Coronary Calcification and Plaque Vulnerability: An Optical Coherence Tomographic Study

Using artificial intelligence to study atherosclerosis from computed tomography imaging: A state-of-the-art review of the current literature

With the enormous progress in the field of cardiovascular imaging in recent years, computed tomography (CT) has become readily available to phenotype atherosclerotic coronary artery disease. New analytical methods using artificial intelligence (AI) enable the analysis of complex phenotypic information of atherosclerotic plaques. In particular, deep learning-based approaches using convolutional neural networks (CNNs) facilitate tasks such as lesion detection, segmentation, and classification. New radiotranscriptomic techniques even capture underlying bio-histochemical processes through higher-order structural analysis of voxels on CT images. In the near future, the international large-scale Oxford Risk Factors And Non-invasive Imaging (ORFAN) study will provide a powerful platform for testing and validating prognostic AI-based models. The goal is the transition of these new approaches from research settings into a clinical workflow. In this review, we present an overview of existing AI-based techniques with focus on imaging biomarkers to determine the degree of coronary inflammation, coronary plaques, and the associated risk. Further, current limitations using AI-based approaches as well as the priorities to address these challenges will be discussed. This will pave the way for an AI-enabled risk assessment tool to detect vulnerable atherosclerotic plaques and to guide treatment strategies for patients.

A Review Paper on Optical Coherence Tomography Evaluation of Coronary Calcification Pattern: Is It Relevant Today?

The process of coronary calcification represents one of the numerous pathophysiological mechanisms involved in the atherosclerosis continuum. Optical coherence tomography (OCT) represents an ideal imaging modality to assess plaque components, especially calcium. Different calcification patterns have been contemporarily described in both early stages and advanced atherosclerosis. Microcalcifications and spotty calcifications correlate positively with macrophage burden and inflammatory markers and are more frequently found in the superficial layers of ruptured plaques in acute coronary syndrome patients. More compact, extensive calcification may reflect a later stage of the disease and was traditionally associated with plaque stability. Nevertheless, a small number of culprit coronary lesions demonstrates the presence of dense calcified plaques. The purpose of the current paper is to review the most recent OCT data on coronary calcification and the interrelation between calcification pattern and plaque vulnerability. How different calcified plaques influence treatment strategies and associated prognostic implications is of great interest.

Identification of potential therapeutic targets for plaque vulnerability based on an integrated analysis

BACKGROUND AND AIMS

This study aimed to explore potential hub genes and pathways of plaque vulnerability and to investigate possible therapeutic targets for acute coronary syndrome (ACS).

METHODS AND RESULTS

Four microarray datasets were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs), weighted gene coexpression networks (WGCNA) and immune cell infiltration analysis (IIA) were used to identify the genes for plaque vulnerability. Then, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, Disease Ontology, Gene Ontology annotation and protein-protein interaction (PPI) network analyses were performed to explore the hub genes. Random forest and artificial neural networks were constructed for validation. Furthermore, the CMap and Herb databases were employed to explore possible therapeutic targets. A total of 168 DEGs with an adjusted P < 0.05 and approximately 1974 IIA genes were identified in GSE62646. Three modules were detected and associated with CAD-Class, including 891 genes that can be found in GSE90074. After removing duplicates, 114 hub genes were used for functional analysis. GO functions identified 157 items, and 6 pathways were enriched for the KEGG pathway at adjusted P < 0.05 (false discovery rate, FDR set at < 0.05). Random forest and artificial neural network models were built based on the GSE48060 and GSE34822 datasets, respectively, to validate the previous hub genes. Five genes (GZMA, GZMB, KLRB1, KLRD1 and TRPM6) were selected, and only two of them (GZMA and GZMB) were screened as therapeutic targets in the CMap and Herb databases.

CONCLUSION

We performed a comprehensive analysis and validated GZMA and GZMB as a target for plaque vulnerability, which provides a therapeutic strategy for the prevention of ACS. However, whether it can be used as a predictor in blood samples requires further experimental verification.

Serial longitudinal changes of coronary calcified plaques with clear outer borders under intensive lipid management: insights from optical coherence tomography

Percutaneous coronary intervention (PCI) for calcified lesions is one of the most challenging procedures related to worse clinical outcomes. To stabilize vulnerable plaques, intensive lipid management is recommended; however, the serial changes of calcified plaques under intensive lipid management are unknown. A total of 31 patients (mean age, 63 ± 10 years; men, 29 patients) who underwent PCI with intensive lipid management were retrospectively studied. We evaluated the serial longitudinal changes of calcified plaques with clear outer borders using optical coherence tomography (OCT) at two time points: at the time of PCI (baseline) and the chronic phase. The median interval from PCI to chronic phase was 287 (233-429) days. Twenty-eight patients (90.3%) had increased calcium volume at the chronic phase compared with those at baseline (2.6 [1.3-5.1] vs. 1.8 [0.7-4.3] mm2, p < 0.05), and the median increase rate of calcium volume was 27.4% at the chronic phase. According to the median increase rate of calcium volume (27.4%), patients were divided into the following two groups: rapid progression (≥ 27.4%, RP group) and non-rapid progression (< 27.4%, non-RP group). The RP group had more patients with diabetes, and diabetes was independently associated with rapid progression by multivariate analysis. Furthermore, patients with diabetes had significantly higher changes in calcium index and volume from the baseline to the chronic phase than those without diabetes. Coronary calcification progression during relatively short intervals was observed using OCT even under intensive lipid management. Diabetes was an independent predictor for rapid coronary calcification progression.

Body mass index and characteristics of coronary plaque in younger patients with type 2 diabetes

BACKGROUND AND AIMS

The association between the body mass index (BMI) and the characteristics of coronary plaque in younger type 2 diabetes (T2D) patients with coronary artery disease (CAD) remains to be elucidated.

METHODS AND RESULTS

A total of 138 consecutive younger (<65 years) T2D patients with CAD, who underwent optical coherence tomography imaging of the culprit lesion were included. The patients were classified into either the higher BMI group (n = 68) or the lower BMI group (n = 70) according to the median of BMI (25.9 kg/m2). The prevalence of thin-cap fibroatheroma (TCFA) (35.3 vs. 17.1 %, p = 0.015) was significantly higher in the higher BMI group than in the lower BMI group. The prevalence of TCFA was significantly higher in patients with higher BMI than in those with lower BMI among patients with hemoglobin A1c (HbA1c) ≥7.0 % (odds ratio [OR] 5.40, 95 % confidence interval [CI] 1.72-17.0, p = 0.003) although the significant difference was not observed among patients with HbA1c <7.0 % (OR 0.89, 95 % CI 0.25-3.13, p = 0.851).

CONCLUSION

Higher BMI was associated with a higher prevalence of TCFA in younger T2D patients with CAD, particularly in patients with HbA1c ≥ 7.0 %.

