A three-vessel virtual histology intravascular ultrasound analysis of frequency and distribution of thin-cap fibroatheromas in patients with acute coronary syndrome or stable angina pectoris

Drug intervention as an emerging concept for secondary prevention in patients with coronary disease

Non-culprit lesion-related coronary events are a significant concern in patients with coronary artery disease (CAD) undergoing coronary intervention. Since several studies using intra-coronary imaging modalities have reported a high prevalence of vulnerable plaques in non-culprit lesions at the initial coronary event, the immediate stabilization of these plaques by intensive pharmacological regimens may contribute to the reduction in the adverse events. Although current treatment guidelines recommend the titration of statin and other drugs to attain the treatment goal of low-density lipoprotein cholesterol (LDL-C) level in patients with CAD, the early prescription of strong LDL-C lowering drugs with more intensive regimen may further reduce the incidence of recurrent cardiovascular events. In fact, several studies with intensive regimen have demonstrated a higher percentage of patients with the attainment of LDL-C treatment goal in the early phase following discharge. In addition to many imaging studies showing plaque stabilization by LDL-C lowering drugs, several recent reports have shown the efficacy of early statin and proprotein convertase subtilisin/kexin type 9 inhibitors on the immediate stabilization of non-culprit coronary plaques. To raise awareness regarding this important concept of immediate plaque stabilization and subsequent reduction in the incidence of recurrent coronary events, the term 'Drug Intervention' has been introduced and gradually applied in the clinical field, although a clear definition is lacking. The main target of this concept is patients with acute coronary syndrome as a higher prevalence of vulnerable plaques in non-culprit lesions in addition to the worse clinical outcomes has been reported in recent imaging studies. In this article, we discuss the backgrounds and the concept of drug intervention.

Intravascular ultrasound insights into the unstable features of the coronary atherosclerotic plaques: A systematic review and meta-analysis

BACKGROUND

There is a lack of a comprehensive picture of plaque geometry and composition of unstable atherosclerotic lesions as observed with intravascular ultrasound techniques. We analysed through a systematic review with meta-analysis 39 characteristics of atherosclerotic plaques in three scenarios involving culprit and non-culprit lesions from acute coronary syndromes vs stable angina pectoris patients, and culprit vs non-culprit lesions in acute coronary syndromes patients.

METHODS

A systematic search of PubMed and EMBASE, from inception to April 2020 was performed. The combined odds ratios or mean differences of all IVUS characteristics were calculated with random-effects models.

RESULTS

Twenty-eight studies involving 5434 subjects, and 5618 lesions were included. Culprit lesions in acute coronary syndromes have larger plaque areas and remodeling indexes (MD = 0.13 [0.08; 0.17], p < 0.001) and contained larger necrotic cores (MD = 0.67 (95% CI 0.19;1.15), p = 0.006) that stable angina culprit lesions. In acute patients, culprit plaques were also more remodeled, had larger necrotic cores and had more frequently a Thin-Cap Fibroatheroma morphology (OR = 1.79 (95% CI 1.21; 2.65), p = 0.004) than non-culprit lesions. Non-culprit lesions in acute syndromes were more often ruptured (OR = 2.25 (95% CI:1.05; 4.82), p = 0.037) or Thin-Cap Fibroatheromas than in stable angina.

CONCLUSION

Culprit lesions from acute coronary patients are larger, more positively remodeled and contained more lipids as compared to stable angina lesions or non-culprit in acute patients. Non culprit lesions are also more often complicated or vulnerable in acute than stable patients.

Morphology and phenotype characteristics of atherosclerotic plaque in patients with acute coronary syndrome: contemporary optical coherence tomography findings

BACKGROUND

Contemporary optical coherence tomography (OCT) findings in patients with acute coronary syndromes (ACS) are still subject of controversy. We sought to use OCT to evaluate plaque morphology and phenotype classification in patients with ACS.

METHODS

Using optical coherence tomography, culprit lesions were morphologically classified as plaque rupture, plaque erosion, calcified nodule, thin-cap fibroatheroma, thick-cap fibroatheroma (TCFA) or fibrotic, fibrocalcific or fibrolipidic plaque. Quantitative and qualitative analyses also included cholesterol crystals, neovascularization, spotty calcification and thrombus.

RESULTS

Of the 110 lesions imaged from June 2012 to April 2016, 54 (49%) were in patients with unstable angina (UA), 31 (28%) were in non-ST-elevation myocardial infarction (STEMI) patients and 25 (23%) were in STEMI patients. Compared with STEMI patients, patients with UA/non-STEMI were older and had more hypertension, hypercholesterolemia, known coronary artery disease, prior myocardial infarction and higher use of antiplatelet therapy. More patients with STEMI had lipidic arc >90% (36.6 versus 70.8%, P = 0.003), red and mixed thrombus (12.9 versus 28.0% and 7.1 versus 44.0%, respectively, all P < 0.001), plaque rupture (29.4 versus 76.0%, P < 0.001) and TCFA (57.1 versus 84.0%; P = 0.01). Predictors of plaque rupture were STEMI at presentation (odds ratio: 9.35, 95% confidence interval: 1.66-52.61, P = 0.01) and diabetes mellitus (odds ratio: 6.16, 95% confidence interval: 1.33-28.58, P = 0.02).

CONCLUSIONS

In this single-center study, the culprit lesion of patients with STEMI had more lipid, red and mixed thrombus, plaque rupture and TCFA versus patients with UA/non-STEMI. Clinical presentation may be driven by distinct pathophysiologic mechanisms in patients with ACS.

Comparison of Intravascular Ultrasound Virtual Histology Parameters in Diabetes versus Non-Diabetes with Acute Coronary Syndrome

INTRODUCTION

The progression and pattern of coronary atherosclerosis in diabetes mellitus (DM) is different from non-DM, leading to a higher rate of vascular complications in DM.

OBJECTIVE

This study aims to assess and compare the high-risk plaque characteristics in the culprit artery of DM and non-DM patients with acute coronary syndrome (ACS) using virtual histology intravascular ultrasound (VH-IVUS).

METHODS

A total of 158 ACS patients were included, 63 of whom were known to have DM. IVUS analysis was done in the de novo target vessel and culprit lesion for which percutaneous coronary intervention was planned. Culprit lesions with a visual-estimate angiographic stenosis of <70% were excluded.

RESULTS

The mean age of patients was 52.4 ± 11.6 years. The study group comprised 82% men, 31% with hypertension, and 39.87% with DM. No significant difference was observed between the DM and non-DM groups in relation to quantitative IVUS parameters like lesion length, minimal lumen area, and plaque area. However, there was a significant difference in VH-IVUS parameters like higher necrotic core and dense calcium in the DM patients than in the non-DM patients (p < 0.01). The occurrence of VH-derived thin-cap fibroatheroma (VH-TCFA) in the culprit vessel was significantly higher in the DM group than in the non-DM group (25.3 vs. 5.2%; p < 0.01). Positive vessel-wall remodeling was noted in both groups without any significant difference (p = 0.74).

CONCLUSION

The DM patients had high-risk plaque composition features like a higher necrotic core, which is a marker of plaque vulnerability. Thus, aggressive medical therapy targeting vascular inflammation using high-dose statins would help in the stabilization of unstable plaque morphology and the reduction of major cardiovascular events.

