Prognostic Value of CT Angiography in Coronary Bypass Patients

Cardiac CT: Competition, complimentary or confounder

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.

Prognostic Value of Coronary Computed Tomography Angiography in Coronary Artery Bypass Graft Patients Systematic Review and Meta-Analysis

We sought to assess the prognostic value of coronary computed tomographic angiography (CCTA) in patients with coronary artery bypass graft (CABG) by meta-analysis. MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Scopus were searched for relevant original articles published up to July 2021. CCTA prognostic studies enrolling patients with CABG were screened and included if outcomes included all-cause mortality or major adverse cardiac events. Maximally adjusted hazard ratios (HRs) were extracted for CCTA-derived prognostic factors. HRs were log-transformed and pooled across studies using the DerSimonian-Laird random-effects model and statistical heterogeneity was assessed using the I² statistic. Of 1,576 screened articles, 4 retrospective studies fulfilled all inclusion criteria. Collectively, a total of 1,809 patients with CABG underwent CCTA (mean [SD] age 67.0 [8.5] years across 3 studies, 81.5% male across 4 studies). Coronary artery disease severity and revascularization were categorized using 2 models: unprotected coronary territories and coronary artery protection score. The pooled HRs from the random-effects models using the most highly adjusted study estimate were 3.64 (95% confidence interval 2.48 to 5.34, I² = 57.8%, p <0.001; 4 studies) and 4.85 (95% confidence interval 3.17 to 7.43, I² = 39.9%, p <0.001; 2 studies) for unprotected coronary territories and coronary artery protection score, respectively. In conclusion, in a limited number of studies, CCTA is an independent predictor of adverse events in patients with CABG. Larger studies using uniform models and endpoints are needed.

Prognostic value of coronary computed tomography angiography compared to radionuclide myocardial perfusion imaging in patients With coronary stents

Objectives

The aim of this study is to compare the prognostic value of coronary computed tomography angiography (CCTA) with single-photon emission computed tomography (SPECT) in predicting cardiovascular events in patients with stents.

Design

Retrospective analysis.

Setting

University Hospital, London, Ontario Canada.

Participants

Between January 2007 and December 2018, 119 patients post-percutaneous coronary intervention (PCI) who were referred for hybrid imaging with CTA and 2-day rest/stress SPECT were enrolled.

Primary and secondary outcome measures

Patients were followed for any major adverse cardiovascular event (MACE) including: All-cause mortality, Non-fatal myocardial infarction (MI), Unplanned revascularization, Cerebrovascular accident and hospitalization for arrhythmia or heart failure. We define hard cardiac events (HCE) as: cardiac death, non-fatal MI or unplanned revascularization. We used two cut-off values to define obstructive lesions with CCTA ≥50% and ≥70% in any coronary segment. SPECT scan defined as abnormal in the presence of &gt;5% reversible myocardial perfusion defect.

Results

During the follow-up period of 7.2 ± 3.4 years. 45/119 (37.8%) patients experienced 57 MACE: Ten deaths (2 cardiac deaths and 8 of non-cardiac deaths), 29 acute coronary syndrome including non-fatal MI (25 required revascularization), 7 hospitalizations for heart failure, 6 cerebrovascular accidents and 5 new atrial fibrillation. 31 HCEs were reported. Cox regression analysis showed that obstructive coronary stenosis (≥50% and ≥70%) and abnormal SPECT were associated of MACE (p = 0.037, 0.018 and 0.026), respectively. In contrast, HCEs were significantly associated with obstructive coronary stenosis of ≥50% and ≥70% with p = 0.004 and p = 0.007, respectively. In contrast, abnormal SPECT was a nonsignificant predictor of HCEs (p = 0.062).

Conclusion

Obstructive coronary artery stenosis on CCTA can predict MACE and HCE. However, abnormal SPECT can only predict MACE but not HCE in patients post-PCI with a follow-up period of approximately 7 years.

Diagnostic and Management Strategies in Patients with Late Recurrent Angina after Coronary Artery Bypass Grafting

PURPOSE OF REVIEW

This review will outline the current evidence on the anatomical, functional, and physiological tools that may be applied in the evaluation of patients with late recurrent angina after coronary artery bypass grafting (CABG). Furthermore, we discuss management strategies and propose an algorithm to guide decision-making for this complex patient population.

