance, and invasive angiography., (Copyright © 2021 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

Objectives: This study sought to assess training volumes and its relationship to learning and identify potential new thresholds for determining expertise., Background: Competency-based medical education (CBME) is being rapidly adopted and therefore training programs will need to adapt and identify new and novel methods of defining, measuring, and assessing clinical skills., Methods: Consecutive cardiac computed tomography (CT) studies were interpreted independently by trainees and expert readers, and their interpretations (Agatston score, coronary artery disease severity, and Coronary Artery Disease Reporting and Data System) were collected. Kappa agreements were measured between trainees and experts for every 50 consecutive cases. Agreements between trainees and experts were tracked and compared with the agreement between expert readers., Results: A total of 36 trainees interpreted 14,432 cardiac CT studies. Agreement between trainees and experts increased with CT case volumes, but trainees learned at different rates. Using a threshold for expertise, skill of measuring coronary calcification was achieved within 50 cases, but expertise for coronary CT angiography appeared to require a mean case volume of 750, comprising 400 abnormal cases., Conclusions: Current volume-based training guidelines may be insufficient and higher case volumes may be required. We demonstrate that tracking cardiac CT learners is feasible and that CBME could be incorporated into CT training programs., Competing Interests: Funding Support and Author Disclosures This study was supported in part by the University of Ottawa Heart Institute AMO Alternate Funding Plan: Innovations Funding. Dr. Chow has received research support from TD Bank, CV Diagnostix, AusculSciences, and Siemens and has equity interest in General Electric. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2021 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objective: We sought to determine the prognostic value of coronary computed tomography angiography (CCTA) in patients with a history of percutaneous coronary intervention (PCI)., Background: Although the prognostic value of CCTA has been well studied, its incremental value in patients with previous PCI has not been robustly investigated., Methods: Consecutive patients with previous PCI were prospectively enrolled and CCTA images were evaluated for coronary artery disease (CAD) severity. Patients were followed for major adverse cardiovascular events (MACE) which was a composite of cardiac death and non-fatal myocardial infarction. All-cause death was assessed as a secondary endpoint., Results: A total of 501 patients were analyzed with a mean follow-up time of 59.5 ± 32.0 months and 52 patients (10.4%) experienced MACE. Multivariable Cox regression analysis showed that CAD severity was a predictor of MACE with 0, 1, 2, and 3 vessel disease having annual rates of 1.3%, 2.2%, 2.2%, and 5.3%, respectively. All-cause death was similar in all categories of CAD., Conclusions: In patients with previous PCI, CAD severity as measured with CCTA has independent and incremental prognostic value., (Copyright © 2020 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.)

Background: Coronary CT angiography (CCTA) is increasing seen as a first line investigation in patients with suspected coronary artery disease. Heart-rate control improves the image quality and diagnostic accuracy of CCTA. Typically, beta-blockers are administered to induce sinus bradycardia. Sinus bradycardia may also be induced by ivabradine. We hypothesized that in a real-world population ivabradine would be an effective alternative to metoprolol at heart rate lowering for CCTA., Methods: This was a retrospective analysis of consecutive patients who were exposed to an ivabradine-based (IB) versus a metoprolol-only (MO) protocol to achieve a target heart rate 65 and received heart-rate lowering medication: 1958 patients had MO, and 718 received IB protocol. Target heart rate of

Background: Through various research lead in the past, it has been made evident that Quebec is home to higher rates of acute myocardial infarction (AMI) and higher prevalence of cardiovascular risk factors than other Canadian provinces. This proposed study will perform a retrospective analysis on Caucasian populations in order to analyze the cardiovascular risk factors in partially francophone populations in comparison to French and Non-French Canadians. Furthermore, we will closely analyze both genders of aforementioned populations., Methods: This population-based retrospective cohort study was achieved using the University of Ottawa Heart Institute CCTA registry. Included are Caucasian patients of all ages who came to UOHI for a CCTA between 2006 and 2018 and provided written informed consent. SPSS was used to compare the different populations (French Canadian, partially French Canadian and non-French Canadian) and sex., Results: The PFC population more closely resembles FC, having higher incidence of cardiovascular risk factors such as smoking, dyslipidemia and type 2 diabetes., Interpretation: Our results suggest that PFC, like FC, may benefit from more intensive education and lifestyle modification techniques., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Objectives: This study sought to develop a clinical model that identifies a lower-risk population for coronary artery disease that could benefit from