Prognostic implications of nonobstructive coronary plaques in patients with non-ST-segment elevation myocardial infarction: a multidetector computed tomography study

Prediction of the development of new coronary atherosclerotic plaques with radiomics

BACKGROUND

Radiomics is expected to identify imaging features beyond the human eye. We investigated whether radiomics can identify coronary segments that will develop new atherosclerotic plaques on coronary computed tomography angiography (CCTA).

METHODS

From a prospective multinational registry of patients with serial CCTA studies at ≥ 2-year intervals, segments without identifiable coronary plaque at baseline were selected and radiomic features were extracted. Cox models using clinical risk factors (Model 1), radiomic features (Model 2) and both clinical risk factors and radiomic features (Model 3) were constructed to predict the development of a coronary plaque, defined as total PV ​≥ ​1 ​mm3, at follow-up CCTA in each segment.

RESULTS

In total, 9583 normal coronary segments were identified from 1162 patients (60.3 ​± ​9.2 years, 55.7% male) and divided 8:2 into training and test sets. At follow-up CCTA, 9.8% of the segments developed new coronary plaque. The predictive power of Models 1 and 2 was not different in both the training and test sets (C-index [95% confidence interval (CI)] of Model 1 vs. Model 2: 0.701 [0.690-0.712] vs. 0.699 [0.0.688-0.710] and 0.696 [0.671-0.725] vs. 0.0.691 [0.667-0.715], respectively, all p ​> ​0.05). The addition of radiomic features to clinical risk factors improved the predictive power of the Cox model in both the training and test sets (C-index [95% CI] of Model 3: 0.772 [0.762-0.781] and 0.767 [0.751-0.787], respectively, all p ​< ​00.0001 compared to Models 1 and 2).

CONCLUSION

Radiomic features can improve the identification of segments that would develop new coronary atherosclerotic plaque.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT0280341.

Cardiac Computed Tomography Angiography in the Evaluation of Coronary Artery Disease: An Interventional Perspective

Cardiac computed tomography angiography (CCTA) has become the gold standard for noninvasive anatomic assessment of the coronary arteries. With high positive predictive value and even higher negative predictive value, CCTA allows for rapid determination of the presence or absence of coronary plaque and triage of patients' need for further invasive evaluation and treatment. From an interventional cardiologist's perspective, CCTA (more so than stress testing) is helpful in determining the need for invasive therapy. In conjunction with functional assessments, the anatomic evaluation from CCTA mirrors the anatomical assessment of a coronary angiogram more than any other noninvasive assessment. This allows for catheter selection, percutaneous coronary intervention preplanning, as well as additional decision making before the patient has entered the catheterization laboratory. This manuscript explores some of the more recent developments in noninvasive coronary angiography and discusses the use and utility of CCTA from an interventional cardiologist's perspective.

The importance of nonobstructive plaque characteristics in symptomatic and asymptomatic coronary artery disease

BACKGROUND

We examined obstructive and nonobstructive plaque volumes in populations with subclinical and clinically manifested coronary artery disease (CAD) using quantitative computed tomography (QCT).

METHODS

855 participants with CAD (274 asymptomatic individuals, 254 acute chest pain patients without acute coronary syndrome (ACS), and 327 patients with ACS) underwent QCT of proximal coronary segments to assess participant-level plaque volumes of dense calcium, fibrous, fibrofatty, and necrotic core tissue.

RESULTS

Nonobstructive (<50% stenosis) plaque volumes were greater than obstructive plaque volumes, irrespective of population (all p<0.0001): Asymptomatic individuals (mean (95% CI)): 218 [190-250] vs. 16 [12-22] mm3; acute chest pain patients without ACS: 300 [263-341] vs. 51 [41-62] mm3; patients with ACS: 370 [332-412] vs. 159 [139-182] mm3. After multivariable adjustment, nonobstructive fibrous and fibrofatty tissue volumes were greater in acute chest pain patients without ACS compared to asymptomatic individuals (fibrous tissue: 122 [107-139] vs. 175 [155-197] mm3, p<0.01; fibrofatty tissue: 44 [38-50] vs. 71 [63-80] mm3, p<0.01. Necrotic core tissue was greater in ACS patients (29 [26-33] mm3) compared to both asymptomatic individuals (15 [13-18] mm3, p<0.0001) and acute chest pain patients without ACS (21 [18-24] mm3, p<0.05). Nonobstructive dense calcium volumes did not differ between the three populations: 29 [24-36], 29 [23-35], and 41 [34-48] mm3, p>0.3 respectively.

CONCLUSION

Nonobstructive CAD was the predominant contributor to total atherosclerotic plaque volume in both subclinical and clinically manifested CAD. Nonobstructive fibrous, fibrofatty and necrotic core tissue volumes increased with worsening clinical presentation, while nonobstructive dense calcium tissue volumes did not.

Low-attenuation coronary plaque burden and troponin release in chronic coronary syndrome: A mediation analysis

BACKGROUND

Coronary low-attenuation plaque (LAP) burden is a strong predictor of myocardial infarction in patients with stable chest pain. We aimed to assess the relationship between LAP burden and circulating levels of high-sensitivity cardiac troponin T (hs-cTnT), and to explore the potential underlying etiology in patients undergoing clinically indicated coronary CT angiography (CCTA).

METHODS

A comprehensive metabolic and lipid panel, as well as C-reactive protein (CRP) and hs-cTnT tests were obtained from consecutive patients with stable chest pain at the time of CCTA. Qualitative and quantitative coronary plaque analysis, CT-derived fractional flow reserve (FFR) calculation, and pericoronary adipose tissue (PCAT) attenuation measurement around the right coronary artery were performed on CCTA images. Linear regression analyses were performed to identify independent associations with hs-cTnT concentration and mediation analysis was used to assess whether ischemia or markers of inflammation mediate hs-cTnT elevation.

RESULTS

In total, 114 patients (56.3 ​± ​10.6 years, 44.7 ​% female) were enrolled. In multivariable analysis, age (β ​= ​0.04 [95%CI: 0.02; 0.06], p ​< ​0.001), female sex (β ​= ​-0.77 [95%CI: -1.20; 0.33], p ​< ​0.001), and LAP burden (β ​= ​0.03 [95%CI: 0.001; 0.06], p ​= ​0.04) were independently associated with hs-cTnT levels. Mediation analysis, on the other hand, did not identify a significant mediating effect of lesion-specific ischemia based on CT-FFR, circulating CRP levels, or PCAT values between LAP burden and hs-cTnT levels (all p ​> ​0.05).

CONCLUSION

Although ischemia and inflammation have previously been proposed to mediate the association between LAP burden and hs-cTnT levels, our results did not confirm the role of these pathophysiological pathways in patients with stable chest pain.

