Evaluation of Large-Scale Proteomics for Prediction of Cardiovascular Events.

Importance: Whether protein risk scores derived from a single plasma sample could be useful for risk assessment for atherosclerotic cardiovascular disease (ASCVD), in conjunction with clinical risk factors and polygenic risk scores, is uncertain. Objective: To develop protein risk scores for ASCVD risk prediction and compare them to clinical risk factors and polygenic risk scores in primary and secondary event populations. Design, Setting, and Participants: The primary analysis was a retrospective study of primary events among 13 540 individuals in Iceland (aged 40-75 years) with proteomics data and no history of major ASCVD events at recruitment (study duration, August 23, 2000 until October 26, 2006; follow-up through 2018). We also analyzed a secondary event population from a randomized, double-blind lipid-lowering clinical trial (2013-2016), consisting of individuals with stable ASCVD receiving statin therapy and for whom proteomic data were available for 6791 individuals. Exposures: Protein risk scores (based on 4963 plasma protein levels and developed in a training set in the primary event population); polygenic risk scores for coronary artery disease and stroke; and clinical risk factors that included age, sex, statin use, hypertension treatment, type 2 diabetes, body mass index, and smoking status at the time of plasma sampling. Main Outcomes and Measures: Outcomes were composites of myocardial infarction, stroke, and coronary heart disease death or cardiovascular death. Performance was evaluated using Cox survival models and measures of discrimination and reclassification that accounted for the competing risk of non-ASCVD death. Results: In the primary event population test set (4018 individuals [59.0% women]; 465 events; median follow-up, 15.8 years), the protein risk score had a hazard ratio (HR) of 1.93 per SD (95% CI, 1.75 to 2.13). Addition of protein risk score and polygenic risk scores significantly increased the C index when added to a clinical risk factor model (C index change, 0.022 [95% CI, 0.007 to 0.038]). Addition of the protein risk score alone to a clinical risk factor model also led to a significantly increased C index (difference, 0.014 [95% CI, 0.002 to 0.028]). Among White individuals in the secondary event population (6307 participants; 432 events; median follow-up, 2.2 years), the protein risk score had an HR of 1.62 per SD (95% CI, 1.48 to 1.79) and significantly increased C index when added to a clinical risk factor model (C index change, 0.026 [95% CI, 0.011 to 0.042]). The protein risk score was significantly associated with major adverse cardiovascular events among individuals of African and Asian ancestries in the secondary event population. Conclusions and Relevance: A protein risk score was significantly associated with ASCVD events in primary and secondary event populations. When added to clinical risk factors, the protein risk score and polygenic risk score both provided statistically significant but modest improvement in discrimination.

Effect of Evolocumab on Coronary Plaque Phenotype and Burden in Statin-Treated Patients Following Myocardial Infarction.

BACKGROUND: The proprotein convertase subtilisin kexin type-9 inhibitor evolocumab produced coronary atheroma regression in statin-treated patients. OBJECTIVES: The purpose of this study was to determine the effect of evolocumab on optical coherence tomography (OCT) measures of plaque composition. METHODS: Patients with a non-ST-segment elevation myocardial infarction were treated with monthly evolocumab 420 mg (n = 80) or placebo (n = 81) for 52 weeks. Patients underwent serial OCT and intravascular ultrasound imaging within a matched arterial segment of a nonculprit vessel. The primary analysis determined the change in the minimum fibrous cap thickness and maximum lipid arc throughout the imaged arterial segment. Additional analyses determined changes in OCT features in lipid-rich plaque regions and plaque burden. Safety and tolerability were evaluated. RESULTS: Among treated patients (age 60.5 ± 9.6 years; 28.6% women; low-density lipoprotein cholesterol [LDL-C], 141.3 ± 33.1 mg/dL), 135 had evaluable imaging at follow-up. The evolocumab group achieved lower LDL-C levels (28.1 vs 87.2 mg/dL; P < 0.001). The evolocumab group demonstrated a greater increase in minimum fibrous cap thickness (+42.7 vs +21.5 µm; P = 0.015) and decrease in maximum lipid arc (-57.5o vs. -31.4o; P = 0.04) and macrophage index (-3.17 vs -1.45 mm; P = 0.04) throughout the arterial segment. Similar benefits of evolocumab were observed in lipid-rich plaque regions. Greater regression of percent atheroma volume was observed with evolocumab compared with placebo (-2.29% ± 0.47% vs -0.61% ± 0.46%; P = 0.009). The groups did not differ regarding changes in microchannels or calcium. CONCLUSIONS: The combination of statin and evolocumab after a non-ST-segment elevation myocardial infarction produces favorable changes in coronary atherosclerosis consistent with stabilization and regression. This demonstrates a potential mechanism for the improved clinical outcomes observed achieving very low LDL-C levels following an acute coronary syndrome. (Imaging of Coronary Plaques in Participants Treated With Evolocumab; NCT03570697).

