Spotty calcification and plaque vulnerability in vivo: frequency-domain optical coherence tomography analysis

CD8+ T Cells Drive Plaque Smooth Muscle Cell Dedifferentiation in Experimental Atherosclerosis

BACKGROUND

Atherosclerosis is driven by the infiltration of the arterial intima by diverse immune cells and smooth muscle cells (SMCs). CD8+ T cells promote lesion growth during atherosclerotic lesion development, but their role in advanced atherosclerosis is less clear. Here, we studied the role of CD8+ T cells and their effects on SMCs in established atherosclerosis.

METHODS

CD8+ T cells were depleted in (SMC reporter) low-density lipoprotein receptor-deficient (Ldlr-/-) mice with established atherosclerotic lesions. Atherosclerotic lesion formation was examined, and single-cell RNA sequencing of aortic SMCs and their progeny was performed. Additionally, coculture experiments with primary aortic SMCs and CD8+ T cells were conducted.

RESULTS

Although we could not detect differences in atherosclerotic lesion size, an increased plaque SMC content was noted in mice after CD8+ T-cell depletion. Single-cell RNA sequencing of aortic lineage-traced SMCs revealed contractile SMCs and a modulated SMC cluster, expressing macrophage- and osteoblast-related genes. CD8+ T-cell depletion was associated with an increased contractile but decreased macrophage and osteoblast-like gene signature in this modulated aortic SMC cluster. Conversely, exposure of isolated aortic SMCs to activated CD8+ T cells decreased the expression of genes indicative of a contractile SMC phenotype and induced a macrophage and osteoblast-like cell state. Notably, CD8+ T cells triggered calcium deposits in SMCs under osteogenic conditions. Mechanistically, we identified transcription factors highly expressed in modulated SMCs, including Runx1, to be induced by CD8+ T cells in cultured SMCs in an IFNγ (interferon-γ)-dependent manner.

CONCLUSIONS

We here uncovered CD8+ T cells to control the SMC phenotype in atherosclerosis. CD8+ T cells promote SMC dedifferentiation and drive SMCs to adopt features of macrophage-like and osteoblast-like, procalcifying cell phenotypes. Given the critical role of SMCs in atherosclerotic plaque stability, CD8+ T cells could thus be explored as therapeutic target cells during lesion progression.

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.

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.

Accuracy and limitation of plaque detection by coronary CTA: a section-to-section comparison with optical coherence tomography

Plaques identified by Coronary CT angiography (CCTA) are important in clinical diagnosis and primary prevention. High-risk plaque features by CCTA have been extensively validated using optical coherence tomography (OCT). However, since their general diagnostic performance and limitations have not been fully investigated, we sought to compare CCTA with OCT among consecutive vessel sections. We retrospectively compared 188 consecutive plaques and 84 normal sections in 41 vessels from 40 consecutive patients referred for chest pain evaluation who had both CCTA and OCT with a median time lapse of 1 day. The distance to reference points were used to co-register between the modalities and the diagnostic performance of CCTA was evaluated against OCT. Plaque categories evaluated by CT were calcified, non-calcified and mixed. The diagnostic performance of CCTA was excellent for detecting any plaque identified by OCT with the sensitivity, specificity, negative and positive predictive values and accuracy of 92%, 98%, 99%, 84% and 93%, respectively. The lower than expected negative predictive value was due to failure of detecting sub-millimeter calcified (≤ 0.25 mm²) (N = 12) and non-calcified plaques (N = 4). Misclassification of plaque type accounted for majority of false negative findings (25/41, 61%) which was most prevalent among the mixed plaque (19/41, 46%). There was calcification within mixed plaques (N = 5) seen by CCTA but missed by OCT. Our findings suggest that CCTA is excellent at identifying coronary plaques except those sub-millimeter in size which likely represent very early atherosclerosis, although the clinical implication of very mild atherosclerosis is yet to be determined.

