Differences in plaque composition and distribution in stable coronary artery disease versus acute coronary syndromes; non‐invasive evaluation with multi‐slice computed tomography

Non-calcified plaque in asymptomatic patients with zero coronary artery calcium score: A systematic review and meta-analysis

BACKGROUND

There is growing interest in understanding the coronary atherosclerotic burden in asymptomatic patients with zero coronary artery calcium score (CACS). In this population, we aimed to investigate the prevalence and severity of non-calcified coronary plaques (NCP) as detected by coronary CT angiography (CCTA), and to analyze the associated clinical predictors.

METHODS

This was a systematic review with meta-analysis of studies indexed in PubMed/Medline and Web of Science from inception of the database to March 31st, 2023. Using the random-effects model, separate Forest and Galbraith plots were generated for each effect size assessed. Heterogeneity was assessed using the I2 statistics whilst Funnel plots and Egger's test were used to assess for publication bias.

RESULTS

From a total of 14 studies comprising 37808 patients, we approximated the pooled summary estimates for the overall prevalence of NCP to be 10% (95%CI: 6%-13%). Similarly, the pooled prevalence of obstructive NCP was estimated at 1.1% (95%CI: 0.7%-1.5%) from a total of 10 studies involving 21531 patients. Hypertension [OR: 1.46 (95%CI:1.31-1.62)] and diabetes mellitus [OR: 1.69 (95%CI: 1.41-1.97)] were significantly associated with developing any NCP, with male gender being the strongest predictor [OR: 3.22 (95%CI: 2.17-4.27)].

CONCLUSION

There is a low burden of NCP among asymptomatic subjects with zero CACS. In a subset of this population who have clinical predictors of NCP, the addition of CCTA has a potential to provide a better insight about occult coronary atherosclerosis, however, a risk-benefit approach must be factored in prior to CCTA use given the low prevalence of NCP.

Characteristics of conventional high-risk coronary plaques and a novel CT defined thin-cap fibroatheroma in patients undergoing CCTA with stable chest pain

BACKGROUND

Coronary computed tomography angiography (CCTA) can identify high-risk coronary plaque types. However, the inter-observer variability for high-risk plaque features, including low attenuation plaque (LAP), positive remodelling (PR), and the Napkin-Ring sign (NRS), may reduce their utility, especially amongst less experienced readers.

METHODOLOGY

In a prospective study, we compared the prevalence, location and inter-observer variability of both conventional CT-defined high-risk plaques with a novel index based on quantifying the ratio of necrotic core to fibrous plaque using individualised X-ray attenuation cut-offs (the CT-defined thin-cap fibroatheroma - CT-TCFA) in 100 patients followed-up for 7 years.

RESULTS

In total, 346 plaques were identified in all patients. Seventy-two (21%) of all plaques were classified by conventional CT parameters as high-risk (either NRS or PR and LAP combined), and 43 (12%) of plaques were considered high-risk using the novel CT-TCFA definition of (Necrotic Core/fibrous plaque ratio of >0.9). The majority (80%) of the high-risk plaques (LAP&PR, NRS and CT-TCFA) were located in the proximal and mid-LAD and RCA. The kappa co-efficient of inter-observer variability (k) for NRS was 0.4 and for PR and LAP combined 0.4. While the kappa co-efficient of inter-observer variability (k) for the new CT-TCFA definition was 0.7. During follow-up, patients with either conventional high-risk plaques or CT-TCFAs were significantly more likely to have MACE (Major adverse cardiovascular events) compared to patients without coronary plaques (p value 0.03 & 0.03, respectively).

CONCLUSION

The novel CT-TCFA is associated with MACE and has improved inter-observer variability compared with current CT-defined high-risk plaques.

The Morphology of Coronary Artery Disease in South Asians versus White Caucasians and its Implications

South Asians (SAs) experience a higher prevalence and earlier onset of coronary artery disease and have worse outcomes relative to White Caucasians (WCs) following invasive revascularization procedures, a mainstay of coronary artery disease (CAD) management. We sought to review the differences in the CAD pattern and risk factors between SA and WC patients and discuss their potential impact on the development of coronary disease, acute coronary syndrome and revascularization outcomes. SAs have a more diffuse pattern with multi-vessel involvement compared to WCs. However, less is known about other morphological characteristics such as calcification of atherosclerotic plaque and coronary diameter in SA populations. Despite a similar coronary calcification burden, higher non-calcified plaque composition, elevated thrombosis and inflammatory markers likely contribute to the disease pattern. While the current evidence on the role of coronary vessel size remains inconsistent, smaller coronary diameters in SAs could play a potential role in the higher disease prevalence. This is especially important given the impact of coronary artery diameter on revascularization outcomes. In conclusion, SAs have a unique CAD risk profile comprised of traditional and novel risk factors. Our findings highlight the need for additional awareness of healthcare professionals of this specific risk profile and potential therapeutic targets, as well as the need for further research in this vulnerable population.

Dual-energy CT plaque characteristics of post mortem thin-cap fibroatheroma in comparison to infarct-related culprit lesions

Improvement of non-invasive identification of high-risk plaque may increase the preventive options of acute coronary syndrome. To describe the characteristics of thin-cap fibroatheroma (TCFA) in a post mortem model in comparison to characteristics of culprit lesions in patients with non-ST-elevation-myocardial-infarction (NSTEMI) using the dual energy computed tomography (DECT). Three post mortem hearts were prepared with iodine-contrast, inserted in a Kyoto phantom and scanned by DECT. Six TCFA were identified using histopathological analysis (cap thickness < 65 μm and necrotic core > 10% of the plaque area). In the NSTEMI group, 29 patients were scheduled to DECT prior to coronary angiography and invasive treatment. Culprit lesions were identified blinded for the patient history by two independent invasive cardiologists using the coronary angiography. The DECT analysis of TCFA and culprit lesions was performed retrospectively with determination of effective atomic number (Effective-Z), Hounsfield Unit (HU), plaque type (non-calcified, predominantly non-calcified, predominantly calcified or calcified), spotty calcification,, plaque length, plaque volume and plaque burden and the remodeling index. The Effective-Z, HU and plaqueburden were significantly different between TCFA and culprit lesions (P < 0.05).The TCFA plaques were more calcified in comparison to culprit lesions (P < 0.05). No significant difference in the other plaque characteristics was observed. The use of DECT demonstrated different Effective-Z values and different characteristics of post mortem TCFA in comparison to in vivo culprit lesions. This finding may highlight, that not all TCFA should be considered as vulnerable.

Prevalence of noncalcified plaques and coronary artery stenosis in patients with coronary calcium scores of zero

OBJECTIVES

A higher coronary artery calcium score (CACS) is associated with increased coronary artery plaque burden resulting in increased cardiovascular risk. Conversely, the absence of calcium indicates a low risk of cardiovascular events. However, coronary plaque calcification is a late manifestation of atherosclerosis; earlier stages of atherosclerosis present noncalcified plaques (NCPs) A recent study demonstrated that the absence of coronary artery calcification deposit does not preclude obstructive stenosis or the need for revascularization in patients with a high suspicion of coronary artery disease (CAD). Our study aimed to investigate the prevalence of NCP and the severity of coronary artery stenosis in symptomatic patients in our local population who were referred for coronary artery computed tomography angiogram (CCTA) with 0 CACS.

METHODS

A total of 299 patients who had undergone CACS and CCTA, and had scored zero for coronary artery calcium. Patients included had clinically appropriate indications, mainly chest pain with variable severity with no history of CAD. The presence of CAD risk factors, such as diabetes, hypertension, and smoking, was obtained from reviewing patient charts. The CCTA analysis was performed to evaluate for coronary artery stenosis and the presence of NCP. The severity of stenosis was quantified by visual estimation and divided into 0% stenosis, 1-25% stenosis, 26-50% stenosis, and more than 50% stenosis.

RESULTS

The prevalence of NCP was 6.4% (19 of the 299). Among the 19 patients with NCP, 52.6% had no identified coronary artery stenosis, 26.3% had less than 25%, and 21% had stenosis between 25 and 50%. None had stenosis greater than 50%. There was a strong association between male sex (P = 0.001), smoking (P = 0.0.004), hypertension, and NCP (P = 0.042), but no association was found between NCP and age or diabetes.