Coronary artery calcification and plaque stability： an optical coherence tomography study

Background

Coronary artery calcification (CAC), a surrogate of atherosclerosis, is related to stent underexpansion and adverse cardiac events. However, the effect of CAC on plaque stability is still controversial and the morphological significance of CAC has yet to be elucidated.

Methods

A retrospective series of 419 patients with acute coronary syndrome (ACS) who underwent optical coherence tomography (OCT) were enrolled. Patients were classified into three groups based on the calcification size in culprit plaques and the features of the culprit and non-culprit plaques among these groups were compared. Logistic regression was used to analyze independent risk factors for culprit plaque rupture and the nonlinear relationship between calcification parameters and culprit plaque rupture. Furthermore, we compared the detailed calcification parameters of different kinds of plaques.

Results

A total of 419 culprit plaques and 364 non-culprit plaques were identified. The incidence of calcification was 53.9 % in culprit plaques and 50.3 % in non-culprit plaques. Compared with culprit plaques without calcification, plaque rupture, macrophages and cholesterol crystals were more frequently observed in the spotty calcification group, and the lipid length was longer; the incidence of macrophages and cholesterol crystals was higher in the macrocalcification group. Calcification tended to be smaller in ruptured plaques than in non-ruptured plaques. Moreover, the arc and length of calcification were greater in culprit plaques than in non-culprit plaques.

Conclusions

Vulnerable features were more frequently observed in culprit plaques with spotty calcification, whereas the presence of macrocalcification calcifications did not significantly increase plaque vulnerability. Calcification tends to be larger in culprit plaques than in non-culprit plaques.

Spotty calcium deposits within acute coronary syndrome (ACS)-causing culprit lesions impact inflammatory vessel-wall interactions and are associated with higher cardiovascular event rates at one year follow-up: Results from the prospective translational OPTICO-ACS study program

BACKGROUND AND AIMS

Spotty calcium deposits (SCD) represent a vulnerable plaque feature which seems to result - as based on recent invitro studies - from inflammatory vessel-wall interactions. SCD can be reliably assessed by optical coherence tomography (OCT). Their prognostic impact is yet unknown. Therefore, the aims of this translational study were to comprehensively characterize different plaque calcification patterns, to analyze the associated inflammatory mechanisms in the microenvironment of acute coronary syndrome (ACS)-causing culprit lesions (CL) and to investigate the prognostic significance of SCD in a large cohort of ACS-patients.

METHODS

CL of the first 155 consecutive ACS-patients from the translational OPTICO-ACS-study program were investigated by OCT-characterization of the calcium phenotype at ACS-causing culprit lesions. Simultaneous immunophenotyping by flow-cytometric analysis and cytokine bead array technique across the CL gradient (ratio local/systemic levels) was performed and incidental major adverse cardiovascular events plus (MACE+) at 12 months after ACS were assessed.

RESULTS

SCD were observed within 45.2% of all analyzed ACS-causing culprit lesions (CL). Culprits containing spotty calcium were characterized by an increased culprit ratio of innate effector cytokines interleukin (IL)-8 [2.04 (1.24) vs. 1.37 (1.10) p < 0.05], as well as TNF (tumor necrosis factor)-α [1.17 (0.93) vs. 1.06 (0.89); p < 0.05)] and an increased ratio of circulating neutrophils [0.96 (0.85) vs. 0.91 (0.77); p < 0.05] as compared to culprit plaques without SCD. Total monocyte levels did not differ between the two groups (p = n.s.). However, SCD-containing CLs were characterized by an increased culprit ratio of intermediate monocytes [(1.15 (0.81) vs. 0.96 (0.84); p < 0.05)] with an enhanced surface expression of the integrin receptor CD49d as compared to intermediate monocytes derived from SCD-free CLs [(1.06 (0.94) vs. 0.97 (0.91)] p < 0.05. Finally, 12 months rates of MACE+ were higher in patients with, as compared to patients without SCD at CL (16.4% vs. 5.3%; p < 0.05).

CONCLUSIONS

This study for the first time identified a specific inflammatory profile of CL with SCD, with a predominance of neutrophils, intermediate monocytes and their corresponding effector molecules. Hence, this study advances our understanding of ACS-causing CL and provides the basis for future personalized anti-inflammatory, therapeutic approaches to ACS.

The role of invasive and non-invasive imaging technologies and calcium modification therapies in the evaluation and management of coronary artery calcifications

The treatment of coronary artery disease (CAD) has advanced significantly in recent years due to improvements in medical therapy and percutaneous or surgical revascularization. However, a persistent obstacle in the percutaneous management of CAD is coronary artery calcification (CAC), which portends to higher rates of procedural challenges, post-intervention complications, and overall poor prognosis. With the advent of novel multimodality imaging technologies spanning from intravascular ultrasound to optical coherence tomography to coronary computed tomography angiography combined with advances in calcium debulking and modification techniques, CACs are now targets for intervention with growing success. This review will summarize the most recent developments in the diagnosis and characterization of CAC, offer a comparison of the aforementioned imaging technologies including which ones are most suitable for specific clinical presentations, and review the CAC modifying therapies currently available.

Microvascular complications identify a specific coronary atherosclerotic phenotype in patients with type 2 diabetes mellitus

Background

Patients with type 2 diabetes mellitus (T2DM) are considered as a homogeneous cohort of patients. However, the specific role of diabetic microvascular complications (DMC), in determining the features of coronary plaques is poorly known. We investigated whether the presence of DMC may identify a different phenotype of patients associated to specific clinical, angiographic, optical coherence tomography (OCT) features and different prognosis.

Methods

We prospectively enrolled consecutive T2DM patients with obstructive coronary artery disease (CAD) at their first coronary event. Patients were stratified according to the presence or absence of DMC, including diabetic retinopathy, diabetic neuropathy, and diabetic nephropathy. OCT assessment of the culprit vessel was performed in a subgroup of patients. The incidence of major adverse cardiac events (MACEs) was assessed at follow-up.

Results

We enrolled 320 T2DM patients (mean age 70.3 ± 8.8 years; 234 [73.1%] men, 40% acute coronary syndrome, 60% chronic coronary syndrome). Patients with DMC (172 [53.75%]) presented a different clinical and biochemical profile and, of importance, a higher prevalence of multivessel CAD (109 [63.4%] vs. 68 [45.9%], p = 0.002). At OCT analysis, DMC was associated to a higher prevalence of large calcifications and healed plaques and to a lower prevalence of lipid plaques. Finally, MACEs rate was significantly higher (25 [14.5%] vs. 12 [8.1%], p = 0.007) in DMC patients, mainly driven by a higher rate of planned revascularizations, and DMC predicted the occurrence of MACEs (mean follow-up 33.4 ± 15.6 months).

Conclusions

The presence of DMC identifies a distinct diabetic population with more severe CAD but with a more stable pattern of coronary atherosclerosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01637-y.