Changes in intra- and extracranial carotid plaque calcification: a 2-year follow-up study

Extra- and intracranial carotid plaque calcification might have plaque-stabilizing effects, yet information on changes in plaque calcification remains scarce. We evaluated changes in carotid plaque calcification over 2 years follow-up in patients with symptomatic carotid artery disease. This study is based on the PARISK-study, a multicenter cohort study, with TIA/minor stroke patients with ipsilateral mild-to-moderate carotid artery stenosis (< 70%). We included 79 patients (25% female, mean age 66 years) who underwent CTA imaging with 2 year interval. We assessed the volume of extra- and intracranial carotid artery calcification (ECAC and ICAC) and calculated the difference between baseline and follow-up ECAC and ICAC volume. We performed multivariable regression analyses to investigate the association between change of ECAC or ICAC with cardiovascular determinants. ECAC. We found increase (46.2%) and decrease (34%) in ECAC volume during 2 year follow-up, both significantly correlation with baseline ECAC volume (OR = 0.72, 95% CI 0.58-0.90 respectively OR = 2.24, 95% CI 1.60-3.13).We found significant correlation for change in ECAC volume with diabetes (β = 0.46, 95% CI 0.03-0.89) and baseline ECAC volume (β = 0.81, 95% CI 0.73-0.88). ICAC. We found increase (45.0%) and decrease (25.0%) in ICAC volume. The ICAC decrease was significantly correlated with baseline ICAC volume (OR = 2.17, 95% CI 1.48-3.16), age (OR = 2.00, 95% CI 1.19-3.38) and use of antihypertensive drugs (OR = 3.79, 95% CI 1.20-11.96]).The overall change of ICAC volume was also significantly correlated with diabetes (β = 0.92, 95% CI 1.59-7.02), use of oral hypoglycemic drugs (β = 0.86, 95% CI 0.12-1.59) and baseline ICAC volume (β = 0.71, 95% CI 0.55-0.87). We provide novel insights into the dynamics of carotid plaque calcification in symptomatic stroke patients.

CD137-CD137L Aggravates Calcification of Vascular Smooth Muscle Cell and Vasculature of ApoE-/- Mice Via Rab7-Mediated Autophagy

Vascular calcification is an independent risk factor for acute cardiovascular events and a predictor of adverse prognosis; the abnormal fusion and degradation of autophagosomes and lysosomes are closely related to the calcification of VSMC and aortic AS plaque in ApoE-/- mice. Rab7 is a member of the Ras protein family and acts as a molecular switch in the fusion between autophagosomes and lysosomes. In this study, we found that the activation of the CD137-CD137L signal promoted calcification by inhibiting the expression and activity of Rab7, which regulates the degradation of autophagic cargo in vascular smooth muscle cells (VSMCs) and aortic atherosclerosis (AS) plaques in ApoE-/- mice. Knockdown of Rab7 impaired its tethering with the downstream molecule FYVE and coiled-coil containing 1 (FYCO1), which transports autophagosomes to lysosomes through microtubule motor kinesins and fuses with lysosomes to degrade the autophagic content. Overexpression of Rab7-alleviated calcification caused by the activation of the CD137 signaling pathway. In addition, FYCO1 knockdown promoted calcification even though the expression and activity of Rab7 were normal. Our results suggest that Rab7 is the target of CD137 signaling; Rab7 cannot interact with its downstream molecule FYCO1 when its activity and expression were inhibited by the activation of CD137 signaling pathway, thus inhibiting the autophagic degradation and promoting calcification.

SPECT/CT imaging of inflammation and calcification in human carotid atherosclerosis to identify the plaque at risk of rupture

BACKGROUND

Calcification and inflammation are atherosclerotic plaque compositional biomarkers that have both been linked to stroke risk. The aim of this study was to evaluate their co-existing prevalence in human carotid plaques with respect to plaque phenotype to determine the value of hybrid imaging for the detection of these biomarkers.

METHODS

Human carotid plaque segments, obtained from endarterectomy, were incubated in [111In]In-DOTA-butylamino-NorBIRT ([111In]In-Danbirt), targeting Leukocyte Function-associated Antigen-1 (LFA-1) on leukocytes. By performing SPECT/CT, both inflammation from DANBIRT uptake and calcification from CT imaging were assessed. Plaque phenotype was classified using histology.

RESULTS

On a total plaque level, comparable levels of calcification volume existed with different degrees of inflammation and vice versa. On a segment level, an inverse relationship between calcification volume and inflammation was evident in highly calcified segments, which classify as fibrocalcific, stable plaque segments. In contrast, segments with little or no calcification presented with a moderate to high degree of inflammation, often coinciding with the more dangerous fibrous cap atheroma phenotype.

CONCLUSION

Calcification imaging alone can only accurately identify highly calcified, stable, fibrocalcific plaques. To identify high-risk plaques, with little or no calcification, hybrid imaging of calcification and inflammation could provide diagnostic benefit.

