Predictive value of the coronary artery calcium score and advanced plaque characteristics: Post hoc analysis of the PREDICT registry

BackgroundWhether coronary plaque characteristics assessed in coronary computed tomography angiography (CCTA) in association with the coronary artery calcium score (CACS) have predictive value for coronary events is unclear. We aimed to examine the predictive value of the CACS and plaque characteristics for the occurrence of coronary events.MethodsAmong 2802 patients who were analyzed in the PREDICT registry, 2083 with suspected coronary artery disease (CAD) were studied using post hoc analysis. High-risk plaques were defined as having ≥2 adverse characteristics, such as low computed tomographic attenuation, positive remodeling, spotty calcification, and napkin-ring sign. An adjudicative composite of coronary events (cardiac death, nonfatal acute coronary syndrome, and coronary revascularization ≥3 months after indexed CCTA) were analyzed.ResultsSeventy-three (3.5%) patients had coronary events and 313 (15.0%) had high-risk plaques. Multivariate Cox proportional hazard analysis showed that high-risk plaques remained an independent predictor of coronary events (adjusted hazard ratio [HR] 1.95, 95% confidence interval [CI] 1.13–3.34, P ?= ?0.0154), as well as the log-transformed CACS (adjusted HR 1.24, 95% CI 1.11–1.39, P ?= ?0.0002) and the presence of obstructive stenosis (adjusted HR 5.63, 95% CI 3.22–10.12, P 0.0001). In subgroup analyses, high-risk plaques were independently predictive only in the low CACS class (<100).ConclusionThis study shows that assessment of adverse features by coronary plaque imaging independently predicts coronary events in patients with suspected CAD and a low CACS. Our findings suggest that the clinical value of high-risk plaques to CACS and stenosis assessment appears marginal.     

Progression of whole-heart Atherosclerosis by coronary CT and major adverse cardiovascular events

BackgroundThe current study aimed to examine the independent prognostic value of whole-heart atherosclerosis progression by serial coronary computed tomography angiography (CCTA) for major adverse cardiovascular events (MACE).MethodsThe multi-center PARADIGM study includes patients undergoing serial CCTA for symptomatic reasons, ≥2 years apart. Whole-heart atherosclerosis was characterized on a segmental level, with co-registration of baseline and follow-up CCTA, and summed to per-patient level. The independent prognostic significance of atherosclerosis progression for MACE (non-fatal myocardial infarction [MI], death, unplanned coronary revascularization) was examined. Patients experiencing interval MACE were not omitted.ResultsThe study population comprised 1166 patients (age 60.5 ?± ?9.5 years, 54.7% male) who experienced 139 MACE events during 8.2 (IQR 6.2, 9.5) years of follow up (15 death, 5 non-fatal MI, 119 unplanned revascularizations). Whole-heart percent atheroma volume (PAV) increased from 2.32% at baseline to 4.04% at follow-up. Adjusted for baseline PAV, the annualized increase in PAV was independently associated with MACE: OR 1.23 (95% CI 1.08, 1.39) per 1 standard deviation increase, which was consistent in multiple subpopulations. When categorized by composition, only non-calcified plaque progression associated independently with MACE, while calcified plaque did not. Restricting to patients without events before follow-up CCTA, those with future MACE showed an annualized increase in PAV of 0.93% (IQR 0.34, 1.96) vs 0.32% (IQR 0.02, 0.90), P ?< ?0.001.ConclusionsWhole-heart atherosclerosis progression examined by serial CCTA is independently associated with MACE, with a prognostic threshold of 1.0% increase in PAV per year.     

Higher coronary artery calcium score is associated with increased risk of atrial fibrillation recurrence after catheter ablation