RECENT FINDINGS

Patients with prior CABG often present with late recurrent angina as a result of bypass graft failure and progression of native coronary artery disease (CAD). These patients are generally older, have a higher prevalence of comorbidities, and more complex atherosclerotic lesion morphology compared to CABG-naïve patients. In addition, guideline recommendations are based on studies in which post-CABG patients have been largely excluded. Several invasive and non-invasive diagnostic tools are currently available to assess graft patency, the hemodynamic significance of native CAD progression, left ventricular function, and myocardial viability. Such tools, in particular the latest generation coronary computed tomography angiography, are part of a systematic diagnostic work-up to guide optimal repeat revascularization strategy in patients presenting with late recurrent angina after CABG.

Appropriateness criteria for the use of cardiac computed tomography, SIC-SIRM part 2: acute chest pain evaluation; stent and coronary artery bypass graft patency evaluation; planning of coronary revascularization and transcatheter valve procedures; cardiomyopathies, electrophysiological applications, cardiac masses, cardio-oncology and pericardial diseases evaluation

In the past 20 years, cardiac computed tomography (CCT) has become a pivotal technique for the noninvasive diagnostic workup of coronary and cardiac diseases. Continuous technical and methodological improvements, combined with fast growing scientific evidence, have progressively expanded the clinical role of CCT. Randomized clinical trials documented the value of CCT in increasing the cost-effectiveness of the management of patients with acute chest pain presenting in the emergency department, also during the pandemic. Beyond the evaluation of stents and surgical graft patency, the anatomical and functional coronary imaging have the potential to guide treatment decision-making and planning for complex left main and three-vessel coronary disease. Furthermore, there has been an increasing demand to use CCT for preinterventional planning in minimally invasive procedures, such as transcatheter valve implantation and mitral valve repair. Yet, the use of CCT as a roadmap for tailored electrophysiological procedures has gained increasing importance to assure maximum success. In the meantime, innovations and advanced postprocessing tools have generated new potential applications of CCT from the simple coronary anatomy to the complete assessment of structural, functional and pathophysiological biomarkers of cardiac disease. In this complex and revolutionary scenario, it is urgently needed to provide an updated guide for the appropriate use of CCT in different clinical settings. This manuscript, endorsed by the Italian Society of Cardiology (SIC) and the Italian Society of Medical and Interventional Radiology (SIRM), represents the second of two consensus documents collecting the expert opinion of cardiologists and radiologists about current appropriate use of CCT.

Coronary Artery Disease Reporting and Data System (CAD-RADS) Adoption: Analysis of Local Trends in a Large Academic Medical Center

Purpose

To perform a retrospective review of Coronary Artery Disease Reporting and Data System (CAD-RADS) adoption at a high-volume cardiac CT service.

Materials and Methods

In this retrospective study, the adoption of CAD-RADS in 6562 coronary CT angiography (CTA) reports from January 1, 2017, to February 13, 2020, was evaluated. Reports without CAD-RADS were classified as opt-outs or exceptions to CAD-RADS. CAD-RADS classifications were retrospectively assigned to the opt-outs and the clinical indications for coronary CTA.

Results

CAD-RADS scores were reported in 95% (6264 of 6562) of cases. Among the 5% (n = 298) of reports not reported according to CAD-RADS, 58% (n = 172) were considered opt-outs and 42% (n = 126) were exceptions. Cases with higher degree of stenosis, stents, and coronary artery bypass grafts (CABGs) occurred more often in opt-outs versus reports with CAD-RADS (odds ratio [OR], 8.3 [95% CI: 1.6, 42.1]; P < .001). The quarterly opt-out rate decreased over consecutive quarters in the 1st year (OR, 0.77 [95% CI: 0.61, 0.96]; P = .01), then stabilized. Quarterly opt-out rate for patients with stents decreased over time (OR, 0.82 [95% CI: 0.73, 0.92]; P = .008), as did the opt-out rates in patients with CABG (OR, 0.83 [95% CI: 0.76, 0.91]; P < .001). Exceptions (n = 126) included coronary dissections (44%), anomalous coronary arteries (41%), coronary artery aneurysms or pseudoaneurysms (10%), vasculitis (2%), stent complications (2%), and extrinsic compression of grafts (2%).