Undertreatment or Overtreatment With Statins: Where Are We?

Statins, in addition to healthy lifestyle interventions, are the cornerstone of lipid-lowering therapy. Other low-density lipoprotein (LDL)-lowering drugs include ezetimibe, bile acid sequestrants, and PCSK9 inhibitors. As new evidence emerges from new clinical trials, therapeutic goals change, leading to renewed clinical guidelines. Nowadays, LDL goals are getting lower, leading to the "lower is better" paradigm in LDL-cholesterol (LDL-C) management. Several observational studies have shown that LDL-C control in real life is suboptimal in both primary and secondary preventions. It is critical to enhance the adherence to guideline recommendations through shared decision-making between clinicians and patients, with patient engagement in selecting interventions based on individual values, preferences, and associated conditions and comorbidities. This narrative review summarizes the evidence regarding the benefits of lipid-lowering drugs in reducing cardiovascular events, the pleiotropic effect of statins, real-world data on overtreatment and undertreatment of lipid-lowering therapies, and the changing LDL-C in targets in the clinical guidelines of dyslipidemias over the years.

Plaque microstructures during metformin therapy in type 2 diabetic subjects with coronary artery disease: optical coherence tomography analysis

BACKGROUND

While metformin is recommended as a first-line cardioprotective therapy for type 2 diabetic patients, whether it exerts direct effects on atherosclerotic plaque remains uncertain. The current study characterized coronary plaque microstructures in type 2 diabetic patients who received metformin.

METHODS

We retrospectively analyzed 409 non-culprit lipid plaques in 313 type 2 diabetic patients with coronary artery disease (CAD) by using frequency-domain optical coherence tomography (FD-OCT) imaging. FD-OCT derived plaque microstructures were compared in patients stratified according to metformin use.

RESULTS

A proportion of 38.6% of study subjects received metformin. Patients receiving metformin more likely exhibited a history of hypertension (79.3% vs. 67.1%, P=0.03) and metabolic syndrome (52.8% vs. 36.4%, P=0.01). On FD-OCT imaging, the prevalence of lipid plaque was lower in the metformin group (66.2% vs. 77.9%, P=0.03). Furthermore, the metformin group demonstrated plaques with a smaller lipid arc (median: 168.7° vs. 208.5°, P=0.008), shorter longitudinal length (media: 5.1 vs. 9.1 mm, P=0.04), and a lower frequency of cholesterol crystal (3.9% vs. 18.2%, P=0.01) and spotty calcification (3.9% vs. 34.8%, P=0.008). These differences remained significant after adjusting for clinical characteristics and glycemic control. However, in patients who received insulin, the favourable effect of metformin on lipid arc was not observed (insulin user: P=0.87; insulin non-user: P=0.009; P value for interaction between two groups, P=0.02).

CONCLUSIONS

Metformin use was associated with a lower prevalence of vulnerable plaque features in type 2 diabetic patients with CAD, especially insulin non-user. These findings suggest the potential of metformin to exert direct plaque stabilization effects in type 2 diabetic subjects.

Identification of Symptomatic Carotid Artery Plaque: A Three-Item Scale Combined Angiography With Optical Coherence Tomography

Introduction: Symptomatic carotid disease conveys a high risk of recurrent stroke. Plaque morphology and specific plaque characteristics are associated with the risk of stroke. This study aimed to evaluate the detailed plaque features by optical coherence tomography (OCT) and develop a simple scale combining clinical indicators, digital subtraction angiography (DSA), and OCT imaging markers to identify symptomatic carotid plaque. Methods: Carotid plaques from consecutive patients who underwent carotid OCT imaging between June 2017 and June 2021 were evaluated. Clinical characteristics, DSA, and OCT data were compared between the symptomatic and asymptomatic groups. Logistic regression was performed to identify the factors associated with symptomatic carotid plaque and to develop a scale. The area under the receiver operating characteristic curve (AUC) was used to evaluate the performance of the scale. Results: A total of 90 carotid plaques from 90 patients were included (symptomatic 35.6%, asymptomatic 64.4%). Three main factors were found to be associated with symptomatic carotid plaque: high-density lipoprotein cholesterol (HDL-C) <0.925 mmol/L (OR, 4.708; 95% CI, 1.640 to 13.517; P = 0.004), irregular plaque (OR, 4.017; 95% CI, 1.250 to 12.910; P = 0.020), and white thrombus (OR, 4.594; 95% CI, 1.141 to 18.487; P = 0.032). The corresponding score of three items produced a scale with good discrimination (AUC, 0.768; 95% CI, 0.665 to 0.871). The optimal cutoff value of the scale was 1.5 points with 59.4% sensitivity and 84.5% specificity. Conclusion: The three-item scale comprising HDL-C <0.925 mmol/L, angiographical irregular plaque, and white thrombus detected by OCT may provide information to identify symptomatic carotid plaque. Further large-scale studies are required to validate whether the symptomatic carotid plaque scale is clinically valuable in recognizing carotid atherosclerosis in the early stages.