Correlation between monocyte chemoattractant protein-1/chemokine (C-C motif) ligand 2 and coronary plaque characteristics

IMPACT STATEMENT

Vulnerable plaques are plaques which are susceptible to rupture or thrombosis and trigger a series of adverse events such as coronary disorders. CCL2 is a soluble basic protein belonging to the CC subfamily. Previous studies have been investigated on the correlation between inflammatory factors and clinical events, but there are few studies on the correlation between CCL2 and plaque characteristics. Our study found that the high expression of CCL2 is involved in multiple processes in the genesis and progression of coronary artery disease, and would be a potential clinical prognostic indicator. In addition, high expression of CCL2 may be related to gene pathways such as Nod-like receptor signaling pathway, suggesting that CCL2 is involved in the inflammatory response and immune process of coronary artery disease.

Revascularization Strategies in Patients Presenting With ST-Elevation Myocardial Infarction and Multivessel Coronary Disease

The optimal revascularization strategy for residual coronary stenosis following primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction (STEMI) and multivessel disease (MVD) remains controversial. This is a retrospective single-centre study including patients with STEMI and MVD. Based on the revascularization strategy, 3 groups were identified: (1) culprit only (CO), (2) ad hoc multivessel revascularization (MVR), and (3) staged MVR. Clinical outcomes were compared in terms of major adverse cardiac events (MACE), a composite of cardiac death, any myocardial infarction, and any unplanned revascularization at a long-term follow-up. A total of 958 patients were evaluated, 489 in the CO, 254 in the ad hoc, and 215 in the staged group. In the staged group, 65.6% of the patients received planned percutaneous coronary intervention, 9.7% coronary artery bypass grafting, 8.4% no further intervention after lesion reassessment, and in 16.3% an event occurred before the planned procedure. At 1,095 days, MACE was 36.1%, 16.7%, and 31% for CO, ad hoc, and staged groups, respectively. A MVR strategy was associated with lower rate of all-cause death compared with CO (HR 0.50; 95%CI [0.31 to 0.80]; p = 0.004). Complete revascularization reduced the rate of MACE (HR 0.30 [0.21 to 0.43] p < 0.001) compared with incomplete revascularization. Ad hoc MVR had lower rate of MACE compared with staged MVR (HR 0.61 [0.39 to 0.96] p = 0.032) mainly driven by less unplanned revascularizations. In conclusion, in patients with STEMI and MVD, complete revascularization reduced the risk of MACE. Ad hoc MVR appeared a reasonable strategy with lower contrast and stent usage and costs.

Current Advances in the Diagnostic Imaging of Atherosclerosis: Insights into the Pathophysiology of Vulnerable Plaque

Atherosclerosis is a lipoprotein-driven inflammatory disorder leading to a plaque formation at specific sites of the arterial tree. After decades of slow progression, atherosclerotic plaque rupture and formation of thrombi are the major factors responsible for the development of acute coronary syndromes (ACSs). In this regard, the detection of high-risk (vulnerable) plaques is an ultimate goal in the management of atherosclerosis and cardiovascular diseases (CVDs). Vulnerable plaques have specific morphological features that make their detection possible, hence allowing for identification of high-risk patients and the tailoring of therapy. Plaque ruptures predominantly occur amongst lesions characterized as thin-cap fibroatheromas (TCFA). Plaques without a rupture, such as plaque erosions, are also thrombi-forming lesions on the most frequent pathological intimal thickening or fibroatheromas. Many attempts to comprehensively identify vulnerable plaque constituents with different invasive and non-invasive imaging technologies have been made. In this review, advantages and limitations of invasive and non-invasive imaging modalities currently available for the identification of plaque components and morphologic features associated with plaque vulnerability, as well as their clinical diagnostic and prognostic value, were discussed.

Low- to high-density lipoprotein cholesterol ratio followed by coronary computed tomography angiography improves coronary plaque classification accuracy

Coronary computed tomography angiography (CCTA) is a noninvasive test for detection and analysis of coronary plaques morphology and classification. The low- to high-density lipoprotein cholesterol (L/H) ratio is associated with plaques vulnerability. The study aims to investigate the diagnostic accuracy of CCTA and L/H ratio for plaques classification. We enrolled 212 patients with coronary artery single-vessel disease who performed preoperative CCTA and Intravascular ultrasound (IVUS)-guided invasive coronary angiography. Patients were assigned to the acute coronary syndrome (ACS) group (n = 129) and stable angina pectoris (SAP) group (n = 83). CCTA showed that patients with ACS had more soft plaque and less calcific plaque than those with SAP. The plaque volume and remodeling index measured by CCTA showed good correlation with those measured by IVUS. IVUS identified 91 soft, 58 mixed and 63 calcific plaques in this cohort. For diagnosis of noncalcified plaque (soft and mixed), CCTA had the sensitivity and specificity of 87.9% and 90.4%, respectively. While refer to the further diagnosis of mixed plaque from noncalcified plaque, the sensitivity and specificity was 88.4% and 88.8%, respectively. The L/H ratio was gradually decreased from soft plaque to calcific plaque. If the patients had both the two characteristics (L/H ≥ 2.55 and CCTA), the sensitivity, and specificity were improved in diagnosing noncalcified plaque or mixed plaque. In conclusion, a combined application of CCTA and L/H ratio improves the diagnostic accuracy for coronary noncalcified plaque or mixed plaque as compared to CCTA along.

Diagnosis of Thin-Capped Fibroatheromas in Intravascular Optical Coherence Tomography Images: Effects of Light Scattering

BACKGROUND

Intravascular optical coherence tomography (IVOCT) images are recorded by detecting light backscattered within coronary arteries. We hypothesize that non-thin-capped fibroatheroma (TCFA) causes may scatter light to create the false appearance of IVOCT TCFA.

METHODS AND RESULTS

Ten human cadaver hearts were imaged with IVOCT (n=14 coronary arteries). IVOCT and histological TCFA images were coregistered and compared. Of 21 IVOCT TCFAs (fibrous cap <65 μm, lipid arc >1 quadrant), only 8 were true histological TCFA. Foam cell infiltration was responsible for 70% of false IVOCT TCFA and caused both thick-capped fibroatheromas to appear as TCFA, and the appearance of TCFAs when no lipid core was present. Other false IVOCT TCFA causes included smooth muscle cell-rich fibrous tissue (12%) and loose connective tissue (9%). If the lipid arc >1 quadrant (obtuse) criterion was disregarded, 45 IVOCT TCFAs were identified, and sensitivity of IVOCT TCFA detection increased from 63% to 87%, and specificity remained high at 92%.

CONCLUSIONS

We demonstrate that IVOCT can exhibit 87% (95% CI, 75%-93%) sensitivity and 92% specificity (95% CI, 86%-96%) to detect all lipid arcs (both obtuse and acute, <1 quadrant) TCFA, and we also propose new mechanisms involving light scattering that explain why other plaque components can masquerade as TCFA and cause low positive predictive value of IVOCT for TCFA detection (47% for obtuse lipid arcs). Disregarding the lipid arc >1 quadrant requirement enhances the ability of IVOCT to detect TCFA.