Residual Risk in Non-ST-Segment Elevation Acute Coronary Syndrome: Quantitative Plaque Analysis at Coronary CT Angiography

Background Lipid-rich plaques detected with intravascular imaging are associated with adverse cardiovascular events in patients with non-ST-segment elevation (NSTE) acute coronary syndrome (ACS). But evidence about the prognostic implication of coronary CT angiography (CCTA) in NSTE ACS is limited. Purpose To assess whether quantitative variables at CCTA that reflect lipid content in nonrevascularized plaques in individuals with NSTE ACS might be predictors of subsequent nonrevascularized plaque-related major adverse cardiovascular events (MACEs). Materials and Methods In this multicenter prospective cohort study, from November 2017 to January 2019, individuals diagnosed with NSTE ACS (excluding those at very high risk) were enrolled and underwent CCTA before invasive coronary angiography (ICA) within 1 day. Lipid core was defined as areas with attenuation less than 30 HU in plaques. MACEs were defined as cardiac death, myocardial infarction, hospitalization for unstable angina, and revascularization. Participants were followed up at 6 months, 12 months, and annually thereafter for at least 3 years (ending by July 2022). Multivariable analysis using Cox proportional hazards regression models was performed to determine the association between lipid core burden, lipid core volume, and future nonrevascularized plaque-related MACEs at both the participant and plaque levels. Results A total of 342 participants (mean age, 57.9 years ± 11.1 [SD]; 263 male) were included for analysis with a median follow-up period of 4.0 years (IQR, 3.6-4.4 years). The 4-year nonrevascularized plaque-related MACE rate was 23.9% (95% CI: 19.1, 28.5). Lipid core burden (hazard ratio [HR], 12.6; 95% CI: 4.6, 34.3) was an independent predictor at the participant level, with an optimum threshold of 2.8%. Lipid core burden (HR, 12.1; 95% CI: 6.6, 22.3) and volume (HR, 11.0; 95% CI: 6.5, 18.4) were independent predictors at the plaque level, with an optimum threshold of 7.2% and 10.1 mm3, respectively. Conclusion In NSTE ACS, quantitative analysis of plaque lipid content at CCTA independently predicted participants and plaques at higher risk for future nonrevascularized plaque-related MACEs. Chinese Clinical Trial Registry no. ChiCTR1800018661 © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Tavakoli and Duman in this issue.

A Novel Classification for Predicting Chronic Total Occlusion Percutaneous Coronary Intervention

Aims

Chronic total occlusion (CTO) percutaneous coronary intervention (PCI) is characterized by a low success rate and an increase in complications. This study aimed to explore a new and simple classification method based on plaque composition to predict guidewire (GW) crossing within 30 min of CTO lesions.

Methods

This study consecutively enrolled individuals undergoing attempted PCI of CTO who underwent coronary computed tomographic angiography (CCTA) within 2 months. Lesions were divided into soft and hard CTO groups according to the necrotic core proportion.

Results

In this study, 207 lesions were divided into soft (20.3%) and hard CTO (79.7%) groups according to a necrotic core percentage cutoff value of 72.7%. The rate of successful GW crossing within 30 min (57.6 vs. 85.7%, p = 0.004) and final success (73.3 vs. 95.2%, p = 0.001) were much lower in the hard CTO group. For patients with hard CTO, previous failed attempt, proximal side branch, bending > 45 degrees calcium ≥ 50% cross-sectional area (CSA), and distal reference diameter ≤ 2.5 mm were demonstrated to be associated with GW failure within 30 min. For patients with soft CTO, only blunt entry was proved to be an independent predictive factor of GW failure within 30 min.

Conclusions

Grouping CTO lesions according to the proportion of necrotic core is reasonable and necessary in predicting GW crossing within 30 min. A soft CTO with a necrotic core is more likely to be recanalized compared with a hard CTO with fibrous and/or dense calcium. Different plaque types have variable predictive factors.

Examining the Potential for Coronary Artery Calcium (CAC) Scoring for Individuals at Low Cardiovascular Risk

Atherosclerosis is the commonest cause of death in Australia. Cardiovascular (CV) risk calculators have an important role in preventative cardiology, although they are are strongly age-dependent and designed to identify individuals at high risk of an imminent event. The imprecision around "intermediate" or "low" risk generates therapeutic uncertainty, and a significant proportion of patients presenting with myocardial infarction come from these groups, often with no warning. This highlights a conundrum: "Low" risk does not mean "no" risk. A fresh approach may be required to address the clinical conundrum around CV preventative approaches in non-high-risk individuals. While probabilistic calculators do not measure atherosclerosis, calculation of Coronary Artery Calcium (CAC) scores by low-dose computed tomography (CT) can provide a snapshot of atherosclerotic burden. In intermediate-risk individuals, CAC is well-established as an aid to CV risk prediction. Although CAC scoring in low-risk asymptomatic people may be considered controversial, CAC has emerged as the single best predictor of CV events in asymptomatic individuals, independent of traditional risk factor calculators. Therefore, apart from the contribution of age and sex, the somewhat arbitrary distinction between "intermediate" and "low" CV risk using probabilistic calculators may need to be reconsidered. A zero CAC score has a very low future event rate and non-zero CAC scores are associated with a progressive, graded increase in risk as the CAC score rises. In this review, we examine the evidence for CAC screening in low-risk individuals, and propose more widespread use of CAC using simple new model intended to enhance established CV risk prediction equations.

Society of Cardiovascular Computed Tomography / North American Society of Cardiovascular Imaging - Expert Consensus Document on Coronary CT Imaging of Atherosclerotic Plaque

Coronary computed tomographic angiography (CCTA) provides a wealth of clinically meaningful information beyond anatomic stenosis alone, including the presence or absence of nonobstructive atherosclerosis and high-risk plaque features as precursors for incident coronary events. There is, however, no uniform agreement on how to identify and quantify these features or their use in evidence-based clinical decision-making. This statement from the Society of Cardiovascular Computed Tomography and North American Society of Cardiovascular Imaging addresses this gap and provides a comprehensive review of the available evidence on imaging of coronary atherosclerosis. In this statement, we provide standardized definitions for high-risk plaque (HRP) features and distill the evidence on the effectiveness of risk stratification into usable practice points. This statement outlines how this information should be communicated to referring physicians and patients by identifying critical elements to include in a structured CCTA report - the presence and severity of atherosclerotic plaque (descriptive statements, CAD-RADS™ categories), the segment involvement score, HRP features (e.g., low attenuation plaque, positive remodeling), and the coronary artery calcium score (when performed). Rigorous documentation of atherosclerosis on CCTA provides a vital opportunity to make recommendations for preventive care and to initiate and guide an effective care strategy for at-risk patients.

Vulnerable Plaque: A Review of Current Concepts in Pathophysiology and Imaging

Advances in our understanding of the natural history and biology of atherosclerotic vascular disease led to the concept of a vulnerable plaque (VP), which is predisposed toward more rapid progression and acute coronary events. With newer technologies, we now have at our disposal high-quality imaging studies, both invasive and noninvasive, which promise in identifying plaque characteristics that make it more vulnerable. Upcoming trials aim to evaluate the utility of imaging VP in predicting clinical events. We discuss the role of VP imaging in managing atherosclerotic vascular disease.

The role of implantable cardioverter-defibrillators and sudden cardiac death prevention: indications, device selection, and outcome

Multiple randomized multicentre clinical trials have established the role of the implantable cardioverter-defibrillator (ICD) as the mainstay in the treatment of ventricular tachyarrhythmias and sudden cardiac death (SCD) prevention. These trials have focused mainly on heart failure patients with advanced left ventricular dysfunction and were mostly conducted two decades ago, whereas a more recent trial has provided conflicting results. Therefore, much remains to be determined on how best to balance the identification of patients at high risk of SCD together with who would benefit most from ICD implantation in a contemporary setting. Implantable cardioverter-defibrillators have also evolved from the simple, defibrillation-only devices implanted surgically to more advanced technologies of multi-chamber devices, with physiologic bradycardic pacing, including cardiac resynchronization therapy, atrial and ventricular therapeutic pacing algorithms, and subcutaneous ICDs. These multiple options necessitate individualized approach to device selection and programming. This review will focus on the current knowledge on selection of patients for ICD treatment, device selection and programming, and future directions of implantable device therapy for SCD prevention.

