Heat production of atherosclerotic plaques and inflammation assessed by the acute phase proteins in acute coronary syndromes

A Hidden Organism, Chlamydia in the Age of Atherosclerosis

Atherosclerosis is a chronic inflammatory disease. It is still the leading cause of mortality and morbidity in the world. Inflammation in the vessels plays the most important role in the pathogenesis of atherosclerosis. Many studies have been emphasized that Chlamydia pneumoniae triggers inflammation in the vessels and associated with atherosclerosis. It is stated that most of the chlamydial infections are asymptomatic and around 40% of adult individuals are infected. Chlamydia has different subgroups. It was thought to be a virus due to its intracellular pathogenicity, but it was included in the bacteria genus because it contains DNA and RNA chromosomes and has enzymatic activity. Chlamidya can easily be transmitted through the respiratory tract and sexual transmission. Seroepidemiological and pathological studies of atherosclerotic plaques showed the presence of Chlamydia in the plaque. This section will provide relationship between Chlamydia and atherosclerosis on the recent researces and current information will be discussed.

Inhibition of miR-652-3p Regulates Lipid Metabolism and Inflammatory Cytokine Secretion of Macrophages to Alleviate Atherosclerosis by Improving TP53 Expression

Purpose

The aim was to elucidate the regulatory function of miR-652-3p on lipid metabolism and inflammatory cytokine secretion of macrophages in atherosclerosis.

Methods

miR-652-3p level in atherosclerosis patients, ox-LDL-treated macrophages, and their controls were monitored by Q-PCR. After ox-LDL treatment and miR-652-3p mimic, si-TP53 and their controls transfection, ELISA, and Q-PCR assays were used to detect IL-1ß, IL-6, and TNF-α levels. oil red O staining was processed to verify cholesterol accumulation. CE/TC and lipid metabolism were also detected. The protein levels of ABCA1, ABCG1, PPARα, CRT1, ADRP, and ALBP were detected by western blot assay. Based on the TargetScan database, the TP53 3′UTR region had complementary bases with miR-652-3p, which was also verified by dual-luciferase reporter gene assay. Finally, the regulation of miR-652-3p and TP53 was confirmed by rescue assay in atherosclerosis.

Results

miR-652-3p is highly expressed in atherosclerosis, miR-652-3p inhibitor decreased IL-1β, IL-6, and TNF-α expression after ox-LDL treatment. Knockdown of miR-652-3p reduces foam formation in ox-LDL-treated macrophages. miR-652-3p inhibitor ameliorates cholesterol accumulation and lipid metabolism disorder. miR-652-3p negatively regulated TP53 in atherosclerosis. Si-TP53 rescued the effect of miR-652 inhibitor in atherosclerosis.

Conclusion

miR-652-3p regulates the lipid metabolism of macrophages to alleviate atherosclerosis by inhibiting TP53 expression. It might be a potential target for atherosclerosis treatment.

Detection of Vulnerable Coronary Plaques Using Invasive and Non-Invasive Imaging Modalities

Acute coronary syndrome (ACS) mostly arises from so-called vulnerable coronary plaques, particularly prone for rupture. Vulnerable plaques comprise a specific type of plaque, called the thin-cap fibroatheroma (TFCA). A TCFA is characterized by a large lipid-rich necrotic core, a thin fibrous cap, inflammation, neovascularization, intraplaque hemorrhage, microcalcifications or spotty calcifications, and positive remodeling. Vulnerable plaques are often not visible during coronary angiography. However, different plaque features can be visualized with the use of intracoronary imaging techniques, such as intravascular ultrasound (IVUS), potentially with the addition of near-infrared spectroscopy (NIRS), or optical coherence tomography (OCT). Non-invasive imaging techniques, such as computed tomography coronary angiography (CTCA), cardiovascular magnetic resonance (CMR) imaging, and nuclear imaging, can be used as an alternative for these invasive imaging techniques. These invasive and non-invasive imaging modalities can be implemented for screening to guide primary or secondary prevention therapies, leading to a more patient-tailored diagnostic and treatment strategy. Systemic pharmaceutical treatment with lipid-lowering or anti-inflammatory medication leads to plaque stabilization and reduction of cardiovascular events. Additionally, ongoing studies are investigating whether modification of vulnerable plaque features with local invasive treatment options leads to plaque stabilization and subsequent cardiovascular risk reduction.

Reliable and Remote Monitoring of Absolute Temperature during Liver Inflammation via Luminescence-Lifetime-Based Nanothermometry

Temperature of tissues and organs is one of the first parameters affected by physiological and pathological processes, such as metabolic activity, acute trauma, or infection-induced inflammation. Therefore, the onset and development of these processes can be detected by monitoring deviations from basal temperature. To accomplish this, minimally invasive, reliable, and accurate measurement of the absolute temperature of internal organs is required. Luminescence nanothermometry is the ideal technology for meeting these requirements. Although this technique has lately undergone remarkable developments, its reliability is being questioned due to spectral distortions caused by biological tissues. In this work, how the use of bright Ag₂ S nanoparticles featuring temperature-dependent fluorescence lifetime enables reliable and accurate measurement of the absolute temperature of the liver in mice subjected to lipopolysaccharide-induced inflammation is demonstrated. Beyond the remarkable thermal sensitivity (≈ 3% °C^-1 around 37 °C) and thermal resolution obtained (smaller than 0.3 °C), the results included in this work set a blueprint for the development of new diagnostic procedures based on the use of intracorporeal temperature as a physiological indicator.

Comparative Efficacy of Danshen Class Injections for Treating Acute Coronary Syndrome: A Multidimensional Bayesian Network Meta-Analysis of Randomized Controlled Trials

Background

Acute coronary syndrome, that is a common and serious cardiovascular disease, imposes a huge economic burden on global public health. And Danshen class injections are commonly used in the treatment of acute coronary syndrome in China. Thus, the Bayesian network meta-analysis was devised to investigate the efficacy of different Danshen class injections against acute coronary syndrome.

