Frequency and Distribution of Thin-Cap Fibroatheroma and Ruptured Plaques in Human Coronary Arteries

Increased incidence of napkin-ring sign plaques on cervicocerebral computed tomography angiography associated with the risk of acute ischemic stroke occurrence

OBJECTIVES

Carotid atherosclerosis plays an essential role in the occurrence of ischemic stroke. This study aimed to investigate whether a larger burden of napkin-ring sign (NRS) plaques on cervicocerebral computed tomography angiography (CTA) increased the risk of acute ischemic stroke (AIS).

METHODS

This retrospective, single-center, cross-sectional study enrolled patients with NRS plaques identified in the subclavian arteries, brachiocephalic trunk, carotid arterial system, and vertebrobasilar circulation on contrast-enhanced cervicocerebral CTA. Patients were divided into AIS and non-AIS groups based on imaging within 12 h of symptom onset. Univariate and multivariate logistic regression analyses were performed to determine the risk factor of AIS occurrence.

RESULTS

A total of 202 patients (66.72 years ± 8.97, 157 men) were evaluated. Plaques with NRS in each subject of the AIS group (N = 98) were significantly more prevalent than that in the control group (N = 104) (1.96 ± 1.17 vs 1.41 ± 0.62). In the AIS group, there were substantially more NRS plaques on the ipsilateral side than contralateral side (1.55 ± 0.90 vs. 0.41 ± 0.66). NRS located on the ipsilateral side of the AIS showed an area under the receiver curve (AUC) of 0.86 to identify ischemic stroke. NRS plaque amounts were an independent risk factor for AIS occurrence (odds ratio, 1.86) after adjusting for other factors.

CONCLUSIONS

Increased incidence of napkin-ring sign plaques on cervicocerebral CTA was positively associated with AIS occurrence, which could aid in detecting asymptomatic atherosclerotic patients at high risk of AIS in routine screening or emergency settings.

CLINICAL RELEVANCE STATEMENT

Napkin-ring sign plaque provides an important imaging target for estimating acute ischemic stroke risk and identifying high-risk patients in routine screening or emergency settings, so that timely anti-atherosclerotic therapy can be used for prevention.

KEY POINTS

• This cross-sectional study investigated the association between high-risk carotid artery plaques and acute ischemic stroke. • Increased incidence of napkin-ring sign plaques on cervicocerebral computed tomography angiography is positively associated with acute ischemic stroke occurrence. • Napkin-ring signs help identify risky patients prone to acute ischemic stroke to facilitate prevention.

Correcting common OCT artifacts enhances plaque classification and identification of higher-risk plaque features

BACKGROUND

Optical coherence tomography (OCT) is used widely to guide stent placement, identify higher-risk plaques, and assess mechanisms of drug efficacy. However, a range of common artifacts can prevent accurate plaque classification and measurements, and limit usable frames in research studies. We determined whether pre-processing OCT images corrects artifacts and improves plaque classification.

METHODS

We examined both ex-vivo and clinical trial OCT pullbacks for artifacts that prevented accurate tissue identification and/or plaque measurements. We developed Fourier transform-based software that reconstructed images free of common OCT artifacts, and compared corrected and uncorrected images.

RESULTS

48 % of OCT frames contained image artifacts, with 62 % of artifacts over or within lesions, preventing accurate measurement in 12 % frames. Pre-processing corrected >70 % of all artifacts, including thrombus, macrophage shadows, inadequate flushing, and gas bubbles. True tissue reconstruction was achieved in 63 % frames that would otherwise prevent accurate clinical measurements. Artifact correction was non-destructive and retained anatomical lumen and plaque parameters. Correction improved accuracy of plaque classification compared against histology and retained accurate assessment of higher-risk features. Correction also changed plaque classification and prevented artifact-related measurement errors in a clinical study, and reduced unmeasurable frames to <5 % ex-vivo and ~1 % in-vivo.

CONCLUSIONS

Fourier transform-based pre-processing corrects a wide range of common OCT artifacts, improving identification of higher-risk features and plaque classification, and allowing more of the whole dataset to be used for clinical decision-making and in research. Pre-processing can augment OCT image analysis systems both for stent optimization and in natural history or drug studies.

Stratified medicine for acute and chronic coronary syndromes: A patient-tailored approach

The traditional approach to management of cardiovascular disease relies on grouping clinical presentations with common signs and symptoms into pre-specified disease pathways, all uniformly treated according to evidence-based guidelines ("one-size-fits-all"). The goal of precision medicine is to provide the right treatment to the right patients at the right time, combining data from time honoured sources (e.g., history, physical examination, imaging, laboratory) and those provided by multi-omics technologies. In patients with ischemic heart disease, biomarkers and intravascular assessment can be used to identify endotypes with different pathophysiology who may benefit from distinct treatments. This review discusses strategies for the application of stratified management to patients with acute and chronic coronary syndromes.

PCSK9 expression in fibrous cap possesses a marker for rupture in advanced plaque

BACKGROUND

To date, PCSK9 inhibitors are well known for eliminating cardiac and cerebral artery ischemia events by lowering the serum lipid level. However, the pathophysiological value of in-plaque PCSK9 expression is still unclear.

METHODS

Advanced plaques removed by carotid endarterectomy were sectioned and stained to identify the PCSK9 expression pattern and its co-expression with rupture-relevant markers. To investigate the correlation of PCSK9 expression with regional blood shear flow, hemodynamic characteristics were analyzed using computational fluid dynamics, and representative parameters were compared between PCSK9 positive and negative staining plaques. To explore this phenomenon in vitro, human aortic vascular smooth muscle cells were used to overexpress and knock down PCSK9. The impacts of PCSK9 modulations on mechanical sensor activity were testified by western blot and immunofluorescence. Real-time polymerase chain reaction was used to evaluate the transcription levels of downstream rupture-prone effectors.

RESULTS

PCSK9 distribution in plaque preferred cap and shoulder regions, residing predominantly in smooth muscle actin-positive cells. Cap PCSK9 expression correlated with fibrous cap thickness negatively and co-expressed with MMP-9, both pointing to the direction of plaque rupture. A hemodynamic profile indicated a rupture-prone feature of cap PCSK9 expression. In vitro, overexpression and knockdown of PCSK9 in human aortic vascular smooth muscle cells has positive modulation on mechanical sensor Yes-associated protein 1 (YAP) activity and transcription levels of its downstream rupture-prone effectors. Serial section staining verified in situ colocalization among PCSK9, YAP, and downstream effectors.

CONCLUSIONS

Cap PCSK9 possesses a biomarker for rupture risk, and its modulation may lead to a novel biomechanical angle for plaque interventions.

Association of Lipoprotein(a) Levels With Myocardial Infarction in Patients With Low-Attenuation Plaque

BACKGROUND

Lipoprotein(a) (Lp[a]) is associated with an increased risk of myocardial infarction (MI). However, the mechanism underlying this association has yet to be fully elucidated.

OBJECTIVES

This multicenter study aimed to investigate whether association between Lp(a) and MI risk is reinforced by the presence of low-attenuation plaque (LAP) identified by coronary computed tomography angiography (CCTA).

METHODS

In a derivation cohort, a total of 5,607 patients with stable chest pain suspected of coronary artery disease who underwent CCTA and Lp(a) measurement were prospectively enrolled. In validation cohort, 1,122 patients were retrospectively collected during the same period. High Lp(a) was defined as Lp(a) ≥50 mg/dL. The primary endpoint was a composite of time to fatal or nonfatal MI. Associations were estimated using multivariable Cox proportional hazard models.

RESULTS

During a median follow-up of 8.2 years (Q1-Q3: 7.2-9.3 years), the elevated Lp(a) levels were associated with MI risk (adjusted HR [aHR]: 1.91; 95% CI: 1.46-2.49; P < 0.001). There was a significant interaction between Lp(a) and LAP (Pinteraction <0.001) in relation to MI risk. When stratified by the presence or absence of LAP, Lp(a) was associated with MI in patients with LAP (aHR: 3.03; 95% CI: 1.92-4.76; P < 0.001). Mediation analysis revealed that LAP mediated 73.3% (P < 0.001) for the relationship between Lp(a) and MI. The principal findings remained unchanged in the validation cohort.

CONCLUSIONS

Elevated Lp(a) augmented the risk of MI during 8 years of follow-up, especially in patients with LAP identified by CCTA. The presence of LAP could reinforce the relationship between Lp(a) and future MI occurrence.

Computed tomography defined femoral artery plaque composition predicts vascular complications during transcatheter aortic valve implantation

OBJECTIVE

Vascular and bleeding complications after transcatheter aortic valve implantation (TAVI) are common and lead to increased morbidity and mortality. Analysis of plaque at the arterial access site may improve prediction of complications.