BackgroundCoronary artery calcium score (CACS) is associated with an increased risk of atrial fibrillation (AF) development, but scarce data are available regarding the impact on AF recurrence. This study aims to assess the impact of CACS on AF recurrence following catheter ablation.MethodsRetrospective study of patients with AF undergoing cardiac computed tomography (CCT) before ablation (2017–2019). Patients with coronary artery disease (CAD), significant valvular heart disease and previous catheter ablation were excluded. A cut-off of CACS ≥ 100 was used according to literature.ResultsA total of 311 patients were included (median age 57 [48, 64] years, 65% men and 21% with persistent AF). More than half of the patients had a CACS > 0 (52%) and 18% a CACS ≥ 100. Patients with CACS ≥ 100 were older (64 [59, 69] vs 55 [46, 63] years, p ?< ?0.001), had more frequently hypertension (68% vs 42%, p ?< ?0.001) and diabetes mellitus (21% vs 10%, p ?= ?0.020). During a median follow-up of 34 months (12–57 months), 98 patients (32%) had AF recurrence. CACS ≥ 100 was associated with increased risk of AF recurrence (unadjusted Cox regression: hazard ratio [HR] 2.0; 95% confidence interval [CI], 1.3–3.1, p ?= ?0.002). After covariate adjustment, CACS ≥ 100 and persistent AF remained independent predictors of AF recurrence (HR, 1.7; 95% CI, 1.0–2.8, p ?= ?0.039 and HR, 2.0; 95% CI, 1.3–3.2, p ?= ?0.004, respectively).ConclusionAn opportunistic evaluation of CACS could be an important tool to improve clinical care considering that CACS ≥ 100 was independently associated with a 69% increase in the risk of AF recurrence after first catheter ablation.     

Sex- and age-specific differences in the long-term prognostic value of morphological plaque features detected by coronary computed tomography angiography

BackgroundAlthough sex- and age-specific differences in coronary plaque features detected by coronary computed tomography angiography (CCTA) are known, insufficient information regarding the long-term prognostic value of these findings exists.MethodsA total of 1615 patients with suspected but not previously diagnosed coronary artery disease (CAD) were examined by CCTA and coronary plaque features were assessed. The median follow-up period was 10.5 (IQR 9.2–11.4) years. Cox proportional-hazards analysis was used for the combined endpoint of cardiac death or nonfatal myocardial infarction.ResultsThe endpoint occurred more often in patients older than 65 years (5.66% vs. 2.05%; p = 0.00029) but similarly between female (3.34%) and male (3.07%) patients (p = 0.76). Both sexes displayed a similar prevalence for noncalcified (female vs. male: 0.77 ± 1.38 vs. 0.89 ± 1.41; p = 0.098) and low-attenuation (female vs. male: 2.6% vs. 4.37%; p = 0.096) plaques. As assessed by p for interaction CADRADS (p for interaction = 0.013), noncalcified plaques (p for interaction = 0.022) and low-attenuation plaques (p for interaction = 0.045) had a better primary endpoint association in women than in men. Concerning age, no difference in outcome association was apparent as evaluated by p for interaction.ConclusionCCTA demonstrates excellent long-term prognostic value irrespective of sex and age and independent from the higher prevalence of atherosclerotic plaques in men and patients older than 65 years. Although similarly prevalent in both sexes, noncalcified and low-attenuation plaques exhibit a better prognostic value in women.     

Comparative analysis of calcification parameters with Agatston Score approximations for ex vivo atherosclerotic lesions

BackgroundThe Agatston Calcium Score is a predictor of major adverse cardiovascular events but it is unable to identify high-risk lesions. Recent research suggests that examining calcification phenotype could be more indicative of plaque stability.ObjectiveTo examine the Agatston score's ability to determine atherosclerotic calcification phenotype.MethodsMicro-Computed Tomography was performed on 20 carotid and 20 peripheral lower limb lesions. ImageJ pixel histogram analysis quantified the non-calcified (≥30HU, <130HU) and calcified (≥130HU) tissue volumes. ImageJ ‘3D Objects Counter’ plugin determined the calcified particle count, volumes and maximum attenuation density of each particle. Image stacks were subsequently downsampled to a resolution of 0.7 × 0.7 × 3 mm and an approximation for the Extra-Coronary Calcium Scores (ECCS) were calculated. Spearman's correlation examined the relationships between ECCS approximations and calcification parameters.ResultsECCS has a strong positive correlation with the Calcified Volume Fraction (CVF) (r_s = 0.865, p < 0.0005), weak positive correlations with Calcified Particle Fraction (CPF) (r_s = 0.422, p = 0.007) and Microcalcification Fraction (micro-CF) (r_s = 0.361, p = 0.022). There is no correlation evident between ECCS and Calcified Particle Index (CPI) (r_s = −0.162, p = 0.318). It is apparent that there is a high prevalence of microcalcifications in both carotid and peripheral lower limb lesions. Additionally, an inverse relationship exists between calcified particle volume and maximum-recorded attenuation density.ConclusionThe density-weighted Agatston calcium scoring methodology needs to be reviewed. Calcium scoring which differentiates between critical calcification morphologies, rather than presenting a density-weighted score, is required to direct high-risk plaques towards tailored treatment.     