Imaging Techniques for the Assessment of Coronary Arteries in Diabetic Patients Undergoing PCI with Bioresorbable Vascular Scaffolds

Patients who suffer from diabetes mellitus and present coronary artery disease are at a higher risk of cardiovascular events. The coronary arteries of diabetic patients present a diffuse process of atherosclerosis with frequent distal involvement, being prone to acute cardiovascular events. Diabetics present an increased rate of developing coronary artery remodeling, negative remodeling being representative for this class of patients; this process is characterized by vessel shrinkage and an increased rate of coronary calcium accumulation that is a predictor for cardiovascular risk. Currently, it is desired to improve the treatment of diabetic patients with bioresorbable vascular scaffolds (BVS), because of their reduced risk of restenosis and the ability to restore coronary function, including vasomotion, adaptive shear stress, and expansive remodeling. Optical coherence tomography, intravascular ultrasound and multi-slice computed tomography are imaging techniques used for a high accuracy of diagnosis in coronary artery disease. This manuscript is a review that aims to highlight imaging techniques used for evaluating the functional impact of coronary lesions in diabetic patients who underwent coronary PCI with bioresorbable scaffolds and to describe the functional markers that show the specificity for predicting coronary artery disease.

Invasive or non-invasive imaging for detecting high-risk coronary lesions?

INTRODUCTION

Advances in our understanding about atherosclerotic evolution have enabled us to identify specific plaque characteristics that are associated with coronary plaque vulnerability and cardiovascular events. With constant improvements in signal and image processing an arsenal of invasive and non-invasive imaging modalities have been developed that are capable of identifying these features allowing in vivo assessment of plaque vulnerability. Areas covered: This review article presents the available and emerging imaging modalities introduced to assess plaque morphology and biology, describes the evidence from the first large scale studies that evaluated the efficacy of invasive and non-invasive imaging in detecting lesions that are likely to progress and cause cardiovascular events and discusses the potential implications of the in vivo assessment of coronary artery pathology in the clinical setting. Expert commentary: Invasive imaging, with its high resolution, and in particular hybrid intravascular imaging appears as the ideal approach to study the mechanisms regulating atherosclerotic disease progression; whereas non-invasive imaging is expected to enable complete assessment of coronary tree pathology, detection of high-risk lesions, more accurate risk stratification and thus to allow a personalized treatment of vulnerable patients.

Tissue characterization and phenotype classification in patients presenting with acute myocardial infarction: Insights from the iWonder study

OBJECTIVES

We sought to assess a new modality of radiofrequency intravascular ultrasound (IVUS) called iMAP-IVUS (Boston Scientific, Santa Clara, California) during the evaluation of patients presenting with high-risk acute coronary syndromes.

BACKGROUND

There are limited data on plaque tissue characterization and phenotype classification using iMAP-IVUS.

METHODS

In the iWonder study patients presenting with ST-elevation myocardial infarction (STEMI) or non-STEMI underwent three-vessel grayscale IVUS and iMAP-IVUS tissue characterization prior to percutaneous intervention. In total 385 lesions from 100 patients were divided into culprit (n = 100) and nonculprit (n = 285) lesions. Lesion phenotype was classified as (i) thin-cap fibroatheroma (iMAP-derived TCFA); (ii) thick-cap fibroatheroma; (iii) pathological intimal thickening; (iv) fibrotic plaque; and (v) fibrocalcific plaque.

RESULTS

Culprit lesions had smaller minimum lumen cross-sectional area (MLA) with greater plaque burden compared to non-culprit lesions. Volumetric analysis showed that culprit lesions had longer length and larger vessel and plaque volumes compared to non-culprit lesions. iMAP-IVUS revealed that culprit lesions presented more NC and fibrofatty volume, both at lesion level and at the MLA site (all P < 0.001). Any fibroatheroma was more frequently identified in culprit lesions compared with non-culprit lesions (93% vs. 78.9%, P = 0.001), anywhere within the lesion 19.0%, P < 0.001) as well as at the MLA site (18.0% vs. 9.5%, P = 0.07).

CONCLUSIONS

Three-vessel radiofrequency iMAP-IVUS demonstrated a greater plaque burden and higher prevalence of any fibroatheroma as well as iMAP-derived TCFAs in culprit versus non-culprit lesions in patients presenting with STEMI or non-STEMI undergoing percutaneous coronary intervention. © 2017 Wiley Periodicals, Inc.

Construction and validation of a plaque discrimination score from the anatomical and histological differences in coronary atherosclerosis: the Liverpool IVUS-V-HEART (Intra Vascular UltraSound-Virtual-Histology Evaluation of Atherosclerosis Requiring Treatment) study

AIMS

New markers to help stratify coronary atherosclerosis are needed. Although attempts have been made to differentiate active lesions from those that are stable, none of these has ever been formalised into a discriminatory score. The aim of this study was to analyse the differences between culprit ACS lesions and culprit stable angina lesions with intravascular ultrasound-derived virtual histology and to construct and validate a plaque score.

METHODS AND RESULTS

Prior to percutaneous coronary intervention (PCI), we performed volumetric, intravascular ultrasound-derived virtual histology (IVUS-VH) analysis in acute coronary syndrome (ACS) culprit lesions (AC - n=70) and stable angina culprit lesions (SC - n=35). A direct statistical comparison of IVUS-VH data and multiple logistic regression analysis was undertaken. Four main factors were found to be associated (p<0.05) with an AC lesion phenotype: necrotic core/dense calcium (NC/DC) ratio; minimum lumen area <4 mm2 (MLA <4); remodelling index @MLA >1.05 and VH-TCFA presence. Calculation of each logistic regression coefficient and the equation produces an active plaque discrimination score with an AUC of 0.96 on receiver operating characteristics (ROC) analysis. Validation of the score in 50 independent plaques from the Thoraxcenter in Rotterdam revealed an AUC of 0.71, confirming continued diagnostic ability.

CONCLUSIONS

We have found four features on IVUS and VH that can predict and discriminate ACS culprit lesion phenotypes from those that are clinically stable. Subsequently, we have constructed and validated the Liverpool Active Plaque Score based upon these features. It is hoped this score may help diagnose active coronary plaques, in the future, to help prevent major adverse cardiac events.

Comparison of plaque characteristics in narrowings with ST-elevation myocardial infarction (STEMI), non-STEMI/unstable angina pectoris and stable coronary artery disease (from the ADAPT-DES IVUS Substudy)

Assessment of Dual Antiplatelet Therapy With Drug-Eluting Stents (ADAPT-DES) was a prospective, multicenter registry of 8,582 consecutive stable and unstable patients who underwent percutaneous coronary intervention using a drug-eluting stent. We sought to identify key morphologic features leading to ST-segment elevation myocardial infarction (STEMI) versus non-STEMI (NSTEMI) or unstable angina pectoris (UA) versus stable coronary artery disease (CAD) presentation. In the prespecified grayscale and virtual histology (VH) substudy of ADAPT-DES, preintervention imaging identified 676 patients with a single culprit lesion. The relation between lesion morphology and clinical presentation was compared among patients with (1) STEMI, (2) NSTEMI or UA, and (3) stable CAD. Intravascular ultrasound identified more plaque rupture and VH thin-cap fibroatheroma (TCFA) in STEMI lesions compared with NSTEMI/UA or stable CAD lesions; conversely, fibroatheromas appeared more often calcified with a thick fibrous cap in stable CAD. Minimum lumen cross-sectional area (MLA) was smaller with larger plaque burden and positive remodeling in STEMI lesions. Lesions with plaque rupture versus those without plaque rupture showed higher prevalence of VH-TCFA and larger plaque burden with positive remodeling, especially in patients with STEMI. Multivariate analysis showed that in the lesions with plaque rupture, plaque burden at the MLA site was the only independent predictor for STEMI (cutoff of plaque burden = 85%) and in lesions without plaque rupture, MLA was the only independent predictor for STEMI (cutoff of MLA = 2.3 mm(2)). In conclusion, culprit lesions causing STEMI have smaller lumen areas, greater plaque burden, and more plaque rupture or VH-TCFA compared with NSTEMI/UA or stable CAD; in lesions with plaque rupture, only plaque burden predicted STEMI, and in lesions without plaque rupture, only MLA area predicted STEMI.

