cGMP modulates hemin-mediated platelet death.

BACKGROUND AND AIMS: Hemolysis is a known risk factor for thrombosis resulting in critical limb ischemia and microcirculatory disturbance and organ failure. Intravasal hemolysis may lead to life-threatening complications due to uncontrolled thrombo-inflammation. Until now, conventional antithrombotic therapies failed to control development and progression of these thrombotic events. Thus, the pathophysiology of these thrombotic events needs to be investigated to unravel underlying pathways and thereby identify targets for novel treatment strategies. METHODS: Here we used classical experimental set-ups as well as high-end flow cytometry, metabolomics and lipidomic analysis to in-depth analyze the effects of hemin on platelet physiology and morphology. RESULTS: Hemin does strongly and swiftly induce platelet activation and this process is modulated by the sGC-cGMP-cGKI signaling axis. cGMP modulation also reduced the pro-aggregatory potential of plasma derived from patients with hemolysis. Furthermore, hemin-induced platelet death evokes distinct platelet subpopulations. Typical cell death markers, such as ROS, were induced by hemin-stimulation and the platelet lipidome was specifically altered by high hemin concentration. Specifically, arachidonic acid derivates, such as PGE2, TXB2 or 12-HHT, were significantly increased. Balancing the cGMP levels by modulation of the sGC-cGMP-cGKI axis diminished the ferroptotic effect of hemin. CONCLUSION: We found that cGMP modulates hemin-induced platelet activation and thrombus formation in vitro and cGMP effects hemin-mediated platelet death and changes in the platelet lipidome. Thus, it is tempting to speculate that modulating platelet cGMP levels may be a novel strategy to control thrombosis and critical limb ischemia in patients with hemolytic crisis.

Large-scale lipidomics profiling reveals characteristic lipid signatures associated with an increased cardiovascular risk.

BACKGROUND AND AIMS: Patients with cardiovascular disease (CVD) are at high risk to develop adverse events. The distinct risk of developing adverse cardiovascular (CV) events is not solely explained by traditional risk factors. Platelets are essentially involved in progression of CVD including coronary artery disease (CAD) and platelet hyperreactivity leads to development of adverse CV events. Alterations in the platelet lipidome lead to platelet hyperresponsiveness and thus might alter the individual risk profile. In this study, we investigate the platelet lipidome of CAD patients by untargeted lipidomics and elucidate alterations in the lipid composition of patients with adverse CV events. METHODS: We characterized the platelet lipidome in a large consecutive CAD cohort (n = 1057) by an untargeted lipidomics approach using liquid chromatography coupled to mass spectrometry. RESULTS: The platelet lipidome in this study identified 767 lipids and characteristic changes occurred in patients with adverse CV events. The most prominent upregulated lipids in patients with cardiovascular events primarily belong to the class of phospholipids and fatty acyls. Further, upregulated platelet lipids are associated with an increased cardiovascular or bleeding risk and independently associated with adverse events. In addition, alterations of the platelet lipidome are associated with modulation of in vitro platelet functions. CONCLUSIONS: Our results reveal that the composition of the platelet lipidome is altered in CVD patients with an increased cardiovascular risk and distinct platelet lipids may indicate adverse events. Results of this study may contribute to improved risk discrimination and classification for cardiovascular events in patients with CVD. Main findings of this study and hypothetical impact of altered platelet lipid signatures in patients with adverse cardiovascular events on platelet function and clinical outcome. LPE lysophosphatidylethanolamines, CAR acylcarnitines, FA fatty acids.

Pharmacological Inhibition of Glycoprotein VI- and Integrin α2ß1-Induced Thrombus Formation Modulated by the Collagen Type.