The effect of patient and imaging characteristics on coronary CT angiography assessed pericoronary adipose tissue attenuation and gradient

BackgroundCoronary CT angiography (CCTA) pericoronary adipose tissue (PCAT) markers are promising indicators of inflammation.ObjectiveTo determine the effect of patient and imaging parameters on the associations between non-calcified plaque (NCP) and PCAT attenuation and gradient.MethodsThis was a single-center, retrospective analysis of consecutive patients with stable chest pain who underwent CCTA and had zero calcium scores. CCTA images were evaluated for the presence of NCP, obstructive stenosis, segment stenosis and involvement score (SSS, SIS), and high-risk plaque (HRP). PCAT markers were assessed using semi-automated software. Uni- and multivariable regression models correcting for patient and imaging characteristics between plaque and PCAT markers were evaluated.ResultsOverall, 1652 patients had zero calcium score (mean age: 51 years ?± ?11 [SD], 871 women); PCAT attenuation values ranged between ?123 HU and ?51 HU, and 649 patients had plaque. In univariable analysis, the presence of NCP, SSS, SIS, and HRP were associated with PCAT attenuation (2, 1, 1, 6 HU; respectively; p ?< ?.001 all); while obstructive stenosis was not (1 HU, p ?= ?.58). In multivariable analysis, none of the plaque markers were associated with PCAT attenuation (0 HU p ?= ?.93, 0 HU p ?= ?.39, 1 HU p ?= ?.18, 2 HU p ?= ?.10, 1 HU p ?= ?.71, respectively), while patient and imaging characteristics showed significant associations, such as: male sex (1 HU, p ?= ?.003), heart rate [1/min] (?0.2 HU, p ?< ?.001), 120 ?kVp (8 HU, p ?< ?.001) and pixel spacing [mm³] (32 HU, p ?< ?.001). Similar results were observed for PCAT gradient.ConclusionPCAT markers were significantly associated with NCP, however the associations did not persist following correction for patient and imaging characteristics.     

Detection of small coronary calcifications in patients with Agatston coronary artery calcium score of zero

BackgroundA coronary artery calcium score (CACS) of 0 is associated with a very low risk of cardiac event. However, the Agatston CACS may fail to detect very small or less dense calcifications. We investigated if an alteration of the Agatston criteria would affect the ability to detect such plaques.MethodsWe evaluated 322 patients, 161 who had a baseline scan with CACS ?= ?0 and a follow-up scan with CACS>0 and 161 with two serial CACS ?= ?0 scans (control group), to identify subtle calcification not detected in the baseline scan because it was not meeting the Agatston size and HU thresholds (≥1 ?mm² and ≥130HU). Size threshold was set to <1 ?mm² and the HU threshold modified in a stepwise manner to 120, 110, 100 and 90. New lesions were classified as true positive or false positive(noise) using the follow-up scan.ResultsWe identified 69 visually suspected subtle calcified lesions in 65/322 (20.2%) patients with CAC ?= ?0 by the Agatston criteria. When size threshold was set as <1 ?mm² and HU ?≥ ?130, 36 lesions scored CACS>0, 34 (94.4%) true positive and 2 (5.6%) false positive. When decrease in HU (120HU, 110HU, 100HU, and 90HU) threshold was added to the reduced size threshold, the number of lesions scoring>0 increased (46, 55, 59, and 69, respectively) at a cost of increased false positive rate (8.7%, 20%, 22%, and 30.4% respectively). Eliminating size or both size and HU threshold to ≥120HU correctly reclassified 9.6% and 12.1% of patients respectively.ConclusionEliminating size and reducing HU thresholds to ≥120HU improved the detection of subtle calcification when compared to the Agatston CACS method.     