Methods

Eligible inclusion and exclusion criteria were established in advance. Then, a systematic literature search was performed in several databases from inception to February 2020. Further, the included randomized controlled trials data were adopted to calculation, prepare graphs and multidimensional cluster analysis by WinBUGS 1.4.3, Stata V.13.0 and R 3.6.1 software, respectively.

Results

A total of 53 eligible randomized controlled trial studies with 6401 patients were obtained that evaluated the clinical effectiveness rate, the level of hypersensitive C-reactive protein, C-reactive protein, interleukin-6, fibrinogen, and adverse reactions after the application of Danshen class injections plus western medicine. Compared with western medicine alone, Danshen class injections combined with western medicine therapy were associated with significantly improved the therapeutic effect. In addition, the results of the multidimensional cluster analysis demonstrated that Danhong injection + western medicine and Danshen injection + western medicine had better therapeutic effects. However, since most eligible randomized controlled trial studies did not focus on the monitoring of adverse reactions, the safety of these Chinese herbal injections needs to be further explored.

Conclusion

Based on this Bayesian network meta-analysis results, Danhong injection + western medicine and Danshen injection + western medicine might have a better impact on acute coronary syndrome patients. Nevertheless, more large samples, high-quality clinical and multicenter randomized controlled trial studies should be tested and verified in the future.

Postmortem plasma pentraxin 3 is a useful marker of fatal acute coronary syndrome

Pentraxin 3 (PTX3) is an acute-phase protein that belongs to the pentraxin superfamily. Recently, many clinical studies have demonstrated that plasma PTX3 concentrations rapidly increase in patients with the acute coronary syndrome (ACS). The aim of this study was to evaluate the forensic utility of postmortem plasma PTX3 as a marker of fatal ACS. We compared the plasma PTX3 concentration in cadavers with suspected fatal ACS to that exhibited in control cases (e.g., asphyxia and immediate death due to a fatal injury). The ACS groups included a coronary stenosis group, which exhibited apparent coronary stenosis, but an absence of coronary thrombi, a coronary thrombi group with thrombi found in the coronary artery, and a group of myocardial rupture following an acute myocardial infarction. The plasma PTX3 concentration was significantly higher in the coronary thrombi group than the control group and other ACS groups. The postmortem plasma PTX3 concentration was higher than the clinical reference values, which appeared to be caused by a postmortem release from circulating neutrophils. In conclusion, although the clinical reference value cannot be applied to postmortem samples, the postmortem plasma PTX3 concentration may be a useful marker of death occurring immediately after the onset of fatal ACS.

Microwave radiometry: a new non-invasive method for the detection of vulnerable plaque

Atherosclerosis and its consequences are the most rapidly growing vascular pathology, with myocardial infarction and ischemic cerebrovascular accident to remain a major cause of premature morbidity and death. In order to detect the morphological and functional characteristics of the vulnerable plaques, new imaging modalities have been developed. Intravascular thermography (IVT) is an invasive method, which provides information on the identification of the high-risk atheromatic plaques in coronary arteries. However, the invasive character of IVT excludes the method from primary prevention. Microwave radiometry (MR) is a new non-invasive method, which detects with high accuracy relative changes of temperature in human tissues whereas this thermal heterogeneity is indicative of inflammatory atherosclerotic plaque. Both experimental and clinical studies have proved the effectiveness of MR in detecting vulnerable plaque whereas recent studies have also revealed its association with plaque neoangiogenesis as assessed by contrast enhanced carotid ultrasound (CEUS).

Improving depression and reducing cardiac events: which is the chicken and which is the egg?

OBJECTIVE

To examine the assumption that depression leads to recurrent cardiac events and death in those with heart disease.

METHODS

Consideration of alternative perspectives and discussion of the literature.

RESULTS

It is not clear from studies like MIND-IT, ENRICHD or SADHART whether depression treatment improves cardiac outcomes. In these studies, recurrent cardiac events and death were recorded 6months or more after study entry, but shorter-term cardiac outcomes (e.g., stabilization of plaque prone to rupture and thrombosis or changes in areas of myocardium prone to life-threatening arrhythmia) were not assessed. Although the prevailing view is that shorter-term improvement in depression is necessary to improve cardiovascular outcomes, the possibility that shorter-term improvement in cardiac status might result in reduced symptoms of depression has not been examined. If correct, this possibility might explain why studies have shown that patients whose depression improves also exhibit improved cardiovascular outcomes and lower mortality, even though randomization to the depression intervention in these studies had no effect.

CONCLUSION

It is not clear whether improving depression comes first and reduced cardiac events follows or whether patients whose cardiac status improves also exhibit improvement in depression. Which is the chicken and which the egg is more than just a philosophical question, since it may affect the direction of future research in this field, and even how we approach the care of patients with heart disease and depression.

Vascular effects of glycoprotein130 ligands--part I: pathophysiological role

The vessel wall is no longer considered as only an anatomical barrier for blood cells but is recognized as an active endocrine organ. Dysfunction of the vessel wall occurs in various disease processes including atherosclerosis, hypertension, peripheral artery disease, aneurysms, and transplant and diabetic vasculopathies. Different cytokines were shown to modulate the behavior of the cells, which constitute the vessel wall such as immune cells, endothelial cells and smooth muscle cells. Glycoprotein 130 (gp130) is a common cytokine receptor that controls the activity of a group of cytokines, namely, interleukin (IL)-6, oncostatin M (OSM), IL-11, ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), cardiotrophin-1 (CT-1), cardiotrophin-like cytokine (CLC), IL-27, and neuropoietin (NP). Gp130 and associated cytokines have abundantly diverse functions. Part I of this review focuses on the pathophysiological functions of gp130 ligands. We specifically describe vascular effects of these molecules and discuss the respective underlying molecular and cellular mechanisms.