METHODS

We investigated the association between demographic and procedural risk factors for Valve Academic Research Consortium (VARC-3) vascular complications in patients undergoing transfemoral TAVI with use of a vascular closure device (ProGlide® or MANTA®) in this retrospective cohort study. The ability of pre-procedure femoral CT angiography to predict complications was investigated including a novel method of quantifying plaque composition of the common femoral artery using plaque maps created with patient specific X-ray attenuation cut-offs.

RESULTS

23 vascular complications occurred in the 299 patients in the study group (7.7%). There were no demographic risk factors associated with vascular complications and no statistical difference between use of closure device (ProGlide® vs MANTA®) and vascular complications. Vascular complications after TAVI were associated with sheath size (OR 1.36, 95% CI 1.08-1.76, P 0.01) and strongly associated with CT-derived necrotic core volume in the common femoral artery of the procedural side (OR 17.49, 95% CI 1.21-226.60, P 0.03).

CONCLUSION

Plaque map analysis of the common femoral artery by CT angiography reveals patients with greater necrotic core are at increased risk of VARC-3 vascular complications.

ADVANCES IN KNOWLEDGE

The novel measurement of necrotic core volume in the common femoral artery on the procedural side by CT analysis was associated with post-TAVI vascular complications, which can be used to highlight increased risk.

Coronary artery calcium testing in young adults

PURPOSE OF REVIEW

To provide a summary of recent literature on coronary artery calcium testing (CAC) for risk stratification in young adults <45 years old.

RECENT FINDINGS

One of every ten young adults in the general population, and one out of every three young adults with traditional atherosclerotic cardiovascular disease (ASCVD) risk factors, have CAC. While the definition of premature CAC has yet to be formally defined in guidelines, it has become increasingly clear that any prevalent CAC among adults <45 years old should be considered premature. Traditional risk factors are strong predictors of CAC in young adults; however, this association has been found to wane over the life course which suggests that the onset and severity of risk factors for calcific atherosclerosis varies as individuals age. Though CAC is a robust predictor of both ASCVD and cancer-related mortality in old age, CAC in young adults confers a stepwise higher risk uniquely for incident ASCVD mortality, and not for non-ASCVD causes. New tools are available to assist in interpretation of CAC in the young, and for estimating the ideal age to initiate CAC scoring.

SUMMARY

The identification of premature CAC is important because it suggests that calcific plaque can be detected with modern imaging earlier in the natural history than previously thought. Taken together, these findings underline a utility of selective use of CAC scoring on non-contrast computed tomography among at-risk young adults to facilitate timely lifestyle modification and pharmacotherapies for the prevention of later life ASCVD.

Pharmaco-invasive therapy: Early implementation of statins and proprotein convertase subtilisin/kexin type 9 inhibitors after acute coronary syndrome

Elevated LDL-cholesterol (LDL-C) plays a major role in atheroma formation and inflammation. Medical therapy to lower elevated LDL-C is the cornerstone for reducing the progression of atherosclerotic cardiovascular disease. Statin therapy, and more recently, other drugs such as proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, have proven efficacy in long-term lowering of LDL-C and therefore diminish cardiovascular risk. During an acute coronary syndrome (ACS), a systemic inflammatory response can destabilize other non-culprit atherosclerotic plaques. Patients with these vulnerable plaques are at high risk of experiencing recurrent cardiovascular events in the first few years post-ACS. Initiating intensive LDL-C lowering therapy in these patients with statins or PCSK9 inhibitors can be beneficial via several pathways. High-intensity statin therapy can reduce inflammation by directly lowering LDL-C, but also through its pleiotropic effects. PCSK9 inhibitors can directly lower LDL-C to recommended guideline thresholds, and could have additional effects on inflammation and plaque stability. We discuss the potential role of early implementation of statins combined with PCSK9 inhibitors to influence these cascades and to mediate the associated cardiovascular risk, over and above the well-known long-term beneficial effects of chronic LDL-C lowering.

Plaque histology and myocardial disease in sudden coronary death: the Fingesture study

AIMS

At least 50% of deaths due to coronary artery disease (CAD) are sudden cardiac deaths (SCDs), but the role of acute plaque complications on the incidence of sudden death in CAD is somewhat unclear. The present study aimed to investigate plaque histology and concomitant myocardial disease in sudden coronary death.

METHODS AND RESULTS

The study population is derived from the Fingesture study, which has collected data from 5869 consecutive autopsy-verified SCD victims in Northern Finland (population ≈600 000) between 1998 and 2017. In this substudy, histological examination of culprit lesions was performed in 600 SCD victims whose death was due to CAD. Determination of the cause of death was based on the combination of medical records, police reports, and autopsy data. Plaque histology was classified as either (i) plaque rupture or erosion, (ii) intraplaque haemorrhage, or (iii) stable plaque. The mean age of the study subjects was 64.9 ± 11.2 years, and 82% were male. Twenty-four per cent had plaque rupture or plaque erosion, 24% had an intraplaque haemorrhage, and 52% had a stable plaque. Myocardial hypertrophy was present in 78% and myocardial fibrosis in 93% of victims. The presence of myocardial hypertrophy or fibrosis was not associated with specific plaque histology.

CONCLUSION

Less than half of sudden deaths due to CAD had evidence of acute plaque complication, an observation which is contrary to historical perceptions. The prevalence of concomitant myocardial disease was high and independent of associated plaque morphology.

Fibrous Cap Thickness Predicts Stable Coronary Plaque Progression: Early Clinical Validation of a Semiautomated OCT Technology

BACKGROUND

Imaging-based characteristics associated with the progression of stable coronary atherosclerotic lesions are poorly defined. Utilizing a combination of optical coherence tomography (OCT) and intravascular ultrasound (IVUS) imaging, we aimed to characterize the lesions prone to progression through clinical validation of a semiautomated OCT computational program.

METHODS

Patients with stable coronary artery disease underwent nonculprit vessel imaging with IVUS and OCT at baseline and IVUS at the 12-month follow-up. After coregistration of baseline and follow-up IVUS images, paired 5-mm segments from each patient were identified, demonstrating the greatest plaque progression and regression as measured by the change in plaque burden. Experienced readers identified plaque features on corresponding baseline OCT segments, and predictors of plaque progression were assessed by multivariable analysis. Each segment then underwent volumetric assessment of the fibrous cap (FC) using proprietary software.

RESULTS

Among 23 patients (70% men; median age, 67 years), experienced-reader analysis demonstrated that for every 100 μm increase in mean FC thickness, plaques were 87% less likely to progress (P = .01), which persisted on multivariable analysis controlling for baseline plaque burden (P = .05). Automated FC analysis (n = 17 paired segments) confirmed this finding (P = .01) and found thinner minimal FC thickness (P = .01) and larger FC surface area of <65 μm (P = .02) and <100 μm (P = .04) in progressing segments than in regressing segments. No additional imaging features predicted plaque progression.

CONCLUSIONS

A semiautomated FC analysis tool confirmed the significant association between thinner FC and stable coronary plaque progression along entire vessel segments, illustrating the diffuse nature of FC thinning and suggesting a future clinical role in predicting the progression of stable coronary artery disease.

X-box Binding Protein 1: An Adaptor in the Pathogenesis of Atherosclerosis

Atherosclerosis (AS), the formation of fibrofatty lesions in the vessel wall, is the primary cause of heart disease and stroke and is closely associated with aging. Disrupted metabolic homeostasis is a primary feature of AS and leads to endoplasmic reticulum (ER) stress, which is an abnormal accumulation of unfolded proteins. By orchestrating signaling cascades of the unfolded protein response (UPR), ER stress functions as a double-edged sword in AS, where adaptive UPR triggers synthetic metabolic processes to restore homeostasis, whereas the maladaptive response programs the cell to the apoptotic pathway. However, little is known regarding their precise coordination. Herein, an advanced understanding of the role of UPR in the pathological process of AS is reviewed. In particular, we focused on a critical mediator of the UPR, X-box binding protein 1 (XBP1), and its important role in balancing adaptive and maladaptive responses. The XBP1 mRNA is processed from the unspliced isoform (XBP1u) to the spliced isoform of XBP1 (XBP1s). Compared with XBP1u, XBP1s predominantly functions downstream of inositol-requiring enzyme-1α (IRE1α) and transcript genes involved in protein quality control, inflammation, lipid metabolism, carbohydrate metabolism, and calcification, which are critical for the pathogenesis of AS. Thus, the IRE1α/XBP1 axis is a promising pharmaceutical candidate against AS.