Optical coherence tomography in coronary atherosclerosis assessment and intervention

Since optical coherence tomography (OCT) was first performed in humans two decades ago, this imaging modality has been widely adopted in research on coronary atherosclerosis and adopted clinically for the optimization of percutaneous coronary intervention. In the past 10 years, substantial advances have been made in the understanding of in vivo vascular biology using OCT. Identification by OCT of culprit plaque pathology could potentially lead to a major shift in the management of patients with acute coronary syndromes. Detection by OCT of healed coronary plaque has been important in our understanding of the mechanisms involved in plaque destabilization and healing with the rapid progression of atherosclerosis. Accurate detection by OCT of sequelae from percutaneous coronary interventions that might be missed by angiography could improve clinical outcomes. In addition, OCT has become an essential diagnostic modality for myocardial infarction with non-obstructive coronary arteries. Insight into neoatherosclerosis from OCT could improve our understanding of the mechanisms of very late stent thrombosis. The appropriate use of OCT depends on accurate interpretation and understanding of the clinical significance of OCT findings. In this Review, we summarize the state of the art in cardiac OCT and facilitate the uniform use of this modality in coronary atherosclerosis. Contributions have been made by clinicians and investigators worldwide with extensive experience in OCT, with the aim that this document will serve as a standard reference for future research and clinical application.

Impact of nodular calcification in patients with acute coronary syndrome (ACS) treated with primary percutaneous coronary intervention (PCI)

BACKGROUND

Calcified plaque is thought to adversely impact outcomes after percutaneous coronary intervention (PCI). This study sought to evaluate the impact of nodular calcification in patients with acute coronary syndrome treated with primary percutaneous coronary intervention.

METHODS

Using optical coherence tomography (OCT), 500 culprit plaques with calcification were analyzed from 495 acute coronary syndrome (ACS) patients on whom PCI was performed. Based on morphology, we classified calcification into two subtypes: nodular calcification and non-nodular calcification. Nodular calcification was defined as protruding mass with an irregular surface, high backscattering, and signal attenuation while non-nodular calcification was defined as an area with low backscattering heterogeneous region with a well-delineated border without protrusion into the lumen on OCT.

RESULTS

Calcified culprit plaques were divided into nodular calcification group (n = 238) and non-nodular calcification group (n = 262). Patients with nodular calcification were older (p < 0.001) and had lower left ventricular ejection fraction (p = 0.006) compared to patients with non-nodular calcification. Minimum stent area (5.0 (3.9, 6.3) mm2 vs. 5.4 (4.2, 6.7) mm2, p = 0.011) and stent expansion (70 (62.7, 81.8) % vs. 75 (65.2, 86.6) %, p = 0.004) were significantly smaller in the nodular calcification group than in the non-nodular calcification group. Stent under-expansion was most frequent (p = 0.003) in the nodular calcification group.

CONCLUSION

This study demonstrate that the presence of nodular calcification is associated with a smaller minimum stent area and a higher incidence of stent under-expansion. Lesions with nodular calcification may be at risk of stent under-expansion.

Coexistence of calcified- and lipid-containing plaque components and their association with incidental rupture points in acute coronary syndrome-causing culprit lesions: results from the prospective OPTICO-ACS study

AIMS

Rupture of the fibrous cap (RFC) represents the main pathophysiological mechanism causing acute coronary syndromes (ACS). Destabilization due to plaque biomechanics is considered to be importantly involved, exact mechanisms triggering plaque ruptures are, however, unknown. This study aims at characterizing the relation between plaque components and rupture points at ACS-causing culprit lesions in a large cohort of ACS-patients assessed by high-resolution intracoronary imaging.

METHODS AND RESULTS

Within the prospective, multicentric OPTICO-ACS study program, the ACS-causing culprit plaques of 282 consecutive patients were investigated following a standardized optical coherence tomography (OCT) imaging protocol. Each pullback was assessed on a frame-by-frame basis for the presence of lipid components (LC), calcium components (CC), and coexistence of both LC and CC (LCC) by two independent OCT-core labs. Of the 282 ACS-patients, 204 patients (72.3%) presented with ACS caused by culprit lesions with rupture of the fibrous cap (RFC-ACS) and 27.7% patients had ACS caused by culprit lesions with intact fibrous cap (IFC-ACS). When comparing RFC-ACS to IFC-ACS, a preferential occurrence of all three plaque components (LC, CC, and LCC) in RFC-ACS became apparent (P < 0.001). Within ruptured culprit lesions, the zone straight at the rupture point [extended rupture zone (RZ)] was characterized by similar (24.7% vs. 24.0%; P = ns) calcium content when compared with the proximal and distal border of the culprit lesion [border zone (BZ)]. The RZ displayed a significantly higher amount of both, LC (100% vs. 69.8%; P < 0.001) and LCC (22.7% vs. 6.8%; P < 0.001), when compared with the BZ. The relative component increase towards the RZ was particularly evident for LCC (+233.8%), while LC showed only a modest increase (+43.3%).

CONCLUSIONS

Calcified- and lipid-containing components characterize ruptured fibrous cap ACS-causing culprit lesions. Their coexistence is accelerated directly at the ruptured point, suggesting a pathophysiological contribution in the development of RFC-ACS.

Impact of triglyceride levels on plaque characteristics in patients with coronary artery disease

BACKGROUND

High triglyceride (TG) levels have been demonstrated to be a risk factor for coronary artery disease. This study aimed to clarify the impact of TG levels on the characteristics of coronary plaques.

METHODS

A total of 850 consecutive patients who underwent optical coherence tomography (OCT) imaging of the culprit lesion were included. The morphologies of culprit plaques were compared between the higher TG group (nonfasting TG levels ≥150 mg/dL, n = 337) and the lower TG group (nonfasting TG <150 mg/dL, n = 513).

RESULTS

The prevalence of lipid-rich plaques (43% vs. 33%, p = 0.005), thin-cap fibroatheromas (TCFAs) (24% vs. 17%, p = 0.015) and macrophages (40% vs. 31%, p = 0.006) was significantly higher in the higher TG group than in the lower TG group. In addition to a high low-density lipoprotein cholesterol (LDL-C) level (≥140 mg/dL), high TGs (≥150 mg/dL) were identified as an independent factor for the presence of TCFAs (odds ratio 1.465, 95% confidence interval 1.004-2.137, p = 0.048). Among patients with lower LDL-C levels (<100 mg/dL), the prevalence of macrophages (38% vs. 26%, p = 0.007) and layered plaques (48% vs. 38%, p = 0.019) was significantly higher in the higher TG group than in the lower TG group.

CONCLUSIONS

Higher TG levels were associated with a higher prevalence of TCFAs in culprit coronary lesions. The prevalence of macrophages and layered plaques was more frequently observed in patients with higher TGs than those with lower TGs among patients with LDL-C < 100 mg/dL.