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Subclinical Atherosclerosis Imaging in People Living with HIV

In many, but not all studies, people living with HIV (PLWH) have an increased risk of coronary artery disease (CAD) events compared to the general population. This has generated considerable interest in the early, non-invasive detection of asymptomatic (subclinical) atherosclerosis in PLWH. Ultrasound studies assessing carotid artery intima-media thickness (CIMT) have tended to show a somewhat greater thickness in HIV+ compared to HIV-, likely due to an increased prevalence of cardiovascular (CV) risk factors in PLWH. Coronary artery calcification (CAC) determination by non-contrast computed tomography (CT) seems promising to predict CV events but is limited to the detection of calcified plaque. Coronary CT angiography (CCTA) detects calcified and non-calcified plaque and predicts CAD better than either CAC or CIMT. A normal CCTA predicts survival free of CV events over a very long time-span. Research imaging techniques, including black-blood magnetic resonance imaging of the vessel wall and 18F-fluorodeoxyglucose positron emission tomography for the assessment of arterial inflammation have provided insights into the prevalence of HIV-vasculopathy and associated risk factors, but their clinical applicability remains limited. Therefore, CCTA currently appears as the most promising cardiac imaging modality in PLWH for the evaluation of suspected CAD, particularly in patients <50 years, in whom most atherosclerotic coronary lesions are non-calcified.

Volumes of coronary plaque disease in relation to body mass index, waist circumference, truncal fat mass and epicardial adipose tissue in patients with type 2 diabetes mellitus and controls

OBJECTIVES

Coronary atherosclerosis in patients with type 2 diabetes mellitus may be promoted by regional fat distribution. We investigated the association between anthropometric measures of obesity, truncal fat mass, epicardial adipose tissue and coronary atherosclerosis in asymptomatic patients and matched controls.

METHODS

We examined 44 patients and 59 controls [mean (standard deviation) age 64.4 ± 9.9 vs 61.8 ± 9.7, male 50% vs 47%, diabetes duration mean (standard deviation) 7.7 ± 1.5] with coronary computed tomography angiography. Coronary plaques were quantified as total, calcified, non-calcified and low-density non-calcified plaque volumes (mm³). Regional fat distribution was assessed by dual-energy X-ray absorptiometry, body mass index (kg/m²), waist circumference (cm) and epicardial fat volume (mm³). Endothelial function and systemic inflammation were evaluated by peripheral arterial tonometry (log transformed Reactive Hyperemia Index) and C-reactive protein (mg/L).

RESULTS

Body mass index and waist circumference (p < 0.02) were associated with coronary plaque volumes. Body mass index was associated with low-density non-calcified plaque volume after adjustment for age, sex and diabetes status (p < 0.01). Truncal fat mass (p > 0.51), waist circumference (p > 0.06) and epicardial adipose tissue (p > 0.17) were not associated with coronary plaque volumes in adjusted analyses.

CONCLUSION

Body mass index is associated with coronary plaque volumes in diabetic as well as non-diabetic individuals.

Coronary plaque composition assessed by cardiac computed tomography using adaptive Hounsfield unit thresholds

PURPOSE

Quantitative computed tomography (QCT) may be useful in detecting high-risk patients with coronary atherosclerosis. Assessment of plaque composition using fixed Hounsfield unit (HU) thresholds is influenced by luminal contrast density. A method using adaptive HU thresholds has therefore been developed. This study investigates agreement between plaque volumes derived using fixed and adaptive HU thresholds and the influence of luminal contrast density on the determination of plaque composition.

METHODS

We performed QCT in 260 patients with recent acute-onset chest pain without acute coronary syndrome. Plaque volumes of necrotic core (NC), fibrous fatty (FF), fibrous (FI) and dense calcium (DC) tissue were measured in 1161 coronary segments. Agreement between plaque volumes using fixed and adaptive HU thresholds was tested using the Bland-Altman method. Additionally, patients were stratified into tertiles of ascending aortic luminal contrast density and plaque volumes were compared.

RESULTS

Bland-Altman plots revealed that fixed HU thresholds underestimated FI and FF plaque volumes and overestimated NC and DC plaque volumes compared to adaptive HU thresholds. Volumes of dense calcium plaque differed with increasing tertiles of luminal contrast density when using fixed HU thresholds but not when using adaptive HU thresholds: DC for fixed HU thresholds (mm³, median (95%CI)): 7.73 (5.17;12.31), 9.83 (6.55;13.57), 12.02 (8.26;16.24); DC for adaptive HU thresholds (mm³, median (95%CI)): 7.34 (5.12;12.03), 7.78 (5.40;12.61), 8.56 (5.22;12.69).

CONCLUSIONS

Plaque volumes by fixed and adaptive HU thresholds differed. Plaque volumes by adaptive HU thresholds were more independent of luminal contrast density for higher attenuation tissues compared to fixed HU thresholds.

Reduced artifacts and improved diagnostic value of 640-slice computed tomography in patients with cardiac pacemakers

Objective

The aim of this study was to compare the feasibility of 640-slice with 64-slice computed tomography (CT) coronary angiography for diagnosing coronary lesions in patients with pacemakers.

Methods

Forty-five and 50 patients with pacemakers and with suspected or known coronary artery disease underwent 64-slice (64 group) and 640-slice (640 group) CT scans, respectively. All segments of the vessels were evaluated according to the 15-segment model recommended by the American Heart Association.

Results

The incidence of moderate or severe artifacts was significantly lower (7.27% vs. 32.17%) and the diagnosable rate for coronary lesions was higher (98.91% vs. 94.19%) in the 640 compared with the 64 group. In the 64 group, the incidence of artifacts in patients with a heart rate >65 bpm (20.98%) was higher than in those with a heart rate <65 bpm (15.67%), although the difference was not significant, while the incidence of artifacts was significantly higher in patients with heart arrhythmia (21.40%) compared with in those with normal heart rhythm (15.09%).

Conclusions

Among patients with pacemakers and a higher heart rate or heart arrhythmia, 640-slice CT may be more effective than 64-slice CT for diagnosing coronary lesions, by reducing moderate and severe artifacts.

Reproducibility of quantitative coronary computed tomography angiography in asymptomatic individuals and patients with acute chest pain

Purpose

Quantitative computed tomography (QCT) provides important prognostic information of coronary atherosclerosis. We investigated intraobserver and interobserver QCT reproducibility in asymptomatic individuals, patients with acute chest pain without acute coronary syndrome (ACS), and patients with acute chest pain and ACS.

Methods

Fifty patients from each cohort, scanned between 01/02/2010-14/11/2013 and matched according to age and gender, were retrospectively assessed for inclusion. Patients with no coronary artery disease, previous coronary artery bypass graft surgery, and poor image quality were excluded. Coronary atherosclerosis was measured semi-automatically by 2 readers. Reproducibility of minimal lumen area (MLA), minimal lumen diameter (MLD), area stenosis, diameter stenosis, vessel remodeling, plaque eccentricity, plaque burden, and plaque volumes was assessed using concordance correlation coefficient (CCC), Bland-Altman, coefficient of variation, and Cohen’s kappa.