Conclusion

CAD-RADS was adopted rapidly and widely. Readers opted out of its use most often in complex cases of CAD, and the most common exceptions were coronary dissections and anomalous coronary artery.Keywords: Coronary Arteries, CT Angiography© RSNA, 2021.

Prognostic Value of Standard Coronary Computed Tomography Angiography Reporting System (CAD-RADS)

Aims  This study evaluated the clinical prospects of Coronary Artery Disease—Reporting and Data System (CAD-RADS) scoring in coronary computed tomography angiography (CTA). The aim of the study was to determine the guidance value of CAD-RADS scoring in patient follow-up after CTA.

Methods and Materials  Reports of cases reported between 2010 and 2013 were reevaluated with CAD-RADS scoring. Clinical risk analysis was performed with initial forms of anamnesis. Clinical follow-up was performed on 7 to 10 years (mean: 8 years, 4 months) hospital records. Univariate and multivariate Cox modeling was performed with Kaplan–Meier method to define the relationship between clinical (age, gender, diabetes mellitus, hypertension, smoking, family history) and CAD-RADS variables, and for risk analysis based on these causes. Cox proportional-hazards analysis results were presented as a hazard ratio with a 95% confidence interval. CAD-RADS scores were evaluated as meaningful determinants of univariate and multivariate Cox proportional survival analysis.

Results  Totally, 359 cases were evaluated in the study. Severe coronary pathology development rate was observed as CAD-RADS 0to 1%, CAD-RADS 1 to 3%, CAD-RADS 2 to 4%, CAD-RADS 3 to 9%, CAD-RADS 4A to 21%, 4B to 25%, CAD-RADS 5 to 50%. There were no coronary artery deaths in CAD-RADS 1,2,3 cases in 10 years of follow-up. Two cases with CAD-RADS 4 A score, three cases with 4 B score, and four patients with CAD-RADS 5 had a history of death as a result of coronary disease.

Conclusions  The cases with a high risk of side effects with CAD-RADS scores were clearly shown. CAD-RADS score accurately identifies risks in postimaging follow-up and is a reliable reporting system in the required treatment planning.

Prognostic value of coronary computed tomography angiography in patients with prior percutaneous coronary intervention

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.

Noninvasive Imaging Risk Stratification with Computed Tomography Angiography for Coronary Artery Disease

The recent technological evolution of coronary computed tomography angiography (CTA) with improved sensitivity and high negative predictive value has extended its potential applications as a gatekeeper test before invasive coronary angiography. However, the definition of the most accurate diagnostic algorithms comprising CTA as a first-line strategy for ruling out coronary artery disease and the correct management of the patients according to the results of imaging tests still warrant better definition.

Relationship between Perioperative Hypotension and Perioperative Cardiovascular Events in Patients with Coronary Artery Disease Undergoing Major Noncardiac Surgery

BACKGROUND

Perioperative hypotension is associated with cardiovascular events in patients having noncardiac surgery. It is unknown if the severity of preexisting coronary artery disease determines susceptibility to the cardiovascular risks of perioperative hypotension.

METHODS

In this retrospective exploratory analysis of a substudy of an international prospective blinded cohort study, 955 patients 45 yr of age or older with history or risk factors for coronary artery disease underwent coronary computed tomographic angiography before elective inpatient noncardiac surgery. The authors evaluated the potential interaction between angiographic findings and perioperative hypotension (defined as systolic blood pressure less than 90 mmHg for a total of 10 min or more during surgery or for any duration after surgery and for which intervention was initiated) on the composite outcome of time to myocardial infarction or cardiovascular death up to 30 days after surgery. Angiography assessors were blinded to study outcomes; patients, treating clinicians, and outcome assessors were blinded to angiography findings.

RESULTS

Cardiovascular events (myocardial infarction or cardiovascular death within 30 days after surgery) occurred in 7.7% of patients (74/955), including in 2.7% (8/293) without obstructive coronary disease or hypotension compared to 6.7% (21/314) with obstructive coronary disease but no hypotension (hazard ratio, 2.51; 95% CI, 1.11 to 5.66; P = 0.027), 8.8% (14/159) in patients with hypotension but without obstructive coronary disease (hazard ratio, 3.85; 95% CI, 1.62 to 9.19; P = 0.002), and 16.4% (31/189) with obstructive coronary disease and hypotension (hazard ratio, 7.34; 95% CI, 3.37 to 15.96; P < 0.001). Hypotension was independently associated with cardiovascular events (hazard ratio, 3.17; 95% CI, 1.99 to 5.06; P < 0.001). This association remained in patients without obstructive disease and did not differ significantly across degrees of coronary disease (P value for interaction, 0.599).