Coronary Computed Tomography Angiography Assessment of High-Risk Plaques in Predicting Acute Coronary Syndrome

Coronary computed tomography angiography (CCTA) is a comprehensive, non-invasive and cost-effective imaging assessment approach, which can provide the ability to identify the characteristics and morphology of high-risk atherosclerotic plaques associated with acute coronary syndrome (ACS). The development of CCTA and latest advances in emerging technologies, such as computational fluid dynamics (CFD), have made it possible not only to identify the morphological characteristics of high-risk plaques non-invasively, but also to assess the hemodynamic parameters, the environment surrounding coronaries and so on, which may help to predict the risk of ACS. In this review, we present how CCTA was used to characterize the composition and morphology of high-risk plaques prone to ACS and the current role of CCTA, including emerging CCTA technologies, advanced analysis, and characterization techniques in prognosticating the occurrence of ACS.

Familial hypercholesterolemia and vulnerability of coronary plaque in patients with coronary artery disease

Objectives

Patients with familial hypercholesterolemia (FH) are at a very high risk of coronary artery diseases. The aim of the present study was to clarify the characteristics of coronary plaque in patients with FH.

Design

and Methods: A total of 569 patients who underwent optical coherence tomography (OCT) imaging of culprit plaque were included. The characteristics of culprit plaque were compared between patients with and without FH.

Results

A total of 38 patients (6.7%) were clinically diagnosed with FH. The location of the culprit plaque was significantly different (p ​< ​0.001) with a trend toward higher frequency of left main lesion in the FH group than in the group with no FH (7.9 vs. 0%). Culprit plaque was significantly shorter in patients with FH than those without FH (28.1 vs. 33.2 ​mm, p ​= ​0.016). A trend toward higher prevalence of plaque with macrophage accumulation in patients with FH than those without FH (50.0 vs. 34.7%, p ​= ​0.056) was observed, although the prevalence of other vulnerable characteristics including thin-cap fibroatheroma (TCFA) was comparable between patients with and without FH. Among patients with FH, significant increases in the prevalence of lipid-rich plaque (p ​= ​0.028) and TCFA (p ​= ​0.003) were observed according to the increase in low-density lipoprotein cholesterol (LDL-C) levels.

Conclusions

Patients with FH had shorter culprit plaque without significant difference in the prevalence of vulnerable plaque components compared with patients without FH. A higher LDL-C level was associated with higher prevalence of vulnerable plaque in patients with FH.

Association of Trimethylamine N-Oxide Levels and Calcification in Culprit Lesion Segments in Patients With ST-Segment-Elevation Myocardial Infarction Evaluated by Optical Coherence Tomography

The presence of calcified plaques is one of the pathological phenotypes of acute coronary syndrome (ACS) and can be frequently found in culprit lesion segments. Trimethylamine N-oxide (TMAO) is reported to be involved in vascular calcification and plaque instability. This study investigated the relationship between plasma TMAO levels and calcified lesions in culprit lesion segments in STEMI patients. A prospective series of 179 patients with STEMI were enrolled, and calcified lesions from 127 patients were analyzed by OCT. The plasma TMAO levels were measured by using stable isotope dilution liquid chromatography tandem mass spectrometry. Patients were divided into two groups according to the median plasma TMAO level. The prevalence of intimal calcified lesions in the high TMAO group was significantly higher than that in the low TMAO group (90.6 vs. 57.1%, p < 0.001; 84.4 vs. 44.4%, p < 0.001). After adjustment of traditional risk factors and medication history, patients with calcification in their culprit lesion segments had higher plasma TMAO levels than those without calcification. Moreover, plasma TMAO levels were significantly positively associated with the parameters of calcium burden, including maximal calcification arc (r = 0.392, p < 0.001), maximal calcification thickness (r = 0.443, p < 0.001), and calcified length (r = 0.466, p < 0.001). These results suggested that the level of TMAO is significantly correlated with the incidence of calcification in the culprit lesion segment, and the measurement of TMAO levels might improve clinical management in patients with heavy calcification. Clinical Trial Registration: This study is registered at ClinicalTrials.gov as NCT03593928.

Predictors for Rapid Progression of Coronary Calcification: An Optical Coherence Tomography Study

Background The role of coronary calcification in cardiovascular events and plaque stabilization is still being debated, and factors involved in the progression of coronary calcification are not fully understood. This study aimed to identify the predictors for rapid progression of coronary calcification. Methods and Results Patients with serial optical coherence tomography imaging at baseline and at 6 months were selected. Changes in the calcification index and predictors for progression of calcification were studied. Calcification index was defined as the product of the mean calcification arc and calcification length. Rapid progression of calcification was defined as an increase in the calcification index above the median value. Among 187 patients who had serial optical coherence tomography imaging, 235 calcified plaques were identified in 105 patients (56.1%) at baseline. After 6 months, the calcification index increased in 95.3% of calcified plaques from 132.0 to 178.2 (P<0.001). In multivariable analysis, diabetes mellitus (odds ratio [OR], 3.911; P<0.001), chronic kidney disease (OR, 2.432; P=0.037), lipid-rich plaque (OR, 2.698; P=0.034), and macrophages (OR, 6.782; P<0.001) were found to be independent predictors for rapid progression of coronary calcification. Interestingly, rapid progression of calcification was associated with a significant reduction of inflammatory features (thin-cap fibroatheroma; from 21.2% to 11.9%, P=0.003; macrophages; from 74.6% to 61.0%, P=0.001). Conclusions Diabetes mellitus, chronic kidney disease, lipid-rich plaque, and macrophages were independent predictors for rapid progression of coronary calcification. Baseline vascular inflammation and subsequent stabilization may be related to rapid progression of calcification. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT01110538.

Superficial Calcification With Rotund Shape Is Associated With Carotid Plaque Rupture: An Optical Coherence Tomography Study

Background: Plaque rupture is an important etiology for symptomatic carotid stenosis. The role of calcification in the plaque vulnerability has been controversial. We aimed to detect the geometric features of calcifications in carotid plaque and to examine its association with plaque rupture. Methods: Optical coherence tomography assessment of carotid plaque was performed in 88 patients. Calcification shape was evaluated through quantitative measurements of the long and short axis, area size, circumference, calcification arc, and longitudinal length. Calcification location was analyzed through the distance to the lumen. Furthermore, we developed idealized fluid-structure interaction models to investigate the association of calcification shape and plaque stress. Results: A total of 33 ruptured plaques and 30 non-ruptured plaques were recognized. Ruptured plaques had more multiple calcifications and protruded calcifications. The calcifications in the ruptured plaques displayed a remarkably lower long-axis/short-axis (L/S) ratio than in the non-ruptured plaques (p = 0.001). We classified calcification shape into crescentic calcification (L/S > 2.5) and rotund calcification (L/S ≤ 2.5). Rotund-shaped calcifications were more common in ruptured plaques than in non-ruptured plaques (p = 0.02). Superficial calcifications with minimal distance to the lumen ≤ 50 μm accounted for 79.4% of all calcifications in the ruptured plaques, and only 7.7% in the non-ruptured plaques (p < 0.001). Biomechanical analysis showed that the plaque with rotund-shaped calcification developed 7.91-fold higher von Mises stress than the plaque with crescentic calcification. Conclusions: Superficial calcifications and rotund-shaped calcifications are associated with carotid plaque rupture, suggesting that calcification location and shape may play a key role in plaque vulnerability.