Optical Coherence Tomography-Derived Changes in Plaque Structural Stress Over the Cardiac Cycle: A New Method for Plaque Biomechanical Assessment

Introduction: Cyclic plaque structural stress has been hypothesized as a mechanism for plaque fatigue and eventually plaque rupture. A novel approach to derive cyclic plaque stress in vivo from optical coherence tomography (OCT) is hereby developed. Materials and Methods: All intermediate lesions from a previous OCT study were enrolled. OCT cross-sections at representative positions within each lesion were selected for plaque stress analysis. Detailed plaque morphology, including plaque composition, lumen and internal elastic lamina contours, were automatically delineated. OCT-derived vessel and plaque morphology were included in a 2-dimensional finite element analysis, loaded with patient-specific intracoronary pressure tracing data, to calculate the changes in plaque structural stress (ΔPSS) on vessel wall over the cardiac cycle. Results: A total of 50 lesions from 41 vessels were analyzed. A significant ΔPSS gradient was observed across the plaque, being maximal at the proximal shoulder (45.7 [32.3, 78.6] kPa), intermediate at minimal lumen area (MLA) (39.0 [30.8, 69.1] kPa) and minimal at the distal shoulder (35.1 [28.2, 72.3] kPa; p = 0.046). The presence of lipidic plaques were observed in 82% of the diseased segments. Larger relative lumen deformation and ΔPSS were observed in diseased segments, compared with normal segments (percent diameter change: 8.2 ± 4.2% vs. 6.3 ± 2.3%, p = 0.04; ΔPSS: 59.3 ± 48.2 kPa vs. 27.5 ± 8.2 kPa, p < 0.001). ΔPSS was positively correlated with plaque burden (r = 0.37, p < 0.001) and negatively correlated with fibrous cap thickness (r = -0.25, p = 0.004). Conclusions: ΔPSS provides a feasible method for assessing plaque biomechanics in vivo from OCT images, consistent with previous biomechanical and clinical studies based on different methodologies. Larger ΔPSS at proximal shoulder and MLA indicates the critical sites for future biomechanical assessment.

Gender-based in vivo comparison of culprit plaque characteristics and plaque microstructures using optical coherence tomography in acute coronary syndrome

Introduction: Women perform worse after acute coronary syndrome (ACS) than men. The reason for these differences is unclear. The aim was to ascertain gender differences in the culprit plaque characteristics in ACS.

Methods: Patients with ACS undergoing percutaneous coronary intervention for the culprit vessel underwent optical coherence tomography (OCT) imaging. Culprit plaque was identified as lipid rich,fibrous, and calcific plaque. Mechanisms underlying ACS are classified as plaque rupture, erosion,or calcified nodule. A lipid rich plaque along with thin-cap fibroatheroma (TCFA) was a vulnerable plaque. Plaque microstructures including cholesterol crystals, macrophages, and microvessels were noted.

Results: A total of 52 patients were enrolled (men=29 and women=23). Baseline demographic features were similar in both the groups except men largely were current smokers (P <0.001). Plaque morphology,men vs. women: lipid rich 88.0% vs. 90.5%; fibrous 4% vs 0%; calcific 8.0% vs. 9.5% (P = 0.64). Of the ACS mechanisms in males versus females; plaque rupture (76.9 % vs. 50 %), plaque erosion (15.4 % vs.40 %) and calcified nodule (7.7 % vs. 10 %) was noted (P = 0.139). Fibrous cap thickness was (50.19 ±11.17 vs. 49.00 ± 10.71 mm, P = 0.71) and thin-cap fibroatheroma (96.2% vs. 95.0%, P = 1.0) in men and women respectively. Likewise no significant difference in presence of macrophages (42.3 % vs. 30%, P = 0.76), microvessels (73.1% vs. 60 %, P = 0.52) and cholesterol crystals (92.3% vs. 80%, P = 0.38).

Conclusion: No significant gender-based in-vivo differences could be discerned in ACS patients’ culprit plaques morphology, characteristics, and underlying mechanisms.

Intravascular imaging of coronary artery: Bridging the gap between clinical needs and technical advances

Coronary artery disease is the leading cause of mortality worldwide. Almost seven million deaths are reported each year due to coronary disease. Coronary artery events in the adult are primarily due to atherosclerosis with seventy-five percent of the related mortality caused by plaque rupture. Despite significant progress made to improve intravascular imaging of coronary arteries, there is still a large gap between clinical needs and technical developments. The goal of this review is to identify the gap elements between clinical knowledge and recent advances in the domain of medical image analysis. Efficient image analysis computational models should be designed with respect to the exact clinical needs, and detailed features of the tissues under review. In this review, we discuss the detailed clinical features of the intracoronary plaques for mathematical and biomedical researchers. We emphasize the importance of integrating this clinical knowledge validated by clinicians to investigate the potentially effective models for proper features efficiency in the scope of leveraging the state-of-the-art of coronary image analyses.

Focal Geometry and Characteristics of Erosion-Prone Coronary Plaques in vivo Angiography and Optical Coherence Tomography Study

Objective: This study compared focal geometry and characteristics of culprit plaque erosion (PE) vs. non-culprit plaques in ST-segment elevated myocardial infarction (STEMI) patients in whom optical coherence tomography (OCT) identified PE as the cause of the acute event.

Background: Culprit PE is a distinct clinical entity with specific coronary risk factors and its own tailored management strategy. However, not all plaques develop erosion resulting in occlusive thrombus formation.

Methods: Between January 2017 and July 2019, there were 484 STEMI patients in whom OCT at the time of primary percutaneous intervention identified culprit lesion PE to be the cause of the event; 484 culprit PE were compared to 1,132 non-culprit plaques within 1,196 imaged vessels.

Results: Culprit PE were highly populated at “hot spots” within the proximal 40 mm in the left anterior descending artery (LAD) and tended to cluster proximal to a nearby bifurcation mainly in the LAD. Minimal lumen area (MLA) <2.51 mm² and AS (area stenosis) >64.02% discriminated culprit PE from non-culprit plaques. In the multivariable analysis, focal geometry (LAD location, distance from coronary ostium <40 mm, and location proximal to a nearby bifurcation), luminal narrowing (MLA <2.51 mm², AS > 64.02%), and TCFA phenotype were independent predictors of culprit PE overall. Cholesterol crystals were predictive of culprit PE with underlying LRP morphology while the absence of calcification and microchannels were risk factors for culprit PE with an underlying non-LRP. Similarities and differences in predictors of culprit PE were found between males and females; distance from coronary ostium <40 mm, MLA <2.51 mm², TCFA, and less spotty calcium were risk factors of culprit PE in males, but not in females while smaller RVD was associated with culprit PE only in females.

Conclusions: Irrespective of underlying lesion substrates and patient risk factors, there are lesion-specific and OCT-identifiable predictors of developing culprit PE in erosion-prone vulnerable patients.

Optical Coherence Tomography of Plaque Vulnerability and Rupture: JACC Focus Seminar Part 1/3

Plaque rupture is the most common cause of acute coronary syndromes and sudden cardiac death. Characteristics and pathobiology of vulnerable plaques prone to plaque rupture have been studied extensively over 2 decades in humans using optical coherence tomography (OCT), an intravascular imaging technique with micron scale resolution. OCT studies have identified key features of plaque vulnerability and described the in vivo characteristics and spatial distribution of thin cap fibroatheromas as major precursors to plaque rupture. In addition, OCT data supports the evolving understanding of coronary heart disease as a panvascular process associated with inflammation. In the setting of high atherosclerotic burden, plaque ruptures often occur at multiple sites in the coronary arteries, and plaque progression and healing are dynamic processes modulated by systemic risk factors. This review details major investigations with intravascular OCT into the biology and clinical implications of plaque vulnerability and plaque rupture.

Optical Coherence Tomography of Coronary Plaque Progression and Destabilization: JACC Focus Seminar Part 3/3

The development of optical coherence tomography (OCT) has revolutionized our understanding of coronary artery disease. In vivo OCT research has paralleled with advances in computational fluid dynamics, providing additional insights in the various hemodynamic factors influencing plaque growth and stability. Recent OCT studies introduced a new concept of plaque healing in relation to clinical presentation. In addition to known mechanisms of acute coronary syndromes such as plaque rupture and plaque erosion, a new classification of calcified plaque was recently reported. This review will focus on important new insights that OCT has provided in recent years into coronary plaque development, progression, and destabilization, with a focus on the role of local hemodynamics and endothelial shear stress, the layered plaque (signature of previous subclinical plaque destabilization and healing), and the calcified culprit plaque.