Detection of the vulnerable coronary atheromatous plaque. Where are we now?

Atherosclerosis is a progressive process with potentially devastating consequences and has been identified as the leading cause of morbidity and mortality, especially in the industrial countries. The underlying mechanisms include endothelial dysfunction, lipid accumulation and enhanced inflammatory involvement resulting in plaque disruption or plaque erosion and subsequent thrombosis. However, it has been made evident, that the majority of rupture prone plaques that produce acute coronary syndromes are not severely stenotic. Conversely, lipid-rich plaques with thin fibrous cap, heavily infiltrated by inflammatory cells have been shown to predispose to rupture and thrombosis, independently of the degree of stenosis. Therefore, given the importance of plaque composition, a continuously growing interest in the development and improvement of diagnostic modalities will promptly and most importantly, accurately detect and characterize the high-risk atheromatous plaque. Use of these techniques may help risk stratification and allow the selection of the most appropriate therapeutic approach.

Imaging of the vulnerable plaque: noninvasive and invasive techniques

In a large proportion of previously asymptomatic individuals, sudden coronary death or acute myocardial infarction occurs as the first manifestation of coronary atherosclerosis. Imaging of coronary atheromatous plaques has traditionally centered on assessing the degree of luminal stenosis. The angiographic techniques that are routinely used to identify stenotic atherosclerotic lesions are unable to identify high-risk plaques; plaques prone to rupture and cause a cardiovascular event. This is partly due to the fact that the majority of culprit lesions that produce acute cardiovascular syndromes are not severely stenotic, possibly due to significant positive remodeling and reduced protective collateral circulation as well as because the risk of plaque rupture is more closely related to plaque content than plaque size. Recently, the focus of new imaging techniques is to identify the high risk plaques; the "vulnerable plaques." In this review, we will refer to the noninvasive and invasive techniques that can detect the vulnerable plaque.

The etiology of 'smoker's paradox' in acute myocardial infarction with special emphasis on the association with inflammation

Despite increased risk for coronary artery disease and acute myocardial infarction (AMI), prior studies have found that smokers with AMI have lower mortality rates than nonsmokers, a phenomenon often termed 'smoker's paradox'. The present study was designed to examine the etiology of 'smoker's paradox', especially with respect to the association with inflammation. The subjects included 528 consecutive AMI patients who were admitted within 24 hours of onset and underwent successful coronary intervention. Of the 528 subjects, 232 (44%) were smokers. The cardiac mortality rates over a 6 month period was significantly lower in the smoking group than the nonsmoking group (3% versus 9%, P = 0.01). There were significantly more male patients in the smoking group, and the smoking group was significantly younger than the nonsmoking group (P < 0.0001). The value of high sensitivity C-reactive protein (hs-CRP) on admission and 24 hours after onset, and serum amyloid A protein (SAA) were significantly higher, and acute phase BNP was significantly lower (hs-CRP on admission 1.36 +/- 1.03 mg/dL versus 0.75 +/- 0.82 mg/dL, P = 0.02, hs-CRP at 24 hours 3.86 +/- 4.32 mg/dL versus 2.90 +/- 3.46 mg/dL, P = 0.008, SAA; 288 +/- 392 microg/dL versus 176 +/- 206 microg/dL, P < 0.05, BNP; 248 +/- 342 pg/mL versus 444 +/- 496 pg/mL, P = 0.0002) in the smoking group than in the nonsmoking group. The early ST-segment resolution rate was higher in the smoking group compared with the nonsmoking group (80% versus 66%, P = 0.003). The reason why smokers with AMI have lower mortality rates than nonsmokers, the so-called 'smoker's paradox', is believed to be because smoking induces inflammation and smokers may have less damage to microvascular function after primary percutaneous coronary intervention.

Limitation of angiography to identify the culprit plaque in acute myocardial infarction with coronary total occlusion utility of coronary plaque temperature measurement to identify the culprit plaque

OBJECTIVES

The purpose of this study was to test the hypothesis that the maximal temperature (Tmax) site, as measured by thermal wire, coincides with the culprit plaque by intravascular ultrasound (IVUS) in patients with acute myocardial infarction (AMI).

BACKGROUND

Subsequent thrombosis developing to the proximal region from the site of plaque rupture or erosion can potentially complicate the ability of coronary angiography to identify the accurate culprit plaque in patients with coronary total occlusion.

METHODS

In 45 consecutive patients with a first anterior AMI, the Tmax site by thermal wire and the culprit plaque by IVUS were evaluated in the left anterior descending coronary artery (LAD).

RESULTS

Twenty-five patients had LAD total occlusion, and the remaining 20 had LAD reperfusion. In both groups of patients, the Tmax site was significantly more distal to the angiographically most stenotic site or occlusive site (reperfusion: mean distance [MD] = 1.1 mm distal, 95% confidence interval [CI] 0.3 to 1.9 mm, p = 0.01; total occlusion: MD = 8.8 mm distal, 95% CI 8.0 to 9.6 mm, p < 0.0001). The culprit plaques by IVUS approximately coincided with those by angiography or thermal wire in patients with reperfusion. However, the angiographic occlusive site was significantly more proximal to the culprit plaque by IVUS (MD = 9.2 mm, 95% CI 7.9 to 10.6 mm, p < 0.0001), but the Tmax site coincided with the culprit plaque by IVUS (MD = 0.3 mm distal, 95% CI 0.3 mm proximal to 1.0 mm distal, p = 0.293) in patients with total occlusion.