Results

A total of 84 patients (63 matched) were included. Intraobserver and interobserver reproducibility estimates were acceptable for MLA (CCC = 0.94 and CCC = 0.91, respectively), MLD (CCC = 0.92 and CCC = 0.86, respectively), plaque burden (CCC = 0.86 and CCC = 0.80, respectively), and plaque volume (CCC = 0.97 and CCC = 0.95, respectively). QCT detected area and diameter stenosis ≥50%, positive remodeling, and eccentric plaque with moderate-good intraobserver and interobserver reproducibility (kappa: 0.64–0.66, 0.69–0.76, 0.46–0.48, and 0.41–0.62, respectively). Reproducibility of plaque composition decreased with decreasing plaque density (intraobserver and interobserver CCC for dense calcium (>0.99; 0.98), fibrotic (0.96; 0.93), fibro-fatty (0.95; 0.91), and necrotic core tissue (0.89; 0.84). Reproducibility generally decreased with worsening clinical risk profile.

Conclusions

Semi-automated QCT of coronary plaque morphology is reproducible, albeit with some decline in reproducibility with worsening patient risk profile.

Relationship between patient presentation and morphology of coronary atherosclerosis by quantitative multidetector computed tomography

Aims

Quantitative computed tomography (QCT) allows assessment of morphological features of coronary atherosclerosis. We aimed to test the hypothesis that clinical patient presentation is associated with distinct morphological features of coronary atherosclerosis.

Methods and results

A total of 1652 participants, representing a spectrum of clinical risk profiles [787 asymptomatic individuals from the general population, 468 patients with acute chest pain without acute coronary syndrome (ACS), and 397 patients with acute chest pain and ACS], underwent multidetector computed tomography. Of these, 274 asymptomatic individuals, 254 patients with acute chest pain without ACS, and 327 patients with acute chest pain and ACS underwent QCT to assess coronary plaque volumes and proportions of dense calcium (DC), fibrous, fibro fatty (FF), and necrotic core (NC) tissue. Furthermore, the presence of vulnerable plaques, defined by plaque volume and tissue composition, was examined. Coronary plaque volume increased significantly with worsening clinical risk profile [geometric mean (95% confidence interval): 148 (129–166) mm3, 257 (224–295) mm3, and 407 (363–457) mm3, respectively, P < 0.001]. Plaque composition differed significantly across cohorts, P < 0.0001. The proportion of DC decreased, whereas FF and NC increased with worsening clinical risk profile (mean proportions DC: 33%, 23%, 23%; FF: 50%, 61%, 57%; and NC: 17%, 17%, 20%, respectively). Significant differences in plaque composition persisted after multivariable adjustment for age, gender, body surface area, hypertension, statin use at baseline, diabetes, smoking, family history of ischaemic heart disease, total plaque volume, and tube voltage, P < 0.01.

Conclusion

Coronary atherosclerotic plaque volume and composition are strongly associated to clinical presentation.

Multicenter AIDS Cohort Study Quantitative Coronary Plaque Progression Study: rationale and design

BACKGROUND AND AIM

The association of HIV with coronary atherosclerosis has been established; however, the progression of coronary atherosclerosis over time among participants with HIV is not well known. The Multicenter AIDS Cohort Study Quantitative Coronary Plaque Progression Study is a large prospective multicenter study quantifying progression of coronary plaque assessed by serial coronary computed tomography angiography (CTA).

PATIENTS AND METHODS

HIV-infected and uninfected men who were enrolled in the Multicenter AIDS Cohort Study Cardiovascular Substudy were eligible to complete a follow-up contrast coronary CTA 3-6 years after baseline. We measured coronary plaque volume and characteristics (calcified and noncalcified plaque including fibrous, fibrous-fatty, and low attenuation) and vulnerable plaque among HIV-infected and uninfected men using semiautomated plaque software to investigate the progression of coronary atherosclerosis over time.

CONCLUSION

We describe a novel, large prospective multicenter study investigating incidence, transition of characteristics, and progression in coronary atherosclerosis quantitatively assessed by serial coronary CTAs among HIV-infected and uninfected men.

Increased high-risk coronary plaque burden is associated with arterial stiffness in patients with type 2 diabetes without clinical signs of coronary artery disease: a computed tomography angiography study

OBJECTIVES

Arterial stiffness and subclinical coronary atherosclerosis may yield valuable information on cardiovascular risk. We aimed to characterize coronary atherosclerosis in asymptomatic patients with type 2 diabetes and healthy controls and to investigate the association between baseline arterial stiffness and coronary plaque volumes after 5-year follow-up.

METHODS

Data from 45 patients and 61 matched controls were available for coronary plaque assessment. For analysis including carotid-femoral pulse wave velocity (PWV), 43 patients and 55 controls were available. At follow-up, mean (SD) age of participants was 63 ± 10 years, and mean diabetes duration (SD) in the patient group was 7.8 ± 1.4 years. Arterial stiffness (PWV) was assessed by tonometry at both visits. Total, calcified, noncalcified, low-density noncalcified coronary plaques volumes and other plaque characteristics were assessed by coronary computed tomography angiography at follow-up.

RESULTS

Despite of similar or better blood pressure and plasma lipid control, patients had, compared with controls, a higher number of plaques with spotty calcifications (P < 0.01) and remodeling index more than 1.1 (P < 0.05), larger calcified plaque volumes [patients vs.

CONTROLS

11 (0-65) vs. 3 (0-30) μl (P = 0.03)] and higher PWV [patients vs. controls at baseline: 9.1 ± 2.2 vs. 7.9 ± 1.4 m/s (P < 0.01), at follow-up: 9.3 ± 2.3 vs. 8.4 ± 1.8 m/s (P = 0.02)]. Baseline PWV was associated with volumes of all plaque types in crude analysis (P < 0.01) and with low-density noncalcified plaque volume in analysis adjusted for age, sex, diabetes and blood pressure (P = 0.01).

CONCLUSION

Coronary plaques with unfavorable characteristics are more prevalent in well controlled asymptomatic patients with type 2 diabetes compared with healthy controls and independently associated with arterial stiffness.Clinical trials registration number: NCT02001532.

Bridging the gap for lipid lowering therapy: plaque regression, coronary computed tomographic angiography, and imaging-guided personalized medicine

INTRODUCTION

Lipid-lowering therapy effectively decreases cardiovascular risk on a population level, but it remains difficult to identify an individual patient's personal risk reduction while following guideline directed medical therapy, leading to overtreatment in some patients and cardiovascular events in others. Recent improvements in cardiac CT technology provide the ability to directly assess an individual's atherosclerotic disease burden, which has the potential to personalize risk assessment for lipid-lowering therapy. Areas covered: We review the current unmet need in identifying patients at elevated residual risk despite guideline directed medical therapy, the evidence behind plaque regression as a potential marker of therapeutic response, and highlight state-of-the-art advances in coronary computed tomographic angiography (CCTA) for measurement of quantitative and qualitative changes in coronary atherosclerosis over time. Literature search was performed using PubMed and Google Scholar for literature relevant to statin therapy and residual risk, coronary plaque regression measurement, and CCTA assessment of quantitative and qualitative change in coronary atherosclerosis. Expert commentary: We discuss the potential ability of CCTA to guide lipid-lowering therapy as a bridge between population and personalized medicine in the future, as well as the potential barriers to its use.

Incremental Prognostic Value of Quantified Vulnerable Plaque by Cardiac Computed Tomography: A Pilot Study

BACKGROUND

Coronary computed tomography (CT) angiography (CCTA) has the ability to detect, characterize, and quantify atherosclerotic plaques. The aim of our study was to evaluate the prognostic power of CCTA-quantified plaque subtypes.