stress-first myocardial perfusion imaging (MPI) protocols and that can be used at point of care to risk stratify patients., Background: There is an increasing interest in stress-first and stress-only imaging to reduce patient radiation exposure and improve patient workflow and experience., Methods: A secondary analysis was conducted on a single-center cohort of patients undergoing single-photon emission computed tomography (SPECT) and positron emission tomography (PET) studies. Normal MPI was defined by the absence of perfusion abnormalities and other ischemic markers and the presence of normal left ventricular wall motion and left ventricular ejection fraction. A model was derived using a cohort of 18,389 consecutive patients who underwent SPECT and was validated in a separate cohort of patients who underwent SPECT (n = 5,819), 1 internal cohort of patients who underwent PET (n=4,631), and 1 external PET cohort (n = 7,028)., Results: Final models were made for men and women and consisted of 9 variables including age, smoking, hypertension, diabetes, dyslipidemia, typical angina, prior percutaneous coronary intervention, prior coronary artery bypass graft, and prior myocardial infarction. Patients with a score ≤1 were stratified as low risk. The model was robust with areas under the curve of 0.684 (95% confidence interval [CI]: 0.674 to 0.694) and 0.681 (95% CI: 0.666 to 0.696) in the derivation cohort, 0.745 (95% CI: 0.728 to 0.762) and 0.701 (95% CI: 0.673 to 0.728) in the SPECT validation cohort, 0.672 (95% CI: 0.649 to 0.696) and 0.686 (95% CI: 0.663 to 0.710) in the internal PET validation cohort, and 0.756 (95% CI: 0.740 to 0.772) and 0.737 (95% CI: 0.716 to 0.757) in the external PET validation cohort in men and women, respectively. Men and women who scored ≤1 had negative likelihood ratios of 0.48 and 0.52, respectively., Conclusions: A novel model, based on easily obtained clinical variables, is proposed to identify patients with low probability of having abnormal MPI results. This point-of-care tool may be used to identify a population that might qualify for stress-first MPI protocols., (Copyright © 2020 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objectives: This study sought to identify culprit lesion (CL) precursors among acute coronary syndrome (ACS) patients based on qualitative and quantitative computed tomography-based plaque characteristics., Background: Coronary computed tomography angiography (CTA) has been validated for patient-level prediction of ACS. However, the applicability of coronary CTA to CL assessment is not known., Methods: Utilizing the ICONIC (Incident COroNary Syndromes Identified by Computed Tomography) study, a nested case-control study of 468 patients with baseline coronary CTA, the study included ACS patients with invasive coronary angiography-adjudicated CLs that could be aligned to CL precursors on baseline coronary CTA. Separate blinded core laboratories adjudicated CLs and performed atherosclerotic plaque evaluation. Thereafter, the study used a boosted ensemble algorithm (XGBoost) to develop a predictive model of CLs. Data were randomly split into a training set (80%) and a test set (20%). The area under the receiver-operating characteristic curve of this model was compared with that of diameter stenosis (model 1), high-risk plaque features (model 2), and lesion-level features of CL precursors from the ICONIC study (model 3). Thereafter, the machine learning (ML) model was applied to 234 non-ACS patients with 864 lesions to determine model performance for CL exclusion., Results: CL precursors were identified by both coronary angiography and baseline coronary CTA in 124 of 234 (53.0%) patients, with a total of 582 lesions (containing 124 CLs) included in the analysis. The ML model demonstrated significantly higher area under the receiver-operating characteristic curve for discriminating CL precursors (0.774; 95% confidence interval [CI]: 0.758 to 0.790) compared with model 1 (0.599; 95% CI: 0.599 to 0.599; p < 0.01), model 2 (0.532; 95% CI: 0.501 to 0.563; p < 0.01), and model 3 (0.672; 95% CI: 0.662 to 0.682; p < 0.01). When applied to the non-ACS cohort, the ML model had a specificity of 89.3% for excluding CLs., Conclusions: In a high-risk cohort, a boosted ensemble algorithm can be used to predict CL from non-CL precursors on coronary CTA., (Copyright © 2020 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background and Aims: The Agatston coronary artery calcium score (CACS) may fail to identify small or less dense coronary calcification that can be detected on coronary CT angiography (CCTA). We investigated the prevalence and prognostic importance of subtle calcified plaques on CCTA among individuals with CACS 0., Methods: From the prospective multicenter CONFIRM registry, we evaluated patients without known CAD who underwent CAC scan and CCTA. CACS was categorized as 0, 1-10, 11-100, 101-400, and >400. Patients with CACS 0 were stratified according to the visual presence of coronary plaques on CCTA. Plaque composition was categorized as non-calcified (NCP), mixed (MP) and calcified (CP). The primary outcome was a major adverse cardiac event (MACE) which was defined as death and myocardial infarction., Results: Of 4049 patients, 1741 (43%) had a CACS 0. NCP and plaques that contained calcium (MP or CP) were detected by CCTA in 110 patients (6% of CACS 0) and 64 patients (4% of CACS 0), respectively. During a 5.6 years median follow-up (IQR 5.1-6.2 years), 413 MACE events occurred (13%). Patients