CONCLUSIONS

Temperature measurement of coronary plaque enables accurate localization of the culprit plaque in AMI with coronary total occlusion.

An analytic and numerical study of intravascular thermography of vulnerable plaque

Intravascular thermography has been proposed as a method for detecting vulnerable plaque. A marker of vulnerability in a plaque is inflammation, which is believed to reduce its mechanical stability. It has been hypothesized that this inflammation leads to a higher metabolic rate and therefore higher heat generation, causing increased temperature in the vicinity of the plaque. This temperature increase could be measured intravascularly using a temperature sensor, e.g., a thermistor or a thermocouple. The aim of this study is to present a thorough mathematical and physical analysis of the thermal distribution that can be expected in the plaque under various physiological conditions. To get reasonable predictions on the expected temperature distributions, idealized models with simple geometries are solved analytically. More realistic models, with more complex geometries, are solved numerically using the finite element method (FEM). Based on this analysis, the maximum temperature increase that can be expected in a plaque due to increased metabolism is less than 0.1 K.

The Relationship Between Acute Phase Serum Amyloid A (SAA) Protein Concentrations and Left Ventricular Systolic Function in Acute Myocardial Infarction Patients Treated With Primary Coronary Angioplasty

BACKGROUND

Our study was planned to investigate the relationship between plasma levels of serum amyloid A protein (SAA) concentrations and the subsequent left ventricular systolic function in patients with acute myocardial infarction (AMI) treated with primary coronary angioplasty.

METHODS AND RESULTS

Reperfusion by primary percutaneous coronary intervention was successful in 486 consecutive AMI patients who were admitted within 12 hours of onset. Plasma SAA concentrations were evaluated 24 hours after onset. Left ventricular (LV) function was serially determined by left ventriculography performed in the acute (soon after recanalization) and chronic phases (6 months after onset). (I) There was no significant correlation between SAA concentration and acute phase left ventricular ejection fraction (LVEF) or regional wall motion (RWM). (II) The SAA concentration was significantly correlated with both highly sensitive C-reactive protein (hs-CRP) and the peak-CK value (hs-CRP: r = 0.69, P < 0.0001, peak-CK: r = 0.21, P = 0.0003). (III) SAA was significantly negatively correlated with both LVEF and RWM in the chronic phase (LVEF: r = -0.42, P = 0.001; RWM: r = -0.41, P = 0.007). (IV) The plasma level of SAA also showed a significant negative correlation with the differences in LVEF between the 2 stages (delta-LVEF) (r = -0.43, P = 0.02).

CONCLUSION

In the setting of AMI, plasma SAA concentrations may be closely related to subsequent left-ventricular systolic dysfunction.

A numerical study on the influence of vulnerable plaque composition on intravascular thermography measurements

Intracoronary thermography is a technique that measures lumen wall temperatures for vulnerable plaque detection. In this paper the influence of vulnerable plaque composition on lumen wall temperatures was studied numerically. Concerning the vulnerable plaque heat generation, the location of the heat source and its heat production were varied. Concerning the heat transfer, the thermal properties of the lipid core and the location of the vasa vasorum were studied. The heat source location was the main determinant of the lumen wall temperature distribution. The strongest effect was noted when the heat producing macrophages were located in the shoulder region leading to focal spots of higher temperature. The maximal lumen wall temperature was mainly determined by the heat production of the macrophages and the cooling effect of blood. The insulating properties of the lipid core increased lumen wall temperatures when the heat source was located in the cap and the presence of vasa vasorum lowered the temperatures. These results show that the lumen wall temperature distribution is influenced by vulnerable plaque composition and that intracoronary thermography techniques require a high spatial resolution. To be able to couple temperature measurements to plaque vulnerability, intracoronary thermography needs to be combined with an imaging modality.

Early and late determinants of C-reactive protein release in patients with acute coronary syndrome

Increased levels of C-reactive protein (CRP) could be detected in subjects with acute coronary syndrome (ACS). Several factors, atherosclerosis, coronary flow impairment, myocardial necrosis, each one acting during a different, earlier or later, phase of ACS, are supposed to be involved in CRP release in case of ACS. Role and relevance of each factor, not mutually exclusive, still need to be comparatively evaluated but a cooperative synergism could be presumably hypothesized.

Assessment of Culprit Plaque Temperature by Intracoronary Thermography Appears Inconclusive in Patients With Acute Coronary Syndromes

OBJECTIVE

Safety and feasibility evaluation of intracoronary temperature measurements in patients with acute coronary syndromes (ACS) using a catheter based thermography system.

METHODS AND RESULTS

Thermography was performed in 40 patients with ACS. A 3.5-F thermography catheter containing 5 thermocouples measuring vessel wall temperature, and 1 thermocouple measuring blood temperature (accuracy 0.05 degrees C) was used. Gradient (deltaTmax) between blood temperature (T(bl)) and the maximum wall temperature during pullback was measured. The device showed satisfactory safety in ACS. Only in 16 patients (40%) deltaTmax was > or = 0.1 degrees C. In 23 patients (57.5%) the highest deltaTmax was found in the culprit segment. DeltaTmax between culprit and adjacent non-culprit segments was observed in patients with transient blood flow interruption during thermography (0.11+/-0.03 versus 0.08+/-0.01; P=0.04), in contrast to patients with preserved flow (0.07+/-0.03 versus 0.06+/-0.02; P=0.058).

CONCLUSIONS

The novel, technically sophisticated intracoronary thermography proved its safety and feasibility. However, we were not able to convincingly and consistently differentiate between different lesions at risk, despite a selection of lesions that should appear most distinct to differentiate. A systematic interruption of flow may be necessary to achieve diagnostic results consistently, although such requirement may unfavorably change the risk-to-benefit ratio of this developing technology.