The relationship between coronary artery calcium density and optical coherence tomography-derived plaque characteristics

BACKGROUND AND AIMS

Although coronary artery calcium (CAC) density has been associated with plaque stability, pathological evidence is lacking. We investigated the relationship between coronary computed tomography (CCT)-derived CAC density and multiple calcified and high-risk plaque (HRP) characteristics using optical coherence tomography (OCT).

METHODS

We analyzed 83 plaques from 33 stable angina patients who underwent both CCT and OCT. CAC density was measured at calcium plaques with ≥90 Hounsfield units (HU) and ≥130 HU using custom CT software. The correlation between median CAC density and OCT-derived calcium size (thickness and area) was assessed. To investigate whether median CAC densities measured at the 90 HU threshold were associated with plaque vulnerability, OCT-derived plaque characteristics and HRP characteristics were compared between the low (90-129 HU), intermediate (130-199 HU) and high (≥200 HU) CAC HU groups.

RESULTS

Median CAC densities at 130 HU were moderately associated with calcium thickness (R = 0.573, p < 0.001) and area (R = 0.560, p < 0.001). Similar results were observed at 90 HU (thickness, R = 0.615, p < 0.001; area, R = 0.612, p < 0.001). Among groups with low, intermediate and high HU levels, calcium thickness (0.42 ± 0.14 mm, 0.60 ± 0.17 mm and 0.77 ± 0.19 mm, respectively; p < 0.001) and area (0.55 ± 0.29 mm², 1.20 ± 0.58 mm² and 1.78 ± 0.87 mm², respectively; p < 0.001) were significantly greater in the high HU group. HRP characteristics, however, did not differ among the three groups.

CONCLUSIONS

OCT-derived calcium size, but not HRP characteristics, were associated with CAC density, suggesting that CAC density is driven mainly by calcified plaque size but not local plaque vulnerability.

Automated classification of coronary plaque calcification in OCT pullbacks with 3D deep neural networks

SIGNIFICANCE

Detection and characterization of coronary atherosclerotic plaques often need reviews of a large number of optical coherence tomography (OCT) imaging slices to make a clinical decision. However, it is a challenge to manually review all the slices and consider the interrelationship between adjacent slices.

APPROACH

Inspired by the recent success of deep convolutional network on the classification of medical images, we proposed a ResNet-3D network for classification of coronary plaque calcification in OCT pullbacks. The ResNet-3D network was initialized with a trained ResNet-50 network and a three-dimensional convolution filter filled with zeros padding and non-zeros padding with a convolutional filter. To retrain ResNet-50, we used a dataset of ∼4860 OCT images, derived by 18 entire pullbacks from different patients. In addition, we investigated a two-phase training method to address the data imbalance. For an improved performance, we evaluated different input sizes for the ResNet-3D network, such as 3, 5, and 7 OCT slices. Furthermore, we integrated all ResNet-3D results by majority voting.

RESULTS

A comparative analysis proved the effectiveness of the proposed ResNet-3D networks against ResNet-2D network in the OCT dataset. The classification performance (F1-scores  =  94  %   for non-zeros padding and F1-score  =  96  %   for zeros padding) demonstrated the potential of convolutional neural networks (CNNs) in classifying plaque calcification.

CONCLUSIONS

This work may provide a foundation for further work in extending the CNN to voxel segmentation, which may lead to a supportive diagnostic tool for assessment of coronary plaque vulnerability.

Calcium deposition within coronary atherosclerotic lesion: Implications for plaque stability

Atherosclerotic lesion progression is associated with intimal calcification. The earliest lesion that shows calcification is pathologic intimal thickening in which calcifications appear as microcalcifications that vary in size from <0.5 to 15 μm. The calcifications become larger as plaques progress, becoming punctate (>15 μm to 1 mm in diameter), fragmented (>1 mm), and eventually sheet-like calcification (>3 mm). When stratified by plaque type, maximum calcifications are observed in fibrocalcific plaques, followed by healed plaque ruptures. Lesions of acute thrombi, i.e., plaque rupture and erosions, which are the most frequent causes of acute coronary syndromes, show much less calcification than stable fibrocalcific plaques. Conversely, a calcified nodule, the least common lesion of acute thrombosis, occurs in highly calcified lesions. Pro-inflammatory cytokines observed in unstable plaques may provoke an early phase of osteogenic differentiation of smooth muscle cells (SMCs), a release of calcifying extracellular matrix vesicles, and/or induce apoptosis of macrophages and SMCs, which also calcify. Recent pathologic and imaging based studies indicate that lesions with dense calcifications are more likely to be stable plaques (fibrocalcific plaques), while micro, punctate, or fragmented calcifications are associated with either early stage plaques or unstable lesions (plaque rupture or erosion). Clinical non-invasive computed tomography (CT) studies show that the greater the calcium score, the higher the likelihood of patients developing future acute coronary events. This appears contradictory with the findings from pathologic autopsy studies. However, CT analysis of calcium subtypes is limited by resolution and blooming artifacts. Thus, areas of heavy calcification may not be the cause of future events as pathologic studies suggest. Rather, calcium may be an overall marker for the extent of disease. These types of discrepancies can perhaps be resolved by invasive or non-invasive high resolution imaging studies carried out at intervals in patients who present with acute coronary syndromes versus stable angina patients. Coronary calcium burden is greater in stable plaques than unstable plaques and there is a negative correlation between necrotic core area and area of calcification. Recent clinical studies have demonstrated that statins can reduce plaque burden by demonstrating a reduction in percent and total atheroma volume. However, calcification volume increases. In summary, pathologic studies show that sheet calcification is highly prevalent in stable plaques, while microcalcifications, punctate, and fragmented calcifications are more frequent in unstable lesions. Both pathologic and detailed analysis of imaging studies in living patients can resolve some of the controversies in our understanding of coronary calcification.

Healed Plaques in Patients With Stable Angina Pectoris

OBJECTIVE

Healed plaques, signs of previous plaque destabilization, are frequently found in the coronary arteries. Healed plaques can now be diagnosed in living patients. We investigated the prevalence, angiographic, and optical coherence tomography features of healed plaques in patients with stable angina pectoris. Approach and Results: Patients with stable angina pectoris who had undergone optical coherence tomography imaging were included. Healed plaques were defined as plaques with one or more signal-rich layers of different optical density. Patients were divided into 2 groups based on layered or nonlayered phenotype at the culprit lesion. Among 163 patients, 87 (53.4%) had layered culprit plaque. Patients with layered culprit plaque had more multivessel disease (62.1% versus 44.7%, P=0.027) and more angiographically complex culprit lesions (64.4% versus 35.5%, P<0.001). Layered culprit plaques had higher prevalence of lipid plaque (83.9% versus 64.5%, P=0.004), macrophage infiltration (58.6% versus 35.5%, P=0.003), calcifications (78.2% versus 63.2%, P=0.035), and thrombus (28.7% versus 14.5%, P=0.029). Lipid index (P=0.001) and percent area stenosis (P=0.015) were greater in the layered group. The number of nonculprit plaques, evaluated using coronary angiograms, tended to be greater in patients with layered culprit plaque (4.2±2.5 versus 3.5±2.1, P=0.053). Nonculprit plaques in patients with layered culprit lesion had higher prevalence of layered pattern (P=0.002) and lipid phenotype (P=0.005). Lipid index (P=0.013) and percent area stenosis (P=0.002) were also greater in this group.