Effects of the PCSK9 antibody alirocumab on coronary atherosclerosis in patients with acute myocardial infarction: a serial, multivessel, intravascular ultrasound, near-infrared spectroscopy and optical coherence tomography imaging study-Rationale and design of the PACMAN-AMI trial

BACKGROUND

The risk for cardiovascular adverse events after acute myocardial infarction (AMI) remains high despite potent medical treatment including low-density lipoprotein cholesterol (LDL-C) lowering with statins. Proprotein convertase subtilisin/kexin type 9 (PCSK9) antibodies substantially reduce LDL-C when added to statin. Alirocumab, a monoclonal antibody to PCSK9, reduces major adverse cardiovascular events after AMI. The effects of alirocumab on coronary atherosclerosis including plaque burden, plaque composition and fibrous cap thickness in patients presenting with AMI remains unknown.

AIMS

To determine the effect of LDL-C lowering with alirocumab on top of high-intensity statin therapy on intravascular ultrasound (IVUS)-derived percent atheroma volume (PAV), near-infrared spectroscopy (NIRS)-derived maximum lipid core burden index within 4 mm (maxLCBI_{4 mm}) and optical coherence tomography (OCT)-derived fibrous cap thickness (FCT) in patients with AMI.

METHODS

In this multicenter, double-blind, placebo-controlled trial, 300 patients with AMI (ST-elevation or non-ST-elevation myocardial infarction) were randomly assigned to receive either biweekly subcutaneous alirocumab (150 mg) or placebo beginning <24 hours after the acute event as add-on therapy to rosuvastatin 20 mg. Patients undergo serial IVUS, NIRS and OCT in the two non-infarct related arteries at baseline (at the time of treatment of the culprit lesion) and at 52 weeks. The primary endpoint, change in IVUS-derived PAV, and the powered secondary endpoints, change in NIRS-derived maxLCBI_{4 mm}, and OCT-derived minimal FCT, will be assessed 52 weeks post randomization.

SUMMARY

The PACMAN-AMI trial will determine the effect of alirocumab on top of high-intensity statin therapy on high-risk coronary plaque characteristics as assessed by serial, multimodality intracoronary imaging in patients presenting with AMI.

CLINICAL TRIAL REGISTRATION

NCT03067844.

Discordance in the diagnostic assessment of vulnerable plaques between radiofrequency intravascular ultrasound versus optical coherence tomography among patients with acute myocardial infarction: insights from the IBIS-4 study

We aimed to evaluate the diagnostic agreement between radiofrequency (RF) intravascular ultrasound (IVUS) and optical coherence tomography (OCT) for thin-cap fibroatheroma (TCFA) in non-infarct-related coronary arteries (non-IRA) in patients with ST-segment elevation myocardial infarction (STEMI). In the Integrated Biomarker Imaging Study (IBIS-4), 103 STEMI patients underwent OCT and RF-IVUS imaging of non-IRA after successful primary percutaneous coronary intervention and at 13-month follow-up. A coronary lesion was defined as a segment with ≥ 3 consecutive frames (≈1.2 mm) with plaque burden ≥ 40% as assessed by grayscale IVUS. RF-IVUS-derived TCFA was defined as a lesion with > 10% confluent necrotic core abutting to the lumen in > 10% of the circumference. OCT-TCFA was defined by a minimum cap thickness < 65 μm. The two modalities were matched based on anatomical landmarks using a dedicated matching software. Using grayscale IVUS, we identified 276 lesions at baseline (N = 146) and follow-up (N = 130). Using RF-IVUS, 208 lesions (75.4%) were classified as TCFA. Among them, OCT identified 14 (6.7%) TCFA, 60 (28.8%) thick-cap fibroatheroma (ThCFA), and 134 (64.4%) non-fibroatheroma. All OCT-TCFA (n = 14) were confirmed as RF-TCFA. The concordance rate between RF-IVUS and OCT for TCFA diagnosis was 29.7%. The reasons for discordance were: OCT-ThCFA (25.8%); OCT-fibrous plaque (34.0%); attenuation due to calcium (23.2%); attenuation due to macrophage (10.3%); no significant attenuation (6.7%). There was a notable discordance in the diagnostic assessment of TCFA between RF-IVUS and OCT. The majority of RF-derived TCFA were not categorized as fibroatheroma using OCT, while all OCT-TCFA were classified as TCFA by RF-IVUS.

ClinicalTrials.gov Identifier NCT00962416.

A deep learning-based model for characterization of atherosclerotic plaque in coronary arteries using optical coherence tomography images

PURPOSE

Coronary artery events are mainly associated with atherosclerosis in adult population, which is recognized as accumulation of plaques in arterial wall tissues. Optical Coherence Tomography (OCT) is a light-based imaging system used in cardiology to analyze intracoronary tissue layers and pathological formations including plaque accumulation. This state-of-the-art catheter-based imaging system provides intracoronary cross-sectional images with high resolution of 10-15 µm. But interpretation of the acquired images is operator dependent, which is not only very time-consuming but also highly error prone from one observer to another. An automatic and accurate coronary plaque tagging using OCT image post-processing can contribute to wide adoption of the OCT system and reducing the diagnostic error rate.

METHOD

In this study, we propose a combination of spatial pyramid pooling module with dilated convolutions for semantic segmentation to extract atherosclerotic tissues regardless of their types and training a sparse auto-encoder to reconstruct the input features and enlarge the training data as well as plaque type characterization in OCT images.

RESULTS

The results demonstrate high precision of the proposed model with reduced computational complexity, which can be appropriate for real-time analysis of OCT images. At each step of the work, measured accuracy, sensitivity, specificity of more than 93% demonstrate high performance of the model.

CONCLUSION

The main focus of this study is atherosclerotic tissue characterization using OCT imaging. This contributes to wide adoption of the OCT imaging system by providing clinicians with a fully automatic interpretation of various atherosclerotic tissues. Future studies will be focused on analyzing atherosclerotic vulnerable plaques, those coronary plaques which are prone to rupture.

Association of the age shock index with coronary plaque characteristics in ST-segment elevation myocardial infarction: A 3-vessel optical coherence tomography study

OBJECTIVES

We investigated whether the age shock index (SI) was associated with coronary plaque characteristics in patients with ST-segment elevation myocardial infarction (STEMI) using optical coherence tomography (OCT).

BACKGROUND

The age SI is a simple clinical parameter that effectively predicts poor clinical outcomes among patients with STEMI.

METHODS

This retrospective study evaluated 408 STEMI patients who underwent 3-vessel OCT during emergency percutaneous coronary interventions at a single center between January 2017 and October 2018. Patients were divided into groups with low or high age SI values (<41 vs. ≥41). Plaque characteristics were compared between the two groups for both culprit lesions (n = 408) and non-culprit lesions (n = 1,077).

RESULTS

In culprit lesions, patients with a high age SI (≥41) were more likely to have plaque rupture (61.0% vs. 56.8%, p = .002) and thinner fibrous caps (fibrous cap thickness [FCT]: 40.0 [33.0-53.0] μm vs. 46.0 [36.0-63.8] μm, p = .021). In non-culprit lesions, patients with a high age SI were more likely to have high-risk plaques (29.9% vs. 17.8%, p = .018; simultaneous presence of a minimal lumen area of <3.5 mm² , maximum lipid arc of >180°, FCT of <75 μm, and macrophage accumulation). Plaque-based analyses revealed that patients with a high age SI had larger lipid cores and lesser FCT.

CONCLUSIONS

Patients with STEMI and a high age SI had increased risks of culprit plaque rupture and high-risk non-culprit plaques, and vulnerable plaque features at the culprit and non-culprit lesions. Therefore, a high age SI in patients with STEMI may indicate greater pancoronary vulnerability.

Associations of NETs with inflammatory risk and atherosclerotic severity in ST-segment elevation myocardial infarction

AIM

To investigate the association between neutrophil extracellular traps (NETs) in coronary thrombus and risk profile of patients with ST-segment elevation myocardial infarction (STEMI).

METHODS

All participants enrolled in the Optical Coherence Tomography Examination in Acute Myocardial Infarction (NCT03593928) registry from March 2017 to November 2019 were screened and 104 patients were qualified for the current analysis. Coronary aspirated materials were collected and culprit lesion characteristics were examined by optical coherence tomography. NETs in thrombus were identified by immunofluorescence as the co-localization of anti-histone H3 and myeloperoxidase, and NETs level was assessed using a semi-quantitative score. Patient-oriented composite endpoint included all-cause death, myocardial infarction, stroke, any revascularization, and re-admission for heart failure.

RESULTS

According to NETs burden, 44 patients were in the low NETs group and 60 in the high NETs group. The two groups were comparable in age, sex, and comorbidities but the high NETs group presented with significantly higher level of high-sensitivity C reactive protein than the low NETs group (median 9.3 mg/L vs 5.2 mg/L, p = 0.036). Although culprit plaque morphology did not differ between groups, the lipid arc was smaller (maximal lipid arc 320° vs 360°, p = 0.012) and the flow area was larger (median 1.85mm² vs 1.65mm², p = 0.041) in the high NETs group. No significant difference was observed between groups in patient-oriented composite endpoint.