BACKGROUND: In secondary cardiovascular disease prevention, treatments blocking platelet-derived secondary mediators pose a risk of bleeding. Pharmacological interference of the interaction of platelets with exposed vascular collagens is an attractive alternative, with clinical trials ongoing. Antagonists of the collagen receptors, glycoprotein VI (GPVI), and integrin α2ß1, include recombinant GPVI-Fc dimer construct Revacept, 9O12 mAb based on the GPVI-blocking reagent Glenzocimab, Syk tyrosine-kinase inhibitor PRT-060318, and anti-α2ß1 mAb 6F1. No direct comparison has been made of the antithrombic potential of these drugs. METHODS: Using a multiparameter whole-blood microfluidic assay, we compared the effects of Revacept, 9O12-Fab, PRT-060318, or 6F1 mAb intervention with vascular collagens and collagen-related substrates with varying dependencies on GPVI and α2ß1. To inform on Revacept binding to collagen, we used fluorescent-labelled anti-GPVI nanobody-28. RESULTS AND CONCLUSION: In this first comparison of four inhibitors of platelet-collagen interactions with antithrombotic potential, we find that at arterial shear rate: (1) the thrombus-inhibiting effect of Revacept was restricted to highly GPVI-activating surfaces; (2) 9O12-Fab consistently but partly inhibited thrombus size on all surfaces; (3) effects of GPVI-directed interventions were surpassed by Syk inhibition; and (4) α2ß1-directed intervention with 6F1 mAb was strongest for collagens where Revacept and 9O12-Fab were limitedly effective. Our data hence reveal a distinct pharmacological profile for GPVI-binding competition (Revacept), GPVI receptor blockage (9O12-Fab), GPVI signaling (PRT-060318), and α2ß1 blockage (6F1 mAb) in flow-dependent thrombus formation, depending on the platelet-activating potential of the collagen substrate. This work thus points to additive antithrombotic action mechanisms of the investigated drugs.

Efficacy and Safety of Revacept, a Novel Lesion-Directed Competitive Antagonist to Platelet Glycoprotein VI, in Patients Undergoing Elective Percutaneous Coronary Intervention for Stable Ischemic Heart Disease: The Randomized, Double-blind, Placebo-Controlled ISAR-PLASTER Phase 2 Trial.

Importance: The assessment of new antithrombotic agents with a favorable safety profile is clinically relevant. Objective: To test the efficacy and safety of revacept, a novel, lesion-directed antithrombotic drug, acting as a competitive antagonist to platelet glycoprotein VI. Design, Setting, and Participants: A phase 2 randomized clinical trial; patients were enrolled from 9 centers in Germany from November 20, 2017, to February 27, 2020; follow-up ended on March 27, 2020. The study included patients with stable ischemic heart disease (SIHD) undergoing elective percutaneous coronary intervention (PCI). Interventions: Single intravenous infusion of revacept, 160 mg, revacept, 80 mg, or placebo prior to the start of PCI on top of standard antithrombotic therapy. Main Outcomes and Measures: The primary end point was the composite of death or myocardial injury, defined as an increase in high-sensitivity cardiac troponin to at least 5 times the upper limit of normal within 48 hours from randomization. The safety end point was bleeding type 2 to 5 according to the Bleeding Academic Research Consortium criteria at 30 days. Results: Of 334 participants (median age, 67.4 years; interquartile range, 60-75.1 years; 253 men [75.7%]; and 330 White participants [98.8%]), 120 were allocated to receive the 160-mg dose of revacept, 121 were allocated to receive the 80-mg dose, and 93 received placebo. The primary end point showed no significant differences between the revacept and placebo groups: 24.4%, 25.0%, and 23.3% in the revacept, 160 mg, revacept, 80 mg, and placebo groups, respectively (P = .98). The high dose of revacept was associated with a small but significant reduction of high-concentration collagen-induced platelet aggregation, with a median 26.5 AU × min (interquartile range, 0.5-62.2 AU × min) in the revacept, 160 mg, group; 43.5 AU × min (interquartile range, 22.8-99.5 AU × min) in the revacept, 80 mg, group; and 41.0 AU × min (interquartile range, 31.2-101.0 AU × min) in the placebo group (P = .02), while adenosine 5'-diphosphate-induced aggregation was not affected. Revacept did not increase Bleeding Academic Research Consortium type 2 or higher bleeding at 30 days compared with placebo: 5.0%, 5.9%, and 8.6% in the revacept, 160 mg, revacept, 80 mg, and placebo groups, respectively (P = .36). Conclusions and Relevance: Revacept did not reduce myocardial injury in patients with stable ischemic heart disease undergoing percutaneous coronary intervention. There were few bleeding events and no significant differences between treatment arms. Trial Registration: ClinicalTrials.gov Identifier: NCT03312855.

Adenosine stress perfusion cardiac magnetic resonance imaging in patients undergoing intracoronary bone marrow cell transfer after ST-elevation myocardial infarction: the BOOST-2 perfusion substudy.