Intracoronary Thermography for Detection of High-Risk Vulnerable Plaques

Up to two-thirds of acute myocardial infarctions develop at sites of culprit lesions without a significant stenosis. New imaging techniques are needed to identify those lesions with an increased risk of developing an acute complication in the near future. Inflammation is a hallmark feature of these vulnerable/high-risk plaques. We have shown that inflamed atherosclerotic plaques are hot and their surface temperature correlates with an increased number of macrophages and decreased fibrous-cap thickness. Multiple animal and human experiments have shown that temperature heterogeneity correlates with arterial inflammation in vivo. Several coronary temperature mapping catheters are currently being developed and studied. These thermography methods can be used in the future to detect vulnerable plaques, potentially to determine patients' prognosis, and to study the plaque-stabilizing effects of different medications.

Intracoronary thermography: does it help us in clinical decision making?

The concept of the "vulnerable" plaque has recently emerged to explain how quiescent atherosclerotic lesions evolve to cause clinical events. The morphologic and immunologic determinants specific for the vulnerable plaque have been reported: a large lipid core (>or=40% plaque volume) composed of free cholesterol crystals, cholesterol esters, and oxidized lipids impregnated with tissue factor; a thin fibrous cap depleted of smooth muscle cells and collagen; an outward (positive) remodeling; inflammatory cell infiltration of fibrous cap and adventitia (mostly monocyte-macrophages, some activated T cells, and mast cells); and increased neovascularity. Despite the large amount of information regarding the morphological characteristics of remote lesions, we lack studies with functional assessment of non-culprit lesions. Coronary thermography is a technique for functional assessment of coronary atherosclerotic plaques. Several catheter designs have been proposed. There are catheters with thermistor(s) and wires with thermal sensors at the distal tip. All designs have several advantages and disadvantages. Despite the current limitations of coronary thermography, we gained important pathophysiological and clinical information regarding the vulnerability of atheromatic plaques. It has been documented both experimentally and clinically that increased heat generation is associated with increased macrophage concentration within the plaque. The correlation between local inflammatory involvement and local heat generation has also been observed with the peripheral inflammatory markers such as C-reactive protein. Whether systemic treatment, with agents such as statins or interventional techniques, such as drug-eluting stents, will have an impact on stabilizing vulnerable plaques need to be determined in future studies. In conclusion, although there are several techniques for evaluating morphologically atheromatic plaques, thermography is a promising method for the functional assessment of vulnerable plaque and has been introduced into clinical practice, with a good predictive value for clinical events in patients with increased temperature in the atherosclerotic plaque.

Serum Amyloid A Protein as a Predictor of Cardiac Rupture in Acute Myocardial Infarction Patients Following Primary Coronary Angioplasty

BACKGROUND

The predictors of cardiac rupture (CR) in patients with acute myocardial infarction (AMI) treated with successful primary coronary angioplasty have not been identified.

METHODS AND RESULTS

Of 433 consecutive AMI subjects who underwent reperfusion by primary coronary angioplasty within 24 h of onset, CR occurred in 11 (2.5%), free wall rupture in 9, and ventricular septal perforation in 2. Rates of females, diabetes mellitus and anterior infarction were higher in the group of CR patients than in the others (p < 0.05). There were no significant differences between the 2 groups in terms of left ventricular (LV) function soon after recanalization, such as LV ejection fraction, regional wall motion, or end-diastolic volume index. Plasma levels of both high-sensitivity C-reactive protein (hsCRP) and serum amyloid-A protein (SAA) were significantly higher in the CR patients than in the others (hsCRP: 6.7 +/- 6.7 mg/dl vs 3.3 +/- 3.8 mg/dl, p = 0.007; SAA: 699 +/- 812 microg/dl vs 208 +/- 273 microg/dl, p < 0.0001). Multivariate analysis identified SAA as an independent predictor of CR (risk ratio: 8.8, 95% confidence interval: 1.7-25.6, p < 0.05). Conclusions In patients with AMI treated with primary coronary angioplasty, inflammation may be closely related to CR, for which SAA is a useful predictor.

Predictors of Sub-Acute Stent Thrombosis in Acute Myocardial Infarction Patients Following Primary Coronary Stenting With Bare Metal Stent

BACKGROUND

The aim of the present study was to identify the relationship between sub-acute stent thrombosis (SAT) and acute-phase inflammatory reactants, such as high-sensitivity C-reactive protein (hs-CRP) and serum amyloid-A protein (SAA), in patients with acute myocardial infarction (AMI) successfully treated with primary coronary stenting.

METHODS AND RESULTS

The 381 consecutive AMI subjects were reperfused by primary coronary stenting within 24 h of onset. SAT was confirmed angiographically in 10 patients (2.6%). There were no significant differences between the patients with or without SAT in terms of patient characteristics, Killip classification on admission, or stent diameter, nor were there significant differences between the 2 groups in terms of left ventricular function soon after stenting (left ventricular ejection fraction) or end-diastolic volume index. The plasma levels of both hs-CRP and SAA were significantly higher in the SAT patients than in the others (hs-CRP: 6.7+/-6.7 mg/dl vs 3.3+/-3.8 mg/dl, p=0.007; SAA: 699+/-812 mug/dl vs 208+/-273 mug/dl, p<0.0001). Multivariate analysis identified SAA as an independent predictor of SAT (risk ratio: 4.9, 95% confidence interval: 1.7-14.9, p<0.05).

CONCLUSION

In patients with AMI who are treated with primary coronary stenting, inflammation may be closely related to SAT, for which SAA is a useful predictor.

Elevated Plaque Temperature in Non-Culprit De Novo Atheromatous Lesions of Patients With Acute Coronary Syndromes

OBJECTIVES

We investigated whether there is increased temperature in non-culprit lesions, and the correlation of clinical syndrome with heat production of non-culprit lesions.

