OBJECTIVE: This study aims to evaluate image quality in patients with heart rates above or equal to 70 beats per minute (bpm), performed on a 16 cm scanner (256-slice General Electric Revolution) in comparison to a CT scanner with only 4 cm of coverage (64 slice Volume CT). BACKGROUND: Recent advancements in image acquisition, such as whole-heart coverage in a single rotation and post-processing methods in coronary computed tomographic angiography (CCTA), include motion-correction algorithms, such as SnapShot Freeze (SSF), which improve temporal resolution and allow for the assessment of coronary artery disease (CAD) with lower motion scores and better image qualities. Studies from the comprehensive evaluation of high temporal- and spatial-resolution cardiac CT using a wide coverage system (CONVERGE) registry (a multicenter registry at four centers) have shown the 16 cm CT scanner having a better image quality in comparison to the 4 cm scanner. However, these studies failed to include patients with undesirable or high heart rates due to well-documented poor image acquisition on prior generations of CCTA scanners. METHODS: A prospective, observational, multicenter cohort study comparing image quality, quantitively and qualitatively, on scans performed on a 16 cm CCTA in comparison to a cohort of images captured on a 4 cm CCTA at four centers. Participants were recruited based on broad inclusion criteria, and each patient in the 16 cm CCTA arm of the study received a CCTA scan using a 256-slice, whole-heart, single-beat scanner. These patients were then matched by age, gender, and heart rate to patients who underwent CCTA scans on a 4 cm CT scanner. Image quality was graded based on the signal-to-noise ratio, contrast-to-noise ratio, and on a Likert scale of 0-4: 0, very poor-4, excellent. RESULTS: 104 patients were evaluated for this study. The mean heart rate was 75 ± 7 in the 4 cm scanner and 75 ± 7 in the 16 cm one (p = 0.426). The signal-to-noise and contrast-to-noise ratios were higher in the 16 cm scanner (p = 0.0001). In addition, more scans were evaluated as having an excellent quality on the 16 cm scanner than on the 4 cm scanner (p < 0.0001) based on a 4-point Likert scale. CONCLUSIONS: The 16 cm scanner has a superior image quality for fast heart rates compared to the 4 cm scanner. This study shows that there is a significantly higher frequency of excellent and good studies showing better contrast-to-noise and signal-to-noise ratios with the 16 cm scanner compared to the 4 cm scanner.

Computed tomographic coronary artery calcium scanning enables cardiovascular risk stratification; however, exposing patients to high radiation levels is an ongoing concern. New-generation computed tomographic systems use lower radiation doses than older systems do. To quantify comparative doses of radiation exposure, we prospectively acquired images from 220 patients with use of a 64-slice GE LightSpeed VCT scanner (control group, n=110) and a 256-slice GE Revolution scanner (study group, n=110). The groups were matched for age, sex, and body mass index; statistical analysis included t tests and linear regression. The mean dose-length product was 21% lower in the study group than in the control group (60.2 ± 27 vs 75.9 ± 22.6 mGy·cm; P <0.001) and also in each body mass index subgroup. Similarly, the mean effective radiation dose was 21% lower in the study group (0.84 ± 0.38 vs 1.06 ± 0.32 mSv) and lower in each weight subgroup. After adjustment for sex, women in the study group had a lower dose-length product (50.4 ± 23.4 vs 64.7 ± 27.6 mGy·cm) than men did and received a lower effective dose (0.7 ± 0.32 vs 0.9 ± 0.38 mSv) (P=0.009). As body mass index and waist circumference increased, so did doses for both scanners. Our study group was exposed to radiation doses lower than the previously determined standard of 1 mSv, even after adjustment for body mass index and waist circumference. In 256-slice scanning for coronary artery calcium, radiation doses are now similar to those in lung cancer screening and mammography.

Background

The natural history of coronary artery disease (CAD) in patients with low-to-intermediate risk is not well characterized. Although earlier invasive serial studies have documented the progression of atherosclerotic burden, most were focused on high-risk patients only. The PARADIGM registry is a large, prospective, multinational dynamic observational registry of patients undergoing serial coronary computed tomographic angiography (CCTA). The primary aim of PARADIGM is to characterize the natural history of CAD in relation to clinical and laboratory data.