CONCLUSION

Increased NETs in aspirated coronary thrombus appear to be associated with more elevated inflammation but less advanced atherosclerosis.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT03593928.

In-vivo mechanical characterization of coronary atherosclerotic plaques in living swine using intravascular laser speckle imaging

The ability to evaluate the viscoelastic properties of coronary arteries is crucial for identifying mechanically unstable atherosclerotic plaques. Here, we demonstrate for the first time in living swine, the capability of intravascular laser speckle imaging (ILSI) to measure an index of coronary plaque viscoelasticity, τ, using a human coronary to swine xenograft model. Cardiac motion effects are evaluated by comparing the EKG-non-gated τ ¯ N G , and EKG-gated τ ¯ G among different plaque types. Results show that both τ ¯ N G and τ ¯ G are significantly lower in necrotic-core plaques compared with stable lesions. Discrete-point pullback measurements demonstrate the capability of ILSI for rapid mechanical characterization of coronary segments under physiological conditions, in-vivo.

Anatomic and Flow Characteristics of Left Anterior Descending Coronary Artery Angiographic Stenoses Predisposing to Myocardial Infarction

The impact of the anatomic characteristics of coronary stenoses on the development of future coronary thrombosis has been controversial. This study aimed at identifying the anatomic and flow characteristics of left anterior descending (LAD) coronary artery stenoses that predispose to myocardial infarction, by examining angiograms obtained before the index event. We identified 90 patients with anterior ST-elevation myocardial infarction (STEMI) for whom coronary angiograms and their reconstruction in the three-dimensional space were available at 6 to 12 months before the STEMI, and at the revascularization procedure. The majority of culprit lesions responsible for STEMI occurred between 20 and 40 mm from the LAD ostium, whereas the majority of stable lesions not associated with STEMI were found in distances >60 mm (p < 0.001). Culprit lesions were significantly more stenosed (diameter stenosis 68.6 ± 14.2% vs 44.0 ± 10.4%, p < 0.001), and significantly longer than stable ones (15.3 ± 5.4 mm vs 9.2 ± 2.5 mm, p < 0.001). Bifurcations at culprit lesions were significantly more frequent (88.8%) compared with stable lesions (34.4%, p < 0.001). Computational fluid dynamics simulations demonstrated that hemodynamic conditions in the vicinity of culprit lesions promote coronary thrombosis due to flow recirculation. A multiple logistic regression model with diameter stenosis, lesion length, distance from the LAD ostium, distance from bifurcation, and lesion symmetry, showed excellent accuracy in predicting the development of a culprit lesion (AUC: 0.993 [95% CI: 0.969 to 1.000], p < 0.0001). In conclusion, specific anatomic and hemodynamic characteristics of LAD stenoses identified on coronary angiograms may assist risk stratification of patients by predicting sites of future myocardial infarction.

Analysis of MicroRNAs Associated With Carotid Atherosclerotic Plaque Rupture With Thrombosis

Atherosclerosis is a progressive vascular wall inflammatory disease, and the rupture of atherosclerotic vulnerable plaques is the leading cause of morbidity and mortality worldwide. This study intended to explore the potential mechanisms behind plaque rupture and thrombosis in ApoE knockout mice. The spontaneous plaque rupture models were established, and left carotid artery tissues at different time points (1-, 2-, 4-, 6-, 8-, 12-, and 16-week post-surgery) were collected. By the extent of plaque rupture, plaque was defined as (1) control groups, (2) atherosclerotic plaque group, and (3) plaque rupture group. Macrophage (CD68), MMP-8, and MMP-13 activities were measured by immunofluorescence. Cytokines and inflammatory markers were measured by ELISA. The left carotid artery sample tissue was collected to evaluate the miRNAs expression level by miRNA-microarray. Bioinformatic analyses were conducted at three levels: (2) vs. (1), (3) vs. (2), and again in seven time series analysis. The plaque rupture with thrombus and intraplaque hemorrhage results peaked at 8 weeks and decreased thereafter. Similar trends were seen in the number of plaque macrophages and lipids, the expression of matrix metalloproteinase, and the atherosclerotic and plasma cytokine levels. MiRNA-microarray showed that miR-322-5p and miR-206-3p were specifically upregulated in the atherosclerotic plaque group compared with those in the control group. Meanwhile, miR-466h-5p was specifically upregulated in the plaque rupture group compared with the atherosclerotic plaque group. The highest incidence of plaque rupture and thrombosis occurred at 8 weeks post-surgery. miR-322-5p and miR-206-3p may be associated with the formation of atherosclerotic plaques. miR-466h-5p may promote atherosclerotic plaque rupture via apoptosis-related pathways.

New Strategy to Prevent Acute Myocardial Infarction by Public Education - A Position Statement of the Committee on Public Education About Emergency Medical Care of the Japanese Circulation Society

Although many efforts have been made to prevent death from acute myocardial infarction (MI) by quick revascularization therapy and use of mechanical circulation support devices, and to prevent the occurrence of acute MI by optimal medical therapy, acute MI is still a leading cause of death worldwide. Because the majority of fatal MI cases occur outside hospital and death occurs so rapidly after MI onset, it is difficult to effectively prevent deaths from acute MI by improving the in-hospital treatment strategy of acute MI or by reducing the prehospital delay in the treatment. Therefore, we need a new strategy to prevent death from acute MI, mainly by preventing the occurrence of acute MI itself. In this review, we summarize the present status and propose a new strategy, the "STOP MI Campaign", to prevent acute MI by public education.

Study on the association of wall shear stress and vessel structural stress with atherosclerosis: An experimental animal study

BACKGROUND AND AIMS

Artery is subject to wall shear stress (WSS) and vessel structural stress (VSS) simultaneously. This study is designed to explore the role of VSS in development of atherosclerosis.

METHODS

Silastic collars were deployed on the carotid to create two constrictions on 13 rabbits for a distinct mechanical environment at the constriction. MRI was performed to visualize arteries' configuration. Animals with high fat (n = 9; Model-group) and normal diet (n = 4; Control-group) were sacrificed after 16 weeks. 3D fluid-structure interaction analysis was performed to quantify WSS and VSS simultaneously.

RESULTS

Twenty plaques were found in Model-group and 3 in Control-group. In Model-group, 8 plaques located proximally to the first constriction (Region-1, close to the heart) and 7 distally to the second (Region-2, close to the head) and 5 plaques were found on the contralateral side of 3 rabbits. Plaques at Region-1 tended to be bigger than those at Region-2 and the macrophage density at these locations was comparable. Minimum time-averaged WSS (TAWSS) in Region-1 was significantly higher than that in Region-2, and both maximum oscillatory shear index (OSI) and particle relative residence time (RRT) were significantly lower. Peak and mean VSS in Region-1 were significantly higher than those in Region-2. Correlation analyses indicated that low TAWSS, high OSI and RRT were only associated with plaque in Region-2, while lesions in Region-1 were only associated with high VSS. Moreover, only VSS was associated with wall thickness of plaque-free regions in both regions.

CONCLUSIONS

VSS might contribute to the initialization and development of atherosclerosis solely or in combination with WSS.

[Computed Tomography Coronary Angiography Possibilities in "High Risk" Plaque Identification in Patients with non-ST-Elevation Acute Coronary Syndrome: Comparison with Intravascular Ultrasound]

Aim      To evaluate structural characteristics of atherosclerotic plaques (ASP) by coronary computed tomography arteriography (CCTA) and intravascular ultrasound (IVUS).Material and methods  This study included 37 patients with acute coronary syndrome (ACS). 64-detector-row CCTA, coronarography, and grayscale IVUS were performed prior to coronary stenting. The ASP length and burden, remodeling index (RI), and known CT signs of unstable ASP (presence of dot calcification, positive remodeling of the artery in the ASP area, irregular plaque contour, presence of a peripheral high-density ring and a low-density patch in the ASP). The ASP type and signs of rupture or thrombosis were determined by IVUS.Results The IVUS study revealed 45 unstable ASP (UASP), including 25 UASP with rupture and 20 thin-cap fibroatheromas (TCFA), and 13 stable ASP (SASP). No significant differences were found between distribution of TCFA and ASP with rupture among symptom-associated plaques (SAP, n=28) and non-symptom-associated plaques (NSAP, n=30). They were found in 82.1 and 73.3 % of cases, respectively (p&gt;0.05), which indicated generalization of the ASP destabilization process in the coronary circulation. However, the incidence of mural thrombus was higher for SAP (53.5 and 16.6 % of ASP, respectively; p&lt;0.001). There was no difference between UASP and SASP in the incidence of qualitative ASP characteristics or in values of quantitative ASP characteristics, including known signs of instability, except for the irregular contour, which was observed in 92.9 % of UASP and 46.1 % of SASP (p=0.0007), and patches with X-ray density ≤46 HU, which were detected in 83.3 % of UASP and 46.1 % of SASP (р=0.01). The presence of these CT criteria 11- and 7-fold increased the likelihood of unstable ASP (odd ratio (OR), 11.1 at 95 % confidence interval (CI), from 2.24 to 55.33 and OR, 7.0 at 95 % CI, from 5.63 to 8.37 for the former and the latter criterion, respectively).Conclusion      According to IVUS data, two X-ray signs are most characteristic for UASP, the irregular contour and a patch with X-ray density ≤46 HU. The presence of these signs 11- and 7-fold, respectively, increases the likelihood of unstable ASP.