MATERIALS AND METHODS

A total of 36 patients with adverse events and 36 Morise score-matched patients who remained event free on follow-up were identified. Using CCTA images, plaque subtype volumes in the major epicardial arteries were analyzed using predetermined attenuation ranges in Hounsfield units (HU): 1 to 30 HU (low attenuating), 31 to 70 HU (intermediate attenuating), 71 to 150 HU (high attenuating), and mean coronary lumen+2 SD to 1000 HU (calcified). Each epicardial artery was divided into proximal, mid, and distal segments, and plaque volumes were normalized for arterial segment length.

RESULTS

The baseline characteristics of the 2 cohorts were similar. Low-attenuation and intermediate-attenuation plaque volumes were greater in the proximal segments as well as in the entire length in the adverse event compared with the event-free group. High-attenuation plaque volume was increased only in the proximal segments in the adverse event group. There was no difference in the volume of calcified plaque between the 2 groups. The log rank test using a cutoff of 3.99 mm/mm for combined intermediate and low plaque volume showed more adverse events in patients with a plaque volume of ≥3.99 mm/mm.

CONCLUSIONS

Adverse events appear to be associated with greater volumes of low-attenuation and intermediate-attenuation plaques that reflect lipid and fibrous atherosclerosis. The difference between the 2 groups is most apparent in the proximal epicardial arteries.

Early Detection and Treatment of the Vulnerable Coronary Plaque

Early identification and treatment of the vulnerable plaque, that is, a coronary artery lesion with a high likelihood of rupture leading to an acute coronary syndrome, have gained great interest in the cardiovascular research field. Postmortem studies have identified clear morphological characteristics associated with plaque rupture. Recent advances in invasive and noninvasive coronary imaging techniques have empowered the clinician to identify suspected vulnerable plaques in vivo and paved the way for the evaluation of therapeutic agents targeted at reducing plaque vulnerability. Local treatment of vulnerable plaques by percutaneous coronary intervention and systemic treatment with anti-inflammatory and low-density lipoprotein–lowering drugs are currently being investigated in large randomized clinical trials to assess their therapeutic potential for reducing adverse coronary events. Results from these studies may enable a more patient-tailored strategy for the treatment of coronary artery disease.

Long-term prognostic implication of coronary plaque characterization as detected by 64-multidetector computed tomography in Egyptian population

OBJECTIVES

We aimed to determine the role of multi-detector computed tomography (MDCT) in prognosis of patients with known or suspected coronary artery disease (CAD) by applying plaque characterization and whether obstructive versus non-obstructive plaque volume is a predictor of future cardiac events.

BACKGROUND

Vulnerable plaques may occur across the full spectrum of severity of stenosis, underlining that also non-obstructive lesions may contribute to coronary events.

METHODS

We included 1000 consecutive patients with intermediate pretest likelihood of CAD who were evaluated by 64-MDCT. Coronary artery calcium scoring, assessment of degree of coronary stenosis and quantitative assessment of plaque composition and volume were performed. The end point was cardiac death, acute coronary syndrome, or symptom-driven revascularization.

RESULTS

After a median follow-up of 16 months, 190 patients had suffered cardiac events. In a multivariate regression analysis for events, the total amount of non-calcified plaque (NCP) in non-obstructive lesions was independently associated with an increased hazard ratio for non-fatal MI (1.01-1.9/100-mm3 plaque volume increase, p = 0.039), total amount of obstructive plaque was independently associated with symptoms driven revascularization (p = 0.04) and coronary artery calcium scoring (CACS) was independently associated with cardiac deaths (p = 0.001).

CONCLUSION

MDCT is a non-invasive imaging modality with a prognostic utility in patients with known or suspected coronary artery disease by applying plaque characterization and it could identify vulnerable plaques by measuring the total amount of NCP in non-obstructive lesions which could be useful for detecting patients at risk of acute coronary syndrome (ACS) and guide further preventive therapeutic strategies. CACS was shown to be an independent predictor of mortality, while total amount of obstructive volume was shown to be an independent predictor of symptoms driven revascularization.

Coronary Computed Tomography Angiography-Derived Plaque Quantification in Patients With Acute Coronary Syndrome

This study investigated the discriminatory value of quantitative atherosclerotic plaque markers derived from coronary computed tomography angiography (cCTA) in patients with first acute coronary syndrome (ACS) compared with patients with stable coronary artery disease (CAD). Forty patients (56.9 ± 9.3 years, 55% men) admitted with their first ACS and Framingham risk score-matched controls with stable CAD were retrospectively analyzed. All patients had undergone cCTA followed by invasive coronary angiography. Total plaque volume, calcified and noncalcified plaque volumes, plaque burden (in %), remodeling index, lesion length, presence of napkin-ring sign, segment involvement score, and segment stenosis score were derived from cCTA and compared between both groups on a per-lesion and per-patient level. Patients with ACS showed a significant higher number of obstructive CAD and higher values for segment stenosis score, segment involvement score, noncalcified plaque volume, lesion length, and remodeling index than the stable angina group (all p <0.05). On a per-lesion level, culprit lesions had significantly higher values for plaque burden, total plaque volume, noncalcified plaque volume, remodeling index, lesion length, and prevalence of napkin-ring sign in comparison to nonculprit lesions (all p <0.05). On receiver-operating characteristics (ROC) analysis, a stepwise model demonstrated incremental discriminatory power for identifying ACS both per-patient (area under the curve 0.92, p <0.0001) as well as per-lesion (area under the curve 0.88, p <0.0001). cCTA-derived culprit plaque markers show discriminatory value both on a per-patient and per-lesion level. A combination of markers added to the Framingham risk score yields the greatest discriminatory ability.

Plaque progression assessed by a novel semi-automated quantitative plaque software on coronary computed tomography angiography between diabetes and non-diabetes patients: A propensity-score matching study

BACKGROUND AND AIMS

We aimed at investigating whether diabetes is associated with progression in coronary plaque components.

METHODS

We identified 142 study subjects undergoing serial coronary computed tomography angiography. The resulting propensity score was applied 1:1 to match diabetic patients to non-diabetic patients for clinical risk factors, prior coronary stenting, coronary artery calcium (CAC) score and the serial scan interval, resulting in the 71 diabetes and 71 non-diabetes patients. Coronary plaque (total, calcified, non-calcified including fibrous, fibrous-fatty and low attenuation plaque [LAP]) volume normalized by total coronary artery length was measured using semi-automated plaque software and its change overtime between diabetic and non-diabetic patients was evaluated.

RESULTS

The matching was successful without significant differences between the two groups in all matched variables. The baseline volumes in each plaque also did not differ. During a mean scan interval of 3.4 ± 1.8 years, diabetic patients showed a 2-fold greater progression in normalized total plaque volume (TPV) than non-diabetes patients (52.8 mm³vs. 118.3 mm³, p = 0.005). Multivariable linear regression model revealed that diabetes was associated with normalized TPV progression (β 72.3, 95%CI 24.3-120.3). A similar trend was observed for the non-calcified components, but not calcified plaque (β 3.8, 95%CI -27.0-34.7). Higher baseline CAC score was found to be associated with total, non-calcified and calcified plaque progression. However, baseline non-calcified volume but not CAC score was associated with LAP progression.

CONCLUSIONS

The current study among matched patients indicates diabetes is associated with a greater plaque progression. Our results show the need for strict adherence of diabetic patients to the current preventive guidelines.

Effects of statin therapy on progression of mild noncalcified coronary plaque assessed by serial coronary computed tomography angiography: A multicenter prospective study

BACKGROUND

There are limited data assessing statin therapy in patients with nonobstructive coronary plaque on coronary computed tomography angiography (CCTA).