Vulnerable atherosclerotic plaque features: findings from coronary imaging

Pathological studies have suggested that features of vulnerable atherosclerotic plaques likely to progress and lead to acute cardiovascular events have specific characteristics. Given the progress of intravascular coronary imaging technology, some large prospective studies have detected features of vulnerable atherosclerotic plaques using these imaging modalities. However, the rate of cardiovascular events, such as acute coronary syndrome, has been found to be considerably reduced in the limited follow-up period available in the statin era. Additionally, not all disrupted plaques lead to thrombus formation with clinical presentation. If sub-occlusive or occlusive thrombus formation does not occur, a thrombus on a disrupted plaque will organize without any symptoms, forming a “healed plaque”. Although vulnerable plaque detection using intracoronary imaging is focused on “thin-cap fibroatheroma” leading to plaque rupture, superficial plaque erosion is increasingly recognized; however, the underlying mechanism of thrombus formation on eroded plaques is not well understood. One of intravascular imaging, optical coherence tomography (OCT) has the highest image resolution and has enabled detailed characterization of the plaque in vivo. Here, we reviewed the status and limitations of intravascular imaging in terms of detecting vulnerable plaque through mainly OCT studies. We suggested that vulnerable plaque should be reconsidered in terms of eroded plaque and healed plaque and that both plaque and circulating blood should be assessed in greater detail accordingly.

Assessing the impact of PCSK9 inhibition on coronary plaque phenotype with optical coherence tomography: rationale and design of the randomized, placebo-controlled HUYGENS study

Background

Technological advances in arterial wall imaging permit the opportunity to visualize coronary atherosclerotic plaque with sufficient resolution to characterize both its burden and compositional phenotype. These modalities have been used extensively in clinical trials to evaluate the impact of lipid lowering therapies on serial changes in disease burden. While the findings have unequivocally established that these interventions have the capacity to either slow disease progression or promote plaque regression, depending on the degree of lipid lowering achieved, their impact on plaque phenotype is less certain. More recently optical coherence tomography (OCT) has been employed with a number of studies demonstrating favorable effects on both fibrous cap thickness (FCT) and the size of lipid pools within plaque in response to statin treatment.

Methods

The phase 3, multi-center, double-blind HUYGENS study will assess the impact of incremental lipid lowering with the proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitor, evolocumab, on plaque features using serial OCT imaging, in statin-treated patients following an acute coronary syndrome (ACS). Subjects with non-ST-elevation ACS (n=150) will be randomized 1:1 into two groups to receive monthly injections of evolocumab 420 mg or placebo.

Results

The primary endpoint is the effect of evolocumab on coronary atherosclerotic plaques will be assessed by OCT at baseline and at week 50.

Conclusions

The HUYGENS study will determine whether intensified lipid lowering therapy with evolocumab in addition to maximally tolerated statin therapy will have incremental benefits on high-risk features of coronary artery plaques.

Trial registration

This study was registered on Clinicaltrials.gov (NCT03570697).

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.

High cardiovascular risk of patients with type 2 diabetes is only partially attributed to angiographic burden of atherosclerosis

BACKGROUND

Patients with type 2 diabetes (T2DM) are at high risk for cardiovascular events and present more severe coronary artery disease (CAD). The Gensini and COURAGE scores are established angiographic instruments to assess CAD severity, which may also predict future cardiovascular risk. However, it is unclear if these scores are able to depict the increased risk of patients with T2DM and stable CAD (T2DM-SAP).

METHODS

We performed quantitative coronary angiography and assessed the Gensini and COURAGE scores in 124 patients with T2DM-SAP. Angiographic data were compared to patients with stable angina without T2DM (Non-DM-SAP, n = 74), and to patients with acute coronary syndrome and T2DM (T2DM-ACS, n = 53).

