Rivaroxaban attenuates neutrophil maturation in the bone marrow niche.

Pharmacological inhibition of factor Xa by rivaroxaban has been shown to mediate cardioprotection and is frequently used in patients with, e.g., atrial fibrillation. Rivaroxaban's anti-inflammatory actions are well known, but the underlying mechanisms are still incompletely understood. To date, no study has focused on the effects of rivaroxaban on the bone marrow (BM), despite growing evidence that the BM and its activation are of major importance in the development/progression of cardiovascular disease. Thus, we examined the impact of rivaroxaban on BM composition under homeostatic conditions and in response to a major cardiovascular event. Rivaroxaban treatment of mice for 7 days markedly diminished mature leukocytes in the BM. While apoptosis of BM-derived mature myeloid leukocytes was unaffected, lineage-negative BM cells exhibited a differentiation arrest at the level of granulocyte-monocyte progenitors, specifically affecting neutrophil maturation via downregulation of the transcription factors Spi1 and Csfr1. To assess whether this persists also in situations of increased leukocyte demand, mice were subjected to cardiac ischemia/reperfusion injury (I/R): 7 d pretreatment with rivaroxaban led to reduced cardiac inflammation 72 h after I/R and lowered circulating leukocyte numbers. However, BM myelopoiesis showed a rescue of the leukocyte differentiation arrest, indicating that rivaroxaban's inhibitory effects are restricted to homeostatic conditions and are mainly abolished during emergency hematopoiesis. In translation, ST-elevation MI patients treated with rivaroxaban also exhibited reduced circulating leukocyte numbers. In conclusion, we demonstrate that rivaroxaban attenuates neutrophil maturation in the BM, which may offer a therapeutic option to limit overshooting of the immune response after I/R.

Microvascular tissue perfusion after postcatheterization pseudoaneurysm treatment.

BACKGROUND: Femoral pseudoaneurysm (PSA) is a severe complication after endovascular procedures. Ultrasound-guided manual compression (MC) and percutaneous thrombin injection (TI) are frequently used treatments. MC is less effective, TI may cause thromboembolic events. OBJECTIVE: Up to date, there is no data regarding impairment of microvascular tissue perfusion after PSA treatment. METHODS: In this single-center, prospective study 22 patients with PSA were included. We compared macro- and microcirculatory perfusion in the treated and untreated leg at baseline before, after and one day after treatment. Leg perfusion was assessed with ultrasound and ankle-brachial index (ABI). Microcirculatory perfusion of the feet was measured with a near-infrared spectroscopy (NIRS) camera generating StO2-tissue-maps. RESULTS: Successful PSA thrombosis was achieved in 16 (100%) patients in TI group and in 4 (66.7%) patients in MC group. There was no evidence of arterial thrombi on ultrasound and the ABI did not differ between groups. NIRS StO2-tissue-maps of the feet showed no significant difference in both groups concerning the treated (p = 0.121) or the untreated (p = 0.198) leg during follow up. CONCLUSIONS: In this small exploratory study, there was no evidence of micro- and macrovascular tissue perfusion impairment after treatment of postcatheterization femoral pseudoaneurysm with thrombin injection underscoring the safety of this approach.

Integrin ß1 polymorphisms and bleeding risk after coronary artery stenting.