CONCLUSIONS

In patients with a high clinical suspicion of CAD, the absence of coronary artery calcification does not rule out CAD; up to 6.4% of these patients have early CAD as evidenced by NCP detected by CCTA, and none have more than 50% stenosis, However, future prognostic and long-term follow-up studies are needed to determine prognostic value of NCP in patients with 0 CACS.

Morphometric and Mechanical Analyses of Calcifications and Fibrous Plaque Tissue in Carotid Arteries for Plaque Rupture Risk Assessment

OBJECTIVE

Atherosclerotic plaque rupture in carotid arteries is a major source of cerebrovascular events. Calcifications are highly prevalent in carotid plaques, but their role in plaque rupture remains poorly understood. This work studied the morphometric features of calcifications in carotid plaques and their effect on the stress distribution in the fibrous plaque tissue at the calcification interface, as a potential source of plaque rupture and clinical events.

METHODS

A comprehensive morphometric analysis of 65 histology cross-sections from 16 carotid plaques was performed to identify the morphology (size and shape) and location of plaque calcifications, and the fibrous tissue fiber organization around them. Calcification-specific finite element models were constructed to examine the fibrous plaque tissue stresses at the calcification interface. Statistical correlation analysis was performed to elucidate the impact of calcification morphology and fibrous tissue organization on interface stresses.

RESULTS

Hundred-seventy-one calcifications were identified on the histology cross-sections, which showed great variation in morphology. Four distinct patterns of fiber organization in the plaque tissue were observed around the calcification. They were termed as attached, pushed-aside, encircling and random patterns. The stress analyses showed that calcifications are correlated with high interface stresses, which might be comparable to or even above the plaque strength. The stress levels depended on the calcification morphology and fiber organization. Thicker calcification with a circumferential slender shape, located close to the lumen were correlated most prominently to high interface stresses.

CONCLUSION

Depending on its morphology and the fiber organization around it, a calcification in an atherosclerotic plaque can act as a stress riser and cause high interface stresses.

SIGNIFICANCE

This study demonstrated the potential of calcifications in atherosclerotic plaques to cause elevated stresses in plaque tissue and provided a biomechanical explanation for the histopathological findings of calcification-associated plaque rupture.

Magnesium-Based Resorbable Scaffold Versus Permanent Metallic Sirolimus-Eluting Stent in Patients With ST-Segment Elevation Myocardial Infarction: The MAGSTEMI Randomized Clinical Trial

BACKGROUND

The use of poly-l-lactide acid-based bioresorbable scaffolds is limited in daily clinical practice because of safety concerns and lack of physiological benefit. Magnesium-based bioresorbable scaffold (MgBRS) presents a short resorption period (<1 year) and have the potential of being thromboresistant and exhibiting early restoration of vasomotor function. To date, however, no randomized clinical trial has investigated the performance of MgBRS. Therefore, this study aimed to compare the in-stent/scaffold vasomotion between MgBRS and permanent metallic sirolimus-eluting stent (SES) at 12-month follow-up in ST-segment-elevation myocardial infarction patients.

METHODS

This investigator-driven, multicenter, randomized, single-blind, controlled trial randomized ST-segment-elevation myocardial infarction patients 1:1 to SES or MgBRS at 11 academic centers. The primary end point was the rate of increase (≥3%) after nitroglycerin in mean lumen diameter of the in-stent/scaffold segment at 12 months with superiority of MgBRS over SES in the as-treated population. The main secondary end points included angiographic parameters of restenosis, device-oriented composite end point, their individual components, and device thrombosis rate. Besides, endothelial-dependent vasomotor response to acetylcholine (ie, endothelial function) was also assessed in a subgroup of patients (n=69).

RESULTS

Between June 2017 and June 2018, 150 ST-segment-elevation myocardial infarction patients were randomized (MgBRS, n=74; SES, n=76). At 1 year, the primary end point was significantly higher in the MgBRS arm (56.5% versus 33.8%; P=0.010). Conversely, late lumen loss was significantly lower in the SES group (in-segment: 0.39±0.49mm versus 0.02±0.27mm, P<0.001; in-device: 0.61±0.55mm versus 0.06±0.21mm; P<0.001). The device-oriented composite end point was higher in the MgBRS arm driven by an increase in ischemia-driven target lesion revascularization rate (12[16.2%] versus 4[5.2%], P=0.030). Definite thrombosis rate was similar between groups (1[1.4%] in the MgBRS arm versus 2[2.6%] in the SES group; P=1.0). Endothelial function assessment at device segment evidenced a more pronounced vasoconstrictive response to maximal dose of acetylcholine in the MgBRS arm (-8.3±3.5% versus -2.4±1.3% in the SES group, P=0.003).

CONCLUSIONS

When compared to SES, MgBRS demonstrated a higher capacity of vasomotor response to pharmacological agents (either endothelium-independent or endothelium-dependent) at 1 year. However, MgBRS was associated with a lower angiographic efficacy, a higher rate of target lesion revascularization, without thrombotic safety concerns.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT03234348.

Comparison of the Left Main Coronary Bifurcating Angle among Patients with Normal, Non-significantly and Significantly Stenosed Left Coronary Arteries

We evaluated the correlation of the left main coronary bifurcating angle (LCBA) with the severity of coronary atherosclerosis, risk factors of coronary artery disease (CAD) and the feasibility of measuring the LBCA using the axial plane. Coronary Computed tomography angiographies (CTAs) of 313 patients between Nov. 2006 and Oct. 2013 were reviewed and separated into three groups. Group I (211 patients) had significant stenosis (≥50%) of the left anterior descending coronary artery (LAD) and/or left circumflex coronary artery (LCX). Group II (62 subjects) had atherosclerosis without significant stenosis. Group III (40 subjects) had unremarkable coronary CTAs. Both Group I and II patients received conventional catheter angiography to confirm the severities of coronary stenoses. Significant differences were found among the groups with respect to risk factors, such as male gender, hypertension and body mass index. Axial plane measurement was feasible in most patients (82.1%), without significant differences among the groups. The mean LCBA was 84.7° among all patients, and significantly differed among groups I, II and III (87.34°, 81.16° and 75.53°, P < 0.001). The LCBA of group I was significantly higher than group III (P < 0.001) in univariate analysis, but insignificant in multivariate analysis (P = 0.064).

Relation of Plasma Lipoprotein(a) to Subclinical Coronary Plaque Volumes, Three-Vessel and Left Main Coronary Disease, and Severe Coronary Stenoses in Apparently Healthy African-Americans With a Family History of Early-Onset Coronary Artery Disease

Serum lipoprotein(a) [Lp(a)] is a coronary artery disease (CAD) risk factor in persons of European ancestry. Levels are twofold to threefold higher in African-Americans (AAs), but reported associations with CAD have been inconsistent. The relation of Lp(a) with the extent and severity of subclinical coronary plaque has not been described in AAs. We screened 269 apparently healthy AAs for risk factors and coronary plaque using advanced coronary computed tomographic angiography. Total coronary plaque (TCP), noncalcified coronary plaque, and calcified coronary plaque volumes (mm(3)) were quantified using a validated automated method. Lp(a) was measured by ELISA. Multivariable modeling was performed with adjustment for traditional CAD risk factors and intrafamilial correlations. Mean age was 51 ± 11 years and 64% were female. Plaque was present in 41%. Lp(a) was independently associated with TCP volume [log(TCP + 1)] (p = 0.04), 3-vessel and/or left main involvement (p = 0.04), and at least 1 stenosis >50% (p = 0.006). Best-fit regression analyses showed that subjects with Lp(a) >40 mg/dl were threefold more likely to have 3-vessel and/or left main disease (95% confidence interval 1.4 to 6.8, p = 0.005) and fourfold more likely to have stenosis >50% (95% confidence interval 1.3 to 15.0, p = 0.02). In subjects with plaque (n = 110), multivariable models showed the Lp(a) level was significantly and independently associated with TCP (p = 0.009), noncalcified coronary plaque (p = 0.01), and calcified coronary plaque (p = 0.003) and affected vessel length (p = 0.01). In conclusion, high Lp(a) is strongly associated with coronary plaque volumes, extent, and severity in apparently healthy AAs. High levels of Lp(a) may be particularly important in the pathogenesis of CAD in AAs.