RESULTS

T2DM-SAP patients had similar Gensini and COURAGE-scores compared to Non-DM-SAP-patients (Gensini: 14.44 ± 27.34 vs 11.49 ± 26.99, p = 0.465; COURAGE: 3.48 ± 4.49 vs 3.60 ± 4.72, p = 0.854). In contrast, T2DM-SAP patients had significantly lower Gensini (14.44 ± 27.34 vs 30.94 ± 48.74, p = 0.003) and lower COURAGE (3.48 ± 4.49 vs 5.30 ± 4.63, p = 0.016) scores compared to T2DM-ACS-patients.

CONCLUSION

Both the Gensini and the COURAGE score fail to predict the high cardiovascular risk of patients with T2DM-SAP. Therefore, these scores should be used with caution in the assessment of future risk of patients with T2DM. However, among T2DM-ACS patients, both scores are increased, reflecting the high cardiovascular risk in this patient population.

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.

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.

The correlation between calcification in carotid plaque and stroke: calcification may be a risk factor for stroke

BACKGROUND

There are few studies on the relationship between calcified plaques and stroke by ultrasound. We investigated the association between calcification in carotid plaque and stroke by analyzing the different characteristics of calcification and neovascularization distribution in heterogeneous plaques by both two-dimensional and contrast-enhanced ultrasound (CEUS).

METHODS

A total of 69 patients who were about to undergo carotid endarterectomy were selected between January 2016 and December 2017. Thirty-eight patients with cerebral ischemia were placed in the symptomatic group (amaurosis, TIA and no disability in the previous 6 months), and the other 31 patients, who were asymptomatic, were placed in the asymptomatic group. Two-dimensional ultrasound and CEUS were used to detect the calcification distribution characteristics and neovascularization in the plaques of all subjects. The differences of the calcification location, shape, quantity, and enhancement in the plaques were compared between the two groups.

RESULTS

There was no significant difference in calcification location between the two groups (P > 0.05). The symptomatic group had more nodular calcification but less strip calcification compared with the asymptomatic group (both P < 0.05). There was no significant difference in mixed morphologic calcification between the two groups (P > 0.05). The symptomatic group had a higher calcification quantity (P < 0.05). The symptomatic group exhibited more fibrous cap fracture and intra-plaque hemorrhage in H&E staining (χ² = 17.133, P < 0.001, χ² = 10.003, P = 0.003) and higher CD31 expression (t = 7.584, P = 0.000).

CONCLUSIONS

The quantity and shape of the calcification, and the presence of neovascularization adjacent to the calcification have certain effects on the stability of plaques. Multiple calcifications, nodular calcification, and neovascularization near calcification may cause plaque rupture and therefore might be risk factors for stroke. Our results suggest that the joint use of two-dimensional ultrasound and CEUS can provide comprehensive information on plaques to assess their stability.

Obstructive sleep apnea is associated with increased coronary plaque instability: an optical frequency domain imaging study

Obstructive sleep apnea (OSA) is associated with coronary artery disease (CAD) and with an increased risk for myocardial infarction, stroke or death due to cardiovascular disease. Optical frequency-domain imaging (OFDI) is a useful modality for evaluating the characteristics of atherosclerotic plaque. The purpose of the study was to use OFDI to investigate the association of OSA with coronary plaque characteristics in patients undergoing percutaneous coronary intervention (PCI). We retrospectively analyzed OFDI data for coronary artery plaques from 15 patients with OSA and 35 non–OSA patients treated between October 2015 and October 2018. Plaque morphology was evaluated for 70 lesions, including 21 from patients with OSA and 49 from non–OSA patients. Compared with the non–OSA group, patients with OSA had significantly higher prevalences of thinned cap fibroatheroma (TCFA) (67% vs. 35%, P = 0.014) and microchannels (86% vs. 55%, P = 0.014); a significantly higher mean lipid index (1392 ± 982 vs. 817 ± 699, P = 0.021), macrophage grade (8.4 ± 6.4 vs. 4.8 ± 4.5, P = 0.030), and maximum number of microchannels (1.5 ± 1.0 vs. 0.7 ± 0.7, P = 0.001); and a significantly lower mean minimum fibrous cap thickness (69.4 ± 28.7 vs. 96.1 ± 51.8 μm, P = 0.008). This OFDI analysis suggests that OSA is associated with unstable plaque characteristics in patients with CAD. More intensive medical management for stabilization of coronary atherosclerotic plaque is required in patients with OSA.