AIMS: In the placebo-controlled, double-blind BOne marrOw transfer to enhance ST-elevation infarct regeneration (BOOST) 2 trial, intracoronary autologous bone marrow cell (BMC) transfer did not improve recovery of left ventricular ejection fraction (LVEF) at 6 months in patients with ST-elevation myocardial infarction (STEMI) and moderately reduced LVEF. Regional myocardial perfusion as determined by adenosine stress perfusion cardiac magnetic resonance imaging (S-CMR) may be more sensitive than global LVEF in detecting BMC treatment effects. Here, we sought to evaluate (i) the changes of myocardial perfusion in the infarct area over time (ii) the effects of BMC therapy on infarct perfusion, and (iii) the relation of infarct perfusion to LVEF recovery at 6 months. METHODS AND RESULTS: In 51 patients from BOOST-2 (placebo, n = 10; BMC, n = 41), S-CMR was performed 5.1 ± 2.9 days after PCI (before placebo/BMC treatment) and after 6 months. Infarct perfusion improved from baseline to 6 months in the overall patient cohort as reflected by the semi-quantitative parameters, perfusion defect-infarct size ratio (change from 0.54 ± 0.20 to 0.43 ± 0.22; P = 0.006) and perfusion defect-upslope ratio (0.54 ± 0.23 to 0.68 ± 0.22; P < 0.001), irrespective of randomised treatment. Perfusion defect-upslope ratio at baseline correlated with LVEF recovery (r = 0.62; P < 0.001) after 6 months, with a threshold of 0.54 providing the best sensitivity (79%) and specificity (74%) (area under the curve, 0.79; 95% confidence interval, 0.67-0.92). CONCLUSION: Infarct perfusion improves from baseline to 6 months and predicts LVEF recovery in STEMI patients undergoing early PCI. Intracoronary BMC therapy did not enhance infarct perfusion in the BOOST-2 trial.

Loss of CXCR4 on non-classical monocytes in participants of the Women's Interagency HIV Study (WIHS) with subclinical atherosclerosis.

AIMS: To test whether human immunodeficiency virus (HIV) infection and subclinical cardiovascular disease (sCVD) are associated with expression of CXCR4 and other surface markers on classical, intermediate, and non-classical monocytes in women. METHODS AND RESULTS: sCVD was defined as presence of atherosclerotic lesions in the carotid artery in 92 participants of the Women's Interagency HIV Study (WIHS). Participants were stratified into four sets (n = 23 each) by HIV and sCVD status (HIV-/sCVD-, HIV-/sCVD+, HIV+/sCVD-, and HIV+/sCVD+) matched by age, race/ethnicity, and smoking status. Three subsets of monocytes were determined from archived peripheral blood mononuclear cells. Flow cytometry was used to count and phenotype surface markers. We tested for differences by HIV and sCVD status accounting for multiple comparisons. We found no differences in monocyte subset size among the four groups. Expression of seven surface markers differed significantly across the three monocyte subsets. CXCR4 expression [median fluorescence intensity (MFI)] in non-classical monocytes was highest among HIV-/CVD- [628, interquartile range (IQR) (295-1389)], followed by HIV+/CVD- [486, IQR (248-699)], HIV-/CVD+ (398, IQR (89-901)), and lowest in HIV+/CVD+ women [226, IQR (73-519)), P = 0.006 in ANOVA. After accounting for multiple comparison (Tukey) the difference between HIV-/CVD- vs. HIV+/CVD+ remained significant with P = 0.005 (HIV-/CVD- vs. HIV+/CVD- P = 0.04, HIV-/CVD- vs. HIV-/CVD+ P = 0.06, HIV+/CVD+ vs. HIV+/CVD- P = 0.88, HIV+/CVD+ vs. HIV-/CVD+ P = 0.81, HIV+/CVD- vs. HIV-/CVD+, P = 0.99). All pairwise comparisons with HIV-/CVD- were individually significant (P = 0.050 vs. HIV-/CVD+, P = 0.028 vs. HIV+/CVD-, P = 0.009 vs. HIV+/CVD+). CXCR4 expression on non-classical monocytes was significantly higher in CVD- (501.5, IQR (249.5-887.3)) vs. CVD+ (297, IQR (81.75-626.8) individuals (P = 0.028, n = 46 per group). CXCR4 expression on non-classical monocytes significantly correlated with cardiovascular and HIV-related risk factors including systolic blood pressure, platelet and T cell counts along with duration of antiretroviral therapy (P < 0.05). In regression analyses, adjusted for education level, study site, and injection drug use, presence of HIV infection and sCVD remained significantly associated with lower CXCR4 expression on non-classical monocytes (P = 0.003), but did not differ in classical or intermediate monocytes. CONCLUSION: CXCR4 expression in non-classical monocytes was significantly lower among women with both HIV infection and sCVD, suggesting a potential atheroprotective role of CXCR4 in non-classical monocytes.