BACKGROUND

There is a controversy regarding whether there is widespread inflammation involving non-culprit lesions, or whether inflammatory involvement is limited to the culprit lesion. Coronary thermography assesses the local inflammatory involvement in atherosclerotic lesions.

METHODS

We included patients suffering from stable angina (SA) or acute coronary syndrome (ACS). All patients had two or more angiographically detectable lesions at different arteries. Culprit lesions should be identified in all patients. Patients with chronic total occlusions and multiple significant lesions at the culprit vessel were excluded. We measured at each non-culprit lesion the temperature difference (DeltaT) between the atherosclerotic plaque and the proximal vessel wall temperature.

RESULTS

The study population included 42 patients: 23 with SA, 19 with ACS. The DeltaT in non-culprit lesions was 0.08 +/- 0.07 degrees C. Patients with ACS had a higher temperature difference in non-culprit lesions compared with patients with SA (ACS 0.11 +/- 0.08 degrees C vs. SA 0.05 +/- 0.06 degrees C; p < 0.01). The mean value of DeltaT in non-culprit lesions was higher in the untreated group compared with the treated group with statins (0.11 +/- 0.10 degrees C vs. 0.06 +/- 0.05 degrees C; p = 0.05).

CONCLUSIONS

The results of this study show that heat is generated in non-culprit lesions. Moreover, in patients with ACS, temperature difference is increased compared with patients with stable angina.

Prognostic value of serum amyloid A protein in patients with acute myocardial infarction

BACKGROUND

The relationship between plasma levels of serum amyloid A protein (SAA) concentrations and clinical course (including mortality) was investigated in patients with acute myocardial infarction (AMI).

METHODS AND RESULTS

The study enrolled 280 consecutive AMI patients who were admitted within 10 h of onset and were successfully reperfused by primary percutaneous coronary intervention. Plasma SAA concentrations were evaluated at 24 h after onset. The threshold of the upper quintile (325 mug/dl) was used to divide patients into 2 groups: either a high SAA (H group: > or =325 mug/dl; n=56) or low SAA (L group: <325 microg/dl; n=224). (I) Left ventricular (LV) ejection fraction in the chronic phase was significantly less in the H group than in the L group (52+/-14% vs 57+/-13%, p=0.03). (II) There were significantly more major complications in the H group than in the L group (cardiac rupture: p=0.0007, cardiogenic shock: p<0.0001; subacute thrombosis: p=0.0007; cardiac death: p=0.0003). (III) Multivariate analysis identified SAA as an independent predictor of 6-month mortality in AMI patients (risk ratio: 5.8, 95%confidence interval: 1.3-27.7, p=0.03).

CONCLUSIONS

In the setting of AMI, plasma SAA concentrations may be closely related to LV systolic dysfunction and poor patient outcomes, including mortality.

In vivo temperature heterogeneity is associated with plaque regions of increased MMP-9 activity

AIMS

Plaque rupture has been associated with a high matrix metalloproteinase (MMP) activity. Recently, regional temperature variations have been observed in atherosclerotic plaques in vivo and ascribed to the presence of macrophages. As macrophages are a major source of MMPs, we examined whether regional temperature changes are related to local MMP activity and macrophage accumulation.

METHODS AND RESULTS

Plaques were experimentally induced in rabbit (n=11) aortas, and at the day of sacrifice, a pull-back was performed with a thermography catheter. Hot (n=10), cold (n=10), and reference (n=11) regions were dissected and analysed for smooth muscle cell (SMC), lipids (L), collagen (COL), and macrophage (MPhi) cell densities (%); a vulnerability index (VI) was calculated as VI=MPhi+L/(SMC+COL). In addition, accumulation and activity of MMP-2 and MMP-9 were determined with zymography. Ten hot regions were identified with an average temperature of 0.40+/-0.03 degrees C (P<0.05 vs. reference) and 10 cold regions with 0.07+/-0.03 degrees C (P<0.05 vs. hot). In the hot regions, a higher macrophage density (173%), less SMC density (77%), and a higher VI (100%) were identified. In addition, MMP-9 (673%) activity was increased. A detailed regression analysis revealed that MMP-9 predicted hot regions better than macrophage accumulation alone.

CONCLUSION

In vivo temperature measurements enable to detect plaques that contain more macrophages, less SMCs, and a higher MMP-9 activity.

Increased heat generation from atherosclerotic plaques in patients with type 2 diabetes: an increased local inflammatory activation

OBJECTIVE

Patients with coronary artery disease (CAD) and diabetes show increased inflammatory activation. Thermography detects local inflammatory involvement as heat generation. The aim of this study was to investigate whether patients with CAD and diabetes have increased local heat generation compared with nondiabetic patients.

RESEARCH DESIGN AND METHODS

We enrolled patients undergoing percutaneous coronary interventions: 45 diabetic patients and 63 nondiabetic patients, serving as the control group, matched for age, type of clinical syndrome, statin and aspirin intake, and angiographic stenosis (%). Coronary thermography was performed, and temperature difference (DeltaT) between the atherosclerotic plaque and the proximal vessel wall was measured.

RESULTS

Patients with diabetes had increased temperature difference compared with nondiabetic patients (DeltaT: 0.17 +/- 0.18 degrees C vs. 0.09 +/- 0.02 degrees C, P = 0.01). Twenty-one diabetic and 22 nondiabetic patients suffered from acute coronary syndromes (ACSs) (P = 0.22). Patients with diabetes and ACSs had increased temperature difference compared with nondiabetic patients with ACSs (DeltaT: 0.29 +/- 0.31 degrees C vs. 0.15 +/- 0.21 degrees C, P = 0.02), which is the same as patients with diabetes and chronic stable angina (DeltaT: 0.09 +/- 0.08 degrees C vs. 0.05 +/- 0.04 degrees C, P = 0.006). Twenty-three diabetic and 30 nondiabetic patients were under therapy with statins (P = 0.72). Patients with diabetes under statins had lower temperature difference compared with untreated patients (DeltaT: 0.11 +/- 0.12 degrees C vs. 0.22 +/- 0.21 degrees C, P = 0.02), which is the same as nondiabetic patients under statins (DeltaT: 0.05 +/- 0.04 degrees C vs. 0.13 +/- 0.18 degrees C, P = 0.01).

