Noninvasive diagnosis of vulnerable coronary plaque

18F-NaF PET uptake characteristics of coronary artery culprit lesions in a cohort of patients of acute coronary syndrome with ST-elevation myocardial infarction and chronic stable angina: A hybrid fluoride PET/CTCA study

BACKGROUND

18F-NaF PET/CT identifies high-risk plaques due to active calcification in coronary arteries with potential to characterize plaques in ST-elevation myocardial infarction (MI) and chronic stable angina (CSA) patients.

METHODS

Twenty-four MI and 17 CSA patients were evaluated with 18F-NaF PET/CTCA for SUVmax and TBR values of culprit and non-culprit plaques in both groups (inter-group and intra-group comparison), and pre- and post-interventional MI plaques sub-analysis.

RESULTS

Culprit plaques in MI patients had significantly higher SUVmax (1.6; IQR 0.6 vs 1.3; IQR 0.3, P = 0.03) and TBR (1.4; IQR 0.6 vs 1.1; IQR 0.4, P = 0.006) than culprit plaques of CSA. Pre-interventional culprit plaques of MI group (n = 11) revealed higher SUVmax (P = 0.007) and TBR (P = 0.008) values than culprit CSA plaques. Culprit plaques showed significantly higher SUVmax (P = 0.006) and TBR (P = 0.0003) than non-culprit plaques in MI group, but without significant difference between culprit and non-culprit plaques in CSA group. With median TBR cutoff value of 1.4 in MI culprit plaques, 6/7 plaques (85.7%) among the event prone non-culprit lesions had TBR values > 1.4 in CSA group.

CONCLUSION

The study shows higher SUVmax and TBR values in MI culprit plaques and comparable TBR values for event prone plaques of CSA group in identifying high-risk plaques.

PET/MRI of atherosclerosis

Myocardial infarction and stroke are the most prevalent global causes of death. Each year 15 million people worldwide die due to myocardial infarction or stroke. Rupture of a vulnerable atherosclerotic plaque is the main underlying cause of stroke and myocardial infarction. Key features of a vulnerable plaque are inflammation, a large lipid-rich necrotic core (LRNC) with a thin or ruptured overlying fibrous cap, and intraplaque hemorrhage (IPH). Noninvasive imaging of these features could have a role in risk stratification of myocardial infarction and stroke and can potentially be utilized for treatment guidance and monitoring. The recent development of hybrid PET/MRI combining the superior soft tissue contrast of MRI with the opportunity to visualize specific plaque features using various radioactive tracers, paves the way for comprehensive plaque imaging. In this review, the use of hybrid PET/MRI for atherosclerotic plaque imaging in carotid and coronary arteries is discussed. The pros and cons of different hybrid PET/MRI systems are reviewed. The challenges in the development of PET/MRI and potential solutions are described. An overview of PET and MRI acquisition techniques for imaging of atherosclerosis including motion correction is provided, followed by a summary of vessel wall imaging PET/MRI studies in patients with carotid and coronary artery disease. Finally, the future of imaging of atherosclerosis with PET/MRI is discussed.

Coronary Plaque Geometry and Thoracic Fat Distribution in Patients with Acute Chest Pain – a CT Angiography Study

The aim of our study was to investigate the correlation between volumes of thoracic fat distributed in different compartments and the geometry of vulnerable coronary plaques assessed by coronary computed tomography angiography (CCTA), in patients with acute chest pain.

Methods: This was a non-randomized, observational, single-center study, including 50 patients who presented in the emergency department with acute chest pain who underwent 128-slice single-source CCTA. Plaque geometry was evaluated in transversal and longitudinal planes, and the assessment of adipose tissue was performed using the Syngo.via Frontier (Siemens AG, Healthcare Sector, Forchheim, Germany) research platform.

Results: Eccentric plaques presented a significantly higher incidence of spotty calcification (40% vs. 22%, p = 0.018), whereas positive remodeling, volume of low attenuation plaque, and incidence of napkin-ring sign were not significantly different between the study groups or in ascending versus descending plaques. The volume of pericoronary fat around the plaque was significantly larger near eccentric lesions (707.68 ± 454.08 mm3 vs. 483.25 ± 306.98 mm3, p = 0.046) and descendent plaques (778.26 ± 479.37 mm3 vs. 473.60 ± 285.27 mm3, p = 0.016). Compared to ascending lesions, descendent ones presented a significantly larger volume of thoracic fat (1,599.25 ± 589.12 mL vs. 1,240.71 ± 291.50 mL), while there was no significant correlation between thoracic fat and cross-sectional eccentricity.

Conclusions: The phenotype of plaque distribution and geometry seems to be associated with a higher vulnerability of coronary lesions and may be influenced by the local accumulation of inflammatory mediators released by the pericoronary epicardial adipose tissue.

Impact of coronary plaque geometry on plaque vulnerability and its association with the risk of future cardiovascular events in patients with chest pain undergoing coronary computed tomographic angiography-the GEOMETRY study: Protocol for a prospective clinical trial

INTRODUCTION

Coronary computed tomography angiography (CCTA) has emerged as a valuable noninvasive imaging tool for assessing atheromatous plaque morphology and composition, and several CCTA features have been validated as reliable indicators of the plaque-associated risk. However, the role of lesion geometry as a CCTA feature of plaque vulnerability has not been investigated so far.