Cardiac Myxoma and Cerebrovascular Events: A Retrospective Cohort Study.

Background: Cardiac myxoma (CM) is the most frequent, cardiac benign tumor and is associated with enhanced risk for cerebrovascular events (CVE). Although surgical CM excision is the only curative treatment to prevent CVE recurrence, in recent reports conservative treatment with antiplatelet or anticoagulant agents in high-risk patients with CM-related CVE has been discussed. Methods: Case records at the University Hospital of Tübingen between 2005 and 2017 were screened to identify patients with CM-related CVE. Clinical features, brain and cardiac imaging findings, histological reports, applied treatments and long-term neurological outcomes were assessed. Results: 52 patients with CM were identified and among them, 13 patients with transient ischemic attack, ischemic stroke or retinal ischemia were included to the (to our knowledge) largest reported retrospective study of CM-related CVE. In all identified patients, CVE was the first manifestation of CM; 61% suffered ischemic stroke, 23% transient ischemic attack and 15% retinal ischemia. In 46% of the patients, CVE occurred under antiplatelet or anticoagulation treatment, while 23% of the patients developed recurrent CVE under bridging-antithrombotic-therapy prior to CM surgical excision. Prolonged time interval between CVE and CM-surgery was significantly associated with CVE recurrence (p = 0.021). One patient underwent i.v. thrombolysis, followed by thrombectomy, with good post-interventional outcome and no signs of hemorrhagic transformation. Discussion: Our results suggest that antiplatelet or anticoagulation treatment is no alternative to cardiac surgery in patients presenting with CM-related CVE. We found significantly prolonged time-intervals between CVE and CM surgery in patients with recurrent CVE. Therefore, we suggest that the waiting- or bridging-interval with antithrombotic therapy until curative CM excision should be kept as short as possible. Based on our data and review of the literature, we suggest that in patients with CM-related CVE, i.v. thrombolysis and/or endovascular interventions may present safe and efficacious acute treatments.

Intracoronary autologous bone marrow cell transfer after myocardial infarction: the BOOST-2 randomised placebo-controlled clinical trial.

AIMS: Intracoronary infusion of autologous nucleated bone marrow cells (BMCs) enhanced the recovery of left ventricular ejection fraction (LVEF) after ST-segment elevation myocardial infarction (STEMI) in the randomised-controlled, open-label BOOST trial. We reassessed the therapeutic potential of nucleated BMCs in the randomised placebo-controlled, double-blind BOOST-2 trial conducted in 10 centres in Germany and Norway. METHODS AND RESULTS: Using a multiple arm design, we investigated the dose-response relationship and explored whether γ-irradiation which eliminates the clonogenic potential of stem and progenitor cells has an impact on BMC efficacy. Between 9 March 2006 and 16 July 2013, 153 patients with large STEMI were randomly assigned to receive a single intracoronary infusion of placebo (control group), high-dose (hi)BMCs, low-dose (lo)BMCs, irradiated hiBMCs, or irradiated loBMCs 8.1 ± 2.6 days after percutaneous coronary intervention (PCI) in addition to guideline-recommended medical treatment. Change in LVEF from baseline (before cell infusion) to 6 months as determined by MRI was the primary endpoint. The trial is registered at Current Controlled Trials (ISRCTN17457407). Baseline LVEF was 45.0 ± 8.5% in the overall population. At 6 months, LVEF had increased by 3.3 percentage points in the control group and 4.3 percentage points in the hiBMC group. The estimated treatment effect was 1.0 percentage points (95% confidence interval, -2.6 to 4.7; P = 0.57). The treatment effect of loBMCs was 0.5 percentage points (-3.0 to 4.1; P = 0.76). Likewise, irradiated BMCs did not have significant treatment effects. BMC transfer was safe and not associated with adverse clinical events. CONCLUSION: The BOOST-2 trial does not support the use of nucleated BMCs in patients with STEMI and moderately reduced LVEF treated according to current standards of early PCI and drug therapy.