High-risk coronary plaque, invasive coronary procedures, and cardiac events among HIV-positive individuals and matched controls

BACKGROUND

Human immunodeficiency virus (HIV) infection is considered a chronic, treatable disease, although treatment is associated with increased rates of coronary artery disease (CAD). We analyzed the utility of coronary CTA in the assessment of CAD among HIV patients and explored whether HIV patients are at greater risk of associated morbidity and mortality compared to HIV-negative controls.

METHODS

In a retrospective, single center cohort study 97 males without history of previous coronary artery disease who had undergone coronary CTA between 2011 and 2014 was analyzed, including 32 HIV positive patients and 65 matched HIV negative controls. Presence and composition of coronary plaque was determined by coronary CTA. Data on subsequent coronary events and coronary intervention was collected.

RESULTS

Patients with HIV had higher rates of non-calcified plaque (0.8 ± 1.5 versus 0.3 ± 0.7, p = 0.03) compared to negative controls. At a median follow-up of 38 months, patients with HIV were at greater risk of non-ST elevation acute coronary syndrome (16% versus 3%, p < 0.04), although there was no difference in the combined endpoint of all acute coronary syndromes (19% versus 6%, p = 0.08). Following baseline coronary TCA, there was a higher rate of coronary intervention in patients without HIV (mean time to event 9.9 ± 3.3 versus 20.6 ± 4.9 months, p < 0.04).

CONCLUSION

Patients with HIV more pronounces coronary atherosclerosis on coronary CTA and higher rates of non-ST elevation acute coronary syndromes compared to negative controls.

Characteristics of high-risk coronary plaques identified by computed tomographic angiography and associated prognosis: a systematic review and meta-analysis

To clarify the potential role of coronary computed tomographic angiography (CCTA) in characterizing and prognosticating high-risk coronary plaques. A systematic review and meta-analysis were conducted to compare high-risk vs. low-risk plaques and culprit vs. non-culprit lesions in patients with acute coronary syndrome (ACS) vs. stable angina (SA). High-risk plaques were defined by at least one of the following features: non-calcified plaque (NCP), the presence of spotty calcified plaque (SCP), or increased remodelling index (RI). Results of included studies were pooled as odds ratios (OR) or weighted mean differences (WMD) with 95% confidence interval (CI). Eighteen eligible studies provided data to compare plaque types, plaque volume, and RI. Six studies provided data on ACS events in vulnerable high-risk vs. low-risk calcified plaques after 35 ± 2 months of follow-up. ACS patients had significantly higher number of NCP and SCP compared with SA patients with OR = 1.96 (1.47-2.60; 95% CI) P = 0.0001 and OR = 4.5 (2.98-6.83; 95% CI) P = 0.0001, respectively. Total plaque volume in ACS was not larger than SA: WMD = 22.9 (-22.1 to 67; 95% CI) mm(3), P = 0.32, but NCP volume was significantly larger: WMD = 28.8 (10.9-46.7; 95% CI) mm(3), P = 0.002. RI was higher in culprit lesions in ACS compared with SA and compared with non-culprit lesions in ACS patients: WMD = 0.48 (0.25-0.70; 95% CI) P = 0.0001 and 0.19 (0.07-0.30) P = 0.0001, respectively. The associated risk of future ACS was significantly higher in high-risk than in low-risk plaques: OR = 12.1 (5.24-28.1; 95% CI) P = 0.0001. CCTA can non-invasively characterize high-risk vulnerable coronary plaques and can predict future ACS events in patients with high-risk plaques.

Different Plaque Composition and Progression in Patients with Stable and Unstable Coronary Syndromes Evaluated by Cardiac CT

Objective. To compare the quantity, subtype, and progression of atherosclerosis by cardiac computed tomography (CT) and intravascular ultrasound (IVUS) in patients with stable (SAP) and unstable angina pectoris or non-ST-elevation myocardial infarction (UAP/n-STEMI). Methods. Forty patients with SAP and 20 with UAP/n-STEMI underwent cardiac CT and angiography with IVUS at baseline and after one year. Atherosclerotic segments were divided into calcified, mixed, or noncalcified subtypes, and significant stenoses were registered. Results. Thirty-two SAP and 15 UAP/n-STEMI patients completed the CT follow-up. At baseline, the number of atherosclerotic segments was higher in UAP/n-STEMI than in SAP (P = 0.039). UAP/n-STEMI patients had more segments with noncalcified plaques (P = 0.0005) whereas SAP patients had more segments with calcified plaques (P = 0.013). The number of segments with significant stenosis did not differ between the groups, but noncalcified plaques more frequently caused significant stenoses in UAP/n-STEMI than in SAP patients (P = 0.0002). After one year the number of segments with atherosclerosis increased in SAP patients (P = 0.0001). The number of atherosclerotic segments remained unchanged in UAP/n-STEMI patients. However, composition was altered as the number of segments with noncalcified plaques decreased (P = 0.018). IVUS data confirmed the CT findings. Conclusion. Quantity, subtype, and progression of atherosclerosis differ between SAP and UAP/n-STEMI patients.

Association between hemoglobin A1c variability and subclinical coronary atherosclerosis in subjects with type 2 diabetes

AIMS

We examined the association between hemoglobin A1c (HbA1c) variability and subclinical coronary atherosclerosis in subjects with type 2 diabetes.

METHODS

We used the multidetector coronary computed tomography data collected from subjects with type 2 diabetes who did not have a history of cardiovascular disease or angina symptoms. HbA1c measurements preceding the date of cardiac imaging were retrospectively collected, and intraindividual SD (HbA1c-SD), CV and adjusted SD of HbA1c measurements were calculated. Subclinical coronary atherosclerosis was defined as calcium score >400 without any cardiac symptoms.

RESULTS

A total of 595 subjects were categorized according to the median value of each HbA1c variability indicators. The prevalence of subclinical coronary atherosclerosis was higher in higher HbA1c variability group compared with lower HbA1c variability group. Multivariable logistic regression analysis showed that higher HbA1c-SD and -CV were associated with the presence of subclinical coronary atherosclerosis, independent of mean HbA1c level in subjects with diabetes duration ≤10 years (OR [95% CI]; HbA1c-SD, 2.894 [1.105-7.584]; HbA1c-CV, 2.540 [1.022-6.316]).

CONCLUSIONS

Long-term stabilization of blood glucose level might be important in preventing subclinical coronary atherosclerosis in subjects with earlier period of type 2 diabetes.

Effects of intensive lipid-lowering therapy on coronary plaques composition in patients with acute myocardial infarction: Assessment with serial coronary CT angiography

BACKGROUND

Statins have been shown to possess favourable effects on the cardiovascular system with stabilization of the vulnerable plaque. We sought to assess the effects of early aggressive statin treatment on plaque composition in patients with acute myocardial infarction (AMI), using serial assessment with coronary CT-angiography (CTA).

METHODS

In a prospective randomized blinded endpoint trial patients with AMI were randomized to an intensive lipid lowering treatment receiving statin loading with 80 mg rosuvastatin followed by 40 mg daily or standard statin therapy according to current guidelines. Patients were assessed with CTA at baseline and after 12 months with evaluation of plaque volume and composition.

RESULTS

In total, 140 patients with AMI were randomized and plaque composition was assessed in 96 patients. In the intensive care group LDL-level was median 1.3 [0.9; 1.5] mmol/l at 12 months follow-up and 2.0 [1.7; 2.4] mmol/l in the usual care group, p < 0.001. Plaque volume increased over 12 months with 43.5 (±225.8) mm(3) in the intensive care group and 19.1 (±190.2) mm(3) in the usual care group, p = 0.57. Plaque composition changed over 12 months with an increase in total dense calcium volume by 11.1 (±39.6) mm(3), corresponding to a 23% increase, in the intensive care group and a decreased by -0.4 (±26.6) mm(3) in the usual care group, p < 0.001. Necrotic core volume increased 26.8 (±122.1) mm(3) in the intensive care group and 25.2 (±80.1) mm(3) in the usual care group, p = 0.94.

CONCLUSIONS

Early aggressive lipid lowering therapy significantly increases dense calcium volume in patients with AMI.

The association of brachial artery diameter with noncalcified coronary plaque burden in apparently healthy individuals

OBJECTIVE

Coronary atherosclerosis has been associated with systemic arterial remodeling even in nonatherosclerotic vessels. However, it is not known whether systemic remodeling is differentially associated with the cumulative atherosclerotic process, reflected by putatively quiescent calcified plaque (CP), or with active atherosclerosis, consisting of noncalcified plaque (NCP). We thus examined the association of brachial artery diameter (BAD), an artery that does not suffer clinical atherosclerosis, with the presence and the extent of coronary CP and NCP.