Deep learning with convolutional neural network for estimation of the characterisation of coronary plaques: Validation using IB-IVUS

IntroductionDeep learning approaches have shown high diagnostic performance in image classifications, such as differentiation of malignant tumors and calcified coronary plaque. However, it is unknown whether deep learning is useful for characterizing coronary plaques without the presence of calcification using coronary computed tomography angiography (CCTA). The purpose of this study was to compare the diagnostic performance of deep learning with a convolutional neural network (CNN) with that of radiologists in the estimation of coronary plaques.MethodsWe retrospectively enrolled 178 patients (191 coronary plaques) who had undergone CCTA and integrated backscatter intravascular ultrasonography (IB-IVUS) studies. IB-IVUS diagnosed 81 fibrous and 110 fatty or fibro-fatty plaques. We manually captured vascular short-axis images of the coronary plaques as Portable Network Graphics (PNG) images (150 × 150 pixels). The display window level and width were 100 and 700 Hounsfield units (HU), respectively. The deep-learning system (CNN; GoogleNet Inception v3) was trained on 153 plaques; its performance was tested on 38 plaques. The area under the curve (AUC) obtained by receiver operating characteristic analysis of the deep learning system and by two board-certified radiologists was compared.ResultsWith the CNN, the AUC and the 95% confidence interval were 0.83 and 0.69–0.96, respectively; for radiologist 1 they were 0.61 and 0.42–0.80; for radiologist 2 they were 0.68 and 0.51–0.86, respectively. The AUC for CNN was significantly higher than for radiologists 1 (p = 0.04); for radiologist 2 it was not significantly different (p = 0.22).ConclusionDL-CNN performed comparably to radiologists for discrimination between fatty and fibro-fatty plaque on CCTA images.Implications for practiceThe diagnostic performance of the CNN and of two radiologists in the assessment of 191 ROIs on CT images of coronary plaques whose type corresponded with their IB-IVUS characterization was comparable.     

Consistency of quantitative analysis of coronary computed tomography angiography

BackgroundThe present study aimed to assess the reliability and reproducibility of coronary computed tomography angiography (CCTA) for the serial quantitative assessment of plaque volume.MethodsPatients who underwent repeated CCTA scans within 90 days were retrospectively screened and enrolled. Clinical data and CCTA imaging data were collected. Paired CCTA scans were analyzed using the quantitative method by separate observers blinded to the other paired CCTA scans. Results were compared between the index CCTA and follow-up CCTA.ResultsPaired CT scans of 95 patients (61 ± 13 years; 56.8% men) with same tube voltages (kVp) at both CCTAs and 24 patients (57 ± 19 years; 48.3% men) with different kVp at two CCTAs were analyzed. In patients with same kVp at both CCTAs, there were no difference in PV and PVs of each components in per-segment analysis and per-lesion analysis (all p > 0.05). In per-lesion analysis of CCTAs from patients who used different kVp between two CCTAs, lesion length, area and diameter stenosis, and PVs were not different between index and follow-up CCTAs (all p > 0.05). Segment length and PV were also showed no difference between two serial CCTAs in per-segment analysis.ConclusionWe showed the reproducibility and reliability of quantitative analysis of CCTA for assessment of coronary plaques. CCTA can be applied for the serial quantitative assessment of coronary artery disease progression, regardless of differences in the image acquisition protocol.     

Accuracy of ultra-high–resolution computed tomography with a 0.3-mm detector for quantitative assessment of coronary artery stenosis grading in comparison with conventional computed tomography: A phantom study

BackgroundThe development of ultra-high–resolution CT (U-HRCT) is expected to improve the accuracy of coronary stenosis evaluation. This study aimed to evaluate the accuracy of the stenosis severities of coronary artery phantoms estimated using U-HRCT by comparing them to those estimated with conventional CT.MethodsCoronary artery phantoms with non-calcified and calcified lesions were scanned with conventional CT (64-row ?× ?0.625 ?mm) and U-HRCT (32-row ?× ?0.3125 ?mm). The coronary artery phantoms had lumen diameters of 2.0, 3.0, and 4.0 ?mm with non-calcified lesions representing 0%, 25%, 50%, and 75% stenosis and 3.0 and 4.0 ?mm with calcified lesions representing 0%, 25%, 50%, and 75% stenosis. The lumen diameters at the stenotic and non-stenotic regions were measured, and the stenosis severities were compared with the true values.ResultsFor non-calcified lesions, conventional CT significantly underestimated the stenosis severity in the phantom showing 75% stenosis with lumen diameters of 2.0 and 3.0 ?mm (p ?< ?0.05), while the estimated stenosis severities were not significantly different from the true values at all settings with U-HRCT. For the calcified lesions, conventional CT overestimated the stenosis severities at all settings (p ?< ?0.05), while U-HRCT yielded estimations closer to the true values, although still with some overestimation (p ?< ?0.05).ConclusionBy using U-HRCT, the estimated stenosis severities of the coronary artery with non-calcified lesion become almost equal to the true value, while those with calcified lesion are still overestimated although they become closer to the true value.     