Assessment of Omecamtiv Mecarbil for the Treatment of Patients With Severe Heart Failure: A Post Hoc Analysis of Data From the GALACTIC-HF Randomized Clinical Trial.

Importance: Heart failure with reduced ejection fraction is a progressive clinical syndrome, and many patients' condition worsen over time despite treatment. Patients with more severe disease are often intolerant of available medical therapies. Objective: To evaluate the efficacy and safety of omecamtiv mecarbil for the treatment of patients with severe heart failure (HF) enrolled in the Global Approach to Lowering Adverse Cardiac Outcomes Through Improving Contractility in Heart Failure (GALACTIC-HF) randomized clinical trial. Design, Setting, and Participants: The GALACTIC-HF study was a global double-blind, placebo-controlled phase 3 randomized clinical trial that was conducted at multiple centers between January 2017 and August 2020. A total of 8232 patients with symptomatic HF (defined as New York Heart Association symptom class II-IV) and left ventricular ejection fraction of 35% or less were randomized to receive omecamtiv mecarbil or placebo and followed up for a median of 21.8 months (range, 15.4-28.6 months). The current post hoc analysis evaluated the efficacy and safety of omecamtiv mecarbil therapy among patients classified as having severe HF compared with patients without severe HF. Severe HF was defined as the presence of all of the following criteria: New York Heart Association symptom class III to IV, left ventricular ejection fraction of 30% or less, and hospitalization for HF within the previous 6 months. Interventions: Participants were randomized at a 1:1 ratio to receive either omecamtiv mecarbil or placebo. Main Outcomes and Measures: The primary end point was time to first HF event or cardiovascular (CV) death. Secondary end points included time to CV death and safety and tolerability. Results: Among 8232 patients enrolled in the GALACTIC-HF clinical trial, 2258 patients (27.4%; mean [SD] age, 64.5 [11.6] years; 1781 men [78.9%]) met the specified criteria for severe HF. Of those, 1106 patients were randomized to the omecamtiv mecarbil group and 1152 to the placebo group. Patients with severe HF who received omecamtiv mecarbil experienced a significant treatment benefit for the primary end point (hazard ratio [HR], 0.80; 95% CI, 0.71-0.90), whereas patients without severe HF had no significant treatment benefit (HR, 0.99; 95% CI, 0.91-1.08; P = .005 for interaction). For CV death, the results were similar (HR for patients with vs without severe HF: 0.88 [95% CI, 0.75-1.03] vs 1.10 [95% CI, 0.97-1.25]; P = .03 for interaction). Omecamtiv mecarbil therapy was well tolerated in patients with severe HF, with no significant changes in blood pressure, kidney function, or potassium level compared with placebo. Conclusions and Relevance: In this post hoc analysis of data from the GALACTIC-HF clinical trial, omecamtiv mecarbil therapy may have provided a clinically meaningful reduction in the composite end point of time to first HF event or CV death among patients with severe HF. These data support a potential role of omecamtiv mecarbil therapy among patients for whom current treatment options are limited. Trial Registration: ClinicalTrials.gov Identifier: NCT02929329.