CONCLUSIONS

Patients with diabetes have increased temperature difference compared with nondiabetic patients. Patients with diabetes under statins showed decreased temperature difference compared with untreated patients, suggesting that statins have a favorable effect in patients with diabetes and CAD.

Detection of increased temperature of the culprit lesion after recent myocardial infarction: the favorable effect of statins

BACKGROUND

Increased thermal heterogeneity has been demonstrated in atherosclerotic plaques, with the higher temperature recorded in acute myocardial infarction (MI). Dietary or treatment interventions reduce heat production. The purpose of the present study was to investigate whether increased plaque temperature is maintained for a prolonged period after MI and the role of statin administration.

METHODS

We enrolled 55 patients, 29 with recent MI and 26 with chronic stable angina (CSA). Total cholesterol, C-reactive protein (CRP), interleukin-6 (IL-6) and soluble adhesion molecules were measured in the study population. All patients underwent coronary plaque temperature measurements. Temperature difference (DeltaT) was designated as the temperature of the culprit atherosclerotic plaque minus the temperature of the proximal healthy vessel wall.

RESULTS

Under treatment with statins were 19 patients with recent MI and 14 with CSA. In patients with recent MI DeltaT was 0.19 +/- 0.18 degrees C, while in patients with CSA was 0.10 +/- 0.08 degrees C (P = .03). Patients treated with statins had lower DeltaT compared to untreated patients (0.10 +/- 0.11 versus 0.20 +/- 0.18 degrees C, P = .01). Treated patients with recent MI had similar DeltaT compared to CSA patients treated with statins (0.13 +/- 0.13 versus 0.07 +/- .06 degrees C, P = .14), while untreated patients with recent MI had substantially increased DeltaT compared to untreated patients with CSA (0.28 +/- 0.22 versus 0.14 +/- 0.10 degrees C, P = .04). DeltaT was positively correlated with CRP (R = 0.50, P < .01), IL-6 (R = 0.58, P < .01), and intercellular adhesion molecule-1 (R = 0.40, P = .03) levels.

CONCLUSION

Increased plaque temperature is observed for an extended period after myocardial infarction, indicating that the inflammatory process is sustained after plaque rupture. Statins have a beneficial effect after MI on plaque temperature.

Finding Vulnerable Atherosclerotic Plaques

Techniques to identify and treat vulnerable plaques are the focus of enormous research. Some have questioned the benefit of locating individual vulnerable plaque in a multifocal disease. On autopsy, it is found that most deaths are caused by thrombotic occlusion of a single plaque; simultaneous occurrence of 2 occlusive thrombi is rare, but a second vulnerable plaque is common, particularly in acute myocardial infarction (MI). Angiographic progression is poorly predicted by risk factors, and angiographic progression is a weak predictor of MI or death. Intravascular ultrasonography (intravascular ultrasound [IVUS]) studies find plaque rupture in most MI patients and in approximately half with unstable angina, but in only a minority of patients with stable angina. IVUS identifies a second vulnerable plaque in many patients with unstable angina, and in most MI patients. Angioscopy reveals a very low incidence of a second vulnerable plaque compared with angiography and IVUS, but identifies additional yellow plaques in many patients with stable angina and in most patients with unstable angina or MI. Using thermography catheters and a temperature cutoff of 0.1 degrees C, approximately half the patients with stable angina have >1 hot lesion; however, if the cutoff is 0.2 degrees C, only approximately 15% have a second hot lesion. New imaging techniques may detect additional characteristics of plaques and new predictive models may assess the risk of vulnerable plaques and patients. This approach enables physicians to "buy time" by application of local therapies until systemic therapies stabilize plaques. This may also reduce the risk in subjects in whom systemic therapies do not work.

Does aggressive statin therapy offer improved cholesterol-independent benefits compared to conventional statin treatment?

There is currently intense research interest in the properties of HMG-CoA reductase inhibitors (statins) beyond their well-documented lipid-lowering action. Studies have consistently demonstrated that administration of statin therapy decreases levels of the inflammatory marker C-reactive protein (CRP), a marker associated with an increased risk of cardiovascular events. This effect appears to be independent of the extent of reduction in total or LDL-cholesterol. Statins also appear to improve endothelial dysfunction by increasing endothelium-dependent vasodilatation. There is also evidence that statins inhibit fibrin formation and thrombus development, an effect that which would be clinically beneficial following plaque fissure or rupture. Early preclinical and clinical evidence suggests that there are quantitative differences between statin regimens in terms of their cholesterol-independent properties. Trials comparing equipotent doses of different statins, based on lipid-lowering efficacy, have not reported any differences in cholesterol-independent properties. However, the current evidence base indicates that more aggressive statin regimens are associated with an enhanced anti-inflammatory effect. Intensive lipid-lowering using statin therapy generates a greater reduction in mortality than standard lipid management, and it is possible that enhanced cholesterol-independent effects may account for some of this excess benefit.