METHODS

Two hundred six consecutive patients with mild noncalcified plaque on CCTA were enrolled in this multicenter prospective observational study. Subjects were divided into 3 groups according to subsequent statin therapy: intensive statin therapy (n = 55), moderate statins (n = 85), and no statin (n = 66). Serial scans were performed after a median interval of 18 months. Low-attenuation plaque (LAP) volume, total plaque volume, and percent plaque volume were measured.

RESULTS

The LAP volume, total plaque volume, and percent plaque volume showed significant regression among intensive-statin compared with no-statin group (annualized changes: -7.1 ± 13.1 vs 0.9 ± 12.7 mm(3), P< .001; -16.4 ± 35.0 vs 12.3 ± 32.4 mm(3), P< .001; and -6.2% ± 11.8% vs 3.5% ± 12.1%, P< .001, respectively). Progression of LAP volume, total plaque volume, and percent plaque volume was retarded among moderate-statin compared with no-statin group (annualized changes: -2.8 ± 7.6 vs 0.9 ± 12.7 mm(3), P= .041; -0.1 ± 25.6 vs 12.3 ± 32.4 mm(3), P= .014; and -1.8% ± 11.2% vs 3.5% ± 12.1%, P= .006, respectively). On multivariable model predicting change in total plaque volume, higher baseline LAP volume, moderate statin therapy, and intensive statin therapy were each independent predictors of plaque regression (standardized coefficients: baseline LAP volume -0.36, P< .001; moderate statin -0.21, P= .004; intensive statin -0.36, P< .001, respectively).

CONCLUSIONS

This study suggests that statin treatment can retard progression and even induce regression of mild noncalcified coronary plaque. Patients with greater baseline LAP volume are more likely to benefit from statin therapy.

Reproducibility of coronary atherosclerotic plaque characteristics in populations with low, intermediate, and high prevalence of coronary artery disease by multidetector computer tomography: a guide to reliable visual coronary plaque assessments

To evaluate the interobserver agreement of visual coronary plaque characteristics by 320-slice multidetector computed tomography (MDCT) in three populations with low, intermediate and high CAD prevalence and to identify determinants for the reproducible assessment of these plaque characteristics. 150 patients, 50 asymptomatic subjects from the general population (low CAD prevalence), 50 symptomatic non-acute coronary syndrome (non-ACS) patients (intermediate CAD prevalence), and 50 ACS patients (high CAD prevalence), matched according to age and gender, were retrospectively enrolled. All coronary segments were evaluated for overall image quality, evaluability, presence of CAD, coronary stenosis, plaque composition, plaque focality, and spotty calcification by four readers. Interobserver agreement was assessed using Fleiss' Kappa (κ) and intra-class correlation (ICC). Widely used clinical parameters (overall scan quality, presence of CAD, and determination of coronary stenosis) showed good agreement among the four readers, (ICC = 0.66, κ = 0.73, ICC = 0.74, respectively). When accounting for heart rate, body mass index, plaque location, and coronary stenosis above/below 50 %, interobserver agreement for plaque composition, presence of CAD, and coronary stenosis improved to either good or excellent, (κ = 0.61, κ = 0.81, ICC = 0.78, respectively). Spotty calcification was the least reproducible parameter investigated (κ = 0.33). Across subpopulations, reproducibility of coronary plaque characteristics generally decreased with increasing CAD prevalence except for plaque composition, (limits of agreement: ±2.03, ±1.96, ±1.79 for low, intermediate and high CAD prevalence, respectively). 320-slice MDCT can be used to assess coronary plaque characteristics, except for spotty calcification. Reproducibility estimates are influenced by heart rate, body size, plaque location, and degree of luminal stenosis.

SYNTAX score-0 patients: risk stratification in nonobstructive coronary artery disease

BACKGROUND

The complexity of coronary artery disease (CAD) is a predictor of cardiovascular events in patients with >50 % diameter stenosis as determined by SYNTAX score. Here, we compare the Gensini score to SYNTAX in patients with CAD as well as apply the Gensini score in patients with nonobstructive CAD (NOB-CAD), defined by ≤50 % diameter stenosis, were the SYNTAX score cannot be utilized to define future risk.

METHODS

The AtheroGene study enrolled 2316 patients [861/37.2 % with acute cardiovascular syndrome (ACS) and 1500/62.8 % with stable CAD (SCAD)]. Of these, 1966 had obstructive CAD (OB-CAD) with SYNTAX and Gensini scores available and 291 events with either cardiovascular mortality or non-fatal myocardial infarction were recorded. Furthermore, 350 patients had NOB-CAD with only Gensini score and 36 events. Median follow-up time was 4.9 years.

RESULTS

In the OB-CAD cohort the SYNTAX and the Gensini score predicted outcome. Kaplan-Meier curve analysis with the dichotomized Gensini score showed a significant result (p = 0.04) in the NOB-CAD cohort. Cox Regression analysis after adjustment showed a hazard ratio (HR) of 1.33 and p = 0.04 for the Gensini score in the NOB-CAD cohort. Receiver operating characteristic curve (ROC) analysis provided the highest area under the curve (AUC) regarding the outcome for the Gensini score with 0.65 (p = 0.004). Comparing the SYNTAX and Gensini score in this cohort showed improved discrimination of patients with events by the Gensini score (p = 0.02).

CONCLUSION

The Gensini score predicted events in patients with ≤50 % diameter lesions. Utilization of this score is useful to define risk in NOB-CAD patients.

Sudden Cardiac Death Risk Stratification - An Update

Sudden cardiac death (SCD) remains a major public health problem worldwide, yet current methods to identify those at greatest risk are inadequate. High-risk individuals may benefit from potentially life-saving treatment, such as insertion of an implantable-cardioverter defibrillator (ICD). However, such treatments are expensive and have their own associated risks. Furthermore, most cases of SCD occur in the general adult population who may be relatively asymptomatic but yet have an underlying predisposition to SCD. Hence, there is great interest and clinical need in improving methods for risk stratification of SCD to identify those at greatest risk and implement the most appropriate treatment. This review provides an update on current risk-stratification methods for SCD in high-risk groups, in particular patients with reduced left ventricular function following acute myocardial infarction and those with non-ischaemic dilated cardiomyopathy, and highlights some novel methods that may have a role to play in future risk-stratification schemes. Approaches and challenges for SCD risk stratification among the general public are also discussed.

Computed tomography-based high-risk coronary plaque score to predict acute coronary syndrome among patients with acute chest pain--Results from the ROMICAT II trial

BACKGROUND

Coronary computed tomography angiography (CTA) can be used to detect and quantitatively assess high-risk plaque features.

OBJECTIVE

To validate the ROMICAT score, which was derived using semi-automated quantitative measurements of high-risk plaque features, for the prediction of ACS.

MATERIAL AND METHODS

We performed quantitative plaque analysis in 260 patients who presented to the emergency department with suspected ACS in the ROMICAT II trial. The readers used a semi-automated software (QAngio, Medis medical imaging systems BV) to measure high-risk plaque features (volume of <60HU plaque, remodeling index, spotty calcium, plaque length) and diameter stenosis in all plaques. We calculated a ROMICAT score, which was derived from the ROMICAT I study and applied to the ROMICAT II trial. The primary outcome of the study was diagnosis of an ACS during the index hospitalization.