Design

The PARADIGM registry (ClinicalTrials.govNCT02803411) comprises ≥2,000 consecutive patients across 9 cluster sites in 7 countries. PARADIGM sites were chosen on the basis of adequate CCTA volume, site CCTA proficiency, local demographic characteristics, and medical facilities to ensure a broad-based sample of patients. Patients referred for clinically indicated CCTA will be followed up and enrolled if they had a second CCTA scan. Patients will also be followed up beyond serial CCTA performance to identify adverse CAD events that include cardiac and noncardiac death, myocardial infarction, unstable angina, target vessel revascularization, and CAD-related hospitalization.

Summary

The results derived from the PARADIGM registry are anticipated to add incremental insight into the changes in CCTA findings in accordance with the progression or regression of CAD that confer prognostic value beyond demographic and clinical characteristics.

We intended to assess the ability of current-generation 256-slice coronary CT angiography (CCTA) to measure left atrial volume (LAV), comparing patients with a high heart rate (HiHR) of at least 70 bpm and patients with heart rate variability such as atrial fibrillation (AFib). Methods: Using the prospective Converge Registry of patients undergoing 256-detector CCTA on a Revolution scanner, we enrolled 121 HiHR patients (74 men; mean age, 62.7 ± 12.5 y) and 102 AFib patients (72 men; mean age, 60.5 ± 11.0 y) after obtaining informed consent. Quantitative data analysis of LAV was performed using automated methods, and end-systolic phases were chosen for measurements from CCTA. A Student t test, Wilcoxon rank-sum test, or χ² test assessed baseline parameters. Univariate and multivariate linear regression analysis was used to assess LAV and LAV index (LAVI) while adjusting potentially confounding variables. Results: Mean LAV was significantly higher in AFib subjects (148.6 ± 57.2 mL) than in HiHR subjects (102.1 ± 36.5 mL) (P < 0.0001). Similarly, mean LAVI was significantly higher in AFib subjects (72.4 ± 28.1 mL/m²) than in HiHR subjects (51.5 ± 19.0 mL/m²) (P < 0.0001). After adjusting for age, body mass index, sex, diabetes, hypertension, hyperlipidemia, and smoking, subjects with AFib had, on average, LAV measures higher by 41.2 ± 6.7 mL and LAVI values higher by 23.1 ± 3.4 mL/m² (P < 0.0001). Conclusion: Misalignment and motion artifacts in CCTA images affect diagnostic CT performance, especially in patients with elevated heart rates or profound arrhythmia. However, the new-generation Revolution CCTA provides detailed information on left-atrium-complex morphology and function, in addition to coronary anatomy, in HiHR and AFib patients without additional radiation, scanning, or contrast requirements.

Aims

This study explored the coronary plaque volume change (PVC) according to the change of percent body mass index (BMI) and categorical BMI group using serial coronary computed tomography angiography (CCTA).

Methods and results

A total of 1568 subjects who underwent serial CCTA with available BMI at baseline (CCTA1) and follow-up (CCTA2) were included. Median inter-scan period was 3.3 (interquartile range: 2.6-4.6) years. Quantitative assessment of coronary plaque was performed at both scans. All participants were categorized into three BMI (kg/m2) groups: normal: <25.0; overweight: 25.0-29.9; and obesity: ≥30.0. During follow-up, there were no significant differences in annualized PVC according to the 5% change of BMI in all BMI groups. Among 1424 (90.8%) subjects in the same BMI group at CCTA1 and CCTA2, a significant difference in annualized (PVC) was observed among the three groups. In 144 (9.2%) subjects with the change in their BMI group at CCTA2 compared their results at CCTA1, annualized PVC was not different compared with subjects in the same BMI group during follow-up. The percent change of BMI was not significantly related to the annualized PVC after adjusting confounding factors. Male gender [odds ratio (OR): 1.38; 95% confidence interval (CI): 1.05-1.81; P = 0.022], baseline plaque volume (OR: 1.07; 95% CI: 1.05-1.09; P < 0.001), and baseline overweight or obesity (OR: 1.35; 95% CI: 1.04-1.77; P = 0.027) were independently associated with coronary plaque progression.

Conclusion

Over the near term, longitudinal small changes in BMI were not associated with changes in coronary plaque volume although baseline BMI was.

Clinical trial registration

ClinicalTrials.gov NCT02803411.

Background

Diagnosis of coronary artery disease and management strategies have relied solely on the presence of diameter stenosis ≥50%. We assessed whether direct quantification of plaque burden (PB) and plaque characteristics assessed by coronary computed tomography angiography could provide additional value in terms of predicting rapid plaque progression.