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).

Designing, Conducting, Monitoring, and Analyzing Data from Pragmatic Randomized Clinical Trials: Proceedings from a Multi-stakeholder Think Tank Meeting.

In late 2018, the Food and Drug Administration (FDA) outlined a framework for evaluating the possible use of real-world evidence (RWE) to support regulatory decision-making. This framework was created to facilitate studies that would generate high-quality RWE, including pragmatic clinical trials (PCTs), which are randomized trials designed to inform clinical or policy decisions by assessing the real-world effectiveness of an intervention. There is general agreement among experts that the use of existing healthcare and patient-generated data holds promise for making randomized trials more efficient, less costly, and more generalizable. Yet the benefits of relying on real-world data sources must be weighed against difficulties with ensuring data integrity and completeness. Additionally, appropriately monitoring patient safety in randomized trials of new drugs using healthcare system data that might not be available in real time can be quite difficult. Recognizing that these and other concerns are critical to the development and acceptability of PCTs, a group of stakeholders from academia, industry, professional organizations, regulatory bodies, government agencies, and patient advocates discussed a path forward for PCT growth and sustainability at a think tank meeting entitled "Monitoring and Analyzing Data from Pragmatic Streamlined Randomized Clinical Trials," which took place in January 2019 (Washington, DC). The goals of this meeting were to: (1) evaluate study design and methodological options specific to PCTs that have the potential to yield high-quality evidence; (2) discuss best practices to ensure data quality in PCTs; and (3) identify appropriate methods for study monitoring. Proceedings from the think tank meeting are summarized in this manuscript.

A Comparison of Ezetimibe and Evolocumab for Atherogenic Lipid Reduction in Four Patient Populations: A Pooled Efficacy and Safety Analysis of Three Phase 3 Studies.

INTRODUCTION: Clinicians, payers, guideline committees, and policymakers support the use of high-intensity statins in patients at high risk for complications of cardiovascular disease (CVD). Guidelines and recommendations provide guidance on next steps for patients with inadequate low-density lipoprotein cholesterol (LDL-C) control on maximally tolerated statin or for those who are statin-intolerant. Ezetimibe and evolocumab improve CV outcomes when added to statins in high-CV-risk populations. The aim of the study was to compare evolocumab and ezetimibe for lipid-lowering efficacy and safety. METHODS: We summarized data from 1427 patients from three phase 3 evolocumab studies comparing double-blinded evolocumab vs. ezetimibe. These studies evaluated four distinct populations: those free of CVD receiving each agent as monotherapy, patients with CVD receiving add-on therapy to low- or high-intensity statin, and statin-intolerant patients. Lipid efficacy and safety were reported at week 12. RESULTS: Across the studies, evolocumab reduced LDL-C by a mean 55-61% from baseline to week 12; ezetimibe lowered LDL-C by 18-20% from baseline (mean difference = 38-43% favoring evolocumab; p < 0.0001). This corresponded to absolute reductions in LDL-C of 60-104 mg/dL with evolocumab vs. 17-35 mg/dL with ezetimibe. Evolocumab also significantly improved other lipids and led to a higher percentage of patients achieving LDL-C goals vs. ezetimibe. Adverse events and discontinuation rates (oral and parenteral therapy) were balanced across groups, suggesting good tolerance and acceptance of both treatments. CONCLUSIONS: Evolocumab outperformed ezetimibe in efficacy and lipid goal attainment. Both products demonstrated good safety/tolerability. These data may help guide access decisions for high-risk patients with inadequate treatment response or intolerance to statin therapy.

Comparison of myocardial tagging and feature tracking in patients with severe aortic stenosis.