with CACS 0 and MP/CP detected by CCTA had similar MACE risk compared to patients with CACS 1-10 (p = 0.868). In patients with CACS 0, after adjustment for risk factors and symptom, MP/CP was associated with an increased MACE risk compared to those with entirely normal CCTA (HR 2.39, 95% CI [1.09-5.24], p = 0.030)., Conclusions: A small but non-negligible proportion of patients with CACS 0 had identifiable coronary calcification, which was associated with increased MACE risk. Modifying CAC image acquisition and/or scoring methods could improve the detection of subtle coronary calcification., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Aims: We aimed to compare semiquantitative coronary computed tomography angiography (CCTA) risk scores - which score presence, extent, composition, stenosis and/or location of coronary artery disease (CAD) - and their prognostic value between patients with and without diabetes mellitus (DM). Risk scores derived from general chest-pain populations are often challenging to apply in DM patients, because of numerous confounders., Methods: Out of a combined cohort from the Leiden University Medical Center and the CONFIRM registry with 5-year follow-up data, we performed a secondary analysis in diabetic patients with suspected CAD who were clinically referred for CCTA. A total of 732 DM patients was 1:1 propensity-matched with 732 non-DM patients by age, sex and cardiovascular risk factors. A subset of 7 semiquantitative CCTA risk scores was compared between groups: 1) any stenosis ≥50%, 2) any stenosis ≥70%, 3) stenosis-severity component of the coronary artery disease-reporting and data system (CAD-RADS), 4) segment involvement score (SIS), 5) segment stenosis score (SSS), 6) CT-adapted Leaman score (CT-LeSc), and 7) Leiden CCTA risk score. Cox-regression analysis was performed to assess the association between the scores and the primary endpoint of all-cause death and non-fatal myocardial infarction. Also, area under the receiver-operating characteristics curves were compared to evaluate discriminatory ability., Results: A total of 1,464 DM and non-DM patients (mean age 58 ± 12 years, 40% women) underwent CCTA and 155 (11%) events were documented after median follow-up of 5.1 years. In DM patients, the 7 semiquantitative CCTA risk scores were significantly more prevalent or higher as compared to non-DM patients (p ≤ 0.022). All scores were independently associated with the primary endpoint in both patients with and without DM (p ≤ 0.020), with non-significant interaction between the scores and diabetes (interaction p ≥ 0.109). Discriminatory ability of the Leiden CCTA risk score in DM patients was significantly better than any stenosis ≥50% and ≥70% (p = 0.003 and p = 0.007, respectively), but comparable to the CAD-RADS, SIS, SSS and CT-LeSc that also focus on the extent of CAD (p ≥ 0.265)., Conclusion: Coronary atherosclerosis scoring with semiquantitative CCTA risk scores incorporating the total extent of CAD discriminate major adverse cardiac events well, and might be useful for risk stratification of patients with DM beyond the binary evaluation of obstructive stenosis alone., Competing Interests: Declaration of competing interest Dr. James K. Min receives funding from the Dalio Foundation, National Institutes of Health, and GE Healthcare. Dr. Min serves on the scientific advisory board of Arineta and GE Healthcare, and has an equity interest in Cleerly. The Department of Cardiology of the Leiden University Medical Center received research grants from Biotronik, Medtronic, Boston Scientific and Edwards Lifesciences. Arthur J.H.A. Scholte received consulting fees from GE Healthcare and Canon., (Copyright © 2020 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.)

Background: While an assessment of the right ventricular (RV) size remains challenging, the entire RV is can be imaged on coronary computed tomography angiography (CCTA) studies. With prospective ECG-triggering, the RV end diastolic volume (RVEDV) cannot be measured; however, the RV mid-diastolic volume (RVMDV) can still be measured accurately from routine CCTA data sets. The objective of this study is to establish normal reference values for RVMDV., Methods: Right ventricular mid-diastolic volumes were measured in 4855 consecutive patients undergoing prospectively ECG-triggered coronary CTA. All patients with known cardiac or pulmonary disease (coronary artery disease, myocardial infarction, revascularization, heart failure, pulmonary hypertension, congenital heart disease, valvular heart disease, atrial fibrillation, implantable cardiac defibrillator implantation, cardiac transplant, or cardiac surgery) or smoking history (3313 patients) were excluded., Results: 1542 patients were analyzed (mean age 56.4 ± 11.1 years, mean BSA 1.96 ± 0.26 and 47% male). The mean RVMDV for men and women was 168.6 ± 37.6 mL and 117.6 ± 26.4 mL, respectively. Mean BSA-indexed RVMDV was 80.0 ± 15.3 mL/m 2 and 64.1 ± 12.2 mL/m 2 for men and women, respectively. The presence of hypertension and diabetes did not have an impact on these values. RVMDV and BSA-indexed RVMDV were lower in women and in older individuals., Conclusion: Normal reference ranges for RVMDV were established using prospectively ECG-triggered coronary CTA studies. This data can be used to identify patients with abnormal RV volumes and potentially RV dysfunction, adding incremental diagnostic value to routine CCTA studies., (Copyright © 2020 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.)