Application of Intravascular Ultrasound in the Emergency Diagnosis and Treatment of Patients with ST-Segment Elevation Myocardial Infarction

PURPOSE

This study aimed to examine the application of intravascular ultrasound (IVUS) in ST-segment elevation myocardial infarction (STEMI) patients with high thrombus burden (thrombus grade ≥3) undergoing emergency diagnosis and primary percutaneous coronary intervention.

METHODS

Eighty STEMI patients were enrolled and randomly assigned to the IVUS-guided group (38 patients) or non-IVUS group (42 patients). Stent implantation was performed in non-IVUS group patients. IVUS group patients were further divided into low-risk and high-risk patients on the basis of IVUS evaluation for determining whether stenting should be performed. Major adverse cardiac event (MACE) rates, changes in the left ventricular end-diastolic diameter (LVEDD) and ejection fraction (EF) values, and stent numbers were examined during hospitalization, and follow-up was performed at 1, 3, 6, and 12 months postoperatively.

RESULTS

During hospitalization, there were no significant differences in the MACE rates, LVEDD, and EF values and in the follow-up outcomes at 1, 3, 6, and 12 months postoperatively among the patients in the 2 groups (P > 0.05). A significantly lower number of stents were implanted in the IVUS group than in the non-IVUS group patients (P < 0.05).

CONCLUSION

During the IVUS-guided emergency intervention, enhanced antithrombotic therapy and best medical care for low-risk STEMI patients may be feasible.

Site-specific intravascular ultrasound analysis of remodelling index and calcified necrosis patterns reveals novel blueprints for coronary plaque instability

AIMS

Post-mortem pathological studies have shown that a "vulnerable" plaque is the dominant patho-physiological mechanism responsible for acute coronary syndromes (ACS). One way to improve our understanding of these plaques in vivo is by using histological "surrogates" created by intravascular ultrasound derived virtual histology (IVUS-VH). Our aim in this analysis was to determine the relationship between site-specific differences in individual plaque areas between ACS plaques and stable plaques (SP), with a focus on remodelling index and the pattern of calcifying necrosis.

METHODS AND RESULTS

IVUS-VH was performed before percutaneous intervention in both ACS culprit plaques (CP) n=70 and stable disease (SP) n=35. A total of 210 plaque sites were examined in 105 lesions at the minimum lumen area (MLA) and the maximum necrotic core site (MAX NC). Each plaque site had multiple measurements made including some novel calculations to ascertain the plaque calcification equipoise (PCE) and the calcified interface area (CIA). CP has greater amounts of positive remodelling at the MLA (RI@MLA): 1.1 (±0.17) vs. 0.95 (±0.14) (P<0.001); lower values for PCE 30% vs. 54% (P<0.001) but a higher CIA 5.38 (±2.72) vs. 3.58 (±2.26) (P=0.001). These features can provide discriminatory ability between plaque types with area under the curve (AUC) measurements between 0.65-0.86. The cut-off values with greatest sensitivity and specificity to discriminate CP morphologies were: RI @ MLA >1.12; RI @ MAX NC >1.22; PCE @ MLA <47.1%; PCE @MAX NC <47.3%; CIA @ MLA >2.6; CIA @ MAX NC >3.1.

CONCLUSIONS

Determining the stage of calcifying necrosis, along with the remodelling index can discriminate between stable and ACS related plaques. These findings could be applied in the future to help detect plaques that have a vulnerable phenotype.

Assessment of plaque composition by intravascular ultrasound and near-infrared spectroscopy: from PROSPECT I to PROSPECT II

Atherosclerosis is the main cause of coronary artery disease (CAD), which is today the leading cause of death worldwide and will continue to be the first in the world in 2030. Vulnerable coronary plaques are usually characterized by a high content of necrotic core, a thin inflamed fibrous cap (intense accumulation of macrophages) and scarce presence of smooth muscle cells. None of these characteristics can be estimated by coronary angiography, which on the contrary underestimates the magnitude of atherosclerotic burden, particularly in earlier stage disease when positive vascular remodeling may allow "normal" lumen caliber despite substantial vascular wall plaque. The recognition of the ubiquity of substantial but non-flow limiting lesions that may be at high risk for subsequent plaque rupture has resulted in a paradigm shift in thinking about the pathophysiology of CAD, with the focus no longer solely on the degree of arterial luminal narrowing. This growing need for more information about coronary atherosclerosis in order to identify patients and lesions at risk for complications during PCI and for future adverse cardiac events has been the primary impetus for the development of novel intracoronary imaging methods able to detect plaque composition, in particular presence of a necrotic core/lipid pool, such as intravascular ultrasound virtual histology and near-infrared spectroscopy. These imaging technologies and their clinical and clinical/research applications are discussed in detail.

Intravascular ultrasound as a clinical adjunct for carotid plaque characterization

OBJECTIVE

Virtual histology intravascular ultrasound (VH IVUS) is valuable for estimating minimal lumen diameter and plaque characterization. The clinical use of IVUS in carotid intervention is not well characterized. We aim to evaluate the role of IVUS in carotid plaque characterization and determine whether it could be predictive of procedure-related microemboli.

METHODS

From July 2010, patients with severe carotid stenosis who underwent elective carotid stenting procedures were prospectively enrolled. IVUS evaluation was performed before stent placement. Patient demographics, comorbidities, and preoperative images were recorded. Comparison of pre- and postoperative diffusion-weighted magnetic resonance images was used to identify the number of procedure-related microemboli. IVUS-derived minimal lumen diameter and vessel wall plaque characteristics were collected. Univariate and multivariate logistic regressions were used to search for associations between IVUS-derived VH data and incidence of microemboli.

RESULTS

A total of 38 high-risk patients receiving carotid stenting were enrolled. Among them, 25 patients had type I aortic arches and 17 of the patients were symptomatic (preoperative stroke or transient ischemic attack). VH IVUS data did not show strong associations with microemboli, however, a trend was found between the area of fibrous tissue and median or more incidence of microemboli (P = .099). IVUS-defined vessel diameter maximum was associated with median or more incidence of microemboli (P = .042). In addition, median or more incidence of microemboli showed trends with proximal common carotid artery calcification (P = .056) and with being over the age of 80 (P = .06). Contralateral carotid occlusion or high-grade stenosis was associated with postoperative contralateral microemboli (P = .036).

CONCLUSIONS

We demonstrate that periprocedural carotid IVUS is clinically feasible. VH IVUS may be helpful in better understanding plaque morphology and determining optimal stent placement. However, its use in predicting microembolization remains limited.