BACKGROUND AND AIM OF THE STUDY: Transcatheter aortic valve implantation (TAVI) has become an effective treatment for severe aortic stenosis (AS) in patients considered to be at high surgical risk. However, data relating to myocardial function and deformation in these patients are rare. Cardiovascular magnetic resonance (CMR) tagging has been established as non-invasive technique for the accurate measurement of myocardial motion. However, additional tagging datasets are necessary and the post-processing procedure is time-consuming. Recently, the novel technique of feature tracking (FT) was introduced, with which myocardial strain can be derived directly from balanced steady-state free precession (bSSFP) cine sequences. The study aim was to compare tagging with FT in patients with high-grade AS and who had been considered for TAVI. METHODS: Thirty patients with severe AS underwent cardiac magnetic resonance imaging at 1.5 T (Philips Achieva). A stack of serial short-axis slices was used to assess left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), and LV mass and function. TomTec 2D Cardiac Performance Analysis software was used to derive myocardial deformation parameters from three short-axis cine views (basal, medial and apical levels) using bSSFP. All patients also underwent myocardial tagging on identical short-axis views, and data acquired from FT and tagging were compared. RESULTS: The mean left ventricular ejection fraction (LVEF), LVEDV and LVESV (57 ± 14%, 158 ± 58 ml, and 74 ± 48 ml, respectively) were all normal. All patients demonstrated concentric hypertrophy of the left ventricle with an increased basal septal thickness (16 ± 3 mm), LV mass (126 ± 40 g) and indexed LV mass (68 ± 23 g/m2, papillary muscles excluded). Bland-Altman analysis revealed a reasonable agreement between basal and medial circumferential strain (cc), and a good correlation was observed between tagging and FT for the derived basal and medial cc (Pearson's correlation coefficient 0.83 for basal, 0.74 for medial). Basal rotation was impaired compared to previous studies in patients with AS, but medial and apical rotations were comparable. The apical peak diastolic rotation velocity was faster compared to earlier analyses. Rotation, peak systolic and end-diastolic rotation velocity did not demonstrate any correlation or acceptable agreement between FT and tagging. The inter-observer agreement as assessed by the intra- class correlation coefficient for FT showed good results for the cc (basal 0.94, medial 0.83, apical 0.75). CONCLUSION: To the present authors' knowledge, this is the first study to assess myocardial motion using tagging and FT in patients with AS prior to TAVI. A reasonable agreement was found for the basal and medial cc between both techniques. Estimated cc-values using FT were systematically higher than those with tagging, but this might have been due to the different techniques employed. Although FT is a promising method to assess cc, further studies including the evaluation of standard values--and investigations with different diseases are necessary.

Reproducibility of small animal cine and scar cardiac magnetic resonance imaging using a clinical 3.0 tesla system.

BACKGROUND: To evaluate the inter-study, inter-reader and intra-reader reproducibility of cardiac cine and scar imaging in rats using a clinical 3.0 Tesla magnetic resonance (MR) system. METHODS: Thirty-three adult rats (Sprague-Dawley) were imaged 24 hours after surgical occlusion of the left anterior descending coronary artery using a 3.0 Tesla clinical MR scanner (Philips Healthcare, Best, The Netherlands) equipped with a dedicated 70 mm solenoid receive-only coil. Left-ventricular (LV) volumes, mass, ejection fraction and amount of myocardial scar tissue were measured. Intra-and inter-observer reproducibility was assessed in all animals. In addition, repeat MR exams were performed in 6 randomly chosen rats within 24 hours to assess inter-study reproducibility. RESULTS: The MR imaging protocol was successfully completed in 32 (97%) animals. Bland-Altman analysis demonstrated high intra-reader reproducibility (mean bias%: LV end-diastolic volume (LVEDV), -1.7%; LV end-systolic volume (LVESV), -2.2%; LV ejection fraction (LVEF), 1.0%; LV mass, -2.7%; and scar mass, -1.2%) and high inter-reader reproducibility (mean bias%: LVEDV, 3.3%; LVESV, 6.2%; LVEF, -4.8%; LV mass, -1.9%; and scar mass, -1.8%). In addition, a high inter-study reproducibility was found (mean bias%: LVEDV, 0.1%; LVESV, -1.8%; LVEF, 1.0%; LV mass, -4.6%; and scar mass, -6.2%). CONCLUSIONS: Cardiac MR imaging of rats yielded highly reproducible measurements of cardiac volumes/function and myocardial infarct size on a clinical 3.0 Tesla MR scanner system. Consequently, more widely available high field clinical MR scanners can be employed for small animal imaging of the heart e.g. when aiming at serial assessments during therapeutic intervention studies.