RESULTS

Patient characteristics (age 57 ± 8 vs. 56 ± 8 years, cardiovascular risk factors) were not different between those with and without ACS (prevalence of ACS 7.8%). There were more men in the ACS group (84% vs. 59%, p = 0.005). When applying the ROMICAT score derived from the ROMICAT I trial to the patient population of the ROMICAT II trial, the ROMICAT score (OR 2.9, 95% CI 1.4-6.0, p = 0.003) was a predictor of ACS after adjusting for gender and ≥ 50% stenosis. The AUC of the model containing ROMICAT score, gender, and ≥ 50% stenosis was 0.91 (95% CI 0.86-0.96) and was better than with a model that included only gender and ≥ 50% stenosis (AUC 0.85, 95%CI 0.77-0.92; p = 0.002).

CONCLUSIONS

The ROMICAT score derived from semi-automated quantitative measurements of high-risk plaque features was an independent predictor of ACS during the index hospitalization and was incremental to gender and presence of ≥ 50% stenosis.

Atherosclerotic plaque characteristics by CT angiography identify coronary lesions that cause ischemia: a direct comparison to fractional flow reserve

OBJECTIVES

This study evaluated the association between atherosclerotic plaque characteristics (APCs) by coronary computed tomographic angiography (CTA), and lesion ischemia by fractional flow reserve (FFR).

BACKGROUND

FFR is the gold standard for determining lesion ischemia. Although APCs by CTA-including aggregate plaque volume % (%APV), positive remodeling (PR), low attenuation plaque (LAP), and spotty calcification (SC)-are associated with future coronary syndromes, their relationship to lesion ischemia is unclear.

METHODS

252 patients (17 centers, 5 countries; mean age 63 years; 71% males) underwent coronary CTA, with FFR performed for 407 coronary lesions. Coronary CTA was interpreted for <50% and ≥50% stenosis, with the latter considered obstructive. APCs by coronary CTA were defined as: 1) PR, lesion diameter/reference diameter >1.10; 2) LAP, any voxel <30 Hounsfield units; and 3) SC, nodular calcified plaque <3 mm. Odds ratios (OR) and net reclassification improvement of APCs for lesion ischemia, defined by FFR ≤0.8, were analyzed.

RESULTS

By FFR, ischemia was present in 151 lesions (37%). %APV was associated with a 50% increased risk of ischemia per 5% additional APV. PR, LAP, and SC were associated with ischemia, with a 3 to 5 times higher prevalence than in nonischemic lesions. In multivariable analyses, a stepwise increased risk of ischemia was observed for 1 (OR: 4.0, p < 0.001) and ≥2 (OR: 12.1, p < 0.001) APCs. These findings were APC dependent, with PR (OR: 5.3, p < 0.001) and LAP (OR: 2.1, p = 0.038) associated with ischemia, but not SC. When examined by stenosis severity, PR remained a predictor of ischemia for all lesions, whereas %APV and LAP were associated with ischemia for only ≥50%, but not for <50%, stenosis.

CONCLUSIONS

%APV and APCs by coronary CTA improve identification of coronary lesions that cause ischemia. PR is associated with all ischemia-causing lesions, whereas %APV and LAP are only associated with ischemia-causing lesions ≥50%. (Determination of Fractional Flow Reserve by Anatomic Computed Tomographic Angiography; NCT01233518).

Incremental prognostic value of coronary computed tomographic angiography high-risk plaque characteristics in newly symptomatic patients

BACKGROUND

The incremental prognostic value of the plaque features in coronary computed tomographic angiography (CTA) has not been well assessed. This study was designed to determine whether CTA high-risk plaques have prognostic value incremental to the Framingham risk score (FRS) and the severity of luminal obstruction.

METHODS

A total of 628 newly symptomatic patients without known coronary artery disease underwent CTA. They were followed for a median of 677 days during which there were 26 cardiac events, including cardiac death, acute myocardial infarction, and hospitalization for unstable angina. Incremental prognostic value of adding plaque characteristics to the number of diseased vessels and the FRS was evaluated using 3 Cox models and net reclassification indexes.

RESULTS

The discrimination index was significantly increased by adding the number of diseased vessels to the FRS (change in c-statistic from 65.8% to 78.6%, p=0.028) but not significantly by further adding plaque characteristics (change in c-statistic from 78.6% to 80.0%, p=0.812). However, improved model-fitting by adding plaque characteristics into the linear combination with risk score and the number of diseased vessels (p=0.007 from likelihood ratio test) and the lowest value of Akaike's information criteria of that model indicated that plaque characteristics improved both predictive accuracy and discrimination perspective. More subjects reclassified by plaque characteristics were moved to directions consistent with their subsequent cardiac event status than in an inconsistent direction.

CONCLUSIONS

Evaluation of CTA plaque characteristics may provide incremental prognostic value to the number of diseased vessels and the FRS.

Near-Infrared Spectroscopy Enhances Intravascular Ultrasound Assessment of Vulnerable Coronary Plaque: A Combined Pathological and In Vivo Study

OBJECTIVES

Pathological studies demonstrate the dual significance of plaque burden (PB) and lipid composition for mediating coronary plaque vulnerability. We evaluated relationships between intravascular ultrasound (IVUS)-derived PB and arterial remodeling with near-infrared spectroscopy (NIRS)-derived lipid content in ex vivo and in vivo human coronary arteries.

APPROACH AND RESULTS

Ex vivo coronary NIRS and IVUS imaging was performed through blood in 116 coronary arteries of 51 autopsied hearts, followed by 2-mm block sectioning (n=2070) and histological grading according to modified American Heart Association criteria. Lesions were defined as the most heavily diseased 2-mm block per imaged artery on IVUS. IVUS-derived PB and NIRS-derived lipid core burden index (LCBI) of each block and lesion were analyzed. Block-level analysis demonstrated significant trends of increasing PB and LCBI across more complex atheroma (Ptrend <0.001 for both LCBI and PB). Lesion-based analyses demonstrated the highest LCBI and remodeling index within coronary fibroatheroma (Ptrend <0.001 and 0.02 versus all plaque groups, respectively). Prediction models demonstrated similar abilities of PB, LCBI, and remodeling index for discriminating fibroatheroma (c indices: 0.675, 0.712, and 0.672, respectively). A combined PB+LCBI analysis significantly improved fibroatheroma detection accuracy (c index 0.77, P=0.028 versus PB; net-reclassification index 43%, P=0.003), whereas further adding remodeling index did not (c index 0.80, P=0.27 versus PB+LCBI). In vivo comparisons of 43 age- and sex-matched patients (to the autopsy cohort) undergoing combined NIRS-IVUS coronary imaging yielded similar associations to those demonstrated ex vivo.

CONCLUSIONS

Adding NIRS to conventional IVUS-derived PB imaging significantly improves the ability to detect more active, potentially vulnerable coronary atheroma.

Prognostic Value of Coronary Computed Tomography (CT) Angiography and Coronary Artery Calcium Score Performed Before Revascularization

BACKGROUND

Cardiac events after revascularization are equally attributable to recurrence at site of culprit lesions and development of nonculprit lesions. We evaluated the hypothesis that coronary computed tomography (CT) angiography and coronary artery calcium score (CACS) performed before revascularization predicts cardiac events after treatment.

METHODS AND RESULTS

Among 2238 consecutive patients without known coronary artery disease who underwent coronary CT angiography and CACS, 359 patients underwent revascularization within 30 days after CT; in 337 of 359 (93.9%) follow-up clinical information was available. In addition to known cardiac risk factors, CT findings were evaluated as predictors of cardiac events after revascularization: CACS and the presence of CT-verified high-risk plaque (CT-HRP). Improvement of predictive accuracy by including CT findings was evaluated from a discrimination (Harrell's C-statistics) standpoint. During the follow-up period (median: 673, interquartile range: 47 to 1529 days), a total of 98 cardiac events occurred. Cox proportional hazard model revealed that age, diabetes, triglyceride, CACS, and nonculprit CT-HRP were significant predictors of overall cardiac events. Although not statistically significant, discriminatory power was greater for the model with CACS (C-stat: 63.2%) and the model with both CACS and CT-HRP (65.8%) compared to the model including neither CACS nor CT-HRP (60.7%).