CONCLUSIONS

In patients having noncardiac surgery, perioperative hypotension was associated with cardiovascular events regardless of the degree of coronary artery disease on preoperative coronary computed tomographic angiography.

Comparison of coronary CT angiography versus functional imaging for CABG patients: A resource utilization analysis

AIMS

The impact of anatomical versus functional testing in patients with prior coronary artery bypass surgery (CABG) is poorly defined. We therefore sought to determine the rates of downstream investigations and the attendant healthcare costs in CABG patients undergoing CCTA versus SPECT.

METHODS AND RESULTS

2754 consecutive CABG patients were imaged by SPECT (2163) or CCTA (591). 425 patients (15.4%) underwent downstream testing which was more common in those imaged with CCTA versus SPECT (23.18% vs 13.31% respectively, p < 0.01). When a propensity score adjustment was made for differences in baseline characteristics, the findings in downstream testing persisted (p < 0.01). When patients who subsequently underwent repeat revascularization (arguably the highest risk patients) were removed from the analysis, downstream testing remained more frequent in CCTA (12.7%) versus SPECT imaged patients (8.8%) (p = 0.01). Costs of downstream tests per patient were two-fold greater in the CCTA group in comparison to the SPECT group ($366.79 ± 29.59 vs $167.35 ± 10.12 respectively, p < 0.01). Conversely, total costs which included the index costs were less in the CCTA group, $764.66 ± 29.59 versus $1396.73 ± 1012 for the SPECT cohort, p < 0.0001).

CONCLUSIONS

Index imaging with SPECT versus CCTA in CABG patients was associated with fewer downstream tests, less ICA, less repeat revascularization but greater expense. Cost however is only part of the decision making process that determines an optimal index test. Until CCTA demonstrates improved risk stratification over SPECT in CABG patients it is likely SPECT will remain the preferred first imaging test.

Hybrid coronary computed tomography angiography and positron emission tomography myocardial perfusion imaging in evaluation of recurrent symptoms after coronary artery bypass grafting

Aims

Recurrent chest pain after coronary artery bypass grafting (CABG) poses a diagnostic challenge. We hypothesized that combining anatomy of bypass grafts and native coronary arteries with ischaemia detection by hybrid imaging could be used to gain valuable and complementary information in patients with recurrent symptoms after CABG.

Methods and results

We analysed 36 consecutive patients (67 ± 9 years, 81% male) who had undergone hybrid imaging using coronary computed tomography angiography (CCTA) and [15O]H2O positron emission tomography (PET) myocardial perfusion imaging due to recurrent symptoms after CABG. Coronary tree and left ventricular myocardium were divided into three main territories, yielding a total of 108 coronary territories in 36 patients. The presence of obstructive (≥50%) stenosis and the patency of grafts were evaluated by CCTA, while myocardial ischaemia was assessed by quantitative adenosine-stress PET. Altogether 28 (78%) of the 36 study patients presented with matched PET/CCTA abnormalities. Forty-one coronary territories were supplied by non-obstructed bypass grafts or native coronary arteries (protected territory). However, 12 (29%) of these presented with a perfusion defect. In six cases, the perfusion defect involved myocardium distal to the graft-coronary anastomosis, as interpreted on the PET/CCTA fusion images. In turn, in 48 coronary territories the supplying artery was obstructed on CCTA (unprotected territory). Of these, 41 (85%, P < 0.001 vs. protected) presented with abnormal perfusion, involving myocardium distal to the anastomosis in 29 cases.

Conclusion

Hybrid imaging provides complementary information on the presence and localization of atherosclerotic lesions and myocardial perfusion abnormalities in symptomatic patients with previous CABG.