Local delivery of IL-2 reduces atherosclerosis via expansion of regulatory T cells.

OBJECTIVE: Recent studies indicate that regulatory T cells (Tregs) attenuate murine atherosclerosis. Since interleukin (IL)-2 induces Tregs proliferation, we tested the impact of L19-IL2, a fusion antibody specific to extra-domain B of fibronectin (ED-B) containing an active human IL-2 molecule, in experimental atherosclerosis. METHODS AND RESULTS: L19-IL2 or appropriate controls were given intravenously to 6 month old Western diet-fed apoE(-/-) mice on day 1, 3, and 5. Human IL-2 was detected on day 7 within atherosclerotic plaques of L19-IL2-treated mice, and magnetic resonance imaging of the plaques showed a significant adventitial gadolinium enhancement on day 7 and 13, suggesting microvascular leakage as a result of the pharmacodynamic activity of L19-IL2. Treatment with L19-IL2 significantly reduced the size of pre-established atherosclerotic plaques at the thoracic aorta (Sudan III stained area) and in the aortic root area (microscopic, morphometric analysis) on day 7 as compared to controls (L19, D1.3-IL2, NaCl) as well as compared to baseline (day 0). Tregs markers Foxp3 and CTLA4 were highly increased in plaques after L19-IL2 treatment compared to controls (p<0.01), whereas the macrophage marker Mac3 was significantly reduced (p<0.03). Co-treatment with IL-2-receptor blocking antibody PC61 abrogated L19-IL2-induced plaque reduction compared with IgG control (p<0.03). CONCLUSION: L19-IL2 delivers functional IL-2 to pre-established atherosclerotic plaques of WD-fed apoE(-/-) mice resulting in significant plaque size reduction mediated by local Tregs.

The role of dobutamine stress cardiovascular magnetic resonance in the clinical management of patients with suspected and known coronary artery disease.

BACKGROUND: Recent studies have demonstrated the consistently high diagnostic and prognostic value of dobutamine stress cardiovascular magnetic resonance (DCMR). The value of DCMR for clinical decision making still needs to be defined. Hence, the purpose of this study was to assess the utility of DCMR regarding clinical management of patients with suspected and known coronary artery disease (CAD) in a routine setting. METHODS AND RESULTS: We prospectively performed a standard DCMR examination in 1532 consecutive patients with suspected and known CAD. Patients were stratified according to the results of DCMR: DCMR-positive patients were recommended to undergo invasive coronary angiography and DCMR-negative patients received optimal medical treatment. Of 609 (40%) DCMR-positive patients coronary angiography was performed in 478 (78%) within 90 days. In 409 of these patients significant coronary stenoses ≥ 50% were present (positive predictive value 86%). Of 923 (60%) DCMR-negative patients 833 (90%) received optimal medical therapy. During a mean follow-up period of 2.1 ± 0.8 years (median: 2.1 years, interquartile range 1.5 to 2.7 years) 8 DCMR-negative patients (0.96%) sustained a cardiac event.In 131 DCMR-positive patients who did not undergo invasive angiography, 20 patients (15%) suffered cardiac events. In 90 DCMR-negative patients (10%) invasive angiography was performed within 2 years (range 0.01 to 2.0 years) with 56 patients having coronary stenoses ≥ 50%. CONCLUSION: In a routine setting DCMR proved a useful arbiter for clinical decision making and exhibited high utility for stratification and clinical management of patients with suspected and known CAD.