Right ventricular dysfunction by computed tomography associates with outcomes in severe aortic stenosis patients undergoing transcatheter aortic valve replacement

BackgroundAlthough cardiac computed tomography angiography (CCTA) assessment of right ventricular dysfunction (RVD) is feasible, the incremental prognostic value remains uncertain in patients undergoing transcatheter aortic valve replacement (TAVR) evaluation. This study sought to determine the incremental clinical utility of RVD identification by CCTA while accounting for clinical and echocardiographic parameters.MethodsPatients who underwent multiphasic ECG-gated functional CCTA using dual-source system for routine TAVR planning were evaluated. Biphasic contrast protocol injection allowed for biventricular contrast enhancement. CCTA-based RVD was defined as right ventricular ejection fraction (RVEF) ?< ?50%. The association of CCTA-RVD with all-cause mortality and the composite outcome of death or heart failure hospitalization after TAVR was evaluated and examined for its incremental utility beyond clinical risk assessment and echocardiographic parameters.ResultsA total of 502 patients were included (median [IQR] age, 82 [77 to 87] years; 56% men) with a median follow-up of 22 [16 to 32] months. Importantly, 126 (25%) patients were identified as having RVD by CCTA that was not identified by echocardiography. CCTA-defined RVD predicted death and the composite outcome in both univariate analyses (HR for mortality, 2.15; 95% CI, 1.44–3.22; p ?< ?0.001; HR for composite outcome, 2.11; 95% CI, 1.48–3.01; p ?< ?0.001) and in multivariate models that included clinical risk factors and echocardiographic findings (HR for mortality, 1.74; 95% CI, 1.11–2.74; p ?= ?0.02; HR for composite outcome, 1.63; 95% CI, 1.09–2.44; p ?= ?0.02).ConclusionsFunctional CCTA assessment pre-TAVR correctly identified 25% of patients with RVD that was not evident on 2D echocardiography. The presence of RVD on CCTA independently associates with clinical outcomes post-TAVR.     

Cumulative exposure amount of PM2.5 in the ambient air is associated with coronary atherosclerosis - Serial coronary CT angiography study

BackgroundWe investigated the change of coronary atherosclerosis with long-term exposure to fine particulate matter of aerodynamic diameter <2.5 ?μm (PM_2.5) using coronary computed tomography angiography (CCTA).MethodsSubjects undergoing serial CCTAs between January 2007 and December 2017 (n ?= ?3,127) were analyzed. Each individual's cumulative amount of PM_2.5 exposure between the two CCTAs was evaluated by Kriging interpolation and zonal analysis, considering the time interval between the two CCTAs. The main outcome was progression of coronary artery calcium (CAC) with additional semiquantitative analysis on the changes in the severity and composition of atherosclerotic plaques.ResultsThe CAC scores increased by 30.8 Agatston units per-year under a median PM_2.5 concentration 24.9 ?μg/m³ and tended to increase with the cumulative amount of PM_2.5 exposure (r ?= ?0.321, p ?<0.001). The CAC progressed in 1,361 (43.5%) subjects during a median 53 months follow-up. The cumulative amount of PM_2.5 exposure was independently associated with CAC progression (adjusted OR 1.09, p ?<0.001). By random forest analysis, the relative impact of cumulative amount of PM_2.5 exposure on CAC progression was higher than that of traditional cardiovascular risk factors and the average concentration of PM_2.5. The extent of coronary atherosclerosis and newly developed calcified plaque on follow-up were also significantly associated with the cumulative amount of PM_2.5 exposure.ConclusionsCumulative exposure to air pollution is associated with the progression of diffuse coronary calcification, the importance of which may be more significant than other traditional cardiovascular risk factors. Further investigations into the causality between PM_2.5 and coronary atherosclerosis are warranted to improve global cardiovascular health.     