Risk of New Native-Vessel Occlusion After Coronary Artery Bypass Grafting

Coronary computed tomography angiography is widely used to evaluate the graft patency, but information on the progression of native-vessel disease remains limited. We sought to evaluate the impact of bypass grafting on native-vessel progression after coronary artery bypass grafting. We evaluated new native-vessel occlusion defined as occlusion length ≥15 mm as a surrogate marker of native-vessel progression. We evaluated 911 patients with 2,271 nonoccluded vessels who underwent coronary artery bypass grafting and received follow-up coronary computed tomography angiography. Over a mean follow-up period of 4.7 years, the new occlusion rates were 9.2% for left anterior descending artery (LAD), and 13.9% for non-LAD, respectively. For non-LAD, new occlusion rate of vessels with bypass grafts was higher compared to those without bypass graft regardless of baseline native-vessel stenosis (intermediate stenosis: 8.6% vs 1.7%, p <0.001; severe stenosis: 20.5% vs 9.9%, p = 0.003). Furthermore, new occlusion rate of vessels with venous graft was the highest, followed by vessels with arterial graft and vessels without bypass graft, regardless of baseline stenosis (intermediate stenosis: 11.1% vs 5.2% vs 1.7%, p <0.001; severe stenosis: 23.7% vs 15.9% vs 9.9%, p <0.001). By multivariate analysis, bypass grafting was associated with new native-vessel occlusion for non-LAD (odds ratio 3.04, 95% confidence interval 1.79 to 5.14; p <0.001). Bypass graft was associated with new native-vessel disease progression regardless of baseline stenosis. In conclusion, the decision to bypass or leave a native vessel with intermediate stenosis should cautiously be considered.

Computed Tomography Angiography of Coronary Artery Bypass Grafts: Low Contrast Media Volume Protocols Adapted to Tube Voltage

OBJECTIVE

The aim of this study was to evaluate the potential of contrast media (CM) reduction in computed tomography angiography (CTA) of coronary artery bypass grafts (CABGs) when adapting CM volume to automatically selected tube voltages.

MATERIAL AND METHODS

Sixty consecutive patients (mean age, 71 ± 14.5 years) with a total of 176 CABGs (692 bypass segments) underwent contrast-enhanced prospectively electrocardiography-gated high-pitch CTA with automated, attenuation-based tube voltage selection (100 ref. peak kilovoltage [kVp], 200 ref. mAs, tube voltages from 70-150 kVp in 10-kVp steps) using a third-generation 192-slice dual-source computed tomography scanner. Volume and flow of CM (370 mg/mL iodine) was adapted according to the tube voltages using iodine attenuation-curves derived from a foregoing phantom study. In patients, CM volumes ranged from 80 mL (flow rate, 7 mL/s) at 120 kVp to 48 mL (flow rate, 4.2 mL/s) at 80 kVp. Two independent, blinded readers evaluated subjective image quality of the proximal anastomosis, bypass graft, distal anastomosis, and postanastomotic native coronary artery using a 3-point Likert scale. Objective image quality (attenuation of graft and noise) was determined and contrast-to-noise ratio (CNR) was calculated. Volume computed tomography dose index and dose-length product of each CTA examination were noted. Cohen κ was used to define interreader agreement of subjective image quality. Regression analysis was used to determine relationships between tube voltage and vascular attenuation, image noise, and CNR.

RESULTS

Using attenuation-based tube voltage selection, 5 patients (8%) were scanned at 80 kVp, 22 (37%) at 90 kVp, 11 (18%) at 100 kVp, 10 (17%) at 110 kVp, and 12 (20%) at 120 kVp. Agreement in subjective image quality between readers was good (κ = 0.678). Diagnostic image quality was achieved in 679 of 692 (98%) bypass segments in 169 of 176 bypass grafts (96%). Thirteen of 692 bypass segments (2%) in 7 of 176 bypass grafts (4%) were rated as nondiagnostic because of severe artifacts caused by motion or beam hardening (2 proximal anastomoses of sequential bypasses, 3 graft bodies, 5 distal anastomoses, and 3 postanastomotic coronary artery segments). Regression analysis revealed no significant relationship between the automatically selected tube voltages and objective image quality parameters (bypass graft attenuation: P = 0.315; noise: P = 0.433; and CNR: P = 0.168), indicating homogenous attenuation, noise, and CNR across tube voltage levels. Mean volume computed tomography dose index was 4.0 ± 0.9 mGy, and mean dose length product was 135.0 ± 29.6 mGy*cm.

CONCLUSION

Adapting CM protocols to automatically selected tube voltage levels allows for low-volume CM CTA examinations of CABG grafts with diagnostic image quality.