Inflammation as a cardiovascular risk factor

Inflammation occurs in the vasculature as a response to injury, lipid peroxidation, and perhaps infection. Various risk factors, including hypertension, diabetes, and smoking, are amplified by the harmful effects of oxidized low-density-lipoprotein cholesterol, initiating a chronic inflammatory reaction, the result of which is a vulnerable plaque, prone to rupture and thrombosis. Epidemiological and clinical studies have shown strong and consistent relationships between markers of inflammation and risk of future cardiovascular events. Inflammation can potentially be detected locally by imaging techniques as well as emerging techniques, such as identification of temperature or pH heterogeneity. It can be detected systemically by measurement of inflammatory markers. Of these, the most reliable and accessible for clinical use is currently high-sensitivity C-reactive protein. A combination of methods may provide the best identification of persons at risk for cardiovascular events who would benefit from treatment. In randomized, controlled trials, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, in the form of statins, have been shown to provide effective therapy for lowering CRP, in conjunction with their lipid-lowering effects. Although the magnitude of risk reduction associated with statin use appears to be largest for those with the highest serum levels of CRP, whether CRP reduction per se lowers cardiovascular risk is unknown.

Vasa vasorum in plaque angiogenesis, metabolic syndrome, type 2 diabetes mellitus, and atheroscleropathy: a malignant transformation

BACKGROUND

Vascularization is an exciting and complex mechanism involving angiogenesis and arteriogenesis. The metabolic syndrome (MS) and type 2 diabetes mellitus (T2DM) are associated with multiple metabolic toxicities, which result in reactive oxygen species (ROS) due to an elevated tension of oxidative-redox stress and an accelerated atherosclerosis termed atheroscleropathy.

RESULTS

This atheroscleropathy is associated with accelerated angiogenesis within the vulnerable, thin-cap fibro-atheroma, prone to rupture resulting in acute coronary syndromes (ACS). The resulting intimopathy with its neovascularization due to angiogenesis of the adventitial vasa vasorum (Vv) is prone to intraplaque hemorrhage (IPH). These IPH are associated with destabilization of the vulnerable plaques resulting in plaque erosion and plaque rupture resulting in ACS. In atheroscleropathy the adventitial Vv invades the plaque in a malignant-like fashion and concurrently is associated with chronic inflammation, as macrophages are being deposited within the shoulder regions of these vulnerable plaques. These angiogenic Vv provide a custom delivery vascular network for multiple detrimental substrates, which further accelerates the growth of these vulnerable plaques and atheroscleropathy. There exists a vascularization paradox in MS and T2DM, in that, angiogenesis within the plaque is induced and arteriogenesis is impaired.

CONCLUSION

This review will attempt to provide a database of knowledge regarding the vascularization process (angiogenesis and arteriogenesis) and its mechanisms to better understand the increased cardiovascular risk and the increased morbidity and mortality associated with MS and T2DM.

Inflammation-sensitive plasma proteins and incidence of myocardial infarction in men with low cardiovascular risk

OBJECTIVE

Myocardial infarction (MI) is sometimes experienced by individuals without any traditional risk factor. This prospective study explored whether incidence of MI in nonsmoking, nondiabetic men with normal blood pressure and serum lipids is related to inflammation-sensitive plasma proteins (ISPs).

METHODS AND RESULTS

Five ISPs (alpha1-antitrypsin, haptoglobin, ceruloplasmin, fibrinogen, orosomucoid) were analyzed in 6075 men, 47+/-3.6 years old. A low-risk group (no traditional risk factor, n=1108) and a high-risk group (> or =2 major risk factors, n=1011) were defined. Incidence of MI (n=227) was monitored over 18.1+/-4.3 years of follow-up. In the low-risk group, the age-adjusted relative risks (RRs) were 1.00 (reference), 1.9 (95% CI, 0.8 to 4.2), 1.8 (95% CI, 0.6 to 5.4), and 2.9 (95% CI, 1.05 to 8.1), respectively, for men with 0, 1, 2 and > or =3 ISPs in the top quartile (trend: P=0.03). In this group, the increased risk was observed only after > or =10 years of follow-up. In the high-risk group, the age-adjusted RRs were 1.00, 1.4 (95% CI, 0.9 to 2.2), 1.9 (95% CI, 1.2 to 3.1), and 2.0 (95% CI, 1.3 to 3.1), respectively, for men with 0, 1, 2, and > or =3 ISPs in the top quartile (trend: P=0.0004).

CONCLUSIONS

Incidence of MI in nonsmoking, nondiabetic men with normal blood pressure and lipids was related to ISPs. The causes for this relationship remain to be explored.

Bovine growth hormone-transgenic mice have major alterations in hepatic expression of metabolic genes

Transgenic mice overexpressing growth hormone (GH) have been extensively used to study the chronic effects of elevated serum levels of GH. GH is known to have many acute effects in the liver, but little is known about the chronic effects of GH overexpression on hepatic gene expression. Therefore, we used DNA microarray to compare gene expression in livers from bovine GH (bGH)-transgenic mice and littermates. Hepatic expression of peroxisome proliferator-activated receptor-alpha (PPARalpha) and genes involved in fatty acid activation, peroxisomal and mitochondrial beta-oxidation, and production of ketone bodies was decreased. In line with this expression profile, bGH-transgenic mice had a reduced ability to form ketone bodies in both the fed and fasted states. Although the bGH mice were hyperinsulinemic, the expression of sterol regulatory element-binding protein (SREBP)-1 and most lipogenic enzymes regulated by SREBP-1 was reduced, indicating that these mice are different from other insulin-resistant models with respect to expression of SREBP-1 and its downstream genes. This study also provides several candidate genes for the well-known association between elevated GH levels and cardiovascular disease, e.g., decreased expression of scavenger receptor class B type I, hepatic lipase, and serum paraoxonase and increased expression of serum amyloid A-3 protein. We conclude that bGH-transgenic mice display marked changes in hepatic genes coding for metabolic enzymes and suggest that GH directly or indirectly regulates many of these hepatic genes via decreased expression of PPARalpha and SREBP-1.