CONCLUSIONS

In patients with stable angina pectoris, healed culprit plaques are common and have more features of vulnerability and advanced atherosclerosis both at culprit and nonculprit lesions.

Age- and Gender-Related Differences in Coronary Lesion Plaque Composition on Optical Coherence Tomography

BACKGROUND

The pathophysiology and chronological course of atherosclerosis seems to be different between men and women due to biological differences, and age and gender differences in plaque composition of coronary lesions remain to be elucidated.

METHODS AND RESULTS

A total of 860 consecutive patients with a median age of 69 years (IQR, 60-78 years) who underwent optical coherence tomography (OCT) of culprit lesions was included. The composition of culprit plaque on OCT was compared between female (n=171) and male (n=689) subjects in younger (<70 years old) and elderly (≥70 years old) patients. In elderly patients, the prevalence of thin-cap fibroatheroma (TCFA) was significantly higher in women than in men (30.6 vs. 15.2%, P<0.001). In younger patients, the prevalence of large calcification was significantly higher in women than in men (60.0 vs. 32.8%, P<0.001). The prevalence of other vulnerable plaque characteristics (i.e., macrophages, microchannels, and spotty calcification), was similar between women and men. Elderly women had a significantly higher prevalence of TCFA (OR, 2.13; 95% CI: 1.33-3.44, P=0.002) than other patients.

CONCLUSIONS

Women had a higher prevalence of TCFA and of large calcification than men in patients ≥70 and <70 years old, respectively. This may facilitate the understanding of gender differences in the pathogenesis of coronary atherosclerosis, and the tailoring of therapy and of prevention according to age and gender.

Calcification in Atherosclerotic Plaque Vulnerability: Friend or Foe?

Calcification is a clinical marker of atherosclerosis. This review focuses on recent findings on the association between calcification and plaque vulnerability. Calcified plaques have traditionally been regarded as stable atheromas, those causing stenosis may be more stable than non-calcified plaques. With the advances in intravascular imaging technology, the detection of the calcification and its surrounding plaque components have evolved. Microcalcifications and spotty calcifications represent an active stage of vascular calcification correlated with inflammation, whereas the degree of plaque calcification is strongly inversely related to macrophage infiltration. Asymptomatic patients have a higher content of plaque calcification than that in symptomatic patients. The effect of calcification might be biphasic. Plaque rupture has been shown to correlate positively with the number of spotty calcifications, and inversely with the number of large calcifications. There may be certain stages of calcium deposition that may be more atherogenic. Moreover, superficial calcifications are independently associated with plaque rupture and intraplaque hemorrhage, which may be due to the concentrated and asymmetrical distribution of biological stress in plaques. Conclusively, calcification of differential amounts, sizes, shapes, and positions may play differential roles in plaque homeostasis. The surrounding environments around the calcification within plaques also have impacts on plaque homeostasis. The interactive effects of these important factors of calcifications and plaques still await further study.

High-resolution MRI assessed carotid atherosclerotic plaque characteristics comparing men and women with elevated ApoB levels

Previous studies demonstrated that men were more likely to have plaque rupture and are at greater risk for myocardial infarction and stroke than women. We evaluated differences in carotid plaque characteristics by MRI between men and women with mild-moderate atherosclerosis and elevated ApoB levels. One hundred eighty-two subjects (104 men and 78 women) with CAD or carotid stenosis (≥ 15% by ultrasound), ApoB ≥ 120 mg/dL and carotid MRI scan were included. Percent wall volume (%WV) was calculated as (wall volume/total vessel volume) × 100%. Three major plaque compositions, fibrous tissue (FT), calcification (CA) and lipid rich necrotic core (LRNC), were identified and quantified using published MRI criteria. Adventitial and plaque neovascularization as fractional plasma volume (V_p) and permeability as transfer constant (K^trans) were analyzed using kinetic modeling. These characteristics were compared between men and women. Men, compared to women, were younger (54 ± 8 vs. 58 ± 8 years, p = 0.01), had higher rate of previous MI (46 vs. 26%, p = 0.005) but lower proportions of metabolic syndrome (37 vs. 59%, p = 0.003). After adjusting for between-gender differences, men were significantly more likely to have LRNC (OR 2.22, 95% CI 1.04-4.89, p = 0.04) and showed significantly larger %LRNC than women (diff = 4.3%, 95% CI 1.6-6.9%, p = 0.002), while %WV, FT, and CA were similar between men and women. There were no statistically significant differences in adventitial and plaque V_p or K^trans. Men were significantly more likely to have LRNC and had larger LRNC than women. However, men and women showed relatively similar levels of adventitial and plaque neovascularization and permeability.Trial registration: NCT00715273 at ClinicalTrials.gov. Registered 15 July 2008, retrospectively registered.

Intrinsic calcification angle: a novel feature of the vulnerable coronary plaque in patients with type 2 diabetes: an optical coherence tomography study

BACKGROUND

Coronary calcification is associated with high risk for cardiovascular events. However, its impact on plaque vulnerability is incompletely understood. In the present study we defined the intrinsic calcification angle (ICA) as the angle externally projected by a vascular calcification and analyzed its role as novel feature of coronary plaque vulnerability in patients with type 2 diabetes.

METHODS

Optical coherence tomography was used to determine ICA in 219 calcifications from 56 patients with stable coronary artery disease (CAD) and 143 calcifications from 36 patients with acute coronary syndrome (ACS). We then used finite elements analysis to gain mechanistic insight into the effects of ICA.

RESULTS

Minimal (139.8 ± 32.8° vs. 165.6 ± 21.6°, p < 0.001) and mean ICA (164.1 ± 14.3° vs. 176.0 ± 8.4°, p < 0.001) were lower in ACS vs. stable CAD patients. Mean ICA predicted ACS with very good diagnostic efficiency (AUC = 0.840, 95% CI 0.797-0.882, p < 0.001, optimal cut-off 175.9°); younger age (OR 0.95 per year, 95% CI 0.92-0.98, p = 0.002), male sex (OR 2.18, 95% CI 1.41-3.38, p < 0.001), lower HDL-cholesterol (OR 0.82 per 10 mg/dl, 95% CI 0.68-0.98, p = 0.029) and ACS (OR 14.71, 95% CI 8.47-25.64, p < 0.001) were determinants of ICA < 175.9°. A lower ICA predicted ACS (OR for 10°-variation 0.25, 95% CI 0.13-0.52, p < 0.001) independently from fibrous cap thickness, presence of macrophages or extension of lipid core. In finite elements analysis we confirmed that lower ICA causes increased stress on a lesion's fibrous cap; this effect was potentiated in more superficial calcifications and adds to the destabilizing role of smaller calcifications.