Prognostic capabilities of coronary computed tomographic angiography before non-cardiac surgery: prospective cohort study

OBJECTIVES

To determine if coronary computed tomographic angiography enhances prediction of perioperative risk in patients before non-cardiac surgery and to assess the preoperative coronary anatomy in patients who experience a myocardial infarction after non-cardiac surgery.

DESIGN

Prospective cohort study.

SETTING

12 centers in eight countries.

PARTICIPANTS

955 patients with, or at risk of, atherosclerotic disease who underwent non-cardiac surgery.

INTERVENTIONS

Coronary computed tomographic angiography was performed preoperatively; clinicians were blinded to the results unless left main disease was suspected. Results were classified as normal, non-obstructive (<50% stenosis), obstructive (one or two vessels with ≥ 50% stenosis), or extensive obstructive (≥ 50% stenosis in two vessels including the proximal left anterior descending artery, three vessels, or left main).

MAIN OUTCOME MEASURE

Composite of cardiovascular death and non-fatal myocardial infarction within 30 days after surgery (primary outcome). This was the dependent variable in Cox regression. The independent variables were scores on the revised cardiac risk index and findings on coronary computed tomographic angiography.

RESULTS

The primary outcome occurred in 74 patients (8%). The model that included both scores on the revised cardiac risk index and findings on coronary computed tomographic angiography showed that coronary computed tomographic angiography provided independent prognostic information (P=0.014; C index=0.66). The adjusted hazard ratios were 1.51 (95% confidence interval 0.45 to 5.10) for non-obstructive disease; 2.05 (0.62 to 6.74) for obstructive disease; and 3.76 (1.12 to 12.62) for extensive obstructive disease. For the model with coronary computed tomographic angiography compared with the model based on the revised cardiac risk index alone, with 30 day risk categories of <5%, 5-15%, and >15% for the primary outcome, the results of risk reclassification indicate that in a sample of 1000 patients that coronary computed tomographic angiography would have resulted appropriately in 17 net patients receiving a higher risk estimation among the 77 patients who would have experienced the primary outcome (P<0.001). Coronary computed tomographic angiography, however, would have resulted inappropriately in 98 net patients receiving a higher risk estimation, among the 923 patients who would not have experienced the primary outcome (P<0.001). Among patients who had a perioperative myocardial infarction, preoperative coronary anatomy showed extensive obstructive disease in 31% (22/71), obstructive disease in 41% (29/71), non-obstructive disease in 24% (17/71), and normal findings in 4% (3/71).

CONCLUSIONS

Though findings on coronary computed tomographic angiography can improve estimation of risk for patients who will experience perioperative cardiovascular death or myocardial infarction, findings are more than five times as likely to lead to an inappropriate overestimation of risk among patients who will not experience these outcomes. Perioperative myocardial infarction occurs across the spectrum of coronary artery disease, suggesting that there could be several pathophysiologic mechanisms.

Coronary computed tomographic angiography in coronary artery bypass grafts: comparison between low-concentration Iodixanol 270 and Iohexol 350

OBJECTIVE

The aim of this study was to evaluate the feasibility of low-concentration iso-osmolar Iodixanol 270 compared with Iohexol 350 in patients with coronary artery bypass grafts (CABGs) undergoing coronary computed tomographic angiography (CCTA).

METHODS

A total of 80 consecutive patients undergoing CABG follow-up with the use of CCTA were prospectively enrolled, with 40 patients assigned to Iodixanol 270 and 40 patients assigned to Iohexol 350. In both groups, the contrast medium was injected at an injection rate of 4.5 mL/s in the patients with a body mass index of greater than 24 kg/m2 and 3.5 mL/s in the patients with a body mass index of 24 kg/m2 or lower. The contrast volume was determined by the flow rate and scan time. Image quality score and visualization of bypass grafts were evaluated. Subjective assessment of image quality for each coronary artery segment was determined using a 4-point grading scale by 2 reviewers, whereas objective evaluation of image quality was conducted by measuring the mean CT attenuation values (hounsfield unit [HU]) in terms of SD, contrast-noise ratio, and signal-noise ratio in the ascending aorta.