METHODS

We studied 688 apparently healthy, asymptomatic participants from 350 families with a history of early-onset coronary artery disease (<60 years of age) by measuring coronary artery disease risk factors and coronary plaque using dual-source computed tomographic angiography. Plaque volumes were quantified using a validated automated method. BAD was measured during diastole using B-mode ultrasound. The association of resting BAD with any detectable plaque, and log-transformed CP and NCP volumes if detectable, was tested using generalized estimating equations adjusted for age, sex, race, current smoking, diabetes, hypertension, BMI, and non-HDL and HDL cholesterol.

RESULTS

Higher quintiles of BAD were associated with greater age and male sex (both P<0.001). In the fully adjusted analysis, CP volume was not associated with BAD (P=0.65) but a 1 ml greater NCP volume was associated with a 0.65 mm larger BAD (P=0.027).

CONCLUSION

Our results suggest that systemic arterial remodeling of nonatherosclerotic arteries is a dynamic process that is correlated with the extent of putatively active atherosclerotic processes in distant beds but not with inactive accumulated plaque burden.

Role of computed tomography for diagnosis and risk stratification of patients with suspected or known coronary artery disease

Cardiac computed tomographic angiography (CCTA) has emerged as a powerful imaging modality for the detection and prognostication of individuals with suspected coronary artery disease. Because calcification of coronary plaque occurs in proportion to the total atheroma volume, the initial diagnostic potential of CCTA focused on the identification and quantification of coronary calcium in low- to intermediate-risk individuals, a finding that tracks precisely with the risk of incident adverse clinical events. Beyond noncontrast detection of coronary calcium, CCTA using iodinated contrast yields incremental information about the degree and distribution of coronary plaques and stenosis, as well as vessel wall morphology and atherosclerotic plaque features. This additive information offers the promise of CCTA to provide a more comprehensive view of total atherosclerotic burden because it relates to myocardial ischemia and future adverse clinical events. Furthermore, emerging data suggest the prognostic and diagnostic importance of stenosis severity detection and atherosclerotic plaque features described by CCTA including positive remodeling, low-attenuation plaque, and spotty calcification, which have been associated with the vulnerability of plaque. We report a summary of the evidence supporting the role of CCTA in the detection of subclinical and clinical coronary artery disease in both asymptomatic and symptomatic patients and discuss the potential of CCTA to augment the identification of at-risk individuals. CCTA and coronary artery calcium scoring offer the ability to improve risk stratification, discrimination, and reclassification of the risk in patients with suspected coronary artery disease and to noninvasively determine the measures of stenosis severity and atherosclerotic plaque features.

Value of multi-detector computed tomography angiography in predicting acute cardiac events in patients with type 2 diabetes

The aim of the present study was to investigate the predictive value of multi-detector computed tomography angiography (MDCTA) on acute coronary artery events in patients with type 2 diabetes mellitus (T2DM). MDCTA was performed in 150 patients with T2DM (males, 74; mean age, 66±6.7 years for all patients) that had experienced atypical chest pains. After a follow-up period of at least 2 years, 55 patients were excluded from the study as they did not exhibit any coronary events. The remaining 95 patients were divided into the study group (n=28), that had experienced an acute coronary event such as acute coronary syndrome, or the control group (n=67) that had stable angina. There were no statistically significant differences in the degree of coronary artery lumen stenosis between the study and control groups (P=0.380). The proportion of calcified plaques in the study group was significantly lower compared with the control group (13.6 vs. 53.2%; P<0.001), while the proportion of soft plaques in the study group was significantly higher compared with the control group (37 vs. 9.3%; P<0.001). Type III plaques showed a sensitivity of 76.2% and a negative predictive value of 64.5% for acute coronary events. By contrast, type IV plaques had a sensitivity of 52.6% and a positive predictive value of 63% for chronic coronary events. Therefore, the results of the present study indicate that MDCTA may be used as a noninvasive modality for evaluating and predicting vulnerable coronary atherosclerosis plaques in patients with T2DM.

Prognostic utility of coronary computed tomographic angiography: a 5-year follow-up in type 2 diabetes patients with suspected coronary artery disease

OBJECTIVES

To analyze the predictive value of coronary computed tomography angiography on acute coronary artery events in patients with type 2 diabetes.

METHODS

Coronary computed tomography angiography was performed in 250 type 2 diabetic patients. After a follow-up for 5 years, 145 patients were excluded as they did not have any coronary events. The remaining 95 patients were divided into study group and control group. According to their density and shape, the coronary artery plaques were classified into 3 types and 4 types, respectively.

RESULTS

There is no statistically significant difference in the degree of stenosis between two groups. The proportion of calcified plaques in the study group was lower than in the control group. The proportion of mixed-calcified plaques in the study group was higher than in the other. Type III plaques have a 76.2% sensitivity and negative predictive value was 64.5% for acute coronary events; type IV plaques have a sensitivity of 52.6% and positive predictive value of 63% for chronic coronary events.

CONCLUSIONS

CCTA may be used as a non-invasive modality for evaluating and predicting vulnerable coronary atherosclerosis plaques in patients with type 2 diabetes.

Noncalcified coronary plaque volumes in healthy people with a family history of early onset coronary artery disease

BACKGROUND

Although age and sex distributions of calcified coronary plaque have been well described in the general population, noncalcified plaque (NCP) distributions remain unknown. This is important because NCP is a putative precursor for clinical coronary artery disease and could serve as a sentinel for aggressive primary prevention, especially in high-risk populations. We examined the distributions of NCP and calcified coronary plaque in healthy 30- to 74-year-old individuals from families with early onset coronary artery disease.

METHODS AND RESULTS

Participants in the GeneSTAR family study (N=805), mean age 51.1±10.8 years, 56% women, were screened for coronary artery disease risk factors and coronary plaque using dual-source computed tomographic angiography. Plaque volumes (mm(3)) were quantified using a validated automated method. The prevalence of coronary plaque was 57.8% in men and 35.8% in women (P<0.0001). NCP volume increased with age (P<0.001) and was higher in men than women (P<0.001). Although NCP, as a percentage of total plaque, was inversely related to age (P<0.01), NCP accounted for most of the total plaque volume at all ages, especially in men and women <55 years (>70% and >80%, respectively). Higher Framingham risk was associated with the number of affected vessels (P<0.01), but 44% of men and 20.8% of women considered intermediate risk had left main and 3-vessel disease involvement.

CONCLUSIONS

The majority of coronary plaque was noncalcified, particularly in younger individuals. These findings support the importance of assessing family history and suggest that early primary prevention interventions may be warranted at younger ages in families with early onset coronary artery disease.

Coronary CT angiography in coronary artery disease: correlation between virtual intravascular endoscopic appearances and left bifurcation angulation and coronary plaques

The aim of this study is to investigate the relationship between intraluminal appearances of coronary plaques and left coronary bifurcation angle and plaque components using coronary CT virtual intravascular endoscopy (VIE). Fifty patients suspected of coronary artery disease undergoing coronary CT angiography were included in the study. The left bifurcation angle in patients with diseased left coronary artery which was measured as 94.3° ± 16.5 is significantly larger than that in patients with normal left coronary artery, which was measured as 76.5° ± 15.9 (P < 0.001). Irregular VIE appearances were found in 10 out of 11 patients with mixed plaques in the left anterior descending (LAD) and left circumflex (LCx), while, in 29 patients with calcified plaques in the LAD and LCx, irregular VIE appearances were only noticed in 5 patients. Using 80° as a cut-off value to determine coronary artery disease, smooth VIE appearances were found in 95% of patients (18/19) with left bifurcation angle of less than 80°, while irregular VIE appearances were observed in nearly 50% of patients (15/31) with left bifurcation angle of more than 80°. This preliminary study shows that VIE appearances of the coronary lumen are directly related to the types of plaques.