MATERIAL AND METHODS

Here we present the study protocol of the GEOMETRY trial, a prospective, single center, cohort study in which we aim to investigate the relationship between plaque geometry (as expressed by cross-sectional and longitudinal plaque eccentricity) and the risk for major adverse cardiac events (MACE) during 2 years of follow-up, in order to validate plaque eccentricity as a new CCTA marker of coronary plaque vulnerability. One thousand patients with suspected coronary artery disease (CAD) and pretest probability of CAD between 15% and 85%, who undergo CCTA and in whom CCTA identifies the presence of at least 1 significant coronary plaque (producing a luminal narrowing of at least 50%) will be enrolled in the study. Based on the results of complex image post-processing and plaque analysis, patients will be divided into 2 groups: group 1-patients in whom CCTA analysis identifies only non-eccentric coronary plaque; and group 2-patients in whom CCTA analysis reveals the presence of at least 1 eccentric significant coronary plaque producing a significant luminal narrowing. Study outcomes will consist in the rate of major cardiovascular events and the rate of plaque progression during follow-up.The study is funded by the Romanian Ministry of European Funds, the Romanian Government and the European Union, as part of the research grant number 103544/2016 - PlaqueIMAGE (contract number 26/01.09.2016).

CONCLUSION

In conclusion, GEOMETRY will be the first CCTA-based study that will investigate the impact of geometric distribution of coronary atheromatous plaque on the future risk of cardiovascular events and on the rate of plaque progression, introducing and validating a new potential feature of plaque vulnerability represented by plaque geometry.

Crocus sativus L. aqueous extract reduces atherogenesis, increases atherosclerotic plaque stability and improves glucose control in diabetic atherosclerotic animals

BACKGROUND AND AIMS

We aimed to evaluate a possible atheroprotective effect of saffron aqueous extract (SFE), and its potential anti-inflammatory mechanisms, in apoE knockout (ApoE^-/-) mice.

METHODS

Fifty male, ApoE^-/- mice, fed a high-fat diet (HFD) for 12 weeks, were randomized into 5 groups: (1) baseline group, euthanatized, without intervention, (2) three saffron groups, receiving HFD and 30,60,90 mg/kg/day of SFE, respectively, for four weeks, per os through gavage, after reconstitution in water for injection (WFI), (3) control group (COG), receiving daily HFD and the same volume of WFI (four weeks). After blood sampling and euthanasia, aortic roots were excised and analyzed for gene expression and/or percentage of aortic stenosis, relative content of macrophages, smooth muscle cells (SMCs), connective tissue, tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), matrix metalloproteinases-2,-3,-9 (MMP-2,-3,-9) and their inhibitor (TIMP-2) and IL-6. SFE doses were determined by a pilot serum pharmacokinetic study in C57BL/6J wild-type mice.

RESULTS

SFE did not affect body weight and total cholesterol levels (p > 0.05), while high SFE dose significantly ameliorated glucose and triglycerides profiles compared to other groups (p < 0.05). SFE considerably decreased aortic stenosis in a dose-dependent manner (p < 0.05). Furthermore, increasing SFE doses proportionally reduced macrophages content and increased within plaques content of collagen, elastin, and SMCs, promoting more stable plaque phenotype compared to COG (p < 0.05). Those effects seemed to be associated with a considerable reduction (>30%) in IL-6, TNF-α, MCP-1, MMP-2,-3,-9 (p < 0.05) and MMP-2/TIMP-2 ratio.

CONCLUSIONS

SFE exerted dose-dependent anti-atherosclerotic and plaque-stabilizing effects in Apo-E^-/- mice, probably mediated by a favorable modification of inflammatory mechanisms, which requires further investigation.

Outcome of revascularisation in stable coronary artery disease without ischaemia: a Danish registry-based follow-up study

OBJECTIVES

In stable coronary artery disease (CAD), coronary revascularisation may reduce mortality of patients with a certain amount of left ventricular myocardial ischaemia. However, revascularisation does not always follow the guidance suggested by ischaemia testing. We compared outcomes in patients without ischaemia who had either revascularisation or medical treatment.

DESIGN AND POPULATION

Based on registries, 1327 consecutive patients with normal myocardial perfusion scintigraphy (MPS) and 278 with fixed perfusion defects were followed for a median of 6.1 years. Most patients received medical therapy alone (Med), but 26 (2%) with a normal MPS and 15 (5%) with fixed perfusion defects underwent revascularisation (Revasc).

OUTCOME MEASURES

Incidence rates of all-cause death (ACD) and rates of cardiac death/myocardial infarction (CD/MI).

RESULTS

With a normal MPS, the ACD rate was 6.2%/year in the Revasc group versus 1.9%/year in the Med group (p=0.01); the CD/MI rates were 6.9%/year and 0.6%/year, respectively (p<0.00001). Results persisted after adjustment for predictors of revascularisation, in particular angina score, and in comparisons of matched Revasc and Med patients. With fixed defects, the ACD rate was 9.1%/year in the Revasc group and 6.7%/year in the Med group (p=0.44); the CD/MI rate was 5.0%/year versus 4.2%/year, respectively (p=0.69). If adjusted for angiographic variables or analysed in matched subsets, differences remained insignificant.

CONCLUSIONS

With normal MPS, revascularisation conferred a higher risk, even after adjustment for predictors of revascularisation. With fixed defects, the Revascversus Med difference was close to equipoise. Hence, in patients with stable CAD without ischaemia, we could not find evidence to justify exceptional revascularisation.