CONCLUSION

Our clinical and mechanistic data for the first time identify ICA as a novel feature of coronary plaque vulnerability.

Association Between Insulin Resistance and Coronary Plaque Vulnerability in Patients With Acute Coronary Syndromes: Insights From Optical Coherence Tomography

We investigated the correlation between insulin resistance (IR) and optical coherence tomography and identified culprit plaque characteristics in patients with acute coronary syndrome (ACS). Patients with ACS who underwent selective coronary intervention were prospectively enrolled. A total of 159 culprit lesions were identified in 145 patients. Culprit plaque characteristics, including thin-cap fibroatheroma (TCFA) and spotty calcification, were analyzed. The IR was assessed using the homeostasis model assessment of IR (HOMA-IR). Patients were divided into 4 interquartile ranges (IQRs) according to HOMA-IR values. The prevalence rates of TCFA were significantly different among the 4 groups (17.5% [IQR1 group] vs 17.9% [IQR2 group] vs 35.0% [IQR3 group] vs 55.0% [IQR4 group]; P = .001). Minimal fibrous cap thickness was inversely correlated with HOMA-IR level (141.35 [56.28] µm vs 142.82 [82.17] µm vs 102.14 [36.52] µm vs 96.00 [41.82] µm; P < .001). Spotty calcification prevalence was also significantly different among the 4 groups (5.9% vs 17.6% vs 32.4% vs 44.1%; P < .001). Compared with the bottom quartile, patients with elevated HOMA-IR values had higher prevalence of macrophage infiltration ( P < .001) and microvessels ( P = .023). On multivariate analysis, Ln HOMA-IR (odds ratio: 6.022; 95% confidence interval: 3.007-12.060; P < .001) was the independent predictor for spotty calcification. The current study showed increased IR was independently associated with plaque vulnerability, spotty calcification in particular, in ACS.

Differences in coronary plaque morphology between East Asian and Western White patients: an optical coherence tomography study

AIMS

Prevalence of coronary artery disease as well as cardiac mortality varies between Asian and White patients. However, the link between race and plaque characteristics in patients with coronary artery disease remains largely unexplored. Thus, we aimed to investigate the detailed culprit plaque characteristics between East Asian and White patients using optical coherence tomography.

PATIENTS AND METHODS

A total of 101 East Asians were matched to 101 White patients. Matching parameters included age, sex, clinical presentation, hyperlipidemia, diabetes mellitus, and lesion location.

RESULTS

There were no differences in underlying pathology (rupture vs. erosion) of acute coronary syndrome (P=0.935). Lesion length was longer (18.0±6.0 vs. 14.6±5.4 mm; P<0.002), lipid length was greater (9.4±4.6 vs. 7.2±3.8 mm; P<0.023), lipid index was higher (1635±987 vs. 1104±730; P=0.002), and mean reference area was larger (8.1±3.0 vs. 6.5±2.4 mm; P<0.021) in White patients compared with East Asian patients.

CONCLUSION

There are significant differences in plaque morphology between East Asian and White patients even after controlling for confounders. Our findings underscore key differences in atherosclerosis between East Asian and White populations, and may have to be taken into consideration when interpreting the results of future research.

Coronary Plaque Characteristics in Patients With Diabetes Mellitus Who Presented With Acute Coronary Syndromes

BACKGROUND

Diabetes mellitus (DM) is a major risk factor for cardiovascular events. We aimed to investigate the coronary plaque phenotype of diabetic patients who presented with acute coronary syndromes by optical coherence tomography.

METHODS AND RESULTS

A total of 322 patients with acute coronary syndromes who underwent preintervention optical coherence tomography imaging of the culprit lesion were included. Culprit plaque characteristics were compared between patients with DM (n=95) and those without DM (n=227). In the subgroup of 250 patients in whom sufficient length of nonculprit region in the culprit vessel was imaged by optical coherence tomography, the characteristics of nonculprit plaques were also evaluated. Patients with DM had a higher prevalence of lipid-rich plaque (58.9% versus 44.9%, P=0.030) and macrophage accumulation (60.0% versus 44.9%, P=0.019) in the culprit lesion compared with patients without DM. The prevalence of plaque rupture (33.7% versus 30.4%, P=0.896) and plaque erosion (21.1% versus 22.0%, P=0.458) was similar. In the nonculprit lesions, the DM group had greater maximal lipid arc (248.9°±83.9° versus 179.9°±58.3°, P=0.006), thinner fibrous cap thickness (103.3±56.2 μm versus 140.7±70.0 μm, P=0.013), and a higher prevalence of thin-cap fibroatheroma (17.2% versus 6.3%, P=0.031), compared with the non-DM group.

CONCLUSIONS

Compared with patients without DM, those with DM had more vulnerable features in both culprit and nonculprit lesions, thus indicating a higher level of panvascular instability.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01110538.

Non-culprit plaque characteristics in acute coronary syndrome patients with raised hemoglobinA1c: an intravascular optical coherence tomography study

Background

Raised hemoglobinA1c (HbA1c) is an indicator of pre-diabetes, which is associated with increased risk of coronary artery disease. However, the detailed morphological characteristics of non-culprit plaques in acute coronary syndrome (ACS) patients remain largely unknown.

Methods

A total of 305 non-culprit plaques from 216 ACS patients were analyzed by intravascular optical coherence tomography. These patients were divided into three groups according to the serum glycosylated hemoglobin level: normal HbA1c (< 5.7%), pre-diabetes with raised HbA1c (5.7–6.4%) and diabetes mellitus (DM).

Results

Plaques in patients with raised HbA1c had a longer lipid length (17.0 ± 8.3 mm vs. 13.9 ± 7.2 mm, P = 0.004) and greater lipid index (2775.0 ± 1694.0 mm° vs. 1592.1 ± 981.2 mm°, P = 0.001) than those with normal HbA1c but were similar to DM. The prevalence of calcification in patients with raised HbA1c was significantly higher (38.7% vs. 26.3%, P = 0.048) than normal HbA1c but was similar to DM. The percentage of macrophage infiltration in the DM group was higher than that in the normal HbA1c group (20.5% vs. 7.4%, P = 0.005).

Conclusions

Compared to patients with normal HbA1c, the non-culprit plaques in ACS patients with raised HbA1c had more typical vulnerable features but were similar to DM.

Predictors for target lesion microcalcifications in patients with stable coronary artery disease: an optical coherence tomography study

BACKGROUND

The minimal fibrous cap thickness overlying the necrotic lipid core as well as the presence of macrophages are established characteristics of coronary plaque vulnerability. Recently, the presence of microcalcifications has emerged as a novel feature of vulnerable lesions. However, clinical and plaque morphological predictors of microcalcifications are unknown.