Comparison of Ventricular Inducibility with Late Gadolinium Enhancement and Myocardial Inflammation in Endomyocardial Biopsy in Patients with Dilated Cardiomyopathy.

BACKGROUND: Risk stratification of patients with non-ischemic dilated cardiomyopathy remains a matter of debate in the era of device implantation. OBJECTIVE: We investigated associations between histopathological findings, contrast-enhanced cardiac MRI and the inducibility of ventricular tachycardia (VT) or fibrillation (VF) in programmed ventricular stimulation. METHODS: 56 patients with impaired left ventricular ejection fraction (LVEF≤50%, mean 36.6±10.5%) due to non-ischemic dilated cardiomyopathy underwent cardiac MRI, programmed ventricular stimulation, and endomyocardial biopsy and were retrospectively investigated. Inducibility was defined as sustained mono- or polymorphic VT or unstable VT/VF requiring cardioversion/defibrillation. Primary study endpoint was defined as the occurrence of hemodynamically relevant VT/VF and/or adequate ICD-therapy during follow-up. RESULTS: Endomyocardial biopsy detected cardiac fibrosis in 18 (32.1%) patients. Cardiac MRI revealed 35 (62.5%) patients with positive late gadolinium enhancement. VT/VF was induced in ten (17.9%) patients during programmed ventricular stimulation. Monomorphic VT was inducible in 70%, while 20% of patients showed polymorphic VT. One patient (10%) presented with VF. Inducibility correlated significantly with the presence of positive late gadolinium enhancement in cardiac MRI (p<0.01). We could not find a significant association between inducibility and the degree of cardiac inflammation and fibrosis in non-site directed routine right ventricular endomyocardial biopsy. During a mean follow-up of 2.6 years, nine (16.1%) patients reached the primary endpoint. Monomorphic VTs were found in 66.7% patients and were terminated by antitachycardia pacing therapy. One patient with polymorphic VT and two patients with VF received adequate therapy by an ICD-shock. However, inducibility did not correlate with the occurrence of endpoints. CONCLUSION: Inducibilty during programmed ventricular stimulation is associated with positive late gadolinium enhancement in cardiac MRI of patients with non-ischemic dilated cardiomyopathy. The presence of myocardial fibrosis or inflammation in undirected endomyocardial biopsy does not seem to be sufficient to predict future ventricular arrhythmias.

Comparison of aortic valve annulus diameter determination through 3-dimensional transesophageal echo with cardiac MDCT and assessment of predictors for annulus sizing.

OBJECTIVES: The long-term success of CoreValve stent prosthesis (Medtronic) implantation for severe aortic valve stenosis is limited in determination of correct aortic valve annulus. METHODS: We retrospectively investigated preinterventional cardiac 256-slice computed tomography (cardiac CT) scans and 3-dimensional transesophageal echocardiography (3D TEE) for assessment of aortic valve annulus to (i) compare both methods as well as (ii) to define predictors for annulus sizing. RESULTS: We investigated 200 consecutive patients with a mean aortic valve annulus (AA) of 24mm and a mean age of 81 years. Primarily we defined mean diameters of AA individually and grouped the different patients according to age, gender, body weight, length, surface area and body mass index. Thereby, we found statistical significant different annulus diameter in age (larger diameter when < 80 years of age), gender (male > femal), and body length (larger diameter when length > 165cm). Secondly, the multivariate analysis demonstrated that the age, the gender and the body length were additionally independent predictors for annulus size. CONCLUSION: Our data demonstrate the feasibility of cardiac CT and 3D TEE with no difference in the quality of the aortic valve annulus diameter determination. We describe predictors for annulus size in age, gender and body length. Conclusive, we support patient dependent parameters as age, gender and body length as predictors that must go into selection of CoreValve stent prosthesis size individually prior to implantation procedure.

Preserved bioactivity and tunable release of a SDF1-GPVI bi-specific protein using photo-crosslinked PEGda hydrogels.