Identification of plaque ruptures using a novel discriminative model comprising biomarkers in patients with acute coronary syndrome

Soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1), neutrophil gelatinase-associated lipocalin (NGAL), and matrix metalloproteinase-9 (MMP-9) are inflammatory biomarkers involved in plaque destabilization resulting in acute coronary syndrome (ACS). This study aimed to investigate the diagnostic value of a combination of biomarkers to discriminate plaque ruptures in the setting of ACS. Eighty-five ACS patients with optical coherence tomography (OCT) images of the culprit plaque were included and categorized into two groups: ACS with plaque rupture (Rupture group, n = 42) or without plaque rupture (Non-rupture group, n = 43) verified by OCT. A discriminative model of plaque rupture using several biomarkers was developed and validated. The Rupture group had higher white blood cell (WBC) counts and peak creatine kinase-myocardial band (CK-MB) levels (13.39 vs. 2.69 ng/mL, p = 0.0016). sLOX-1 (227.9 vs. 51.7 pg/mL, p < 0.0001) and MMP-9 (13.4 vs. 6.45 ng/mL, p = 0.0313) levels were significantly higher in the Rupture group, whereas NGAL showed a trend without statistical significance (59.03 vs. 53.80 ng/mL, p = 0.093). Receiver operating characteristic curves to differentiate Rupture group from Non-rupture group calculated the area under the curve for sLOX-1 (p < 0.001), MMP-9 (p = 0.0274), and NGAL (p = 0.0874) as 0.763, 0.645, and 0.609, respectively. A new combinatorial discriminative model including sLOX-1, MMP-9, WBC count, and the peak CK-MB level showed an area under the curve of 0.8431 (p < 0.001). With a cut-off point of 0.614, the sensitivity and specificity of plaque rupture were 62.2% and 97.6%, respectively. The new discriminative model using sLOX-1, MMP-9, WBC count, and peak CK-MB levels could better identify plaque rupture than each individual biomarker in ACS patients.

Frequency, Predictors, Distribution, and Morphological Characteristics of Layered Culprit and Nonculprit Plaques of Patients With Acute Myocardial Infarction

Background:

Subclinical atherothrombosis and plaque healing may lead to rapid plaque progression. The histopathologic healed plaque has a layered appearance when imaged using optical coherence tomography. We assessed the frequency, predictors, distribution, and morphological characteristics of optical coherence tomography layered culprit and nonculprit plaques in patients with acute myocardial infarction.

Methods:

A prospective series of 325 patients with acute myocardial infarction underwent optical coherence tomography imaging of all 3 native coronary arteries. Layered plaque phenotype had heterogeneous signal-rich layered tissue located close to the luminal surface that was clearly demarcated from the underlying plaque.

Results:

Layered plaques were detected in 74.5% of patients with acute myocardial infarction. Patients with layered culprit plaques had more layered nonculprit plaques; and they more often had preinfarction angina, ST-segment–elevation myocardial infarction, higher low-density lipoprotein cholesterol, and absence of antiplatelet therapy. Layered plaques tended to cluster in the proximal segment of the left anterior descending artery and left circumflex artery but were more uniformly distributed in the right coronary artery. As compared with nonlayered plaques, layered plaques had greater optical coherence tomography lumen area stenosis at both culprit and nonculprit sites. The frequency of layered plaque phenotype ( P =0.038) and maximum area of layered tissue ( P <0.001) increased from nonculprit thin-cap fibroatheromas to nonculprit ruptures to culprit ruptures.

Conclusions:

Layered plaques were identified in 3-quarters of patients with acute myocardial infarction, especially in the culprit plaques of patients with ST-segment–elevation myocardial infarction. Layered plaques had a limited, focal distribution in the left anterior descending artery, and left circumflex artery but were more evenly distributed in the right coronary artery and were characterized by greater lumen narrowing at both culprit and nonculprit sites.

Graphic Abstract:

A graphic abstract is available for this article.

Relationship between arterial remodelling and serial changes in coronary atherosclerosis by intravascular ultrasound: an analysis of the IBIS-4 study

AIMS

Arterial remodelling is an important determinant of coronary atherosclerosis. Assessment of the remodelling index, comparing a lesion to a local reference site, is a suboptimal correlate of serial vascular changes. We assessed a novel approach which, unlike the local-reference approach, uses the entire artery's global remodelling as reference.

METHODS AND RESULTS

Serial (baseline and 13 months) intravascular ultrasound was performed in 146 non-infarct-related arteries of 82 patients treated with high-intensity statin. Arteries were divided into 3-mm segments (n = 1479), and focal remodelling was characterized in individual segments at both timepoints applying the global arterial reference approach. First, we compared preceding vascular changes in relation to follow-up remodelling. Second, we examined whether baseline remodelling predicts subsequent plaque progression/regression. At follow-up, segments with constrictive vs. compensatory or expansive remodelling had greater preceding reduction of vessel area (-0.67 vs. -0.38 vs. -0.002 mm2; P < 0.001) and lumen area (-0.82 vs. -0.09 vs. 0.40 mm2; P < 0.001). Overall, we found significant regression in percent atheroma volume (PAV) [-0.80% (-1.41 to -0.19)]. Segments with constrictive remodelling at baseline had greater subsequent PAV regression vs. modest regression in the compensatory, and PAV progression in the expansive remodelling group (-6.14% vs. -0.71% vs. 2.26%; P < 0.001). Lesion-level analyses (n = 118) showed no differences when remodelling was defined by the local reference approach at baseline or follow-up.

CONCLUSION

Remodelling assessment using a global arterial reference approach, but not the commonly used, local reference site approach, correlated reasonably well with serial changes in arterial dimensions and identified arterial segments with subsequent PAV progression despite intensive statin treatment and overall atheroma regression.

Transient increase in blood thrombogenicity may be a critical mechanism for the occurrence of acute myocardial infarction

Although the mechanism for the occurrence of acute myocardial infarction (MI) has been investigated by many pathological and clinical studies, it has not been adequately clarified yet. Although the disruption of vulnerable plaque is a well-known cause of acute MI, there are many silent plaque disruptions detected in the coronary artery by intravascular imaging studies. Therefore, many vulnerable plaques may disrupt and heal without causing acute MI. Some additional mechanisms other than the disruption of vulnerable plaque would be essential for the onset of acute MI. On the other hand, blood thrombogenicity would change dynamically due to circadian rhythms and many other factors. The combination of plaque and blood thrombogenicity would play an important and determinant role for the onset of acute MI.

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.

From Detecting the Vulnerable Plaque to Managing the Vulnerable Patient: JACC State-of-the-Art Review

The past decades have seen tremendous progress on elucidating mechanisms leading to acute coronary syndrome and sudden cardiac death. Pathology and imaging studies have identified features of coronary atherosclerosis that precede acute coronary events. However, many factors influence the risk of adverse events from coronary atherosclerotic disease and available data support our transition from focusing on individual "vulnerable plaque," coronary arterial stenosis, and inducible myocardial ischemia to understanding coronary heart disease as multifactorial, chronic disease. The concept of the vulnerable patient has evolved, with the atheroma burden, its metabolic activity, and the disposition to vascular thrombosis building a platform for assessing central aspects of coronary heart disease. In turn, this model has directed us to a focus on controlling the activity of atherosclerotic disease and on modifying the susceptibility of vascular thrombosis which has led to reduced morbidity and mortality from coronary heart disease.

Spatial Distribution of Vulnerable Plaques: Comprehensive In Vivo Coronary Plaque Mapping

OBJECTIVES

The authors performed a comprehensive analysis on the distribution of coronary plaques with different phenotypes from our 3-vessel optical coherence tomography (OCT) database.

BACKGROUND

Previous pathology studies demonstrated that thin-cap fibroatheroma (TCFA) is localized in specific segments of the epicardial coronary arteries. A detailed description of in vivo coronary plaques of various phenotypes has not been reported.