Comparison of diagnostic accuracy between multidetector computed tomography and virtual histology intravascular ultrasound for detecting optical coherence tomography-derived fibroatheroma

Histopathological studies have reported that optical coherence tomography (OCT) can accurately detect fibroatheroma that is involved in not only culprit lesion of acute coronary syndrome but also no-reflow phenomenon after percutaneous coronary intervention. Studies have demonstrated superiority of OCT in plaque characterization and interruption of arterial wall component. At current, multidetector computed tomography (MDCT) and virtual histology intravascular ultrasound (VH-IVUS) are considered as alternative imaging devices for coronary plaque characterization. This study aimed to compare the diagnostic accuracy for detecting fibroatheroma between MDCT and VH-IVUS using OCT as the reference standard. Forty-three lesions from 27 patients assessed by MDCT, VH-IVUS, and OCT were included in this study. Fibroatheroma was defined by OCT as a signal-poor region with a fast signal drop-off and little or no signal backscattering within the lesion. From 43 lesions, OCT revealed 21 fibroatheromas. Ring-like sign assessed by MDCT and positive remodeling assessed by IVUS were more frequently observed in OCT-fibroatheroma than non-OCT-fibroatheroma. The remodeling index of OCT-fibroatheroma assessed by MDCT and IVUS were higher than those of non-OCT-fibroatheroma. The sensitivity, specificity, positive predict values, negative predict values and accuracy of ring-like sign by MDCT and VH-IVUS for detecting OCT-fibroatheroma were 43, 95, 90, 64, 70 % and 71, 45, 56, 63, 58 %, respectively. Our results suggest that both accuracies of MDCT and VH-IVUS to detect OCT-fibroatheroma are insufficient. We need to apply appropriate device for searching vulnerable plaque.

Atherosclerotic plaque composition and classification identified by coronary computed tomography: assessment of computed tomography-generated plaque maps compared with virtual histology intravascular ultrasound and histology

BACKGROUND

Computed tomography (CT) is used routinely for coronary angiography, and higher-risk features of plaques can also be identified. However, the ability of CT to discriminate individual plaque components and classify plaques according to accepted histological definitions is unknown.

METHODS AND RESULTS

We first determined CT attenuation ranges for individual plaque components using combined in vivo CT coregistered with virtual histology intravascular ultrasound (VH-IVUS) in 108 plaques from 57 patients. Comparison with contrast attenuation created plaque/contrast attenuation ratios that were significantly different for each component. In a separate validation cohort of 47 patients, these Plaque Maps correlated significantly with VH-IVUS-determined plaque component volumes (necrotic core: r=0.41, P=0.002; fibrous plaque: r=0.54, P<0.001; calcified plaque: r=0.59, P<0.001; total plaque: r=0.62, P<0.001). We also assessed VH-IVUS and CT Plaque Maps against coregistered histology in 72 (VH-IVUS) and 87 (CT) segments from 8 postmortem coronary arteries. The diagnostic accuracy of CT to detect calcified plaque (83% versus 92%), necrotic core (80% versus 65%), and fibroatheroma (80% versus 79%) was comparable with VH-IVUS. However, although VH-IVUS could identify thin-cap fibroatheromas (TCFA) with a diagnostic accuracy of between 74% and 82% (depending on the TCFA definition used), the spatial resolution of CT prevented direct identification of TCFA.

CONCLUSIONS

CT-derived Plaque Maps based on contrast-adjusted attenuation ranges can define individual plaque components with a similar accuracy to VH-IVUS ex vivo. However, coronary CT Plaque Maps could not reliably classify plaques and identify TCFA, such that high-risk plaques may be misclassified or overlooked.

Effect of folic acid supplementation on levels of circulating Monocyte Chemoattractant Protein-1 and the presence of intravascular ultrasound derived virtual histology thin-cap fibroatheromas in patients with stable angina pectoris

BACKGROUND

Virtual Histology Intravascular Ultrasound (VH-IVUS) may be used to detect early signs of unstable coronary artery disease. Monocyte Chemoattractant Protein-1 (MCP-1) is linked with coronary atherosclerosis and plaque instability and could potentially be modified by folic acid treatment.

METHODS

In a randomized, prospective study, 102 patients with stable angina pectoris (SAP) received percutaneous coronary intervention and established medical treatment as well as either homocysteine-lowering folic acid/vitamin B12 (± B6) or placebo (± B6) for 1 year before VH-IVUS was performed. The presence of VH-Thin-Cap Fibroatheroma (VH-TCFA) in non-intervened coronary vessels was registered and serum levels of MCP-1 were measured. The patients were subsequently followed for incident myocardial infarction (MI).

RESULTS

Patients treated with folic acid/vitamin B12 had a geometric mean (SD) MCP-1 level of 79.95 (1.49) versus 86.00 (1.43) pg/mL for patients receiving placebo (p-value 0.34). VH-TCFA lesions were present in 7.8% of patients and did not differ between intervention arms (p-value 0.47). Serum levels of MCP-1 were 1.46 (95% CI 1.12 to 1.92) times higher in patients with VH-TCFA lesions than in those without (p-value 0.005). Afterwards, patients were followed for median 2.1 years and 3.8% experienced a myocardial infarction (MI), which in post-hoc Cox regression analyses was independently predicted by both MCP-1 (P-value 0.006) and VH-TCFA (p-value 0.01).

CONCLUSIONS

In patients with SAP receiving established medical treatment, folic acid supplementation is not associated with either presence of VH-TCFA or levels of MCP-1. MCP-1 is however associated with VH-TCFA, a finding corroborated by increased risk for future MI. ClinicalTrials.gov Identifier: NCT00354081.

Dynamic nature of nonculprit coronary artery lesion morphology in STEMI: a serial IVUS analysis from the HORIZONS-AMI trial

OBJECTIVES

The authors sought to report the temporal stability of an untreated, nonculprit lesion phenotype in patients presenting with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

The temporal stability of the untreated, nonculprit lesion phenotype has been studied using intravascular ultrasound-virtual histology (IVUS) in patients with stable ischemic heart disease, but not in STEMI patients.

METHODS

As part of a formal substudy of the HORIZONS-AMI (Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction) trial, baseline and 13-month follow-up IVUS was performed in 99 untreated nonculprit lesions in 63 STEMI patients. Lesions were classified as pathological intimal thickening (PIT), IVUS-derived thin-cap fibroatheroma (TCFA), thick-cap fibroatheroma (ThCFA), fibrotic plaque, or fibrocalcific plaque.

RESULTS

The frequency of TCFA increased from 41% at baseline to 54% at follow-up, whereas ThCFAs decreased from 41% to 34% and PIT decreased from 16% to 8%. Among the 41 lesions classified at baseline as TCFA, at follow-up, 32 (78%) were still classified as TCFA, whereas 9 (22%) were classified as ThCFAs or fibrotic plaques. An additional 21 lesions at follow-up were newly classified as TCFA, developing from either PIT or ThCFA. TCFA at baseline that evolved into non-TCFAs trended toward a more distal location than TCFA that did not change (p = 0.12). In lesions classified as TCFA, the minimum lumen area (MLA) decreased from 8.1 (interquartile range [IQR]: 7.4 to 8.8) mm(2) at baseline to 7.8 (IQR: 7.2 to 8.4) mm(2) at follow-up, p < 0.05; this was associated with an increase in percent necrotic core at the MLA site (14% [IQR: 12 to 16] to 19% [IQR: 17 to 22], p < 0.0001) and over the entire length of the lesion (14% [IQR: 12 to 16] to 18% [IQR: 17 to 20], p < 0.0001).