Objectives: This study sought to: 1) determine if the current training volume guidelines are reasonable for attaining competence for interpreting myocardial perfusion imaging (MPI); and if not, 2) identify potential thresholds for training volumes and competence., Background: There is a growing desire to adopt competency-based medical education (CBME). As such, the implementation of CBME will require new and novel methods of defining, measuring, and assessing clinical competence. The potential use of CBME in cardiac imaging has not been well studied., Methods: Consecutive MPI studies were interpreted independently by trainees, and expert readers reviewed the same studies. Studies were quantified using summed scores and % left ventricular (LV) ischemia and the kappa agreement between trainee and expert were measured every 50 cases. Agreement for all MPI and abnormal MPI cases was calculated., Results: A total of 24 trainees interpreted 9,668 MPI studies over 37 months. Agreement between trainees and expert readers increased with MPI case volumes but at different rates. The threshold for competence was set at 2 SDs below expert interobserver agreement. The average trainee surpassed this threshold for both summed stress score and %LV ischemia after 800 studies and after 400 abnormal MPI studies. Trainees learned at different rates and surpassed the competence threshold after different case volumes., Conclusions: The use of CBME within nuclear cardiology appears to be feasible. Our results suggest that current guidelines may be insufficient to ensure competence and would support the need to increase the MPI case volumes. The use of CBME principles would suggest that trainees may achieve competence at different rates and our results suggest a shift in focus from volume-based learning toward target agreement thresholds., (Copyright © 2019 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Obesity is an in independent risk factor for cardiovascular disease., Goal: To describe the early LV remodelling pattern in patients with overweight and obesity and structurally normal hearts., Methods: Consecutive patients (n = 2374), with structurally normal hearts and BMI ≥ 18.5 kg/m 2 , undergoing prospective mid-diastolic ECG gated CTCA were selected. Left ventricular mass (LVM) and Left ventricular mid-diastolic volume (LVMDV) were measured. The concentricity index (LVM/LVMDV) were calculated. According to the definitions of the World Health Organization (WHO), the patients were divided into weight categories., Results: The mean LVM ± Std. deviation in the subgroups according to WHO classification was 101.68 ± 28.99 g (normal weight), 115.79 ± 29.14 g (overweight), 123.8 ± 33.44 g (class I obesity), 125.85 ± 32.89 g (class II obesity) and 132.45 ± 37.85 g (class III obesity). (p < 0.001) The mean LVMDV progressed with increasing WHO weight category from 112.37 ± 36.46 in patients with normal BMI to 140.26 ± 43.78 in patients with class III obesity. (p < 0.001) The concentricity index was 0.935 ± 0.216 g/ml in patients with normal BMI, 0.979 ± 0.253 g/ml, 1.058 ± 0.635 g/ml, 0.996 ± 0.284 g/ml and 0.9768 ± 0.244 g/ml in patients with BMI categories 25-29.99, 30-34.99, 35-39.99 and ≥40 kg/m 2 , respectively., Conclusions: Our study demonstrates a non-linear (inverse U-shape) relationship between increasing BMI class and concentricity index, reaching its maximum at a BMI of 30-34.99 kg/m 2 . Further increase in BMI results in LV dilation., (Copyright © 2019 Asia Oceania Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.)