Chemokine-induced stem cell recruitment is a promising strategy for post myocardial infarction treatment. Injection of stromal cell-derived factor 1 (SDF1) has been shown to attract bone marrow-derived progenitor cells (BMPCs) from the blood that have the potential to differentiate into cardiovascular cells, which support angiogenesis, enabling the improvement of myocardial function. SDF1-GPVI bi-specific protein contains a glycoprotein VI (GPVI)-domain that serves as an anchor for collagen type I (Col I) and III, which are exposed in the wall of injured vasculature. In this study, we generated a cytocompatible hydrogel via photo-crosslinking of poly(ethylene glycol) diacrylate that serves as a reservoir for SDF1-GPVI. Controlled and sustained release of SDF1-GPVI was demonstrated over a period of 7 days. Release features were modifiable depending on the degree of the crosslinking density. Functionality of the GPVI-domain was investigated using a GPVI-binding ELISA to Col I. Activity of the SDF1-domain was tested for its CXCR4 binding potential. Preserved functionality of SDF1-GPVI bi-specific protein after photo-crosslinking and controllable release was successfully demonstrated in vitro supporting the implementation of this drug delivery system as a powerful tool for therapeutic protein delivery in the treatment of cardiovascular ischemic disease.

Non-invasive and invasive evaluation of aortic valve area in 100 patients with severe aortic valve stenosis: comparison of cardiac computed tomography with ECHO (transesophageal/transthoracic) and catheter examination.

BACKGROUND: Current guidelines place emphasis on the determination of aortic valve area (AVA) for defining an appropriate treatment strategy. Invasive and non-invasive modalities are used to perform planimetric [transesophageal echocardiography (TEE) and cardiac multidetector computed tomography (MDCT)] and calculated [catheter examination (CE), transthoracic echocardiography (TTE)] AVA measurements. PURPOSE AND METHODS: We investigated 100 patients admitted to evaluate the AVA using cardiac MDCT (CT), TEE/TTE as well as invasive CE. RESULTS: In all 100 patients we calculated a mean AVA of 0.79±0.29cm(2) (female 50/100, 0.70±0.19cm(2), male 0.9±0.21cm(2)) determined by all investigated examinations (mean±SEM). AVA measurements determined by CT were significantly greater (0.86±0.25cm(2)) than those determined by CE: 0.75±0.18cm(2), p=0.01. Echocardiographically determined AVA was comparable to CE (statistically not significant). Similar results were seen in all patients regardless of gender, presence of atrial fibrillation, and heart rate. We calculated a mean AVA for each patient and evaluated the variance of the AVA determined through investigated specific examinations as the bias. Overall, we found for CT 0.13±0.1cm(2), CE 0.13±0.11cm(2), TEE 0.16±0.09cm(2), and for TTE 0.16±0.08cm(2) a specific statistical non-significant variance. On subgroups: sinus rhythm, atrial fibrillation, females, males or combination, we found no further significant relevance for the specific variance. CONCLUSION: Our data suggest the feasibility of cardiac MDCT to evaluate the correct AVA regardless of rhythm, heart rate, and sex. The planimetric concept to determine the AVA with CT displaces the "gold-standard" CE with respect to elucidating the potencies for complications, i.e. cerebral stroke. Regardless of CT's accessing of AVA measurement the TTE examination should remain the primary method of screening for aortic valve pathologies.

High resolution myocardial magnetic resonance stress perfusion imaging at 3 T using a 1 M contrast agent.

OBJECTIVE: Stress perfusion magnetic resonance imaging (MSPMRI) is an established technique for the assessment of myocardial perfusion. Shortcomings at 1.5 T are low signal to noise ratio (SNR) and contrast to noise ratio (CNR). One approach to overcome these shortcomings is to increase field strength and contrast concentration. The aim of our study was to investigate the diagnostic capability of high resolution MSPMRI at 3-T field strength using a 1 M contrast agent. MATERIAL AND METHODS: Fifty-seven patients (62.3 +/- 11.0 years) with symptoms of coronary artery disease (CAD) were examined at 3 T. MMRSPI was assessed using a 2D saturation recovery gradient echo (SR GRE) sequence in short axis orientation (TR 1.9 ms, TE 1.0 ms, flip 12 degrees , 0.1 mmol gadobutrol/kg body weight (bw), 140 microg adenosine/kg bw/min). Perfusion images were assessed visually and semiquantitatively (upslope, peak signal intensity (SI), and myocardial perfusion reserve index (MPRI)). Standard of reference was invasive coronary angiography. RESULTS: Stress-induced hypoperfusion was found in 43 patients. Sensitivity for hemodynamically relevant CAD (stenoses greater than 70%) was 95%/98%, specificity 80%/87%, diagnostic accuracy 91%/95% (reader 1/reader 2). The MPRI was significantly lower in hypoperfused myocardium (1.3 +/- 0.2) compared with normal myocardium (2.6 +/- 0.7). CONCLUSION: High resolution MMRSPI at 3 T using 1 M contrast agent under daily routine conditions provides reliable detection of stress-induced myocardial hypoperfusion with higher diagnostic accuracy than 1.5-T conditions.