A novel density-volume calcium score by non-contrast CT predicts coronary plaque burden on coronary CT angiography: Results from the MACS (Multicenter AIDS cohort study)

BackgroundThe purpose of this study is to determine if a new score calculated with coronary artery calcium (CAC) density and volume is associated with total coronary artery plaque burden and composition on coronary CT angiography (CCTA) compared to the Agatston score (AS).MethodsWe identified 347 men enrolled in the Multicenter AIDS cohort study who underwent contrast and non-contrast CCTs, and had CAC>0. CAC densities (mean Hounsfield Units [HU]) per plaque) and volumes on non-contrast CCT were measured. A Density-Volume Calcium score was calculated by multiplying the plaque volume by a factor based on the mean HU of the plaque (4, 3, 2 and 1 for 130–199, 200–299, 300–399, and ≥400HU). Total Density-Volume Calcium score was determined by the sum of these individual scores. The semi-quantitative partially calcified and total plaque scores (PCPS and TPS) on CCTA were calculated. The associations between Density-Volume Calcium score, PCPS and TPS were examined.ResultsOverall, 2879 CAC plaques were assessed. Multivariable linear regression models demonstrated a stronger association between the log Density-Volume Calcium score and both the PCPS (β 0.99, 95%CI 0.80–1.19) and TPS (β 2.15, 95%CI 1.88–2.42) compared to the log of AS (PCPS: β 0.77, 95%CI 0.61–0.94; TPS: β 1.70, 95%CI 1.48–1.94). Similar results were observed for numbers of PC or TP segments.ConclusionThe new CAC score weighted towards lower density demonstrated improved correlation with semi-quantitative PC and TP burden on CCTA compared to the traditional AS, which suggests it has utility as an alternative measure of atherosclerotic burden.     

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

ObjectiveWe sought to determine the prognostic value of coronary computed tomography angiography (CCTA) in patients with a history of percutaneous coronary intervention (PCI).BackgroundAlthough the prognostic value of CCTA has been well studied, its incremental value in patients with previous PCI has not been robustly investigated.MethodsConsecutive 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.ResultsA 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.ConclusionsIn patients with previous PCI, CAD severity as measured with CCTA has independent and incremental prognostic value.     

Increased coronary pericoronary adipose tissue attenuation in diabetic patients compared to non-diabetic controls: A propensity score matching analysis

BackgroundPericoronary adipose tissue (PCAT) attenuation is an indicator of active inflammation of perivascular adipose tissue, which is supposed to increase in diabetic patients. We aimed to investigate the PCAT attenuation values and high-risk plaque (HRP) features in diabetic and non-diabetic subjects with different stenotic extents.MethodsConsecutive type 2 diabetes patients and non-diabetic patients with chest pain and intermediate pre-test probability of coronary artery disease (CAD) were prospectively enrolled and underwent coronary computed tomography angiography (CCTA). At per-patient level, PCAT attenuation values of three major epicardial coronary vessels, as well as HRP features were measured. PCAT attenuation values and HRP features were compared between diabetic and non-diabetic subjects according to the presence or absence of obstructive stenosis.Results1700 patients (mean age: 65.5 ?± ?11.7, 940 males) were divided into two groups according to presence of obstructive stenosis on CCTA. Propensity score matching was performed in further analysis. RCA_PCAT was significantly higher in diabetic subjects than that in non-diabetic subjects, regardless of the presence of obstructive stenosis (?83.60 ?± ?9.51 HU vs. ?88.58 ?± ?9.37 HU, p ?< ?0.001) or absence of obstructive stenosis (?83.70 ?± ?10.32 HU vs. ?88.76 ?± ?8.28 HU, p ?< ?0.001). In contrast, HRP features were more commonly presented in diabetic patients with obstructive stenosis than in those without obstructive stenosis. According to subgroup analysis based on acquisition tube voltage, RCA_PCAT was the only parameter showing consistent difference between diabetic and non-diabetic patients.ConclusionsRCA_PCAT was significantly higher in diabetic patients than that in non-diabetic patients regardless of stenotic severity and plaque vulnerability.     