Background: In breast cancer patients, coincidental detection of CAC at chest CT may be important in determining cardiovascular (CV) outcomes and facilitate CV disease primary prevention strategies., Methods: 408 consecutive breast cancer patients referred to cardiac oncology clinic were included in the study. 256 patients without a prior history of coronary artery disease had undergone a chest CT. CT images were reviewed to detect CAC. Framingham risk score (FRS) was calculated and patient electronic medical records were interrogated to document the incidence of a composite clinical end point of all-cause mortality and cardiac events (coronary revascularization, heart failure hospitalization and de novo atrial fibrillation). Prevalence of statin prescribing was also collected., Results: Patients were followed for a median of 6.5 years. 112 clinical events occurred. Clinical follow up was 98%. CAC was found in 26% of patients. On multivariable analysis, CAC and advance cancer stage, but not FRS predicted the composite clinical end point (OR for CAC 2.59, p < 0.01). CAC but not FRS also predicted the incidence of cardiac events (OR for CAC 4.90, p < 0.01). CAC was present in 7.3% of patients with low FRS; none had been prescribed a statin. In patients with CAC and FRS ≥ 10%, 45% were not on a statin., Conclusion: CAC is a common coincidental finding at CT chest in breast cancer patients referred to cardiac oncology. CAC but not FRS was predictive of composite clinical events and cardiac events. Detection of CAC at chest CT could alter the prescribing of primary prevention strategies to help prevent future cardiac events in breast cancer patients., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Coronary computed tomography angiography (CCTA) left ventricle (LV) volumes have prognostic value. LV measurements however can differ depending on post-processing software. Two common methods are the contour (CON) or attenuation (ATT) based methods. This study aims to determine differences in LV volume measurements using the 2 methods., Methods: LV mid-diastolic volumes (LVMDV) were measured using both ATT and CON from 2 vendors in 750 consecutive patients undergoing CCTA. 500 were measured in a derivation cohort to establish a linear regression equation that would correct for any detected differences between the two methods. The equation was then assessed in 250 cases in the validation cohort. Comparisons were made between intra-vendor LVMDV CON and LVMDV ATT as well as inter-vendor LVMDV ATT ., Results: In the derivation cohort, the correlation between the two methods and vendors were very good (0.98 and 0.97 respectively). LVMDV CON was 20.4 ± 7.4% greater than LVMDV ATT . LVMDV ATT was 9.2 ± 6.6% greater with one vendor compared to the other. Validation cohort corrected LVMDV ATT was not statistically different to measured LVMDV ATT (p = 0.45)., Conclusion: A systematic difference was found between ATT and CON measuring methods. Using a derived linear regression equation, we were able to correct for differences in measurement techniques. The method of LVMDV measurement requires careful consideration when establishing reference values and extrapolating published study results., (Copyright © 2019 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.)

Introduction: Non-statin therapy (NST) is used as second-line treatment when statin monotherapy is inadequate or poorly tolerated., Objective: To determine the association of NST with plaque composition, alone or in combination with statins, in patients undergoing coronary computed tomography angiography (coronary CTA)., Methods: From the multicenter CONFIRM registry, we analyzed individuals who underwent coronary CTA with known lipid-lowering therapy status and without prior coronary artery disease at baseline. We created a propensity score for being on NST, followed by stepwise multivariate linear regression, adjusting for the propensity score as well as risk factors, to determine the association between NST and the number of coronary artery segments with each plaque type (non-calcified (NCP), partially calcified (PCP) or calcified (CP)) and segment stenosis score (SSS)., Results: Of the 27,125 subjects in CONFIRM, 4,945 met the inclusion criteria; 371 (7.5%) took NST. At baseline, patients on NST had more prevalent risk factors and were more likely to be on concomitant cardiac medications. After multivariate and propensity score adjustment, NST was not associated with plaque composition: NCP (0.07 increase, 95% CI: -0.05, 0.20; p = 0.26), PCP (0.10 increase, 95% CI: -0.10, 0.31; p = 0.33), CP (0.18 increase, 95% CI: -0.10, 0.46; p = 0.21) or SSS (0.45 increase, 95% CI: -0.02,0.93; p = 0.06). The absence of an effect of NST on plaque type was not modified by statin use (p for interaction > 0.05 for all)., Conclusion: In this cross-sectional study, non-statin therapy was not associated with differences in plaque composition as assessed by coronary CTA., (Copyright © 2019. Published by Elsevier Inc.)