RESULTS

The mean (SD) contrast volume for the Iodixanol 270 and Iohexol 350 groups was 66.28 (12.00) and 64.98 (8.12) mL, respectively, with no significant difference (P = 0.57). The mean (SD) CT attenuation value in the Iodixanol 270 group was 414.72 (101.47), which was lower than in the Iohexol 350 group, which was 478.85 (108.73) (P = 0.01). The subjective image quality for the Iodixanol 270 group was superior to that for the Iohexol 350 group in the arterial graft vessels (P = 0.027), whereas there was no significant difference between the 2 groups in the venous graft vessels (P = 0.377). There was no significant difference in terms of SD of the ascending aorta, signal-noise ratio, and contrast-noise ratio between the 2 groups.

CONCLUSIONS

Low-concentration iso-osmolar Iodixanol 270 provides image quality comparable with that of Iohexol 350, allowing diagnostic CCTA follow-up of patients with CABGs.

Use of cardiac CT and calcium scoring for detecting coronary plaque: implications on prognosis and patient management

Clinicians often use risk factor-based calculators to estimate an individual's risk of developing cardiovascular disease. Non-invasive cardiovascular imaging, particularly coronary artery calcium (CAC) scoring and coronary CT angiography (CTA), allows for direct visualization of coronary atherosclerosis. Among patients without prior coronary artery disease, studies examining CAC and coronary CTA have consistently shown that the presence, extent and severity of coronary atherosclerosis provide additional prognostic information for patients beyond risk factor-based scores alone. This review will highlight the basics of CAC scoring and coronary CTA and discuss their role in impacting patient prognosis and management.

A combination of anatomical and functional evaluations improves the prediction of cardiac event in patients with coronary artery bypass

OBJECTIVE

To study the usefulness of combined risk stratification of coronary CT angiography (CTA) and myocardial perfusion imaging (MPI) in patients with previous coronary-artery-bypass grafting (CABG).

DESIGN

A retrospective, observational, single centre study.

SETTING AND PATIENTS

204 patients (84.3% men, mean age 68.7±7.6) undergoing CTA and MPI.

MAIN OUTCOME MEASURES

CTA defined unprotected coronary territories (UCT; 0, 1, 2 or 3) by evaluating the number of significant stenoses which were defined as the left main trunk ≥50% diameter stenosis, other native vessel stenosis ≥70% or graft stenosis ≥70%. Using a cut-off value with receiver-operating characteristics analysis, all patients were divided into four groups: group A (UCT=0, summed stress score (SSS)<4), group B (UCT≥1, SSS<4), group C (UCT=0, SSS≥4) and group D (UCT≥1, SSS≥4).

RESULTS

Cardiac events, as a composite end point including cardiac death, non-fatal myocardial infarction, unstable angina requiring revascularisation and heart-failure hospitalisation, were observed in 27 patients for a median follow-up of 27.5 months. The annual event rates were 1.1%, 2%, 5.7% and 12.9% of patients in groups A, B, C and D, respectively (log rank p value <0.0001). Adding UCT or SSS to a model with significant clinical factors including left ventricular ejection fraction, time since CABG and Euro SCORE II improved the prediction of events, while adding UCT and SSS to the model improved it greatly with increasing C-index, net reclassification improvement and integrated discrimination improvement.

CONCLUSIONS

The combination of anatomical and functional evaluations non-invasively enhances the predictive accuracy of cardiac events in patients with CABG.

CT vs SPECT: CT is the first-line test for the diagnosis and prognosis of stable coronary artery disease

Non-invasive cardiac imaging is pivotal in the diagnosis and prognosis of patients with stable CAD. Nuclear SPECT, PET, stress echocardiography and more recently cardiac magnetic resonance imaging have been utilized with excellent diagnostic accuracy. However, along with their inherent individual limitations, most modalities detect ischemia but lack the ability to define coronary anatomy or evaluate for subclinical atherosclerosis. A modality that not only accurately diagnoses obstructive CAD and also facilitates early identification of non-obstructive CAD may be of interest because it may allow for earlier aggressive risk factor modification and primary prevention. Cardiac computerized tomographic angiography (CCTA) has the potential to accurately detect or exclude luminal stenosis, as well as identify and quantify subclinical atherosclerosis in the absence if luminal narrowing. However CCTA, being a relatively a new modality, has less supporting evidence when compared to more mature modalities such as SPECT. Therefore, the question that begs to be addressed is whether CCTA can be utilized as a first line test in establishing the diagnosis and prognosis of CAD.