CONCLUSIONS

High CACS and the presence of nonculprit CT-HRP performed before revascularization are significant predictors of cardiac events after revascularization.

Sudden cardiac death risk stratification

Arrhythmic sudden cardiac death (SCD) may be caused by ventricular tachycardia/fibrillation or pulseless electric activity/asystole. Effective risk stratification to identify patients at risk of arrhythmic SCD is essential for targeting our healthcare and research resources to tackle this important public health issue. Although our understanding of SCD because of pulseless electric activity/asystole is growing, the overwhelming majority of research in risk stratification has focused on SCD-ventricular tachycardia/ventricular fibrillation. This review focuses on existing and novel risk stratification tools for SCD-ventricular tachycardia/ventricular fibrillation. For patients with left ventricular dysfunction or myocardial infarction, advances in imaging, measures of cardiac autonomic function, and measures of repolarization have shown considerable promise in refining risk. Yet the majority of SCD-ventricular tachycardia/ventricular fibrillation occurs in patients without known cardiac disease. Biomarkers and novel imaging techniques may provide further risk stratification in the general population beyond traditional risk stratification for coronary artery disease alone. Despite these advances, significant challenges in risk stratification remain that must be overcome before a meaningful impact on SCD can be realized.

Finding the Gatekeeper to the Cardiac Catheterization Laboratory: Coronary CT Angiography or Stress Testing?

Functional capacity is a robust predictor of clinical outcomes, and stress testing is used in current practice paradigms to guide referral to invasive coronary angiography. However, invasive coronary angiography is driven by ongoing symptoms, as well as risk of adverse outcomes. The limitations of current functional testing-based paradigms might be avoided by using coronary computed tomographic angiography (CCTA) for exclusion of obstructive coronary artery disease. The growth of CCTA has been supported by comparative prognostic evidence with CCTA and functional testing, as well as radiation dose reduction. Use of CCTA for physiological evaluation of coronary lesion-specific ischemia may facilitate evaluation of moderate stenoses, designation of the culprit lesion, and prediction of benefit from revascularization. The potential of CCTA to serve as an effective gatekeeper to invasive coronary angiography will depend, in part, on the adoption of these new developments, as well as definition of the benefit of detecting high-risk plaque for guiding the management of selected patients.

Structured learning algorithm for detection of nonobstructive and obstructive coronary plaque lesions from computed tomography angiography

Visual identification of coronary arterial lesion from three-dimensional coronary computed tomography angiography (CTA) remains challenging. We aimed to develop a robust automated algorithm for computer detection of coronary artery lesions by machine learning techniques. A structured learning technique is proposed to detect all coronary arterial lesions with stenosis [Formula: see text]. Our algorithm consists of two stages: (1) two independent base decisions indicating the existence of lesions in each arterial segment and (b) the final decision made by combining the base decisions. One of the base decisions is the support vector machine (SVM) based learning algorithm, which divides each artery into small volume patches and integrates several quantitative geometric and shape features for arterial lesions in each small volume patch by SVM algorithm. The other base decision is the formula-based analytic method. The final decision in the first stage applies SVM-based decision fusion to combine the two base decisions in the second stage. The proposed algorithm was applied to 42 CTA patient datasets, acquired with dual-source CT, where 21 datasets had 45 lesions with stenosis [Formula: see text]. Visual identification of lesions with stenosis [Formula: see text] by three expert readers, using consensus reading, was considered as a reference standard. Our method performed with high sensitivity (93%), specificity (95%), and accuracy (94%), with receiver operator characteristic area under the curve of 0.94. The proposed algorithm shows promising results in the automated detection of obstructive and nonobstructive lesions from CTA.

Effects of statin therapy on coronary artery plaque volume and high-risk plaque morphology in HIV-infected patients with subclinical atherosclerosis: a randomised, double-blind, placebo-controlled trial

BACKGROUND

HIV-infected patients have a high risk of myocardial infarction. We aimed to assess the ability of statin treatment to reduce arterial inflammation and achieve regression of coronary atherosclerosis in this population.

METHODS

In a randomised, double-blind, placebo-controlled trial, 40 HIV-infected participants with subclinical coronary atherosclerosis, evidence of arterial inflammation in the aorta by fluorodeoxyglucose (FDG)-PET, and LDL-cholesterol concentration of less than 3.37 mmol/L (130 mg/dL) were randomly assigned (1:1) to 1 year of treatment with atorvastatin or placebo. Randomisation was by the Massachusetts General Hospital (MGH) Clinical Research Pharmacy with a permuted-block algorithm, stratified by sex with a fixed block size of four. Study codes were available only to the MGH Research Pharmacy and not to study investigators or participants. The prespecified primary endpoint was arterial inflammation as assessed by FDG-PET of the aorta. Additional prespecified endpoints were non-calcified and calcified plaque measures and high risk plaque features assessed with coronary CT angiography and biochemical measures. Analysis was done by intention to treat with all available data and without imputation for missing data. The trial is registered with ClinicalTrials.gov, number NCT00965185.

FINDINGS

The study was done from Nov 13, 2009, to Jan 13, 2014. 19 patients were assigned to atorvastatin and 21 to placebo. 37 (93%) of 40 participants completed the study, with equivalent discontinuation rates in both groups. Baseline characteristics were similar between groups. After 12 months, change in FDG-PET uptake of the most diseased segment of the aorta was not different between atorvastatin and placebo, but technically adequate results comparing longitudinal changes in identical regions could be assessed in only 21 patients (atorvastatin Δ -0.03, 95% CI -0.17 to 0.12, vs placebo Δ -0.06, -0.25 to 0.13; p=0.77). Change in plaque could be assessed in all 37 people completing the study. Atorvastatin reduced non-calcified coronary plaque volume relative to placebo: median change -19.4% (IQR -39.2 to 9.3) versus 20.4% (-7.1 to 94.4; p=0.009, n=37). The number of high-risk plaques was significantly reduced in the atorvastatin group compared with the placebo group: change in number of low attenuation plaques -0.2 (95% CI -0.6 to 0.2) versus 0.4 (0.0, 0.7; p=0.03; n=37); and change in number of positively remodelled plaques -0.2 (-0.4 to 0.1) versus 0.4 (-0.1 to 0.8; p=0.04; n=37). Direct LDL-cholesterol (-1.00 mmol/L, 95% CI -1.38 to 0.61 vs 0.30 mmol/L, 0.04 to 0.55, p<0.0001) and lipoprotein-associated phospholipase A2 (-52.2 ng/mL, 95% CI -70.4 to -34.0, vs -13.3 ng/mL, -32.8 to 6.2; p=0.005; n=37) decreased significantly with atorvastatin relative to placebo. Statin therapy was well tolerated, with a low incidence of clinical adverse events.

INTERPRETATION

No significant effects of statin therapy on arterial inflammation of the aorta were seen as measured by FDG-PET. However, statin therapy reduced non-calcified plaque volume and high-risk coronary plaque features in HIV-infected patients. Further studies should assess whether reduction in high-risk coronary artery disease translates into effective prevention of cardiovascular events in this at-risk population.

FUNDING

National Institutes of Health, Harvard Clinical and Translational Science Center, National Center for Research Resources.