CONCLUSIONS

Untreated nonculprit lesions in STEMI patients frequently have TCFA morphology that does not change during 13-month follow-up and is accompanied by a decrease in MLA and an increase in necrotic core. (Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction [HORIZONS-AMI]; NCT00433966).

Correlation between plaque composition as assessed by virtual histology and C-reactive protein

Background

Previous studies have shown that coronary plaque composition plays a pivotal role in plaque instability, and imaging modalities and serum biomarkers have been investigated to identify vulnerable plaque. Virtual histology IVUS (VH-IVUS) characterizes plaque components as calcified, fibrotic, fibrofatty, or necrotic core. C-reactive protein (hsCRP) is an independent risk factor and a powerful predictor of future coronary events. However, a relationship between inflammatory response indicated by CRP and plaque characteristics in ACS patients remains not well established.

Objective

To determine, by using VH-IVUS, the relation between coronary plaque components and plasma high-sensitivity CRP levels in patients with acute coronary syndromes (ACS).

Methods

52 patients with ACS were enrolled in this prospective study. Electrocardiographically-gated VH-IVUS were performed in the culprit lesion before PCI. Blood sample was drawn from all patients before the procedure and after 24 hours, and hs-CRP levels were determined.

Results

Mean age was 55.3±4.9 years, 76.9% were men and 30.9% had diabetes. Mean MLA was 3.9±1.3 mm², and plaque burden was 69±11.3%, as assessed by IVUS. VH-IVUS analysis at the minimum luminal site identified plaque components: fibrotic (59.6±15.8%), fibrofatty (7.6±8.2%), dense calcium (12.1±9.2%) and necrotic core (20.7±12.7%). Plasma hs-CRP (mean 16.02±18.07 mg/L) did not correlate with necrotic core (r=-0.089, p = 0.53) and other plaque components.

Conclusions

In this prospective study with patients with ACS, the predominant components of the culprit plaque were fibrotic and necrotic core. Serum hs C-reactive protein levels did not correlate with plaque composition.

Systems biology of the functional and dysfunctional endothelium

This review provides an overview of the effect of blood flow on endothelial cell (EC) signalling pathways, applying microarray technologies to cultured cells, and in vivo studies of normal and atherosclerotic animals. It is found that in cultured ECs, 5-10% of genes are up- or down-regulated in response to fluid flow, whereas only 3-6% of genes are regulated by varying levels of fluid flow. Of all genes, 90% are regulated by the steady part of fluid flow and 10% by pulsatile components. The associated gene profiles show high variability from experiment to experiment depending on experimental conditions, and importantly, the bioinformatical methods used to analyse the data. Despite this high variability, the current data sets can be summarized with the concept of endothelial priming. In this concept, fluid flows confer protection by an up-regulation of anti-atherogenic, anti-thrombotic, and anti-inflammatory gene signatures. Consequently, predilection sites of atherosclerosis, which are associated with low-shear stress, confer low protection for atherosclerosis and are, therefore, more sensitive to high cholesterol levels. Recent studies in intact non-atherosclerotic animals confirmed these in vitro studies, and suggest that a spatial component might be present. Despite the large variability, a few signalling pathways were consistently present in the majority of studies. These were the MAPK, the nuclear factor-κB, and the endothelial nitric oxide synthase-NO pathways.

MDCT coronary angiography -- postprocessing, reading, and reporting: last but not least

Significant literature on MDCT coronary angiography (MDCT-CA) has emerged in the last decade concerning patient's selection, technical aspects of different generations of CT equipment, ECG gating, contrast material and beta-blockade administration, acquisition parameters, and radiation dose. However, the literature regarding postprocessing, reading, and reporting is not so extensive. This review highlights the main elements of MDCT-CA data analysis, thereby allowing the radiologist to take full advantage of this technology and enable a structured report to be generated, promoting best practice with high-quality results.

Nonculprit coronary plaque characteristics of chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) promotes the development of atherosclerosis and increases the risk of cardiovascular disease. The aim of the present study was to compare the coronary plaque characteristics of patients with and without CKD using optical coherence tomography.

METHODS AND RESULTS

We identified 463 nonculprit plaques from 287 patients from the Massachusetts General Hospital (MGH) optical coherence tomography registry. CKD was defined as estimated glomerular filtration rate <60 mL/min per 1.73 m(2). A total of 402 plaques (250 patients) were in the non-CKD group and 61 plaques (37 patients) were in the CKD group. Compared with non-CKD plaques, plaques with CKD had a larger lipid index (mean lipid arc×lipid length, 1248.4±782.8 mm° [non-CKD] versus 1716.1±1116.2 mm° [CKD]; P=0.003). Fibrous cap thickness was not significantly different between the groups. Calcification (34.8% [non-CKD] versus 50.8% [CKD]; P=0.041), cholesterol crystals (11.2% [non-CKD] versus 23.0% [CKD]; P=0.048), and plaque disruption (5.5% [non-CKD] versus 13.1% [CKD]; P=0.049) were more frequently observed in the CKD group. In the multivariate linear regression model, a lower estimated glomerular filtration rate and diabetes mellitus were independent risk factors for a larger lipid index.

CONCLUSIONS

Compared with non-CKD patients, the patients with CKD had a larger lipid index with a higher prevalence of calcium, cholesterol crystals, and plaque disruption. The multivariate linear regression model demonstrated that a lower estimated glomerular filtration rate was an independent risk factor for a larger lipid index.

Intravascular multispectral optoacoustic tomography of atherosclerosis: prospects and challenges

The progression of atherosclerosis involves complex changes in the structure, composition and biology of the artery wall. Currently, only anatomical plaque burden is routinely characterized in living patients, whereas compositional and biological changes are mostly inaccessible. However, anatomical imaging alone has proven to be insufficient for accurate diagnostics of the disease. Multispectral optoacoustic tomography offers complementary data to anatomical methods and is capable of imaging both tissue composition and, via the use of molecular markers, the biological activity therein. In this paper we review recent progress in multispectral optoacoustic tomography imaging of atherosclerosis with specific emphasis on intravascular applications. The potential capabilities of multispectral optoacoustic tomography are compared with those of established intravascular imaging techniques and current challenges on the road towards a clinically viable imaging modality are discussed.

Relation of ruptured plaque culprit lesion phenotype and outcomes in patients with ST elevation acute myocardial infarction

We used virtual histology intravascular ultrasound (VH-IVUS) to assess culprit plaque rupture in 172 patients with ST-segment elevation acute myocardial infarction. VH-IVUS-defined thin-capped fibroatheroma (VH-TCFA) had necrotic core (NC) > 10% of plaque area, plaque burden > 40%, and NC in contact with the lumen for ≥ 3 image slices. Ruptured plaques were present in 72 patients, 61% of which were located in the proximal 30 mm of a coronary artery. Thirty-five were classified as VH-TCFA and 37 as non-VH-TCFA. Vessel size, lesion length, plaque burden, minimal lumen area, and frequency of positive remodeling were similar in VH-TCFA and non-VH-TCFA. However, the NC areas within the rupture sites of VH-TCFAs were larger compared to non-VH-TCFAs (p = 0.002), while fibrofatty plaque areas were larger in non-VH-TCFAs (p < 0.0001). Ruptured plaque cavity size was correlated with distal reference lumen area (r = 0.521, p = 0.00002), minimum lumen area (r = 0.595, p < 0.0001), and plaque area (r = 0.267, p = 0.033). Sensitivity and specificity curve analysis showed that a minimum lumen area of 3.5 mm2, a distal reference lumen area of 7.5 mm2, and a maximum NC area of 35% best predicted plaque rupture. Although VH-TCFA (35 of 72) was the most frequent phenotype of plaque rupture in ST-segment elevation myocardial infarction, plaque rupture also occurred in non-VH-TCFA: pathologic intimal thickening (8 of 72), thick-capped fibroatheroma (1 of 72), and fibrotic (14 of 72) and fibrocalcified (14 of 72) plaque. In conclusion, not all culprit plaque ruptures in patients with ST-segment elevation myocardial infarction occur as a result of TCFA rupture; a prominent fibrofatty plaque, especially in a proximal vessel, may be another form of vulnerable plaque. Further study should identify additional factors causing plaque rupture.