Bleeding complications following percutaneous coronary intervention associate with increased mortality. However, the underlying molecular mechanisms are insufficiently understood. Platelet recruitment and activation at sites of vascular injury depends on the function of integrin adhesion receptors. Besides GPIIbIIIa as the most abundant integrin receptor, platelets relevantly express ß1 integrins. Experimental evidence from in vivo studies suggests a significant role of ß1 integrins in primary haemostasis. However, little is known about the clinical impact of genetic alterations of the ß1 subunit, which might contribute to bleeding complications in patients. In this study, we performed DNA sequencing of patients suffering from bleeding complications after coronary artery stenting according to TIMI or BARC classification. We isolated DNA samples from 741 patients out of a cohort from 14,160 patients recruited in seven randomized clinical trials between June 2000 and May 2011. Subsequently, Sanger sequencing was performed covering the ß1 integrin cytoplasmic activation domain (exon16) and its non-coding upstream region. Out of 764 patients suffering from bleeding complications, 741 DNA samples were successfully sequenced. Genotype variation was detected for SNP rs2153875 located within the non-coding upstream region with following allele frequency in study population: CC (7.3%), CA (35%) and AA (57.8%), which is similar to a general population cohort. Further, genotype variation in SNP rs2153875 do not associate with the frequency of TIMI or BARC classified access or non-access site bleedings. Genotype variations of the ß1 integrin activation domain do not associate with bleeding risk after PCI.

Platelet function testing: dead or alive.

Essentials Pharmacodynamic response to antiplatelet medication is heterogeneous. Platelet reactivity to dual antiplatelet therapy was analyzed by three platelet function assays. The prevalence of high and low platelet reactivity differed significantly between assays. Future trials are needed to determine the best assay to analyze platelet function. SUMMARY: Background High on-treatment platelet reactivity (HTPR) to antiplatelet medication leads to ischemic events, whereas low on-treatment platelet reactivity (LTPR) increases bleeding risk. However, various trials have failed to demonstrate superiority of tailored antiplatelet regimens (ARCTIC, ANTARCTIC, Trigger-PCI, and GRAVITAS). TROPICAL-ACS was the first study that demonstrated the benefit of tailoring antiplatelet medication according to platelet function analysis. A potential reason may be that different platelet function assays were used in these trials. Objectives To evaluate whether the results of platelet function tests are comparable. Patients/Methods We tested three commonly used assays - light transmission aggregometry (LTA), (Multiplate impedance aggregometry [MP]), and vasodilator-stimulated phosphoprotein phosphorylation assay (VASP) - in 23 patients receiving dual antiplatelet therapy with aspirin and clopidogrel. Results With LTA, HTPR occurred in 57% of patients; with VASP, it occurred in 43% of patients; and with MP, it occurred in 13% of patients. According to LTA, only 35% of patients were in the therapeutic window; according to VASP, 57% of patients were in the therapeutic window; and according to MP, 48% of patients were in the therapeutic window. With LTA, LTPR occurred in 9% of patients; with VASP, it occurred in 0% of patients; and with MP, it occurred in 39% of patients. Therefore, the prevalences of HTPR and LTPR differed significantly between assays. Remarkably, in 17% of patients, one assay showed HTPR whereas another showed LTPR. Conclusions The results of different platelet function assays differ substantially. Up to now, only TROPICAL-ACS had demonstrated a benefit of tailoring antiplatelet medication according to platelet function analysis. Future trials are needed to evaluate whether the platelet function assay used in TROPICAL-ACS is the 'correct' one and revives platelet function testing.

[Procedures on patients receiving NOACs : What's possible?] / Eingriffe unter NOAK : Was ist möglich?

Non-vitamin K antagonist oral anticoagulants (NOACs) are increasingly used in patients with deep vein thrombosis (DVT), pulmonary embolism (PE) and atrial fibrillation (AF). However, there is insufficient data concerning the periinterventional, perioperative, and intensive care management of patients on NOACs. Therefore, the recommendations regarding this management rely on pharmacokinetics of the particular NOAC in combination with the individual patient's characteristics, bleeding risk of the planned intervention/surgery, and urgency of the procedure. This review summarizes evidence and recommendations regarding the optimal periinterventional/perioperative antithrombotic management of patients on NOACs.

Safety and efficacy of transseptal puncture guided by real-time fusion of echocardiography and fluoroscopy.