Adenosine stress first pass perfusion for the detection of coronary artery disease in patients with aortic stenosis: a feasibility study.

PURPOSE: Detection of coronary artery disease (CAD) with magnetic resonance imaging (MRI) using adenosine stress first pass perfusion in patients with aortic stenosis in comparison with invasive angiography. Twenty-three consecutive patients (15 male, mean age 68 +/- 12 years) with relevant aortic stenosis (aortic valve area 0.90 +/- 0.41 cm(2)) were examined by MRI (1.5 T, Philips Intera CV). Contrast-enhanced first pass perfusion was performed with adenosine stress (140 microg/kg/min) and under rest conditions. The results were compared with invasive coronary angiography with regard to the presence of a relevant coronary artery stenosis (>70%). Three of 23 patients (13%) had contraindications for adenosine administration (one patient with atrioventricular block, two patients with mild claustrophobia). In the remaining 20 patients, adenosine stress perfusion could be performed without any complications. CAD was correctly detected in eight patients and correctly ruled out in 10 of 12 patients. False-positive results were seen in two patients with severe myocardial hypertrophy. Sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 80%, 83%, and 100%, respectively. Adenosine stress perfusion can be performed without complications even in patients with high grade aortic stenosis. MRI is helpful to detect and rule out significant CAD in these patients. Severe myocardial hypertrophy may lead to false-positive results. Our initial results indicate that due to a high negative predictive value pre-operative invasive coronary angiography might probably be waived in patients without perfusion defects in stress MRI.

Platelet-associated LIGHT (TNFSF14) mediates adhesion of platelets to human vascular endothelium.

LIGHT (TNFSF 14) belongs to the tumor necrosis factor super-family and is expressed by different types of immune cells. Recently, LIGHT was found to be associated with platelets and released upon activation. Activation of endothelial cells by recombinant LIGHT results in pro-inflammatory and pro-thrombotic changes, qualitatively comparable to effects of CD40 ligand. Given the important role of platelet-associated CD40 ligand in vascular inflammatory responses we investigated the role of LIGHT for activation of endothelium and adhesion of platelets to endothelial cells. Expression of LIGHT was detected on thrombocytes upon exposure to ADP or TRAP-1. The expression of the LIGHT receptors TR2 and LTbetaR on native human endothelial cells was confirmed by FACS analysis. LIGHT mediated adhesion of platelets to endothelium significantly, occurring both under static and dynamic flow conditions. This interaction was inhibited by a monoclonal antibody to LIGHT but not a control IgG. Moreover, in-vitro stimulation of endothelial cells with recombinant soluble human LIGHT (rhLIGHT) resulted in significantly increased transcriptional and translational upregulation of inflammatory markers ICAM-1, tissue factor (TF) and IL-8. This activation of endothelial cells by LIGHT was mediated by NFkappaB activation and qualitatively comparable to that induced by membrane-bound CD40-ligand on transfected cells. Furthermore, plasma levels of patients with myocardial infarction, in those with ST-elevation myocardial infarction (STEMI), showed increased plasma levels of LIGHT compared with healthy controls. In conclusion, platelet-associated LIGHT is involved in adhesion of platelets to endothelium while soluble LIGHT induces a pro-inflammatory state in vascular endothelial cells. LIGHT may thus be implicated in the pathogenesis of atherosclerosis and acute coronary syndrome, as evidenced by serum levels.

Magnetic resonance imaging to assess acute changes in atrial and ventricular parameters after transcatheter closure of atrial septal defects.