Coronary computed tomographic angiography as a gatekeeper to invasive diagnostic and surgical procedures: results from the multicenter CONFIRM (Coronary CT Angiography Evaluation for Clinical Outcomes: an International Multicenter) registry

OBJECTIVES

This study sought to examine patterns of follow-up invasive coronary angiography (ICA) and revascularization (REV) after coronary computed tomography angiography (CCTA).

BACKGROUND

CCTA is a noninvasive test that permits direct visualization of the extent and severity of coronary artery disease (CAD). Post-CCTA patterns of follow-up ICA and REV are incompletely defined.

METHODS

We examined 15,207 intermediate likelihood patients from 8 sites in 6 countries; these patients were without known CAD, underwent CCTA, and were followed up for 2.3 ± 1.2 years for all-cause mortality. Coronary artery stenosis was judged as obstructive when ≥50% stenosis was present. A multivariable logistic regression was used to estimate ICA use. A Cox proportional hazards model was used to estimate all-cause mortality.

RESULTS

During follow-up, ICA rates for patients with no CAD to mild CAD according to CCTA were low (2.5% and 8.3%), with similarly low rates of REV (0.3% and 2.5%). Most ICA procedures (79%) occurred ≤3 months of CCTA. Obstructive CAD was associated with higher rates of ICA and REV for 1-vessel (44.3% and 28.0%), 2-vessel (53.3% and 43.6%), and 3-vessel (69.4% and 66.8%) CAD, respectively. For patients with <50% stenosis, early ICA rates were elevated; over the entirety of follow-up, predictors of ICA were mild left main, mild proximal CAD, respectively, or higher coronary calcium scores. In patients with <50% stenosis, the relative hazard for death was 2.2 (p = 0.011) for ICA versus no ICA. Conversely, for patients with CAD, the relative hazard for death was 0.61 for ICA versus no ICA (p = 0.047).

CONCLUSIONS

These findings support the concept that CCTA may be used effectively as a gatekeeper to ICA.

Prognostic value of cardiovascular CT: is coronary artery calcium screening enough? The added value of CCTA

Coronary artery disease (CAD) is the primary cause of death in adults in the United States. Only 50% of patients who present with a myocardial infarction have a prior history of CAD. Non-invasive cardiac imaging tests have been developed to diagnose CAD. Current guidelines and systematic reviews have tried to determine the prognostic value of the coronary artery calcium (CAC) scoring and the coronary computed tomography angiography (CCTA) for major adverse cardiovascular events. Several studies support the roles of CCTA and CAC scoring for the diagnosis of CAD in asymptomatic patients. Further studies are needed to confirm the superior role of CCTA over CAC scoring in symptomatic patients.

Value of coronary computed tomography as a prognostic tool

Coronary computed tomography angiography (CCTA) has become an important part of our armamentarium for noninvasive diagnosis of coronary artery disease (CAD). Emerging technologies have produced lower radiation dose, improved spatial and temporal resolution, as well as information about coronary physiology. Although the prognostic role of coronary artery calcium scoring is known, similar evidence for CCTA has only recently emerged. Initial, small studies in various patient populations have indicated that CCTA-identified CAD may have a prognostic value. These findings were confirmed in a recent analysis of the international, prospective Coronary CT Angiography Evaluation For Clinical Outcomes: An International Multicenter (CONFIRM) registry. An incremental increase in mortality was found with a worse severity of CAD on a per-patient, per-vessel, and per-segment basis. In addition, age-, sex-, and ethnicity-based differences in mortality were also found. Whether changing our management algorithms based on these findings will affect outcomes is unclear. Large prospective studies utilizing targeted management strategies for obstructive and nonobstructive CAD are required to incorporate these recent findings into our daily practice.

The prognostic significance of coronary CT angiography

Coronary computed tomography angiography (CTA) is an increasingly utilized, highly accurate noninvasive test for the diagnosis of coronary artery disease. Accumulating data have convincingly demonstrated that the presence, extent, and location of both obstructive and nonobstructive coronary atherosclerosis visualized on coronary CTA conveys powerful prognostic information, incremental to that provided by clinical variables and coronary calcium scoring. Proposed markers of future plaque instability and coronary risk, such as the degree of vessel remodeling and low-attenuation plaque volume, as well as measures of CT myocardial perfusion, may further improve the prognostic value of CTA. Ultimately, studies are needed to assess whether the prognostic information provided by coronary CTA testing results in sustained changes in patient and provider behaviors that cost effectively improve patient outcomes.