Noninvasive cardiac imaging is widely used for the diagnosis and management of cardiac patients. The increasing demand for cardiac imaging begins to exceed the number of available interpreting physicians, leaving less time to interpret studies. In addition, the busy clinician is facing the increasingly daunting task of keeping abreast of current medical advancements and the ongoing changes in disease diagnosis and therapy. Committing to memory and recalling such large volumes of information is challenging and is responsible for difficulties in adopting the rapid changes in imaging practice, and is likely partially responsible for errors in patient diagnosis and management. Diagnostic errors rank high in the cause of death in the United States, and are more common than any other medical error and are responsible for most malpractice claims. Most of these errors are related to cognitive errors. The use of artificial intelligence systems that can serve as complementary methods to assist humans with decision making can potentially prevent these errors. The past decades witnessed the development and integration of these tools, which can assist physicians with image interpretation. These tools work to optimize image quality for better visualization and accompany all imaging modalities, starting from patient selection for the appropriate test, patient preparation, image acquisition, processing, and finally interpretation. Current and future directions for technologies that support cardiac imaging physicians are discussed in this review., (Copyright © 2018 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

Introduction: Machine learning (ML) is a field in computer science that demonstrated to effectively integrate clinical and imaging data for the creation of prognostic scores. The current study investigated whether a ML score, incorporating only the 16 segment coronary tree information derived from coronary computed tomography angiography (CCTA), provides enhanced risk stratification compared with current CCTA based risk scores., Methods: From the multi-center CONFIRM registry, patients were included with complete CCTA risk score information and ≥3 year follow-up for myocardial infarction and death (primary endpoint). Patients with prior coronary artery disease were excluded. Conventional CCTA risk scores (conventional CCTA approach, segment involvement score, duke prognostic index, segment stenosis score, and the Leaman risk score) and a score created using ML were compared for the area under the receiver operating characteristic curve (AUC). Only 16 segment based coronary stenosis (0%, 1-24%, 25-49%, 50-69%, 70-99% and 100%) and composition (calcified, mixed and non-calcified plaque) were provided to the ML model. A boosted ensemble algorithm (extreme gradient boosting; XGBoost) was used and the entire data was randomly split into a training set (80%) and testing set (20%). First, tuned hyperparameters were used to generate a trained model from the training data set (80% of data). Second, the performance of this trained model was independently tested on the unseen test set (20% of data)., Results: In total, 8844 patients (mean age 58.0 ± 11.5 years, 57.7% male) were included. During a mean follow-up time of 4.6 ± 1.5 years, 609 events occurred (6.9%). No CAD was observed in 48.7% (3.5% event), non-obstructive CAD in 31.8% (6.8% event), and obstructive CAD in 19.5% (15.6% event). Discrimination of events as expressed by AUC was significantly better for the ML based approach (0.771) vs the other scores (ranging from 0.685 to 0.701), P < 0.001. Net reclassification improvement analysis showed that the improved risk stratification was the result of down-classification of risk among patients that did not experience events (non-events)., Conclusion: A risk score created by a ML based algorithm, that utilizes standard 16 coronary segment stenosis and composition information derived from detailed CCTA reading, has greater prognostic accuracy than current CCTA integrated risk scores. These findings indicate that a ML based algorithm can improve the integration of CCTA derived plaque information to improve risk stratification., (Published by Elsevier Inc.)

Background: Infective endocarditis (IE) is a serious, potentially life-threatening condition. Currently, the modified Duke criteria is used to assist with the diagnosis of IE, but it can still remain difficult. Growing data supports the potential use of molecular imaging to assist in the diagnosis of IE. Our objective was to understand the potential utility of 18 F-fluorodeoxyglucose ( 18 F-FDG) positron emission tomography-computed tomography (PET-CT), 67 Ga citrate and radiolabeled white blood cell (WBC) scintigraphy in the diagnosis of IE., Methods and Results: A systematic review of the literature and meta-analysis on the use of all 3 modalities in IE was conducted. The literature search identified 2753 articles. A total of 14 studies met the inclusion criteria (10 for 18 F-FDG, 3 for WBC and 1 for both modalities). No 67 Ga citrate study met the inclusion criteria. Pooled sensitivity of 18 F-FDG studies with adequate cardiac preparation for the diagnosis of IE was 81% (95% CI, 73%-86%) and pooled specificity was 85% (95% CI, 78%-91%). There was good overall accuracy with an area under the curve (AUC) of 0.897. Pooled sensitivity of WBC for the diagnosis of IE was 86% (95% CI, 77%-92%) and pooled specificity was 97% (95% CI, 92%-99%). The overall accuracy of WBC was excellent with an AUC of 0.957., Conclusions: Both 18 F-FDG and WBC have good sensitivity, specificity and accuracy for the diagnosis of IE. Both modalities are useful in the investigation of IE, and should be considered in cases where the diagnosis is uncertain., (Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.)