Methods and results

From a 13-center, 7-country prospective observational registry, 1345 patients (60.4±9.4 years old; 57.1% male) who underwent repeated coronary computed tomography angiography >2 years apart were enrolled. For conventional angiographic analysis, the presence of stenosis ≥50%, number of vessel involved, segment involvement score, and the presence of high-risk plaque feature were determined. For quantitative analyses, PB and annual change in PB (△PB/y) in the entire coronary tree were assessed. Clinical outcomes (cardiac death, nonfatal myocardial infarction, and coronary revascularization) were recorded. Rapid progressors, defined as a patient with ≥median value of △PB/y (0.33%/y), were older, more frequently male, and had more clinical risk factors than nonrapid progressors (all P<0.05). After risk adjustment, addition of baseline PB improved prediction of rapid progression to each angiographic assessment of coronary artery disease, and the presence of high-risk plaque further improved the predictive performance (all P<0.001). For prediction of adverse outcomes, adding both baseline PB and △PB/y showed best predictive performance (C statistics, 0.763; P<0.001).

Conclusions

Direct quantification of atherosclerotic PB in addition to conventional angiographic assessment of coronary artery disease might be beneficial for improving risk stratification of coronary artery disease.

Clinical trial registration

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02803411.

BACKGROUND:The aim of the study is examine the impact of non-obstructive (<50%stenosis) left main (LM) disease on the natural history of coronary artery disease using serial coronary computed tomography angiography (CTA). METHODS:CTAs from the PARADIGM (Progression of atherosclerotic plaque determined by computed tomographic angiography imaging) study, a prospective multinational registry of patients who underwent serial CTA at a ≥2 year interval were analyzed. Those without evidence of CAD on their baseline scan were excluded, as were those with obstructive left main disease. Coronary artery vessels and their branches underwent quantification of: plaque volume and composition; diameter stenosis; presence of high-risk plaque. RESULTS:Of 944 (62 ± 9 years, 60% male) who had evidence of CAD at baseline, 444 (47%) had LM disease. Those with LM disease had a higher baseline plaque volume (194.8 ± 221mm3 versus 72.9 ± 84.3mm3, p < 0.001) and a higher prevalence of high-risk plaque (17.5% versus 13%, p < 0.001) than those without LM disease. On multivariable general linear model, patients with LM disease had greater annual rates of progression of total (26.5 ± 31.4mm3/yr versus 14.9 ± 20.1mm3/yr, p < 0.001) and calcified plaque volume (17 ± 24mm3/yr versus 7 ± 11mm3/yr, p < 0.001), with no difference in fibrous, fibrofatty or necrotic core plaque components. CONCLUSION:The presence of non-obstructive LM disease is associated with greater rates of plaque progression and a higher prevalence of high-risk plaque throughout the entire coronary artery tree compared to CAD without LM involvement. Our data suggests that non-obstructive LM disease may be a marker for an aggressive phenotype of CAD that may benefit from more intensive treatment strategies.

Objectives

This study sought to describe the impact of statins on individual coronary atherosclerotic plaques.

Background

Although statins reduce the risk of major adverse cardiovascular events, their long-term effects on coronary atherosclerosis remain unclear.

Methods

We performed a prospective, multinational study consisting of a registry of consecutive patients without history of coronary artery disease who underwent serial coronary computed tomography angiography at an interscan interval of ≥2 years. Atherosclerotic plaques were quantitatively analyzed for percent diameter stenosis (%DS), percent atheroma volume (PAV), plaque composition, and presence of high-risk plaque (HRP), defined by the presence of ≥2 features of low-attenuation plaque, positive arterial remodeling, or spotty calcifications.

Results

Among 1,255 patients (60 ± 9 years of age; 57% men), 1,079 coronary artery lesions were evaluated in statin-naive patients (n = 474), and 2,496 coronary artery lesions were evaluated in statin-taking patients (n = 781). Compared with lesions in statin-naive patients, those in statin-taking patients displayed a slower rate of overall PAV progression (1.76 ± 2.40% per year vs. 2.04 ± 2.37% per year, respectively; p = 0.002) but more rapid progression of calcified PAV (1.27 ± 1.54% per year vs. 0.98 ± 1.27% per year, respectively; p < 0.001). Progression of noncalcified PAV and annual incidence of new HRP features were lower in lesions in statin-taking patients (0.49 ± 2.39% per year vs. 1.06 ± 2.42% per year and 0.9% per year vs. 1.6% per year, respectively; all p < 0.001). The rates of progression to >50% DS were not different (1.0% vs. 1.4%, respectively; p > 0.05). Statins were associated with a 21% reduction in annualized total PAV progression above the median and 35% reduction in HRP development.