CT assessment of the left atrial appendage post-transcatheter occlusion – A systematic review and meta analysis

BackgroundTransesophageal echocardiography (TEE) is the standard imaging modality used to assess the left atrial appendage (LAA) after transcatheter device occlusion. Cardiac computed tomography angiography (CCTA) offers an alternative non-invasive modality in these patients. We aimed to conduct a comparison of the two modalities.MethodsWe performed a comprehensive systematic review of the current literature pertaining to CCTA to establish its usefulness during follow-up for patients undergoing LAA device closure. Studies that reported the prevalence of inadequate LAA closure on both CCTA and TEE were further evaluated in a meta-analysis. 19 studies were used in the systematic review, and six studies were used in the meta-analysis.ResultsThe use of CCTA was associated with a higher likelihood of detecting LAA patency than the use of TEE (OR, 2.79, 95% CI 1.34–5.80, p ?= ?0.006, I² ?= ?70.4%). There was no significant difference in the prevalence of peridevice gap ≥5 ?mm (OR, 3.04, 95% CI 0.70–13.17, p ?= ?0.13, I² ?= ?0%) between the two modalities. Studies that reported LAA assessment in early and delayed phase techniques detected a 25%–50% higher prevalence of LAA patency on the delayed imaging.ConclusionCCTA can be used as an alternative to TEE for LAA assessment post occlusion. Standardized CCTA acquisition and interpretation protocols should be developed for clinical practice.     

CT multivessel aggregate stenosis score: A novel point-of-care tool for predicting major adverse cardiac events

BackgroundWe evaluated the utility of a novel 15-point multivessel aggregate stenosis (MVAS) score for predicting major adverse cardiac events (MACE) in low-risk patients with suspected ischaemic symptoms undergoing CTCA. Prognostic performance was compared with the Coronary Artery Disease Reporting and Data System (CAD-RADS) classification and the 16-point Segment Involvement Score (SIS).Methods772 consecutive patients underwent CTCA and coronary artery calcification scoring (CACS) from 2010 to 2015. Coronary artery disease severity was calculated according to CAD-RADS class (0–5 ?± ?vulnerability modifier), the SIS (0–16), and an MVAS score (0–15) based on the aggregate stenosis severity in all 4 coronary vessels (maximum 12 points) plus the presence of any high-risk plaque features (additional 3 points). 52 patients were referred directly for coronary angiography based on CTCA findings and were excluded; the remainder were followed-up for 64.6 ?± ?19.1 months.Results54 ?MACE were observed in 720 patients (7.5%); MACE patients had higher CAD-RADS class (3.92 ?± ?0.7 vs 0.91 ?± ?1.2, p ?< ?0.0001), SIS (4.59 ?± ?2.7 vs 0.79 ?± ?1.2, p ?< ?0.0001), and MVAS scores (10.1 ?± ?1.7 vs 1.7 ?± ?2.1, p ?< ?0.0001). Adjusted Cox proportional hazards analysis identified CAD-RADS class (HR 2.96 (2.2–4), p ?< ?0.0001), SIS (HR 1.29 (1.2–1.4, p ?< ?0.0001), and MVAS score (HR 1.82 (1.6–2.1), p ?< ?0.0001) as predictors of MACE. Adjusted receiver operating characteristic (ROC) analysis found MVAS a more powerful predictor of MACE than CAD-RADS and SIS (AUC: 0.92 vs 0.84 vs 0.83, p ?= ?0.018).ConclusionsCAD-RADS and SIS are reliable predictors of MACE, and the MVAS score provided incremental prognostic data. MVAS may potentiate risk stratification, particularly in institutions without advanced plaque analysis software.     

Are risk factors necessary for pretest probability assessment of coronary artery disease? A patient similarity network analysis of the PROMISE trial