Small animal Look-Locker inversion recovery (SALLI) for simultaneous generation of cardiac T1 maps and cine and inversion recovery-prepared images at high heart rates: initial experience.

PURPOSE: To develop a single magnetic resonance (MR) imaging approach for comprehensive assessment of cardiac function and tissue properties in small animals with high heart rates. MATERIALS AND METHODS: All animal studies were approved by the local animal care committee. Small animal Look-Locker inversion recovery (SALLI) was implemented on a clinical 3.0-T MR unit equipped with a 70-mm solenoid coil. SALLI combines a segmented, electrocardiographically gated, inversion recovery-prepared Look-Locker-type pulse sequence with a multimodal reconstruction framework. Temporal undersampling and radial nonbalanced steady-state free precession enabled acceleration of data acquisition and reduction of motion artifacts, respectively. Nine agarose gel phantoms were used to investigate different sequence settings. For in vivo studies, 10 Sprague-Dawley rats were evaluated to establish normal T1 values before and after injection of gadopentetate dimeglumine. Seven rats with surgically induced acute myocardial infarction were examined to test the feasibility of detecting myocardial injury. In vitro T1 behavior was studied with linear regression analysis, and in vivo T1 differences between infarcted and remote areas were tested by using the Wilcoxon signed rank test. RESULTS: Phantom studies demonstrated systematic behavior of the T1 measurements, and T1 error could be reduced to 1.3% ± 7.4 by using a simple linear correction algorithm. The pre- and postcontrast T1 of myocardium and blood showed narrow normal ranges. In the area of infarction, SALLI demonstrated hypokinesia (on cine images), myocardial edema (on precontrast T1 maps), and myocardial necrosis (on postcontrast T1 maps and late gadolinium enhancement images). CONCLUSION: An MR imaging method enabling simultaneous generation of cardiac T1 maps and cine and inversion recovery-prepared images at high heart rates is presented. SALLI allows for simultaneous and time-efficient assessment of cardiac T1 behavior, function, and late gadolinium enhancement at high heart rates.

Influence of left ventricular hypertrophy and geometry on diagnostic accuracy of wall motion and perfusion magnetic resonance during dobutamine stress.

BACKGROUND: The purpose of this study was to determine the influence of left ventricular (LV) hypertrophy and geometry on the diagnostic accuracy of wall motion and additional perfusion imaging during high-dose dobutamine/atropine stress magnetic resonance for the detection of coronary artery disease. METHODS AND RESULTS: Combined dobutamine stress magnetic resonance (DSMR)-wall motion and DSMR-perfusion imaging was performed in a single session in 187 patients scheduled for invasive coronary angiography. Patients were classified into 4 categories on the basis of LV mass (normal, ≤ 81 g/m(2) in men and ≤ 62 g/m(2) in women) and relative wall thickness (RWT) (normal, <0.45) as follows: normal geometry (normal mass, normal RWT), concentric remodeling (normal mass, increased RWT), concentric hypertrophy (increased mass, increased RWT), and eccentric hypertrophy (increased mass, normal RWT). Wall motion and perfusion images were interpreted sequentially, with observers blinded to other data. Significant coronary artery disease was defined as ≥ 70% stenosis. In patients with increased LV concentricity (defined by an RWT ≥ 0.45), sensitivity and accuracy of DSMR-wall motion were significantly reduced (63% and 73%, respectively; P<0.05) compared with patients without increased LV concentricity (90% and 88%, respectively; P<0.05). Although accuracy of DSMR-perfusion was higher than that of DSMR-wall motion in patients with concentric hypertrophy (82% versus 71%; P < 0.05), accuracy of DSMR-wall motion was superior to DSMR-perfusion (90% versus 85%; P < 0.05) in patients with eccentric hypertrophy. CONCLUSIONS: The accuracy of DSMR-wall motion is influenced by LV geometry. In patients with concentric remodeling and concentric hypertrophy, additional first-pass perfusion imaging during high-dose dobutamine stress improves the diagnostic accuracy for the detection of coronary artery disease.