PURPOSE: To evaluate acute changes in atrial and ventricular parameters by the use of cardiac magnetic resonance imaging (MRI) in patients with percutaneous transcatheter atrial septal defects (ASD) closure. MATERIALS AND METHODS: The study included 14 patients (six males and eight females, 45 +/- 18 years) with congenital ASD. Cardiac MRI (1.5T Philips Intera CV) was performed before and within 24 hours after transcatheter ASD closure. Right atrial (RA) and left atrial (LA) dimensions, as well as right (RV) and left (LV) ventricular end-diastolic (ED) volumes were determined. Atrial size was assessed by planimetry of the maximum RA and LA areas in a standard four-chamber view, and ventricular volumes were calculated according to a modified Simpson's rule in short-axis views. RESULTS: The mean RA decreased significantly from 27.6 +/- 6.4 cm(2) before closure to 24.4 +/- 5.6 cm(2) after the procedure (P = 0.0018), whereas the LA area did not change (24.1 +/- 4.7 cm(2) vs. 23.8 +/- 5.2 cm(2), P = 0.76). The RV volumes, volume index, and ejection fraction (EF) decreased significantly from 229 +/- 64 mL to 181 +/- 43 mL (P < 0.001, average reduction = 19% +/- 15%), from 126.0 +/- 37.2 mL/m(2) to 96.6 +/- 28.6 mL/m(2) (P < 0.0001) and from 64 +/- 5% to 58% +/- 7% (P = 0.01), respectively. The LV volumes and volume index remained unchanged (114 +/- 25 mL vs. 118 +/- 22 mL, P = 0.18, 63.5 +/- 13.5 mL/m(2) vs. 63.0 +/- 17.4 mL/m(2), P = 0.83). Left-right shunting decreased from 40% +/- 15% to 9% +/- 15% (P < 0.001). CONCLUSION: Cardiac MRI can reveal detailed information on acute changes in shunt fraction and ventricular dimensions after ASD closure. ASD closure by percutaneous transcatheter device implantation results within 24 hours in a significant reduction of shunt fraction, RA and RV sizes, and RV function, whereas LA and LV dimensions remain unchanged.

Assessment of left ventricular outflow tract geometry in non-stenotic and stenotic aortic valves by cardiovascular magnetic resonance.

PURPOSE: To assess the geometry and area of the left ventricular outflow tract (LVOT) in non-stenotic and stenotic aortic valves and to determine the aortic valve area (AVA) in non-stenotic valves by magnetic resonance imaging (MRI) using a modified continuity equation. METHODS: Twenty patients (10 male, mean age 54.8 +/- 15 years) without known aortic valve disease and 10 patients (7 male, mean age 65.1 +/- 14 years) with moderate to severe aortic stenosis were included in this study. MRI was performed using a 1.5 T scanner (Philips Intera CV). AVA was assessed by planimetry on high quality SSFP cine sequences and used as reference standard. LVOT area was defined by calculating a circular area using the LVOT diameter from the 3 chamber view (3CV) and by planimetry. Peak flow velocity was assessed in the LVOT and the proximal aorta. AVA was calculated by a modified Gorlin equation, the continuity equation and a modified continuity equation using the planimetric LVOT area. RESULTS: Planimetric AVA ranged from 2.9 to 6.4 cm2 in patients with non-stenotic and from 0.3 to 1.3 cm2 with stenotic valves, LVOT area from 3.4 to 6.1 cm2 and from 2.6 to 6.5 cm2, respectively. The LVOT area based on the LVOT diameter derived from the 3CV was significantly underestimated in comparison to planimetry in non-stenotic and stenotic aortic valves (3.3 +/- 0.7 vs. 4.7 +/- 1.0 cm2, p < 0.0001; mean difference 1.1 +/- 0.12 cm2, CI 0.86-1.36 and 3.7 +/- 1.2 vs. 4.7 +/- 1.5 cm2, p < 0.05; mean difference 1.0 +/- 1.0 cm2, CI 0.24-1.71). The Gorlin formula showed a poor agreement with planimetry, whereas continuity equation and the modified continuity equation revealed a very good agreement. Planimetry of the LVOT displayed an elliptic shape of the LVOT in all patients with the minimum diameter perpendicular to the 3CV, which was the reason for the above mentioned underestimation. CONCLUSION: The LVOT area calculated from the 3CV-LVOT diameter underestimates the LVOT area compared to planimetry due to an elliptic shape of the LVOT in patients with non-stenotic as well as with stenotic aortic valves. The modified Gorlin equation proved to be less useful to assess AVA in non-stenotic valves, whereas the continuity equation and a modified continuity equation displayed a very good agreement with planimetric area measurements.