Conclusions

Statins were associated with slower progression of overall coronary atherosclerosis volume, with increased plaque calcification and reduction of high-risk plaque features. Statins did not affect the progression of percentage of stenosis severity of coronary artery lesions but induced phenotypic plaque transformation. (Progression of AtheRosclerotic PlAque DetermIned by Computed TomoGraphic Angiography Imaging [PARADIGM]; NCT02803411).

Patient-specific phenotyping of coronary atherosclerosis would facilitate personalized risk assessment and preventive treatment. We explored whether unsupervised cluster analysis can categorize patients with coronary atherosclerosis according to their plaque composition, and determined how these differing plaque composition profiles impact plaque progression. Patients with coronary atherosclerotic plaque (n = 947; median age, 62 years; 59% male) were enrolled from a prospective multi-national registry of consecutive patients who underwent serial coronary computed tomography angiography (median inter-scan duration, 3.3 years). K-means clustering applied to the percent volume of each plaque component and identified 4 clusters of patients with distinct plaque composition. Cluster 1 (n = 52), which comprised mainly fibro-fatty plaque with a significant necrotic core (median, 55.7% and 16.0% of the total plaque volume, respectively), showed the least total plaque volume (PV) progression (+ 23.3 mm³), with necrotic core and fibro-fatty PV regression (- 5.7 mm³ and - 5.6 mm³, respectively). Cluster 2 (n = 219), which contained largely fibro-fatty (39.2%) and fibrous plaque (46.8%), showed fibro-fatty PV regression (- 2.4 mm³). Cluster 3 (n = 376), which comprised mostly fibrous (62.7%) and calcified plaque (23.6%), showed increasingly prominent calcified PV progression (+ 21.4 mm³). Cluster 4 (n = 300), which comprised mostly calcified plaque (58.7%), demonstrated the greatest total PV increase (+ 50.7mm³), predominantly increasing in calcified PV (+ 35.9 mm³). Multivariable analysis showed higher risk for plaque progression in Clusters 3 and 4, and higher risk for adverse cardiac events in Clusters 2, 3, and 4 compared to that in Cluster 1. Unsupervised clustering algorithms may uniquely characterize patient phenotypes with varied atherosclerotic plaque profiles, yielding distinct patterns of progressive disease and outcome.

Background

Atherosclerosis-related adverse events are commonly observed even in conditions with low cardiovascular (CV) risk. Longitudinal data regarding the association of normal systolic blood pressure maintenance (SBP_maintain ) with coronary plaque volume changes (PVC) has been limited in adults without traditional CV disease.

Hypothesis

Normal SBP_maintain is important to attenuate coronary atherosclerosis progression in adults without baseline CV disease.

Methods

We analyzed 95 adults (56.7 ± 8.5 years; 40.0% men) without baseline CV disease who underwent serial coronary computed tomographic angiography with mean 3.5 years of follow-up. All participants were divided into two groups of normal SBP_maintain (follow-up SBP < 120 mm Hg) and ≥elevated SBP_maintain (follow-up SBP ≥ 120 mm Hg). Annualized PVC was defined as PVC divided by the interscan period.

Results

Compared to participants with normal SBP_maintain , those with ≥elevated SBP_maintain had higher annualized total PVC (mm³ /year) (0.0 [0.0-2.2] vs. 4.1 [0.0-13.0]; p < .001). Baseline total plaque volume (β = .10) and the levels of SBP_maintain (β = .23) and follow-up high-density lipoprotein cholesterol (β = -0.28) were associated with annualized total PVC (all p < .05). The optimal cutoff of SBP_maintain for predicting plaque progression was 118.5 mm Hg (sensitivity: 78.2%, specificity: 62.5%; area under curve: 0.700; 95% confidence interval [CI]: 0.59-0.81; p < .05). SBP_maintain  ≥ 118.5 mm Hg (odds ratio [OR]: 4.03; 95% CI: 1.51-10.75) and baseline total plaque volume (OR: 1.03; 95% CI: 1.01-1.06) independently influenced coronary plaque progression (all p < .05).

Conclusion

Normal SBP_maintain is substantial to attenuate coronary atherosclerosis progression in conditions without established CV disease.