High resolution magnetic resonance imaging in atherosclerotic mice treated with ezetimibe.

High field magnetic resonance imaging (MRI) was performed to investigate the long-term effect of ezetimibe (eze), a cholesterol resorption blocker, on atherosclerotic lesion formation in the thoracic aorta of apolipoprotein E-deficient mice (apoE ( -/- )) in comparison to wild type mice (WT). Fifteen-month-old apoE ( -/- ) (Western type diet), apoE ( -/-eze ) (Western type diet with eze) which received eze (5 mc/kg/day) continuously, and age-matched WT (normal chow) were studied using contrast-enhanced 3D turbo-spin-echo sequences (RARE factor 2) on a 7 Tesla scanner. Vessel parameters were analyzed in the aortic root (AR) and aortic arch (AA) and compared to those found in histology. Plasma cholesterol levels were reduced at 15 months by 71% (P < 0.01) in apoE ( -/-eze ) compared to apoE ( -/- ). Vessel wall thickness was increased in the AR and AA in apoE ( -/- ) by 189.1 and 147.2%, respectively compared to WT. ApoE ( -/-eze ) showed reduced wall thickness in the AR (127.4%) and AA (102.8%, both P < 0.05 vs. apoE ( -/- )). A significant increase in total aortic vessel area was determined in the AR and AA in apoE ( -/- ) by 134.7 and 118.3%, respectively, compared to WT. This effect was inhibited in apoE ( -/-eze ) (AR: 126.7%, AA: 86.4%, both P < 0.05). Histological analysis confirmed the effect of eze observed by MRI and demonstrated a significant correlation between the two techniques (P < 0.001). MRI demonstrates that ezetimibe significantly reduces atherosclerotic disease in apoE ( -/- ). MRI is therefore a useful technique to perform in vivo interventional studies in experimental atherosclerosis.

Angiotensin II type 2 receptor stimulation: a novel option of therapeutic interference with the renin-angiotensin system in myocardial infarction?

BACKGROUND: This study is the first to examine the effect of direct angiotensin II type 2 (AT(2)) receptor stimulation on postinfarct cardiac function with the use of the novel nonpeptide AT(2) receptor agonist compound 21 (C21). METHODS AND RESULTS: Myocardial infarction (MI) was induced in Wistar rats by permanent ligation of the left coronary artery. Treatment with C21 (0.01, 0.03, 0.3 mg/kg per day IP) was started 24 hours after MI and was continued until euthanasia (7 days after MI). Infarct size was assessed by magnetic resonance imaging, and hemodynamic measurements were performed via transthoracic Doppler echocardiography and intracardiac Millar catheter. Cardiac tissues were analyzed for inflammation and apoptosis markers with immunoblotting and real-time reverse transcription polymerase chain reaction. C21 significantly improved systolic and diastolic ventricular function. Scar size was smallest in the C21-treated rats. In regard to underlying mechanisms, C21 diminished MI-induced Fas-ligand and caspase-3 expression in the peri-infarct zone, indicating an antiapoptotic effect. Phosphorylation of the p44/42 and p38 mitogen-activated protein kinases, both involved in the regulation of cell survival, was strongly reduced after MI but almost completely rescued by C21 treatment. Furthermore, C21 decreased MI-induced serum monocyte chemoattractant protein-1 and myeloperoxidase as well as cardiac interleukin-6, interleukin-1beta, and interleukin-2 expression, suggesting an antiinflammatory effect. CONCLUSIONS: Direct AT(2) receptor stimulation may be a novel therapeutic approach to improve post-MI systolic and diastolic function by antiapoptotic and antiinflammatory mechanisms.