METHODS

OCT images of all 3 coronary arteries in 131 patients were analyzed every 1 mm to assess plaque phenotype and features of vulnerability. In addition, plaques were divided into tertiles according to percent area stenosis (%AS).

RESULTS

Among 534 plaques identified in 393 coronary arteries, 27.0% were fibrous plaques, 13.3% were fibrocalcific plaques, 40.8% were thick-cap fibroatheromas, and 18.9% were TCFAs. TCFAs showed clustering in the proximal segment, particularly in the left anterior descending artery. On the other hand, fibrous plaques were relatively evenly distributed throughout the entire length of the coronary arteries. In patients with acute coronary syndromes (ACS), TCFAs showed stronger proximal clustering in the left anterior descending, 2 clustering peaks in the right coronary artery, and 1 clustering peak in the circumflex artery. The pattern of TCFA distribution was less obvious in patients without ACS. The prevalence of TCFA was higher in the highest %AS tertile, compared with the lowest %AS tertile (30% vs. 9%; p < 0.001).

CONCLUSIONS

The present 3-vessel OCT study showed that TCFAs cluster at specific locations in the epicardial coronary arteries, especially in patients with ACS. TCFA was more prevalent in segments with tight stenosis. (The Massachusetts General Hospital Optical Coherence Tomography Registry; NCT01110538).

Biomechanical Stress Profiling of Coronary Atherosclerosis: Identifying a Multifactorial Metric to Evaluate Plaque Rupture Risk

OBJECTIVES

The purpose of this study was to derive a biomechanical stress metric that was based on the multifactorial assessment of coronary plaque morphology, likely related to the propensity of plaque rupture in patients.

BACKGROUND

Plaque rupture, the most frequent cause of coronary thrombosis, occurs at locations of elevated tensile stress in necrotic core fibroatheromas (NCFAs). Finite element modeling (FEM), typically used to calculate tensile stress, is computationally intensive and impractical as a clinical tool for locating rupture-prone plaques. This study derived a multifactorial stress equation (MSE) that accurately computes peak stress in NCFAs by combining the influence of several morphological parameters.

METHODS

Intravascular ultrasound and optical frequency domain imaging were conducted in 30 patients, and plaque morphological parameters were defined in 61 NCFAs. Multivariate regression analysis was applied to derive the MSE and compute a peak stress metric (PSM) that was based on the analysis of plaque morphological parameters. The accuracy of the MSE was determined by comparing PSM with FEM-derived peak stress values. The ability of the PSM in locating plaque rupture sites was tested in 3 additional patients.

RESULTS

The following parameters were found to be independently associated with peak stress: fibrous cap thickness (p < 0.0001), necrotic core angle (p = 0.024), necrotic core thickness (p < 0.0001), lumen area (p < 0.0001), necrotic core including calcium areas (p = 0.017), and plaque area (p = 0.003). The PSM showed excellent correlation (R = 0.85; p < 0.0001) with FEM-derived peak stress, thus confirming the accuracy of the MSE. In only 56% (n = 34) of plaques, the thinnest fibrous cap thickness was a determining parameter in identifying the cross section with highest PSM. In coronary segments with plaque ruptures, the MSE precisely located the rupture site.

CONCLUSIONS

The MSE shows potential to calculate the PSM in coronary lesions rapidly. However, further studies are warranted to investigate the use of biomechanical stress profiling for the prognostic evaluation of patients with atherosclerosis.

Intracoronary Imaging for Assessment of Vascular Healing and Stent Follow-up in Bioresorbable Vascular Scaffolds

Bioresorbable Vascular Scaffolds (BVS) are polymer-based materials implanted in the coronary arteries in order to treat atherosclerotic lesions, based on the concept that once the lesion has been treated, the material of the implanted stent will undergo a process of gradual resorption that will leave, in several years, the vessel wall smooth, free of any foreign material and with its vasomotion restored. However, after the first enthusiastic reports on the efficacy of BVSs, the recently published trials demonstrated disappointing results regarding long-term patency following BVS implantation, which were mainly attributed to technical deficiencies during the stenting procedure. Intracoronary imaging could play a crucial role for helping the operator to correctly implant a BVS into the coronary artery, as well as providing relevant information in the follow-up period. This review aims to summarize the role of intracoronary imaging in the follow-up of coronary stents, with a particular emphasis on the role of intravascular ultrasound and optical coherence tomography for procedural guidance during stent implantation and also for follow-up of bioabsorbable scaffolds.

Average daily ischemic versus bleeding risk in patients with ACS undergoing PCI: Insights from the BleeMACS and RENAMI registries

BACKGROUND

The risk of recurrent ischemia and bleeding after percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS) may vary during the first year of follow-up according to clinical presentation, and medical and interventional strategies.

METHODS

BleeMACS and RENAMI are 2 multicenter registries enrolling patients with ACS treated with PCI and clopidogrel, prasugrel, or ticagrelor. The average daily ischemic and bleeding risks (ADIR and ADBR) in the first year after PCI were the primary end points. The difference between ADBR and ADIR was calculated to estimate the potential excess of bleeding/ischemic events in a given period or specific subgroup.

RESULTS

A total of 19,826 patients were included. Overall, in the first year after PCI, the ADBR was 0.008085%, whereas ADIR was 0.008017% (P = .886). In the first 2 weeks ADIR was higher than ADBR (P = .013), especially in patients with ST-segment elevation myocardial infarction or incomplete revascularization. ADIR continued to be, albeit non-significantly, greater than ADBR up to the third month, whereas ADBR became higher, although not significantly, afterward. Patients with incomplete revascularization had an excess in ischemic risk (P = .003), whereas non-ST-segment elevation ACS patients and those on ticagrelor had an excess of bleeding (P = .012 and P = .022, respectively).

CONCLUSIONS

In unselected ACS patients, ADIR and ADBR occurred at similar rates within 1 year after PCI. ADIR was greater than ADBR in the first 2 weeks, especially in ST-segment elevation myocardial infarction patients and those with incomplete revascularization. In the first year, ADIR was higher than ADBR in patients with incomplete revascularization, whereas ADBR was higher in non-ST-segment elevation ACS patients and in those discharged on ticagrelor.

In vivo predictors of plaque erosion in patients with ST-segment elevation myocardial infarction: a clinical, angiographical, and intravascular optical coherence tomography study

Aims

Plaque erosion is a significant substrate of acute coronary thrombosis. This study sought to determine in vivo predictors of plaque erosion in patients with ST-segment elevation myocardial infarction (STEMI).

Methods and results

A prospective series of 822 STEMI patients underwent pre-intervention optical coherence tomography. Using established diagnostic criteria, 209 had plaque erosion (25.4%) and 564 had plaque rupture (68.6%). Plaque erosion was more frequent in women <50 years when compared with those ≥50 years of age (P = 0.009). There was a similar, but less striking, trend in men (P = 0.011). Patients with plaque erosion were more frequently current smokers but had fewer other coronary risk factors (dyslipidaemia, hypertension, chronic kidney disease, and diabetes mellitus) than those with plaque rupture. There was a preponderance of plaque erosion in the left anterior descending artery (LAD; 61.2%), whereas plaque rupture was more equally distributed in both the LAD (47.0%) and right coronary artery (43.3%). Despite the similar spatial distribution of erosions and ruptures over the lengths of the coronary arteries, plaque erosion occurred more frequently near a bifurcation (P < 0.001). In the multivariable analysis, age <50 years, current smoking, absence of other coronary risk factors, lack of multi-vessel disease, reduced lesion severity, larger vessel size, and nearby bifurcation were significantly associated with plaque erosion. Nearby bifurcation and current smoking were especially notable in men, while age <50 years was most predictive in women.

Conclusions

Plaque erosion was a predictable clinical entity distinct from plaque rupture in STEMI patients, and gender-specific role of risk factors in plaque erosion should be considered.

Identification of patients and plaques vulnerable to future coronary events with near-infrared spectroscopy intravascular ultrasound imaging: a prospective, cohort study

BACKGROUND

Near-infrared spectroscopy (NIRS) intravascular ultrasound imaging can detect lipid-rich plaques (LRPs). LRPs are associated with acute coronary syndromes or myocardial infarction, which can result in revascularisation or cardiac death. In this study, we aimed to establish the relationship between LRPs detected by NIRS-intravascular ultrasound imaging at unstented sites and subsequent coronary events from new culprit lesions.