A voxel-map quantitative analysis approach for atherosclerotic noncalcified plaques of the coronary artery tree

Noncalcified plaques (NCPs) are associated with the presence of lipid-core plaques that are prone to rupture. Thus, it is important to detect and monitor the development of NCPs. Contrast-enhanced coronary Computed Tomography Angiography (CTA) is a potential imaging technique to identify atherosclerotic plaques in the whole coronary tree, but it fails to provide information about vessel walls. In order to overcome the limitations of coronary CTA and provide more meaningful quantitative information for percutaneous coronary intervention (PCI), we proposed a Voxel-Map based on mathematical morphology to quantitatively analyze the noncalcified plaques on a three-dimensional coronary artery wall model (3D-CAWM). This approach is a combination of Voxel-Map analysis techniques, plaque locating, and anatomical location related labeling, which show more detailed and comprehensive coronary tree wall visualization.

Quantitative analysis of coronary plaque composition by dual-source CT in patients with acute non-ST-elevation myocardial infarction compared to patients with stable coronary artery disease correlated with virtual histology intravascular ultrasound

RATIONALE AND OBJECTIVES

To quantitatively assess coronary atherosclerotic plaque composition in patients with acute non-ST elevation myocardial infarction (NSTEMI) and patients with stable coronary artery disease (CAD) by coronary computed tomography angiography (cCTA) correlated with virtual histology intravascular ultrasound (VH-IVUS).

MATERIALS AND METHODS

Sixty patients (35 with NSTEMI) were included. Corresponding plaques were assessed by dual-source cCTA and VH-IVUS regarding volumes and percentages of fatty, fibrous, and calcified component; overall plaque burden; and maximal percent area stenosis. Possible differences between patient groups were investigated. Concordance between cCTA and VH-IVUS measurements was validated by Bland-Altman analysis.

RESULTS

Forty corresponding plaques (22 of patients with NSTEMI) were finally analyzed by cCTA and VH-IVUS. cCTA plaque analysis revealed no significant differences between plaques of patients with NSTEMI and stable CAD regarding absolute and relative amounts of any plaque component (fatty: 20 mm³/13% versus 17 mm³/14%; fibrous: 81 mm³/63% versus 80 mm³/53%; calcified: 16 mm³/14% versus 26 mm³/26%; all P > .05) or overall plaque burden (153 mm³ versus 165 mm³; P > .05), nor did VH-IVUS plaque analysis. VH-IVUS measured a higher area stenosis in patients with NSTEMI compared to patients with stable CAD (76% versus 68%, P = .01; in cCTA 69% versus 65%, P = .2). Volumes of fatty component were measured systematically lower in cCTA, whereas calcified and fibrous volumes were higher. No significant bias was observed comparing volumes of overall noncalcified component and overall plaque burden.

CONCLUSION

Plaques of patients with acute NSTEMI and of patients with stable CAD cannot be differentiated by quantification of plaque components. cCTA and VH-IVUS differ in plaque component analysis.

Relationship between amount of cigarette smoking and coronary atherosclerosis on coronary CTA in asymptomatic individuals

Current smoking is a powerful independent predictor of coronary atherosclerosis in asymptomatic individuals. Many researchers have suggested a cigarette dose-response relationship between smoking and subclinical coronary atherosclerosis. Our study purposes were (a) to investigate the prevalence and plaque characteristics of coronary atherosclerosis in asymptomatic smokers and (b) to assess the cigarette dose-response relationship between smoking and subclinical coronary atherosclerosis using coronary CT angiography (CTA). We consecutively enrolled 7,104 self-referred asymptomatic subjects who underwent coronary CTA as part of a general health evaluation. Current smokers (n = 1,784) were categorized according to total pack years (TPY) with four grades (A, 0.1-10; B, 10-20; C, 20-30; D, >30), smoking duration (SD, years) with four grades (A, 0.1-10; B, 10-20; C, 20-30; D, >30), and number of cigarettes per day (CPD) with four grades (A, 1-20; B, 10-20; C, 20-40; D, >40). After adjusting for other cardiovascular risk factors, adjusted odds ratios for current smokers versus never-smokers as a control group were estimated for the presence of plaques, significant stenosis, and non-calcified plaques (NCP). Current smokers had a statistically significant higher prevalence of any plaque, significant stenosis, NCP, and coronary artery calcium score >100 than never-smokers. According to each categorization of TPY, SD, and CPD, the subclinical coronary atherosclerosis risk increased as grades increased in asymptomatic current smokers relative to never-smokers after adjusting for variable clinical and chemical risk factors. Our study suggests a cigarette dose-response relationship between current smoking and coronary atherosclerosis in asymptomatic individuals.

Additive value of semiautomated quantification of coronary artery disease using cardiac computed tomographic angiography to predict future acute coronary syndrome

OBJECTIVES

The purpose of this study was to investigate whether the use of a semiautomated plaque quantification algorithm (reporting volumetric and geometric plaque properties) provides additional prognostic value for the development of acute coronary syndromes (ACS) as compared with conventional reading from cardiac computed tomography angiography (CCTA).

BACKGROUND

CCTA enables the visualization of coronary plaque characteristics, of which some have been shown to predict ACS.

METHODS

A total of 1,650 patients underwent 64-slice CCTA and were followed up for ACS for a mean 26 ± 10 months. In 25 patients who had ACS and 101 random controls (selected from 993 patients with coronary artery disease but without coronary event), coronary artery disease was evaluated using conventional reading (calcium score, luminal stenosis, morphology), and then independently quantified using semiautomated software (plaque volume, burden area [plaque area divided by vessel area times 100%], noncalcified percentage, attenuation, remodeling). Clinical risk profile was calculated with Framingham risk score (FRS).

RESULTS

There were no significant differences in conventional reading parameters between controls and patients who had ACS. Semiautomated plaque quantification showed that compared to controls, ACS patients had higher total plaque volume (median: 94 mm(3) vs. 29 mm(3)) and total noncalcified volume (28 mm(3) vs. 4 mm(3), p ≤ 0.001 for both). In addition, per-plaque maximal volume (median: 56 mm(3) vs. 24 mm(3)), noncalcified percentage (62% vs. 26%), and plaque burden (57% vs. 36%) in ACS patients were significantly higher (p < 0.01 for all). A receiver-operating characteristic model predicting for ACS incorporating FRS and conventional CCTA reading had an area under the curve of 0.64; a second model also incorporating semiautomated plaque quantification had an area under the curve of 0.79 (p < 0.05).

CONCLUSIONS

The semiautomated plaque quantification algorithm identified several parameters predictive for ACS and provided incremental prognostic value over clinical risk profile and conventional CT reading. The application of this tool may improve risk stratification in patients undergoing CCTA.

Imaging atherosclerosis with hybrid [18F]fluorodeoxyglucose positron emission tomography/computed tomography imaging: what Leonardo da Vinci could not see

Prodigious efforts and landmark discoveries have led toward significant advances in our understanding of atherosclerosis. Despite significant efforts, atherosclerosis continues globally to be a leading cause of mortality and reduced quality of life. With surges in the prevalence of obesity and diabetes, atherosclerosis is expected to have an even more pronounced impact upon the global burden of disease. It is imperative to develop strategies for the early detection of disease. Positron emission tomography (PET) imaging utilizing [(18)F]fluorodeoxyglucose (FDG) may provide a non-invasive means of characterizing inflammatory activity within atherosclerotic plaque, thus serving as a surrogate biomarker for detecting vulnerable plaque. The aim of this review is to explore the rationale for performing FDG imaging, provide an overview into the mechanism of action, and summarize findings from the early application of FDG PET imaging in the clinical setting to evaluate vascular disease. Alternative imaging biomarkers and approaches are briefly discussed.

Racial differences in the association between carotid plaque and aortic and coronary artery calcification among women transitioning through menopause

OBJECTIVE

Carotid atherosclerosis is a marker for atherosclerotic disease in other vascular beds; however, racial differences in this association have not been fully examined. The purpose of this report was to evaluate racial differences in the relationship between carotid plaque and calcification in the aorta and coronary arteries among women transitioning through menopause.

METHODS

A total of 540 African American and white women with a median age of 50 years were evaluated from the Study of Women's Health Across the Nation. Carotid plaque (none vs. any) was assessed with B-mode ultrasound, and aortic calcification (AC; 0, >0-100, and >100) and coronary artery calcification (CAC; 0, >0-10, and >10) were assessed with CT.