METHODS

In patients with stable coronary artery disease, analysis of plaque morphology (n = 112) was performed using optical coherence tomography prior to coronary intervention to assess predictors of microcalcifications.

RESULTS

Microcalcifications were present in 21/112 (18.7%) lesions. Segments with microcalcifications showed a higher total number of calcifications per lesion (6.7 ± 3.0 vs. 3.2 ± 2.5, p < 0.001), a lower percent area stenosis (70.9 ± 11.1 vs. 76.2 ± 9.7%, p = 0.028), and a higher frequency of macrophage infiltration (66.7 vs. 37.4%, p = 0.014). In lesions with vs. without microcalcifications, macrophage infiltration was characterized by a wider macrophage angle (31.1° ± 34.4° vs. 13.7° ± 20.6°, p = 0.003), a higher macrophage index (105.6 ± 269.0 vs. 31.6 ± 66.5° mm, p = 0.020), and an increased frequency of calcium-macrophage co-localization (47.6 vs. 15.6%, p = 0.001). In multivariable logistic regression analysis, the total number of calcifications per lesion (OR 1.53, 95% CI 1.23-1.91, p < 0.001), average macrophage angle (OR 1.28 for 10°-variation, 95% CI 1.03-1.60, p = 0.024), and percent area stenosis (OR 0.59 for 10% increase, 95% CI 0.34-1.04, p = 0.070) were independent predictors for the presence of microcalcifications, whereas the latter did not reach statistical significance.

CONCLUSION

Microcalcifications are related to a less advanced stenosis severity and to extensive plaque inflammation, but not to clinical parameters. Our data may add to the understanding and role of microcalcifications in coronary artery lesions.

Nonculprit Plaque Characteristics in Patients With Acute Coronary Syndrome Caused by Plaque Erosion vs Plaque Rupture: A 3-Vessel Optical Coherence Tomography Study

Importance

Patients with culprit plaque rupture are known to have pancoronary plaque vulnerability. However, the characteristics of nonculprit plaques in patients with acute coronary syndromes caused by plaque erosion are unknown.

Objective

To investigate the nonculprit plaque phenotype in patients with acute coronary syndrome according to culprit plaque pathology (erosion vs rupture) by 3-vessel optical coherence tomography imaging.

Design, Setting, and Participants

In this observational cohort study, between August 2010 and May 2014, 82 patients with acute coronary syndrome who underwent preintervention optical coherence tomography imaging of all 3 major epicardial coronary arteries were enrolled at the Massachusetts General Hospital Optical Coherence Tomography Registry database. Analysis of the data was conducted between November 2016 and July 2017. Patients were classified into 2 groups based on the culprit lesion pathology: 17 patients with culprit plaque erosion and 34 patients with culprit plaque rupture. Thirty-one patients with the absence of culprit rupture or erosion were excluded from further analysis.

Exposures

Preintervention 3-vessel optical coherence tomography imaging.

Main Outcomes and Measures

Plaque characteristics at the culprit and nonculprit lesions evaluated by optical coherence tomography.

Results

In 51 patients (37 men; mean age, 58.7 years), the characteristics of 51 culprit plaques and 216 nonculprit plaques were analyzed. In patients with culprit erosion, the mean (SD) number of nonculprit plaques per patient was smaller (3.4 [1.9] in erosion vs 4.7 [2.1] in rupture, P = .05). Patient-based analysis showed that none of 17 patients with culprit plaque erosion had nonculprit plaque rupture, whereas 26% of the patients (9 of 34) with culprit plaque rupture had nonculprit plaque rupture (P = .02). Plaque-based analysis showed that, compared with the culprit rupture group (n = 158), the culprit erosion group (n = 58) had lower prevalence of plaque rupture (0% vs 8%; P < .001), macrophage accumulation (29% vs 53%; P = .01), microvessels (21% vs 42%; P = .003), and spotty calcium (5% vs 22%; P = .006) in the nonculprit lesions. The prevalence of lipid-rich plaque, thin-cap fibroatheroma, and thrombus did not differ between the groups.

Conclusions and Relevance

Compared with those with culprit plaque rupture, patients with acute coronary syndrome caused by culprit plaque erosion had a smaller number of nonculprit plaques and the lower levels of panvascular instability, affirming that distinct pathophysiologic mechanisms operate in plaque erosion and plaque rupture.

Type 2 diabetes mellitus is associated with a lower fibrous cap thickness but has no impact on calcification morphology: an intracoronary optical coherence tomography study

Background

Patients with type 2 diabetes (T2DM) are at high risk for cardiovascular events, which usually arise from the rupture of a vulnerable coronary plaque. The minimal fibrous cap thickness (FCT) overlying a necrotic lipid core is an established predictor for plaque rupture. Recently, coronary calcification has emerged as a relevant feature of plaque vulnerability. However, the impact of T2DM on these morphological plaque parameters is largely unexplored. Therefore, this study aimed to compare differences of coronary plaque morphology in patients with and without T2DM with a particular focus on coronary calcification.

Methods

In 91 patients (T2DM = 56, non-T2DM = 35) with 105 coronary de novo lesions (T2DM = 56, non-T2DM = 49) plaque morphology and calcification were analyzed using optical coherence tomography (OCT) prior to coronary intervention.

Results

Patients with T2DM had a lower minimal FCT (80.4 ± 27.0 µm vs. 106.8 ± 27.8 µm, p < 0.001) and a higher percent area stenosis (77.9 ± 8.1% vs. 71.7 ± 11.2%, p = 0.001) compared to non-diabetic subjects. However, patients with and without T2DM had a similar total number of calcifications (4.0 ± 2.6 vs. 4.2 ± 3.1, p = ns) and no significant difference was detected in the number of micro- (0.34 ± 0.79 vs. 0.31 ± 0.71), spotty (2.11 ± 1.77 vs. 2.37 ± 1.89) or macro-calcifications (1.55 ± 1.13 vs. 1.53 ± 0.71, all p = ns). The mean calcium arc (82.3 ± 44.8° vs. 73.7 ± 31.6), the mean thickness of calcification (0.54 ± 0.13 mm vs. 0.51 ± 0.15 mm), the mean calcified area (0.99 ± 0.72 mm² vs. 0.78 ± 0.49 mm²), the mean depth of calcification (172 ± 192 μm vs. 160 ± 76 μm) and the cap thickness overlying the calcification (50 ± 71 μm vs. 62 ± 61 μm) did not differ between the diabetic and non-diabetic groups (all p = ns).

Conclusion

T2DM has an impact on the minimal FCT of the coronary target lesion, but not on localization, size, shape or extent of calcification. Thus, the minimal FCT overlying the necrotic lipid core but not calcification is likely to contribute to the increased plaque vulnerability observed in patients with T2DM.