Identification of coronary plaque sub-types using virtual histology intravascular ultrasound is affected by inter-observer variability and differences in plaque definitions

BACKGROUND

Recent studies show that virtual histology intravascular ultrasound (VH-IVUS) can identify plaques at high risk of rupture, such as thin-capped fibroatheromata, raising the possibility of immediate targeted intervention. However, plaque classification entails border recognition and subjective assessment of plaque architecture, introducing inter-observer variability without confirmation by core-labs. Furthermore, the accuracy of local versus core-laboratory VH-IVUS plaque classification and effects of different plaque definitions have not been examined.

METHODS AND RESULTS

Local observers classified 100 VH-IVUS-defined coronary plaques to determine single center inter-observer variability; multi-center variability was determined by comparison with VH-IVUS core-laboratory analysis, and compared with gray-scale IVUS. Frequency of plaque types using different published plaque definitions also was determined. Single-center VH-IVUS inter-observer agreement was strong (kappa=0.86), but lower for thin-capped fibroatheromatas (k=0.59) because of observer judgments on presence and location of confluent necrotic core. Multi-center inter-observer agreement for plaque classification was lower again (k=0.71), particularly for thin-capped fibroatheromatas (k=0.56). Different plaque definitions further reduced VH-IVUS-defined thin-capped fibroatheromata numbers by 44%. The diagnostic accuracy of gray-scale IVUS to identify thin-capped fibroatheromata was poor for both observers (21 and 29% correct), with low inter-observer agreement (k=0.14).

CONCLUSIONS

VH-IVUS plaque classification, and particularly VH-IVUS-defined thin-capped fibroatheromata identification, varies significantly between local observers, and particularly in comparison with core-laboratory analysis. Differences in VH-IVUS plaque definitions introduce further variability between studies. These factors reduce the use of VH-IVUS plaque classification to guide intervention in a "live" clinical setting, and also affect comparison of diagnostic accuracy and natural history of plaques between studies.

A patient with significant slow-flow phenomenon during percutaneous coronary intervention for ST elevation myocardial infarction associated with scattered necrotic core by virtual histology intravascular ultrasound

A 68-year-old man with acute ST elevation myocardial infarction (STEMI) underwent emergent coronary angiography which showed total occlusion in the proximal right coronary artery (RCA). Gray-scale intravascular ultrasound (IVUS) revealed the culprit lesion was expansively remodeled and contained ruptured and echolucent plaques with spotty calcification, whereas thin-capped fibroatheroma and a large amount of scattered necrotic core were observed by virtual histology (VH)-IVUS. After stent implantation in the proximal RCA under a filter protection, filter-no-reflow phenomenon occurred and thrombus-like defect was observed in the mid RCA. Under these conditions, VH-IVUS detected a large amount of scattered necrotic core in the mid RCA. We suggest scattered necrotic core detected by VH-IVUS may be associated with slow-flow phenomenon during percutaneous coronary intervention in our patient with STEMI.

Detection and quantification of coronary atherosclerotic plaque by 64-slice multidetector CT: a systematic head-to-head comparison with intravascular ultrasound

OBJECTIVE

We evaluated the ability of 64-slice multidetector computed tomography (MDCT)-derived plaque parameters to detect and quantify coronary atherosclerosis, using intravascular ultrasound (IVUS) as the reference standard.

METHODS

In 32 patients, IVUS and 64-MDCT was performed. The MDCT and IVUS datasets of 44 coronary arteries were co-registered using a newly developed fusion technique and quantitative parameters were derived from both imaging modalities. The threshold of >0.5 mm of maximum wall thickness was used to establish plaque presence on MDCT and IVUS.

RESULTS

We analyzed 1364 coregistered 1-mm coronary cross-sections and 255 segments of 5-mm length. Compared with IVUS, 64-MDCT enabled correct detection in 957 of 1109 cross-sections containing plaque (sensitivity 86%). In 180 of 255 cross-sections atherosclerosis was correctly excluded (specificity 71%). On the segmental level, MDCT detected 213 of 220 segments with any atherosclerotic plaque (sensitivity 96%), whereas the presence of any plaque was correctly ruled out in 28 of 32 segments (specificity 88%). Interobserver agreement for the detection of atherosclerotic cross-sections was moderate (Cohen's kappa coefficient K=0.51), but excellent for the atherosclerotic segments (K=1.0). Pearson's correlation coefficient for vessel plaque volumes measured by MDCT and IVUS was r=0.91 (p<0.001). Bland-Altman analysis showed a slight non-significant underestimation of any plaque volume by MDCT (p=0.5), with a trend to underestimate noncalcified and overestimate mixed/calcified plaque volumes (p=0.22 and p=0.87 respectively).

CONCLUSION

MDCT is able to detect and quantify atherosclerotic plaque. Further improvement in CT resolution is necessary for more reliable assessment of very small and distal coronary plaques.

[Intravascular ultrasound for recognition of atherosclerotic plaques and plaque composition. Current state of the diagnostic value]

Coronary atherosclerosis including acute coronary syndrome (ACS) is the leading cause of death in the western world and in the majority of patients is caused by plaque rupture in flow-limiting and non-flow-limiting angiographically intermediate stenoses. Histopathologic analyses have shown the relationship of plaque composition to acute clinical events and therefore to the vulnerability of coronary lesions. Knowledge of remodeling processes of the coronary artery has focused interest on non-flow-limiting lesions of the coronary tree. Intravascular ultrasound (IVUS) can demonstrate discrepancies between the extent of coronary atherosclerosis and angiographic imaging by in vivo plaque imaging. In addition the spectral analysis of IVUS-derived radiofrequency (RF) data enables more precise analysis of the plaque composition and plaque type.As IVUS is best able to assess stent underexpansion and malapposition the guidance of catheter-based coronary interventions plays a major role in angiographically unclear lesions even in the drug-eluting stent era. In the field of percutaneous coronary interventions (PCI) IVUS can influence the therapy and therefore optimize the stratification of patients.In terms of secondary prevention it is of great clinical importance to detect progression of coronary artery disease and moreover to predict coronary lesions with significant progression up to ACS. Coronary angiography and clinical parameters are poor surrogates to predict future events in a broad cohort of patients after PCI. In addition non-invasive imaging fails to identify coronary plaques with potential rupture and subsequent ACS. This highlights the need to identify potentially high risk lesions. However, prospective studies with IVUS-RF imaging to detect lesions that are considered to be prone to rupture showed no evidence for catheter-based invasive treatment of a non-flow-limiting high risk plaque.In the future the integrated combination of multiple technologies (e.g. IVUS-RF and optical coherence tomography) can further improve the accuracy of the analysis of high risk lesions.