BackgroundPretest probability (PTP) calculators utilize epidemiological-level findings to provide patient-level risk assessment of obstructive coronary artery disease (CAD). However, their limited accuracies question whether dissimilarities in risk factors necessarily result in differences in CAD. Using patient similarity network (PSN) analyses, we wished to assess the accuracy of risk factors and imaging markers to identify ≥50% luminal narrowing on coronary CT angiography (CCTA) in stable chest-pain patients.MethodsWe created four PSNs representing: patient characteristics, risk factors, non-coronary imaging markers and calcium score. We used spectral clustering to group individuals with similar risk profiles. We compared PSNs to a contemporary PTP score incorporating calcium score and risk factors to identify ≥50% luminal narrowing on CCTA in the CT-arm of the PROMISE trial. We also conducted subanalyses in different age and sex groups.ResultsIn 3556 individuals, the calcium score PSN significantly outperformed patient characteristic, risk factor, and non-coronary imaging marker PSNs (AUC: 0.81 vs. 0.57, 0.55, 0.54; respectively, p ?< ?0.001 for all). The calcium score PSN significantly outperformed the contemporary PTP score (AUC: 0.81 vs. 0.78, p ?< ?0.001), and using 0, 1–100 and ?> ?100 cut-offs provided comparable results (AUC: 0.81 vs. 0.81, p ?= ?0.06). Similar results were found in all subanalyses.ConclusionCalcium score on its own provides better individualized obstructive CAD prediction than contemporary PTP scores incorporating calcium score and risk factors. Risk factors may not be able to improve the diagnostic accuracy of calcium score to predict ≥50% luminal narrowing on CCTA.     

The direct costs of coronary CT angiography relative to contrast-enhanced thoracic CT: Time-driven activity-based costing

BackgroundCoronary CT angiography (CCTA) and contrast-enhanced thoracic CT (CECT) are distinctly different diagnostic procedures that involve intravenous contrast-enhanced CT of the chest. The technical component of these procedures is reimbursed at the same rate by the Centers for Medicare and Medicaid Services (CMS). This study tests the hypothesis that the direct costs of performing these exams are significantly different.MethodsDirect costs for both procedures were measured using a time-driven activity-based costing (TDABC) model. The exams were segmented into four phases: preparation, scanning, post-scan monitoring, and image processing. Room occupancy and direct labor times were collected for scans of 54 patients (28 CCTA and 26 CECT studies), in seven medical facilities within the USA and used to impute labor and equipment cost. Contrast material costs were measured directly. Cost differences between the exams were analyzed for significance and variability.ResultsMean CCTA duration was 3.2 times longer than CECT (121 and 37 ​min, respectively. p ​< ​0.01). Mean CCTA direct costs were 3.4 times those of CECT ($189.52 and $55.28, respectively, p ​< ​0.01). Both labor and capital equipment costs for CCTA were significantly more expensive (6.5 and 1.8-fold greater, respectively, p ​< ​0.001). Segmented by procedural phase, CCTA was both longer and more expensive for each (p ​< ​0.01). Mean direct costs for CCTA exceeded the standard CMS technical reimbursement of $182.25 without accounting for indirect or overhead costs.ConclusionThe direct cost of performing CCTA is significantly higher than CECT, and thus reimbursement schedules that treat these procedures similarly undervalue the resources required to perform CCTA and possibly decrease access to the procedure.     

Feasibility of extracellular volume fraction calculation using myocardial CT delayed enhancement with low contrast media administration

BackgroundMyocardial extracellular volume fraction (ECV) derived from CT delayed enhancement (CTDE) may allow assessment of diffuse myocardial fibrosis. However, the amount of contrast medium required for ECV estimation has not been established. Since ECV estimation by CT is typically performed in combination with coronary CT angiography (CCTA) in clinical settings, we aimed to investigate whether reliable ECV estimation is possible using the contrast dose optimized for CCTA without additional contrast administration.MethodsTwenty patients with known or suspected coronary artery disease who underwent CTDE with a dual-source scanner using two protocols (Protocols A and B) within 2 years were retrospectively enrolled. In Protocol A, CTDE was obtained with 0.84 ml/kg of iopamidol (370 mgI/ml) injected for CCTA. In Protocol B, stress CT perfusion imaging, which requires 40 ml of contrast medium, was added to Protocol A. ECV values calculated from the two protocols were compared.ResultsDespite the different contrast doses, no significant difference in mean myocardial ECV was seen between Protocols A and B at the patient level (28.7 ± 4.3% vs. 28.7 ± 4.4%, respectively, P = 0.868). Excellent correlations in ECV were seen between the two protocols (r = 0.942, P < 0.001). Bland-Altman analysis showed slight bias (+0.06%), within a 95% limit of agreement of −2.9% and 3.0%. The coefficient of variation was 5.2%.ConclusionReliable ECV estimation can be achieved with the contrast doses optimized for CCTA. Despite the differing contrast administration schemes and doses, ECV values calculated from the two protocols showed excellent agreement, indicating the robustness of ECV estimation by CT.