Objectives: This study sought to assess clinical outcomes associated with the novel Coronary Artery Disease-Reporting and Data System (CAD-RADS) scores used to standardize coronary computed tomography angiography (CTA) reporting and their potential utility in guiding post-coronary CTA care., Background: Clinical decision support is a major focus of health care policies aimed at improving guideline-directed care. Recently, CAD-RADS was developed to standardize coronary CTA reporting and includes clinical recommendations to facilitate patient management after coronary CTA., Methods: In the multinational CONFIRM (COronary CT Angiography EvaluatioN For Clinical Outcomes: An InteRnational Multicenter) registry, 5,039 patients without known coronary artery disease (CAD) underwent coronary CTA and were stratified by CAD-RADS scores, which rank CAD stenosis severity as 0 (0%), 1 (1% to 24%), 2 (25% to 49%), 3 (50% to 69%), 4A (70% to 99% in 1 to 2 vessels), 4B (70% to 99% in 3 vessels or ≥50% left main), or 5 (100%). Kaplan-Meier and multivariable Cox models were used to estimate all-cause mortality or myocardial infarction (MI). Receiver-operating characteristic (ROC) curves were used to compare CAD-RADS to the Duke CAD Index and traditional CAD classification. Referrals to invasive coronary angiography (ICA) after coronary CTA were also assessed., Results: Cumulative 5-year event-free survival ranged from 95.2% to 69.3% for CAD-RADS 0 to 5 (p < 0.0001). Higher scores were associated with elevations in event risk (hazard ratio: 2.46 to 6.09; p < 0.0001). The ROC curve for prediction of death or MI was 0.7052 for CAD-RADS, which was noninferior to the Duke Index (0.7073; p = 0.893) and traditional CAD classification (0.7095; p = 0.783). ICA rates were 13% for CAD-RADS 0 to 2, 66% for CAD-RADS 3, and 84% for CAD-RADS ≥4A. For CAD-RADS 3, 58% of all catheterizations occurred within the first 30 days of follow-up. In a patient subset with available medication data, 57% of CAD-RADS 3 patients who received 30-day ICA were either asymptomatic or not receiving antianginal therapy at baseline, whereas only 32% had angina and were receiving medical therapy., Conclusions: CAD-RADS effectively identified patients at risk for adverse events. Frequent ICA use was observed among patients without severe CAD, many of whom were asymptomatic or not taking antianginal drugs. Incorporating CAD-RADS into coronary CTA reports may provide a novel opportunity to promote evidence-based care post-coronary CTA., (Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: The segment involvement score (SIS) is a semiquantitative measure of the extent of atherosclerosis burden by coronary computed tomography angiography (CTA). We sought to evaluate by meta-analysis the prognostic value of SIS, and to compare it with other CTA measures of coronary artery disease (CAD)., Methods: Electronic databases from 1946 to January 2016 were searched. Studies reporting SIS, or an equivalent measure by coronary CTA, and clinical outcomes were included. Maximally adjusted hazard ratios (HR), predominantly for clinical variables, were extracted for SIS, obstructive CAD, Agatston coronary artery calcium score, and plaque composition. These were pooled using DerSimonian-Laird random effects models., Results: Eleven nonrandomized studies with good methodological quality enrolling 9777 subjects (mean age 61 ± 11 years, 57% male, mean follow up 3.3 years) who had 472 (4.8%) MACE (cardiac or all cause death, non-fatal myocardial infarction or late revascularization), were included. SIS (per segment increase) had pooled HR of 1.25 (95% CI: 1.16,1.35; I 2  = 71.4%, p < 0.001) for MACE. HR for MACE was 1.37 (95% CI: 1.32,1.42; I 2  = 95.6%, p < 0.001) for number of segments with stenosis (per segment increase), 3.39 (95% CI: 1.65,6.99; I 2  = 87.8%, p = 0.001) for obstructive CAD (binary variable) and 1.00 (95% CI: 1.00,1.01; I 2  = 75.0%, p = 0.490) for Agatston score (per unit increase). HRs by plaque composition (calcified, non-calcified and mixed; per segment change) were 1.24 (95% CI: 1.10,1.39; I 2  = 81.6%, p = 0.001), 1.20 (95% CI: 0.97,1.48; I 2  = 92.9%, p = 0.093) and 1.27 (95% CI: 1.03,1.58; I 2  = 89.8%, p = 0.029), respectively., Conclusion: Despite heterogeneity in endpoints, extent of CAD as quantified by SIS on coronary CTA is a strong, independent predictor of cardiovascular events., (Copyright © 2017 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.)