Leukocyte telomere length is associated with high-risk plaques on virtual histology intravascular ultrasound and increased proinflammatory activity

OBJECTIVE

Leukocyte telomere length (LTL), a marker of cellular senescence, is inversely associated with cardiovascular events. However, whether LTL reflects plaque extent or unstable plaques, and the mechanisms underlying any association are unknown.

METHODS AND RESULTS

One hundred seventy patients with stable angina or acute coronary syndrome referred for percutaneous coronary intervention underwent 3-vessel virtual histology intravascular ultrasound; 30 372 mm of intravascular ultrasound pullback and 1096 plaques were analyzed. LTL was not associated with plaque volume but was associated with calcified thin-capped fibroatheroma (OR, 1.24; CI, 1.01-1.53; P=0.039) and total fibroatheroma numbers (OR, 1.19; CI, 1.02-1.39; P=0.027). Monocytes from coronary artery disease patients showed increased secretion of proinflammatory cytokines. To mimic leukocyte senescence, we disrupted telomeres and binding and expression of the telomeric protein protection of telomeres protein-1, inducing DNA damage. Telomere disruption increased monocyte secretion of monocyte chemoattractant protein-1, IL-6, and IL-1β and oxidative burst, similar to that seen in coronary artery disease patients, and lymphocyte secretion of IL-2 and reduced lymphocyte IL-10.

CONCLUSIONS

Shorter LTL is associated with high-risk plaque morphology on virtual histology intravascular ultrasound but not total 3-vessel plaque burden. Monocytes with disrupted telomeres show increased proinflammatory activity, which is also seen in coronary artery disease patients, suggesting that telomere shortening promotes high-risk plaque subtypes by increasing proinflammatory activity.

Assessment of coronary atherosclerosis by IVUS and IVUS-based imaging modalities: progression and regression studies, tissue composition and beyond

Cardiovascular disease remains the leading cause of mortality, morbidity and disability in the developed world, predominantly affecting the adult population. In the early 1990s coronary heart disease (CHD) was established as affecting one in two men and one in three women by the age of forty. Despite the dramatic progress in the field of cardiovascular medicine in terms of diagnosis and treatment of heart disease, modest improvements have only been achieved when the reduction of cardiovascular mortality and morbidity indices are assessed. To better understand coronary atherosclerosis, new imaging modalities have been introduced. These novel imaging modalities have been used in two ways: (1) for the characterization of plaque types; (2) for the assessment of the progression and regression of tissue types. These two aspects will be discussed in this review.

Localization of culprit lesions in coronary arteries of patients with ST-segment elevation myocardial infarctions: relation to bifurcations and curvatures

BACKGROUND

Although culprit lesions in ST-segment elevation myocardial infarction (STEMI) cluster in the proximal coronary arteries, their relationship to bifurcations and curvatures, where blood flow is disturbed, is unknown. We hypothesized that (a) culprit lesions localize to disturbed flow distal to bifurcations and curvatures and (b) the distribution of culprit lesions in the left (LCA) and right coronary arteries (RCA) and resulting infarct size are related to the location of bifurcations and curvatures.

METHODS

Emory University's contribution to the National Cardiovascular Data Registry was queried for STEMIs. Using quantitative coronary angiography, the distances from the vessel ostium, major bifurcations, and major curvatures to the culprit lesion were measured in 385 patients.

RESULTS

Culprit lesions were located within 20 mm of a bifurcation in 79% of patients and closer to the bifurcation in the LCA compared with the RCA (7.4 ± 7.3 vs 17.7 ± 14.8 mm, P < .0001). Of RCA culprit lesions, 45% were located within 20 mm of a major curvature. Compared with those in the RCA, culprit lesions in the LCA were located more proximally (24.4 ± 16.5 vs 44.7 ± 28.8 mm, P = .0003) and were associated with larger myocardial infarctions as assessed by peak creatine kinase-MB (208 ± 222 vs 140 ± 153 ng/dL, P = .001) and troponin I (59 ± 62 vs 40 ± 35 ng/dL, P = .0006) and with higher in-hospital mortality (5.2% vs 1.1%, P = .04).

CONCLUSIONS

In patients with STEMI, culprit lesions are frequently located immediately distal to bifurcations and in proximity to major curvatures where disturbed flow is known to occur. This supports the role of wall shear stress in the pathogenesis of STEMI.

Features of Disrupted Plaques by Coronary Computed Tomographic Angiography

Background—

This study was designed as a “proof-of-concept” to establish whether coronary computed tomographic angiography (CTA) has the capability to identify morphological features of plaque disruption.

Methods and Results—

In patients with unstable angina undergoing CTA and invasive coronary angiography within 30 days, quantitative CTA analysis was performed on all plaques for percent stenosis, volume, remodeling index, and volume of low-attenuation plaque (<50 Hounsfield units). Plaques with >25% stenosis were evaluated for CTA features of disruption, including ulceration and intraplaque dye penetration. Using invasive coronary angiography complex plaque as the reference standard for disruption, the sensitivity and specificity of ulceration and intraplaque dye penetration by CTA were determined. In 60 patients, 294 plaques were identified by CTA, of which 109 (37%) had features of disruption, including ulceration in 53 (18%) lesions and intraplaque dye penetration in 80 (27%). Compared with nondisrupted lesions, plaques with ulceration or intraplaque dye penetration by CTA were more voluminous (313±356 mm 3 versus 118±93 mm 3 P <0.0001), more often positively remodeled (94.5% versus 44.3%, P <0.0001), contained more low-attenuation plaque (99±161 mm 3 versus 19±18 mm 3 , P <0.0001), and were more often complex by ICA (57.8% versus 8.1%, P <0.0001). CTA features of disruption demonstrated modest to good sensitivity (53% to 81%) and good specificity (82% to 95%) for complex plaque by invasive coronary angiography.

Conclusions—

In this highly selected group of patients with unstable angina, CTA can delineate features of plaque disruption, including ulceration and intraplaque dye penetration, which are specific markers of invasively identified complex plaque. Further studies are needed to confirm the generalizability of the results and to explore the clinical and prognostic implications of these findings.

Intravascular imaging of vulnerable coronary plaque: current and future concepts

Advances in coronary imaging are needed to enable the early detection of plaque segments considered to be 'vulnerable' for causing clinical events. Pathological studies have contributed to our current understanding of these vulnerable or unstable segments of plaque. Intravascular ultrasonography (IVUS) has provided insights into the morphology of atherosclerosis, the mediators of plaque progression and the factors associated with acute coronary syndrome (ACS). In addition, the demonstration of pancoronary arterial instability has highlighted that ACS involves a multifocal disease process. Various second-generation intravascular imaging technologies-employing advanced processing of ultrasound radiofrequency backscatter signals, light-based imaging, spectroscopic imaging and molecular targeting-possess inherent advantages for the identification of meaningful surrogates of plaque instability. The fusion of these imaging technologies within a single imaging catheter is likely to allow for greater synergism in image quality and early disease detection. However, natural-history studies to validate the use of these novel imaging tools for enhanced risk prediction are needed before these strategies can be incorporated into mainstream clinical practice.