METHODS

In this prospective, cohort study (LRP), patients from 44 medical centres were enrolled in Italy, Latvia, Netherlands, Slovakia, UK, and the USA. Patients with suspected coronary artery disease who underwent cardiac catheterisation with possible ad hoc percutaneous coronary intervention were eligible to be enrolled. Enrolled patients underwent scanning of non-culprit segments using NIRS-intravascular ultrasound imaging. The study had two hierarchal primary hypotheses, patient and plaque, each testing the association between maximum 4 mm Lipid Core Burden Index (maxLCBI_4mm) and non-culprit major adverse cardiovascular events (NC-MACE). Enrolled patients with large LRPs (≥250 maxLCBI_4mm) and a randomly selected half of patients with small LRPs (<250 maxLCBI_4mm) were followed up for 24 months. This study is registered with ClinicalTrials.gov, NCT02033694.

FINDINGS

Between Feb 21, 2014, and March 30, 2016, 1563 patients were enrolled. NIRS-intravascular ultrasound device-related events were seen in six (0·4%) patients. 1271 patients (mean age 64 years, SD 10, 883 [69%] men, 388 [31%]women) with analysable maxLCBI_4mm were allocated to follow-up. The 2-year cumulative incidence of NC-MACE was 9% (n=103). Both hierarchical primary hypotheses were met. On a patient level, the unadjusted hazard ratio (HR) for NC-MACE was 1·21 (95% CI 1·09-1·35; p=0·0004) for each 100-unit increase maxLCBI_4mm) and adjusted HR 1·18 (1·05-1·32; p=0·0043). In patients with a maxLCBI_4mm more than 400, the unadjusted HR for NC-MACE was 2·18 (1·48-3·22; p<0·0001) and adjusted HR was 1·89 (1·26-2·83; p=0·0021). At the plaque level, the unadjusted HR was 1·45 (1·30-1·60; p<0·0001) for each 100-unit increase in maxLCBI_4mm. For segments with a maxLCBI_4mm more than 400, the unadjusted HR for NC-MACE was 4·22 (2·39-7·45; p<0·0001) and adjusted HR was 3·39 (1·85-6·20; p<0·0001).

INTERPRETATION

NIRS imaging of non-obstructive territories in patients undergoing cardiac catheterisation and possible percutaneous coronary intervention was safe and can aid in identifying patients and segments at higher risk for subsequent NC-MACE. NIRS-intravascular ultrasound imaging adds to the armamentarium as the first diagnostic tool able to detect vulnerable patients and plaques in clinical practice.

FUNDING

Infraredx.

Prevalence and characteristics of dual left anterior descending artery in adult patients undergoing coronary angiography

Aim: To determine the prevalence and characteristics of dual left anterior descending artery (LAD) in adults undergoing catheter coronary angiography. Materials & methods: We identified cases with dual LAD by retrospectively analyzing 3233 angiograms done from January 2017 to June 2019. Results: Dual LAD was seen in 22 patients (0.68%). We identified type I dual LAD in 14 cases, type II in 7 cases and type III in 1 case. Significant stenosis was seen in proximal part of long LAD in 12 cases, in LAD proper in 7 cases and in proximal part of short LAD in 4 cases. Conclusion: Dual LAD is a rare anomaly. Its sound knowledge is essential for proper management of patients with coronary artery disease.

Coronary Artery Microcalcification: Imaging and Clinical Implications

Strategies to prevent acute coronary and cerebrovascular events are based on accurate identification of patients at increased cardiovascular (CV) risk who may benefit from intensive preventive measures. The majority of acute CV events are precipitated by the rupture of the thin cap overlying the necrotic core of an atherosclerotic plaque. Hence, identification of vulnerable coronary lesions is essential for CV prevention. Atherosclerosis is a highly dynamic process involving cell migration, apoptosis, inflammation, osteogenesis, and intimal calcification, progressing from early lesions to advanced plaques. Coronary artery calcification (CAC) is a marker of coronary atherosclerosis, correlates with clinically significant coronary artery disease (CAD), predicts future CV events and improves the risk prediction of conventional risk factors. The relative importance of coronary calcification, whether it has a protective effect as a stabilizing force of high-risk atherosclerotic plaque has been debated until recently. The extent of calcium in coronary arteries has different clinical implications. Extensive plaque calcification is often a feature of advanced and stable atherosclerosis, which only rarely results in rupture. These macroscopic vascular calcifications can be detected by computed tomography (CT). The resulting CAC scoring, although a good marker of overall coronary plaque burden, is not useful to identify vulnerable lesions prone to rupture. Unlike macrocalcifications, spotty microcalcifications assessed by intravascular ultrasound or optical coherence tomography strongly correlate with plaque instability. However, they are below the resolution of CT due to limited spatial resolution. Microcalcifications develop in the earliest stages of coronary intimal calcification and directly contribute to plaque rupture producing local mechanical stress on the plaque surface. They result from a healing response to intense local macrophage inflammatory activity. Most of them show a progressive calcification transforming the early stage high-risk microcalcification into the stable end-stage macroscopic calcification. In recent years, new developments in noninvasive cardiovascular imaging technology have shifted the study of vulnerable plaques from morphology to the assessment of disease activity of the atherosclerotic lesions. Increased disease activity, detected by positron emission tomography (PET) and magnetic resonance (MR), has been shown to be associated with more microcalcification, larger necrotic core and greater rates of events. In this context, the paradox of increased coronary artery calcification observed in statin trials, despite reduced CV events, can be explained by the reduction of coronary inflammation induced by statin which results in more stable macrocalcification.

Heterogeneity of Plaque Structural Stress Is Increased in Plaques Leading to MACE: Insights From the PROSPECT Study

Objectives

This study sought to determine if plaque structural stress (PSS) and other plaque stress parameters are increased in plaques that cause future major adverse cardiovascular event(s) (MACE) and if incorporating these parameters improves predictive capability of intravascular ultrasonography (IVUS).

Background

Less than 10% of coronary plaques identified as high-risk by intravascular imaging result in subsequent MACE. Thus, more specific measurements of plaque vulnerability are required for effective risk stratification.

Methods

Propensity score matching in the PROSPECT (Providing Regional Observations to Study Predictors of Events in the Coronary Tree) study plaque cohort resulted in 35 nonculprit lesions (NCL) associated with future MACE and 66 matched NCL that remained clinically silent. PSS was calculated by finite element analysis as the mechanical loading within the plaque structure in the periluminal region.

Results

PSS was increased in the minimal luminal area (MLA) regions of NCL MACE versus no MACE plaques for all plaques (PSS: 112.1 ± 5.5 kPa vs. 90.4 ± 3.3 kPa, respectively; p = 0.001) and virtual histology thin-cap fibroatheromas (VH-TCFAs) (PSS: 119.2 ± 6.6 kPa vs. 95.8 ± 5.0 kPa, respectively; p = 0.005). However, PSS was heterogeneous over short segments, and PSS heterogeneity index (HI) was markedly greater in NCL MACE than in no-MACE VH-TCFAs (HI: 0.43 ± 0.05 vs. 0.29 ± 0.03, respectively; p = 0.01). Inclusion of PSS in plaque assessment improved the identification of NCLs that led to MACE, including in VH-TCFAs (p = 0.03) and plaques with MLA ≤4 mm² (p = 0.03). Incorporation of an HI further improved the ability of PSS to identify MACE NCLs in a variety of plaque subtypes including VH-TCFA (p = 0.001) and plaques with MLA ≤4 mm² (p = 0.002).

Conclusions

PSS and variations in PSS are increased in the peri-MLA regions of plaques that lead to MACE. Moreover, longitudinal heterogeneity in PSS is markedly increased in MACE plaques, especially VH-TCFAs, potentially predisposing to plaque rupture. Incorporation of PSS and heterogeneity in PSS may improve the ability of IVUS to predict MACE.

Pressure overload leads to coronary plaque formation, progression, and myocardial events in ApoE-/- mice

Hypercholesterolemia and hypertension are two major risk factors for coronary artery diseases, which remain the major cause of mortality in the industrialized world. Current animal models of atherosclerosis do not recapitulate coronary plaque disruption, thrombosis, and myocardial infarction occurring in humans. Recently, we demonstrated that exposure of the heart to high pressure, by transverse aortic constriction (TAC), induced coronary lesions in ApoE-/- mice on chow diet. The aim of this study was to characterize the magnitude and location of coronary lesions in ApoE-/- mice after TAC and to assess the susceptibility of coronary plaque to disruption, leading to myocardial events. Here, we describe a reliable pathological condition in mice characterized by the development of coronary lesions and its progression, leading to myocardial infarction; this model better recapitulates human disease. Following TAC surgery, about 90% of ApoE-/- mice developed coronary lesions, especially in the left anterior descending artery, with 59% of the mice manifesting a different magnitude of LAD stenosis. Myocardial events, identified in 74% of the mice, were mainly due to coronary plaque thrombosis and occlusion. That TAC-induced development and progression of coronary lesions in ApoE-/- mice, leading to myocardial events, represents a potentially novel and important tool to investigate the development of coronary lesions and its sequelae in a setting that better resemble human conditions.