Background and Aims: Coronary artery calcium (CAC) scoring is a predictor of future adverse clinical events, and a surrogate measure of overall coronary artery plaque burden. Coronary computed tomographic angiography (CCTA) is a contrast-enhanced method that allows for visualization of plaque as well as whether that plaque causes luminal narrowing. To date, the prognosis of individuals with CAC but without stenosis has not been reported. We explored the prevalence of CAC>0 and its prognostic utility for future mortality for patients without luminal narrowing by CCTA., Methods: From 17 sites in 9 countries, we identified patients without known coronary artery disease, who underwent CAC scoring and CCTA, and were followed for >3 years. CCTA was graded for % stenosis according to a modified American Heart Association 16-segment model. We calculated hazard ratios (HR) with 95% confidence intervals (95% CI) for incident mortality and compared risk of death for patients as a function of presence or absence of CAC and presence or absence of luminal narrowing by CCTA., Results: Among 6656 patients who underwent CCTA and CAC scoring, 399 patients (6.0%) had no coronary luminal narrowing but CAC>0. During a median follow-up of 5.1 years (IQR: 3.9-5.9 years), 456 deaths occurred. Compared to individuals without luminal narrowing or CAC, individuals without luminal narrowing but CAC>0 were older, more likely to be male and had higher rates of diabetes, hypertension, and dyslipidemia. Individuals without luminal narrowing but CAC experienced a 2-fold increased risk of mortality, with increasing risk of mortality with higher CAC score. Following adjustment, incident death persisted (HR, 1.8; 95% CI, 1.1-2.9, p = 0.02) among patients without luminal narrowing but with CAC>0 compared with patients whose CACS = 0. Individuals without luminal narrowing but CAC ≥100 had mortality risks similar to individuals with non-obstructive CAD (0 < stenosis<50%) by CCTA [HR 2.5 (95% CI 1.3-4.9) and 2.2 (95% CI 1.6-3.0), respectively]., Conclusions: Patients without luminal narrowing but with CAC experience greater risk of 5-year mortality. Patients with CAC score ≥100 and no coronary luminal narrowing experience death rates similar to those with non-obstructive CAD., (Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Downstream resource utilization and its impact on outcomes after a canceled CCTA have not been well studied. We sought to understand downstream resource utilization and patient outcomes after canceled CCTA., Methods and Results: Consecutive patients were prospectively enrolled into an institutional cardiac CT registry. Patients who had the CCTA study canceled because of severe coronary calcification were followed for downstream resource utilization and the composite of all-cause mortality and non-fatal myocardial infarction (MI). 463 patients had their CCTA canceled due to severe coronary calcification and follow-up was available for 453 (97.8%) patients (median follow-up=36.0months). There were a total of 62 events (41 all-cause deaths and 21 non-fatal MI) with an annualized event rate of 4%. Three hundred and twenty patients underwent downstream CAD (ICA or MPI or EST) investigations. Age, NCEP/ATP III risk, beta-blocker use, Agatston and downstream CAD testing were associated with the primary outcome. There were fewer events in those that received downstream CAD testing (30 (9.7%) versus 32 (22.4%)). The annualized event rates for those who did and did not receive downstream CAD testing were 2.8% and 6.2%, respectively. Multivariable analysis confirmed that downstream CAD testing was an independent predictor of event-free survival and that the absence of additional CAD testing was associated with worse outcome (HR: 2.58 (95% CI: 1.54-4.31))., Conclusions: Patients with canceled CCTA due to severe and/or extensive CAC have high rates of death and non-fatal MI. The use of additional CAD testing appears to be associated with improved outcomes., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Objectives: This study sought to develop a clinical model that identifies patients with and without high-risk coronary artery disease (CAD)., Background: Although current clinical models help to estimate a patient's pre-test probability of obstructive CAD, they do not accurately identify those patients with and without high-risk coronary anatomy., Methods: Retrospective analysis of a prospectively collected multinational coronary computed tomographic angiography (CTA) cohort was conducted. High-risk anatomy was defined as left main diameter stenosis ≥50%, 3-vessel disease with diameter stenosis ≥70%, or 2-vessel disease involving the proximal left anterior descending artery. Using a cohort of 27,125, patients with a history of CAD, cardiac transplantation, and congenital heart disease were excluded. The model was derived from 24,251 consecutive patients in the derivation cohort and an additional 7,333 nonoverlapping patients in the validation cohort., Results: The risk score consisted of 9 variables: age, sex, diabetes, hypertension, current smoking, hyperlipidemia, family history of CAD, history of peripheral vascular disease, and chest pain symptoms. Patients were divided into 3 risk categories: low (≤7 points), intermediate (8 to 17 points) and high (≥18 points). The model was statistically robust with area under the curve of 0.76 (95% confidence interval [CI]: 0.75 to 0.78) in the derivation cohort and 0.71 (95% CI: 0.69 to 0.74) in the validation cohort. Patients who scored ≤7 points had a low negative likelihood ratio (<0.1), whereas patients who scored ≥18 points had a high specificity of 99.3% and a positive likelihood ratio (8.48). In the validation group, the prevalence of high-risk CAD was 1% in patients with ≤7 points and 16.7% in those with ≥18 points., Conclusions: We propose a scoring system, based on clinical variables, that can be used to identify patients at high and low pre-test probability of having high-risk CAD. Identification of these populations may detect those who may benefit from a trial of medical therapy and those who may benefit most from an invasive strategy., (Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)