RESULTS

For the total cohort, higher prevalence of plaque was significantly associated with higher levels of AC but not CAC. The interaction of race and carotid plaque was significant in models with AC and CAC as dependent variables (P = 0.03 and 0.002, respectively). Among African Americans, there was an inverse relationship, although not significant, between carotid plaque and high AC (>100; odds ratio [OR], 0.75; 95% CI, 0.10-5.48) and between plaque and high CAC (>10; OR, 0.20; 95% CI, 0.03-1.52) in fully adjusted models. In contrast, for whites, significant positive associations existed between carotid plaque and high AC (OR, 4.12; 95% CI, 1.29-13.13) and borderline associations for high CAC (OR, 1.83; 95% CI, 0.66-5.19).

CONCLUSIONS

This study demonstrates that the presence of carotid plaque seemed to be a marker for AC and potentially CAC in white women, but not African American middle-aged women, during the menopausal transition.

Effect of calcification on the mechanical stability of plaque based on a three-dimensional carotid bifurcation model

Background

This study characterizes the distribution and components of plaque structure by presenting a three-dimensional blood-vessel modelling with the aim of determining mechanical properties due to the effect of lipid core and calcification within a plaque. Numerical simulation has been used to answer how cap thickness and calcium distribution in lipids influence the biomechanical stress on the plaque.

Method

Modelling atherosclerotic plaque based on structural analysis confirms the rationale for plaque mechanical examination and the feasibility of our simulation model. Meaningful validation of predictions from modelled atherosclerotic plaque model typically requires examination of bona fide atherosclerotic lesions. To analyze a more accurate plaque rupture, fluid-structure interaction is applied to three-dimensional blood-vessel carotid bifurcation modelling. A patient-specific pressure variation is applied onto the plaque to influence its vulnerability.

Results

Modelling of the human atherosclerotic artery with varying degrees of lipid core elasticity, fibrous cap thickness and calcification gap, which is defined as the distance between the fibrous cap and calcification agglomerate, form the basis of our rupture analysis. Finite element analysis shows that the calcification gap should be conservatively smaller than its threshold to maintain plaque stability. The results add new mechanistic insights and methodologically sound data to investigate plaque rupture mechanics.

Conclusion

Structural analysis using a three-dimensional calcified model represents a more realistic simulation of late-stage atherosclerotic plaque. We also demonstrate that increases of calcium content that is coupled with a decrease in lipid core volume can stabilize plaque structurally.

Significance of noncalcified coronary plaque in asymptomatic subjects with low coronary artery calcium score: assessment with coronary computed tomography angiography

We aimed to investigate the prevalence and severity of noncalcified coronary plaques (NCP) using coronary CT angiography (CCTA) and analyze predictors of significant coronary stenosis by NCP in asymptomatic subjects with low coronary artery calcium score (CACS). The institutional review board approved this retrospective study and all patients gave written, informed consent. The presence of plaque, severity of stenosis, plaque characteristics, and CACS were assessed in 7,515 asymptomatic subjects. We evaluated the prevalence and severity of NCP in subjects having low CACS (707 subjects; men with CACS from 1 to 50 and women from 1 to 10) in comparison to those having 0 CACS (6,040 subjects) as the reference standard. Conventional risk factors were assessed for predictors of NCP and significant stenosis by NCP. We also investigated the cardiac events of the patients through medical records. Compared to subjects with 0 CACS, those with low CACS showed higher prevalence of NCP (6.9% vs. 31.5%, P < 0.001) and significant stenosis caused by NCP (0.8% vs. 7.5%, P < 0.001). In the low CACS group, independent predictors for significant NCP included diabetes mellitus (DM), hypertension, and elevated low-density lipoprotein (LDL)-cholesterol (all P < 0.05). However, 47.2% of subjects with significant NCP were classified into the low to intermediate risk according to Framingham Risk Score. At the median follow up of 42 months (range: 3-60 months), cardiac events were significantly higher in the low CACS group compared to the 0 CACS group (2.6% vs. 0.27%, P < 0.001). In asymptomatic subjects having low CACS, the prevalence and severity of NCP were higher as compared to subjects having zero CACS and predictors of significant stenosis by NCP were DM, hypertension and LDL-Cholesterol. Therefore, CCTA may be useful for risk stratification of coronary artery disease as added value over CACS in selected populations with low CACS who have predictors of significant NCP.

Association between renal dysfunction and the mixed plaque of coronary artery on computed tomographic angiography

Coronary artery plaque is related to development of coronary artery disease (CAD), and chronic kidney disease is associated with CAD. However, the association of renal dysfunction (RD) with coronary artery plaque characteristics has not been fully elucidated. We evaluated the association between RD and coronary artery plaque characteristics in patients with suspected CAD, who underwent multislice computed tomographic angiography (CTA). A total of 918 patients were classified into 4 groups: group with no plaque (NP) (48.9%), group with calcified plaque (CP) (16.0%), group with noncalcified plaque (NCP) (22.4%), and group with mixed plaque (MP) (12.7%). NCP is considered as rupture-prone soft plaque, and CP as more stable lesion. The mean of estimated glomerular filtration rate (eGFR) was 82.5 ± 15.4 mL/min/1.73 m(2), and the prevalence of RD (defined as eGFR < 60 mL/min/1.73 m(2)) was 6.3%. The prevalence of RD was 3.3% in the NP group, 10.2% in the CP group, 5.3% in the NCP group, and 14.5% in the MP group (P < 0.001 by ANOVA tests). The adjusted odds ratio for RD was 3.38 (95% confidence interval, 1.27-9.04) for the MP group, compared with the NP group. The presence of RD showed an independent association with the MP counts (r = 0.155, P < 0.001); however, there was no association between RD and other plaque characteristics. In conclusion, RD is associated with MP rather than CP or NCP, compared with NP, which may reflect one of the developmental processes of CAD in patients with RD.

Noncalcified plaque: relationship between results of multislice computed tomography, risk factors, and late clinical outcome

BACKGROUND

Contrast-enhanced multislice computed tomographic angiography (MSCTA) detects noncalcified plaque (NCP) in coronary arteries and associated coronary stenoses. However, the clinical relevance of NCP is poorly defined.

OBJECTIVES

Our goal was to examine the relationship NCP, risk factors (RFs), and clinical follow-up in unselected outpatients undergoing MSCTA.

METHODS

Five hundred six patients undergoing contrast MSCTA were evaluated for NCP (intraluminal density 25 < Hounsfield units < 130). One hundred twenty-four patients (24.5%) had calcium scores (CAC) of zero. Of these, 111 patients were examined for RFs and followed clinically for a mean of 34 months.

RESULTS

Of 124 patients with zero CAC, 111 (89.5%) included 52 (46.8%) with no NCP, 40 (36.0%) with NCP, and mild luminal stenosis, 14 (12.6%) and 5 (4.5%) with NCP causing significant and severe stenosis, respectively. Patients in each group were similar in age but differed significantly in number of RFs. Current or former smokers, hypertensive, and obese patients had more NCP and associated stenosis. At a mean of 34 months, there were no events in the no NCP group, 2/54 (3.7%) events in the NCP without severe stenosis group (one sudden cardiac death and one ventricular tachycardia), and 2/5 (40.0%) patients had revascularization in the NCP with severe stenosis group.

CONCLUSIONS

(1) In patients with zero CAC, presence of NCP on MSCTA was associated with more RFs, especially smoking, obesity, and hypertension. (2) NCP can result in severe coronary stenosis. (3) NCP detected by MSCTA in patients with zero CAC may identify patients with late cardiac events.

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

OBJECTIVES

We sought to determine whether the amount of noncalcified plaque (NCP) in nonobstructive coronary lesions as detected by multidetector computed tomography (MDCT) was a predictor of future coronary events.

BACKGROUND

Patients presenting with non-ST-segment elevation myocardial infarction (NSTEMI) frequently have multiple coronary plaques, which may be detected with MDCT.

METHODS

We included 312 consecutive patients presenting with NSTEMI, who underwent 64-slice MDCT coronary angiography and coronary artery calcium scoring before invasive coronary angiography. All patients were treated according to current guidelines based on an invasive treatment approach. Quantitative measurements of plaque composition and volume were performed by MDCT in all nonobstructive coronary lesions. The endpoint was cardiac death, acute coronary syndrome, or symptom-driven revascularization.