Senescent Cells in Early Vascular Ageing and Bone Disease of Chronic Kidney Disease-A Novel Target for Treatment

Together with bone-mineral disorders, premature vascular ageing is a common feature of the uremic phenotype. A detailed understanding of mechanisms involved remains unclear and warrants further research. Available treatment options for end stage renal disease are principally dialysis and organ transplantation, as other treatment alternatives have proven insufficient. Chronic kidney disease (CKD) has been proposed as a model of early vascular and bone ageing, with accumulating evidence supporting the contribution of cellular senescence and the senescence-associated secretory phenotype (SASP) to cardiovascular pathology in CKD. Correspondingly, novel therapies based around the use of senolytic compounds and nuclear factor-erythroid-2-related factor 2 (Nrf2) agonists, have been suggested as attractive novel treatment options. In this review, we detail the contribution of the uremic environment to these processes underpinning ageing and how these relate to vascular health.

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.

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.

Spotty Carotid Plaques Are Associated with Inflammation and the Occurrence of Cerebrovascular Symptoms

Background

Echolucent carotid plaques have been related to an increased risk of ischemic cerebrovascular events. The aim of the present study was to evaluate whether a new objective ultrasonographic parameter, the statistical geometric feature (SGF), reflecting spottiness of carotid plaques, can be associated with cerebrovascular symptoms and with a rupture-prone plaque phenotype.

Methods

The plaques of 144 patients who underwent carotid endarterectomy were included in this study. SGF and plaque area were estimated by outlining the plaque on ultrasound (US) images. The correlation coefficient for inter- and intraobserver variability was 0.69 and 0.93, respectively. The SGF values were normalized to the degree of stenosis (SGF/DS). The plaques collected at surgery 1 day after the US were analyzed histologically, and inflammatory markers and matrix metalloproteinases (MMPs) were measured.

Results

Patients with ipsilateral hemispheric symptoms had higher SGF/DS compared to patients without symptoms (0.82 [0.59–1.16] vs. 0.70 [0.56–0.89], p = 0.01). Analysis of plaque components revealed a positive correlation between SGF/DS and the percentage of the plaque area stained for lipids, macrophages, and hemorrhage. A correlation was also found between SGF/DS and plaque expression of interleukin-6, monocyte chemoattractant protein-1, macrophage inflammatory protein-1β, vascular endothelial growth factor A, C-C motif chemokine 3 and 20, and MMP-9. An inverse correlation was found with plaque levels of osteoprotegerin.

Conclusions

The present study supports the concept that spottiness is a feature of the carotid plaques rich in inflammation and can be associated with the typical phenotype of high-risk plaques.

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.

Noninvasive Molecular Imaging of Disease Activity in Atherosclerosis

Major focus has been placed on the identification of vulnerable plaques as a means of improving the prediction of myocardial infarction. However, this strategy has recently been questioned on the basis that the majority of these individual coronary lesions do not in fact go on to cause clinical events. Attention is, therefore, shifting to alternative imaging modalities that might provide a more complete pan-coronary assessment of the atherosclerotic disease process. These include markers of disease activity with the potential to discriminate between patients with stable burnt-out disease that is no longer metabolically active and those with active atheroma, faster disease progression, and increased risk of infarction. This review will examine how novel molecular imaging approaches can provide such assessments, focusing on inflammation and microcalcification activity, the importance of these processes to coronary atherosclerosis, and the advantages and challenges posed by these techniques.

Local Inhibition of Macrophage and Smooth Muscle Cell Proliferation to Suppress Plaque Progression

Atherosclerosis is a complex process responsible for a major burden of cardiovascular morbidity and mortality. Macrophages and smooth muscle cells (SMCs) are abundant within atherosclerotic plaques. This review discusses the role of macrophages and SMCs in plaque progression and provides an overview of nanoparticle-based approaches and other current methods for local targeting of atherosclerotic plaques.

Stabilization of high-risk plaques

The prevalence of atherosclerotic cardiovascular diseases (ASCVDs) is increasing globally and they have become the leading cause of death in most countries. Numerous experimental and clinical studies have been conducted to identify major risk factors and effective control strategies for ASCVDs. The development of imaging modalities with the ability to determine the plaque composition enables us to further identify high-risk plaque and evaluate the effectiveness of different treatment strategies. While intensive lipid-lowering by statins can stabilize or even regress plaque by various mechanisms, such as the reduction of lipid accumulation in a necrotic lipid core, the reduction of inflammation, and improvement of endothelial function, there are still considerable residual risks that need to be understood. We reviewed important findings regarding plaque vulnerability and some encouraging emerging approaches for plaque stabilization.