RESULTS

After a median follow-up of 16 months, 23 patients had suffered a cardiac event. Age, male sex, and diabetes mellitus were all associated with an increasing amount of NCP. In a multivariate regression analysis for events, the total amount of NCP in nonobstructive lesions was independently associated with an increased hazard ratio (1.18/100-mm(3) plaque volume increase, p = 0.01). Contrary to this, neither Agatston score nor the amount of calcium in nonobstructive lesions was associated with an increased risk.

CONCLUSIONS

Multidetector computed tomography plaque imaging identified patients at increased risk of recurrent coronary events after NSTEMI by measuring the total amount of NCP in nonobstructive lesions. The amount of calcified plaque was not associated with an increased risk.

Coronary atherosclerosis imaging by coronary CT angiography: current status, correlation with intravascular interrogation and meta-analysis

Coronary computed tomography angiography (CTA) allows coronary artery visualization and the detection of coronary stenoses. In addition; it has been suggested as a novel, noninvasive modality for coronary atherosclerotic plaque detection, characterization, and quantification. Emerging data show that coronary CTA-based semiquantitative plaque characterization and quantification are sufficiently reproducible for clinical purposes, and fully quantitative approaches may be appropriate for use in clinical trials. Furthermore, several lines of investigation have validated plaque imaging by coronary CTA against other imaging modalities such as intravascular ultrasound/"virtual histology" and optical coherence tomography, and there are emerging data using biochemical modalities such as near-infrared spectroscopy. Finally, clinical validation in patients with acute coronary syndrome and in the outpatient setting has shown incremental value of CTA-based plaque characterization for the prediction of major cardiovascular events. With recent developments in image acquisition and reconstruction technologies, coronary CTA can be performed with relatively low radiation exposure. With further technological innovation and clinical research, coronary CTA may become an important tool in the quest to identify vulnerable plaques and the at-risk patient.

Comparison of the relation between the calcium score and plaque characteristics in patients with acute coronary syndrome versus patients with stable coronary artery disease, assessed by computed tomography angiography and virtual histology intravascular ultrasound

A considerable number of patients with an acute coronary syndrome (ACS) who present with a 0 or low calcium score (CS) still demonstrate coronary artery disease (CAD) and significant stenosis. The aim of the present study was to evaluate the relation between the CS and the degree and character of atherosclerosis in patients with suspected ACS versus patients with stable CAD obtained by computed tomography angiography and virtual histology intravascular ultrasound (VH IVUS). Overall 112 patients were studied, 53 with ACS and 59 with stable CAD. Calcium scoring and computed tomography angiography were performed and followed by VH IVUS. On computed tomography angiography each segment was evaluated for plaque and classified as noncalcified, mixed, or calcified. Vulnerable plaque characteristics on VH IVUS were defined by percent necrotic core and presence of thin-cap fibroatheroma. If the CS was 0, patients with ACS had a higher mean number of plaques (5.0 ± 2.0 vs 2.0 ± 1.9, p <0.05) and noncalcified plaques (4.6 ± 3.5 vs 1.3 ± 1.9, p <0.05) on computed tomography angiography than those with stable CAD. If the CS was 0, VH IVUS demonstrated that patients with ACS had a larger amount of necrotic core area (0.58 ± 0.73 vs 0.22 ± 0.43 mm(2), p <0.05) and a higher mean number of thin-cap fibroatheromas (0.6 ± 0.7 vs 0.1 ± 0.3, p <0.05) than patients with stable CAD. In conclusion, even in the presence of a 0 CS, patients with ACS have increased plaque burden and increased vulnerability compared to patients with stable CAD. Therefore, absence of coronary calcification does not exclude the presence of clinically relevant and potentially vulnerable atherosclerotic plaque burden in patients with ACS.

Can non-calcified coronary artery plaques be detected on non-contrast CT calcium scoring studies?

RATIONALE AND OBJECTIVES

Coronary computed tomographic (CT) angiography has been shown to detect noncalcified coronary artery plaque. Depending on tissue composition, noncalcified plaque differs in CT attenuation from blood and epicardial fat. The aim of this study was to determine whether noncalcified plaque can be visually detected on non-contrast-enhanced CT calcium scoring studies.

MATERIALS AND METHODS

A total of 106 patients (40 women; mean age, 59 years) who underwent coronary calcium scoring, coronary CT angiography, and quantitative catheter angiography were prospectively investigated. Two blinded observers independently reviewed calcium scoring studies for positive vascular remodeling and hypoattenuation within the vessel wall, suggestive of noncalcified plaque. Findings on calcium scoring studies were compared with those on coronary CT angiography and quantitative catheter angiography.

RESULTS

The mean Agatston score was 515.8 ± 826.8. Overall interobserver agreement for the identification of noncalcified lesions was substantial (κ = 0.69). Observer 1 and observer 2 identified 21 and 17 patients, respectively, with 38 and 35 lesions suggestive of noncalcified plaque. Coronary CT angiography confirmed noncalcified plaque in 33 of 38 (86.8%; observer 1) and 31 of 35 (88.6%; observer 2) lesions. Thus, the overall positive predictive value for correct identification of noncalcified plaque on calcium scoring studies was 0.88, although overall sensitivity was low at 0.39.

CONCLUSIONS

Noncalcified plaque can be visually detected on calcium scoring studies. Review of calcium scoring studies for features of noncalcified plaque may enhance the identification of patients with more active disease and higher cardiovascular risk.

Multislice CT angiography assessment of left coronary artery: correlation between bifurcation angle and dimensions and development of coronary artery disease

PURPOSE

To investigate the relationship between left coronary bifurcation and dimensional changes and development of coronary artery disease using multislice CT angiography.

MATERIALS AND METHODS

30 patients (18 men, 12 women, mean age, 56 years ± 8) suspected of coronary artery disease undergoing 64- and 256-slice CT angiography were included in the study. Left bifurcation angle and left coronary diameter were measured to determine the relationship between angulation and plaque formation and subsequent dimensional changes.

RESULTS

Plaques were present in the left coronary artery in 22 patients with variable angulations and dimensional changes. The mean bifurcation angle between left anterior descending and left circumflex arteries was measured 89.1° ± 13.1° (range, 55.3°, 134.5°) among all patients. The mean bifurcation angle measured in patients with normal and diseased left coronary artery was 75.5° ± 19.8° (range, 60°, 96.1°), and 94° ± 19.7° (range, 55.3°, 134.5°), respectively, with significant difference between these two groups (p=0.02). Similarly, there is a significant difference in the mean diameters of left anterior descending and left circumflex between patients with normal and diseased left coronary artery (p<0.001), which were measured 2.8 ± 0.3mm (range, 2.2, 3.2mm) and 2.1 ± 0.4mm (range, 1.9, 2.9 mm) for the normal left coronary arteries, 4.0 ± 0.8mm (range, 2.5, 6.1mm) and 2.9 ± 0.5mm (range, 1.6, 3.9 mm) for the diseased left coronary arteries, respectively.

CONCLUSION

There is a direct correlation between left bifurcation angle and dimensional changes and formation of plaques. Multislice CT angiography can be used to provide relevant features of left coronary atherosclerosis.

Small calcified coronary atherosclerotic plaque simulation model: minimal size and attenuation detectable by 64-MDCT and MicroCT

Zero calcium score may not reflect the absence of calcifications as small calcifications could be missed. This study aimed to evaluate minimal size and minimal attenuation of coronary calcifications detectable by computed tomography (CT) and to determine the minimal spatial resolution required for detecting calcification onset. Using open source CT simulation software, CTSim^©, several 50%-stenotic coronary artery phantoms were designed with 5 μm resolution, realistic morphology and tissue-specific Hounsfield Unit (HU) values. The plaque had an attenuation resembling fibrous plaque and contained a single calcification. X-ray projections were simulated with settings resembling non-contrast-enhanced 64 multi detector-row CT (64-MDCT). Scanning and reconstruction were simulated with spatial resolution of a 64-MDCT (0.4mm) and of a MicroCT (48 μm). Starting from a single calcium granule, the calcification was simulated to grow in size and attenuation until it could be detected using clinically accepted calcium determination scheme on MicroCT and 64-MDCT images. The smallest coronary calcifications detectable at MicroCT and 64-MDCT, which had a realistic attenuation (−1,024 to 3,072 HU), were of 25 μm and 215 μm diameter, respectively. The area was overestimated 7.7 and 8.8 times, respectively. Calcifications with smaller size need to have an unrealistically high attenuation to be detectable by 64-MDCT. In conclusion, 64-MDCT is only able to detect coronary calcifications with minimal diameter of 215 μm. Consequently, early onset of calcification in coronary plaque will remain invisible when using CT and a zero calcium score can not exclude the presence of coronary calcification.