Progression of coronary artery calcification at the crossroads: sign of progression or stabilization of coronary atherosclerosis?

Coronary artery calcification (CAC) has been strongly established as an independent predictor of adverse events, with a significant incremental prognostic value over traditional risk stratification algorithms. CAC progression has been associated with a higher rate of events. In parallel, several randomized studies and meta-analysis have shown the effectiveness of statins to slow progression and even promote plaque regression. However, evidence regarding the effect of routine medical therapy on CAC has yielded conflicting results, with initial studies showing significant CAC regression, and contemporaneous data showing rather the opposite. Accordingly, there is currently a great controversy on whether progression of CAC is a sign of progression or stabilization of coronary artery disease (CAD). The finding of inexorable CAC progression despite the implementation of intensive contemporaneous medical therapy suggests that further understanding of this phenomenon should be undertaken before the implementation of CAC as a surrogate endpoint for longitudinal studies, or for prospective follow-up of patients under routine medical treatment.

New insights into spotty calcification and plaque rupture in acute coronary syndrome: an optical coherence tomography study

Although recent optical coherence tomography (OCT) studies have focused on spotty calcification, whether there were any characteristics in the concomitant existence of calcification and plaque rupture remains unknown. The aim of the present study was to investigate the characteristics of spotty calcification in acute coronary syndrome (ACS) patients with or without plaque rupture, using OCT. This study enrolled 98 consecutive patients with ACS. OCT image acquisitions were performed in the culprit lesions, and patients were divided into the plaque rupture group (n = 38) and the non-rupture group (n = 60). The frequency of spotty calcification (p = 0.006), thin-capped fibroatheroma (p = 0.012), macrophage infiltration (p = 0.022), and the number of spotty calcification per patient (p < 0.001) were significantly higher and the largest arc and the minimum depth of spotty calcification from the luminal surface were significantly smaller in the rupture group. Moreover, in the rupture group, most of the spotty calcifications in the site nearest to the minimum lumen area were observed in the proximal portion of that site, and tended to be located near the plaque rupture. Multivariate analysis revealed that the presence of spotty calcification (OR 3.19, 95 % CI 1.12-9.76, p = 0.030) and age (OR 1.08, 95 % CI 1.02-1.14, p = 0.008) were independent predictive factors for plaque rupture. This study demonstrates the characteristics of spotty calcification in ACS patients with plaque rupture and the positional relationship between spotty calcification and plaque rupture. These detailed observations could impact on treatment strategies for the prevention of ACS.

Mechanisms of ectopic calcification: implications for diabetic vasculopathy

Vascular calcification (VC) is the deposition of calcium/phosphate in the vasculature, which portends a worse clinical outcome and predicts major adverse cardiovascular events. VC is an active process initiated and regulated via a variety of molecular signalling pathways. There are mainly two types of calcifications: the media VC and the intima VC. All major risk factors for cardiovascular disease (CVD) have been linked to the presence/development of VC. Besides the risk factors, a genetic component is also operative to determine arterial calcification. Several events take place before VC is established, including inflammation, trans-differentiation of vascular cells and homing of circulating pro-calcific cells. Diabetes is an important predisposing factor for VC. Compared with non-diabetic subjects, patients with diabetes show increased VC and higher expression of bone-related proteins in the medial layer of the vessels. In this review we will highlight the mechanisms underlying vascular calcification in diabetic patients.

Non-invasive evaluation of culprit lesions by PET imaging: shifting the clinical paradigm away from resultant anatomy toward causative physiology

Although coronary angiography is the gold standard for assessing coronary artery disease (CAD), there is at best a weak correlation between degree of stenosis and the risk of developing cardiac events. Plaque rupture is the most common type of plaque complication, accounting for about 70% of fatal acute myocardial infarctions or sudden coronary deaths. Recently, the feasibility of (18)F-fluoride PET/CT in the evaluation of atherosclerotic lesions was assessed. Radionuclide techniques allow non-invasive biologic assessment of atherosclerotic plaques. This may help to further shift the clinical paradigm in coronary disease away from anatomy toward causative physiology and biology.