Usefulness of hypertriglyceridemic waist phenotype in type 2 diabetes mellitus to predict the presence of coronary artery disease as assessed by computed tomographic coronary angiography

The present study tested whether in patients with type 2 diabetes mellitus (DM) the combination of increased waist circumference and increased plasma triglyceride (TG) levels can predict the presence of coronary artery disease (CAD) as assessed by multidetector computed tomographic coronary angiography (CTA). In 202 patients with type 2 DM who were clinically referred for CTA, waist circumference and TG levels were measured. Patients were divided into 4 groups according to waist circumference measurements and TG levels. Increased waist circumference and TG levels (n = 61, 31%) indicated the presence of the hypertriglyceridemic waist phenotype. Patients with low waist circumference and TG (n = 49, 24%) were considered the reference group. Physical examination and blood measurements were performed. CTA was used to determine presence and severity of CAD. In addition, plaque type was evaluated. Plasma cholesterol levels were significantly increased in the group with increased TG levels and waist circumference, whereas high-density lipoprotein cholesterol was significantly lower than in the reference group. There was a significant increase in the presence of any CAD (odds ratio 3.3, confidence interval 1.31 to 8.13, p <0.05) and obstructive CAD (≥50%, odds ratio 2.9, confidence interval 1.16 to 7.28, p <0.05) in the group with increased TG level and waist circumference. In addition, a significantly larger number of noncalcified and mixed plaques was observed. In conclusion, in patients with type 2 DM, presence of the hypertriglyceridemic waist phenotype translated into a deteriorated blood lipid profile and more extensive CAD on CTA. Accordingly, the hypertriglyceridemic waist phenotype may serve as a practical clinical biomarker to improve risk stratification in patients with type 2 DM.

Characteristics of coronary artery disease in symptomatic type 2 diabetic patients: evaluation with CT angiography

BACKGROUND

Coronary artery disease (CAD) is a common and severe complication of type 2 diabetes mellitus (DM). The aim of this study is to identify the features of CAD in diabetic patients using coronary CT angiography (CTA).

METHODS

From 1 July 2009 to 20 March 2010, 113 consecutive patients (70 men, 43 women; mean age, 68 ± 10 years) with type 2 DM were found to have coronary plaques on coronary CTA. Their CTA data were reviewed, and extent, distribution and types of plaques and luminal narrowing were evaluated and compared between different sexes.

RESULTS

In total, 287 coronary vessels (2.5 ± 1.1 per patient) and 470 segments (4.2 ± 2.8 per patient) were found to have plaques, respectively. Multi-vessel disease was more common than single vessel disease (p < 0.001), and the left anterior descending (LAD) artery (35.8%) and its proximal segment (19.1%) were most frequently involved (all p < 0.001). Calcified plaques (48.8%) were the most common type (p < 0.001) followed by mixed plaques (38.1%). Regarding the different degrees of stenosis, mild narrowing (36.9%) was most common (p < 0.001); however, a significant difference was not observed between non-obstructive and obstructive stenosis (50.4% vs. 49.6%, p = 0.855). Extent of CAD, types of plaques and luminal narrowing were not significantly different between male and female diabetic patients.

CONCLUSIONS

Coronary CTA depicted a high plaque burden in patients with type 2 DM. Plaques, which were mainly calcified, were more frequently detected in the proximal segment of the LAD artery, and increased attention should be paid to the significant prevalence of obstructive stenosis. In addition, DM reduced the sex differential in CT findings of CAD.

Calcium scoring and chest pain: is it dead on arrival?

Coronary artery calcium (CAC) scoring has been shown to be a measure of overall coronary artery disease (CAD) burden and is a well-validated screening test that significantly improves cardiovascular risk prediction in asymptomatic adults beyond that provided with standard risk factors. The absence of coronary artery calcification identifies persons at very low cardiovascular risk. Among symptomatic patients, calcium scans have been shown to have high sensitivity for the presence of obstructive CAD among stable, low-intermediate risk middle-aged adults. This has prompted many to advocate for the expanded use of calcium scanning as a diagnostic test in symptomatic patients to rapidly identify patients without CAD, serving as a filter for invasive coronary angiography or hospital admission or both. However, recent studies suggest that the negative predictive value of CAC scoring to exclude obstructive CAD may be significantly decreased among patients at higher pretest likelihood for obstructive CAD, consistent with Bayesian reasoning. In a point-counterpoint format, this article discusses several considerations and potential limitations to the widespread use of CAC to exclude obstructive CAD in symptomatic patients which include (1) the effect of pretest disease prevalence on test accuracy, (2) limited clinical efficiency due to low specificity for obstructive CAD and myocardial ischemia and high background prevalence of CAC in adults, (3) occurrence of CAC relatively late in the atherosclerotic process, (4) lack of association of CAC with vulnerable and culprit coronary artery lesions, and (5) interindividual and racial heterogeneity in the process of atherosclerosis calcification.

Influence of slice thickness and reconstruction kernel on the computed tomographic attenuation of coronary atherosclerotic plaque

BACKGROUND

The computed tomographic (CT) attenuation of coronary atherosclerotic plaque has been proposed as a marker for tissue characterization and may thus potentially contribute to the assessment of plaque instability.

OBJECTIVE

We analyzed the influence of reconstruction parameters on CT attenuation measured within noncalcified coronary atherosclerotic lesions.

METHODS

Seventy-two patients were studied by contrast-enhanced dual-source CT coronary angiography (330 millisecond rotation time, 2 x 64 x 0.6 mm collimation, 120 kV, 400 mAs, 80 mL contrast agent intravenously at 6 mL/s), and a total of 100 distinct noncalcified coronary atherosclerotic plaques were identified. Image data sets were reconstructed with a soft (B20f), medium soft (B26f), and sharp (B46f) reconstruction kernel. With the medium soft kernel, image data sets were reconstructed with a slice thickness/increment of 0.6/0.3 mm, 0.75/0.4 mm, and 1.0/0.5mm. Within each plaque, CT attenuation was measured.

RESULTS

Mean CT attenuation using the medium soft kernel was 109 +/- 58 HU (range, -16 to 168 HU). Using the soft kernel, mean density was 113 +/- 57 HU (range, -13 to 169 HU), and using a sharp kernel, mean density was 97 +/- 49 HU (range, -23 to 131 HU). Similarly, reconstructed slice thickness had a significant influence on the measured CT attenuation (mean values for medium soft kernel: 102 +/- 52 HU versus 109 +/- 58 HU versus 113 +/- 57 HU for 0.6-mm, 0.75-mm, and 1.0-mm slice thickness). The differences between 0.75-mm and 0.6-mm slice thickness (P = 0.05) and between medium sharp and sharp kernels (P = 0.02) were statistically significant.

CONCLUSIONS

Image reconstruction significantly influences CT attenuation of noncalcified coronary atherosclerotic plaque. With decreasing spatial resolution (softer kernel or thicker slices), CT attenuation increases significantly. Using absolute CT attenuation values for plaque characterization may therefore be problematic.

The value of multi-slice-computed tomography coronary angiography for risk stratification

Multi-slice-computed tomography coronary angiography (CTA) provides direct non-invasive anatomic assessment of the coronary arteries allowing for early identification of coronary artery disease (CAD). This information is useful for diagnosis of CAD, particularly the rule out of CAD. In addition, early identification of CAD with CTA may also be useful for risk stratification. The purpose of this review is to provide an overview of the current literature on the prognostic value of CTA and to discuss how the prognostic information obtained with CTA can be used to further integrate the technique into clinical practice. Non-invasive anatomic assessment of plaque burden, location, composition, and remodeling using CTA may provide prognostically relevant information. This information has been shown to be incremental to the Framingham risk score, coronary artery calcium scoring, and myocardial perfusion imaging. Characterization of atherosclerosis non-invasively has the potential to provide important prognostic information enabling a more patient-tailored approach to disease management.Future studies assessing outcome after CTA-based risk adjustments are needed to further understand the value of detailed non-invasive anatomic imaging.