AIMS: Visual guidance through echocardiography and fluoroscopy is crucial for a successful transseptal puncture (TSP) in a prespecified region of the fossa ovalis. The novel EchoNavigator system Release II (EchoNav II, Philips Healthcare, Andover, Massachusetts, USA) enables the real-time fusion of fluoroscopic and echocardiographic images. We evaluated this new imaging method in respect to safety and efficacy of TSP during MitraClip implantation and left atrial appendage closure. METHODS: Forty-four patients before (-EchoNav) and 44 patients after (+EchoNav) the introduction of real-time fusion were included in our retrospective, single-centre study. The primary endpoint was the occurrence of adverse events due to TSP. Secondary endpoints were successful puncture at the prespecified region and time until TSP (min). RESULTS: In both groups TSP was performed successfully in the prespecified region and no adverse events occurred during or due to the accomplishment of TSP. Time until TSP was significantly reduced in the +EchoNav group in comparison with the EchoNav group (18.48 ± 5.62 min vs. 23.20 ± 9.61 min, p = 0.006). CONCLUSIONS: Real-time fusion of echocardiography and fluoroscopy proved to be as safe and successful as standard best practice for TSP. Moreover, efficacy was improved through significant reduction of time until TSP.

Percutaneous closure of a left atrial appendage with relevant suture dehiscence.

Atrial fibrillation is a widespread disease and highly relevant as it carries an extended risk for ischaemic stroke. Surgical closure of the left atrial appendage is routinely performed during open heart surgery in patients with atrial fibrillation with the aim of thromboembolic protection. In this report we present a successful percutaneous closure of a left atrial appendage, which showed clinically relevant suture dehiscence several years after surgical closure.

Dabigatran enhances platelet reactivity and platelet thrombin receptor expression in patients with atrial fibrillation.

Essentials Whether or not dabigatran enhances the risk of myocardial infarction is under discussion. We measured platelet reactivity and thrombin receptor expression in dabigatran patients. Platelet reactivity and thrombin receptor expression is enhanced during dabigatran treatment. This should be considered when choosing the optimal direct oral anticoagulant for individuals. SUMMARY: Background The direct oral anticoagulant (DOAC) dabigatran is a direct thrombin inhibitor. Its landmark trial, the RE-LY study, observed a trend towards a higher incidence of myocardial infarctions (MIs) in dabigatran-treated patients. Since then, there have been discussions on whether dabigatran increases the risk of MI. Objective In this study, we aimed to assess platelet reactivity and platelet thrombin receptor expression in dabigatran-treated patients. Methods We conducted a cross-sectional study in 13 hospitalized patients with planned initiation of dabigatran medication. Platelet reactivity was measured by light-transmission aggregometry and platelet thrombin receptor expression was measured by flow cytometry analysis. Results Platelet reactivity was higher after initiation of dabigatran medication as compared with baseline (baseline 44 ± 24% vs. dabigatran 70 ± 25%). Accordingly, the density of both platelet thrombin receptors (protease activated receptor [PAR]-1 and PAR-4) on platelets increased during dabigatran treatment (PAR1, baseline 63 ± 11% vs. dabigatran 70 ± 10%; PAR4, baseline 1.1 ± 0.5% vs. dabigatran 1.6 ± 0.9%). Conclusions Dabigatran increases platelet reactivity by enhancing the thrombin receptor density on platelets. This finding should be considered while choosing the optimal DOAC in individualized medicine.

Antiplatelet effects of aspirin in chronic kidney disease patients.

UNLABELLED: ESSENTIALS: Chronic kidney disease (CKD) patients have a high risk of cardiovascular events. A pharmacodynamic evaluation of the effects of aspirin in 116 patients was carried out. The antiplatelet effects of aspirin are associated with impaired renal function. The optimal antithrombotic regimen in CKD patients must be investigated on a larger scale. BACKGROUND: The pharmacodynamic response to aspirin varies significantly between individuals. Insufficient antiplatelet effects of aspirin are associated with increased risk of ischemic events. Chronic kidney disease (CKD) is suggested to affect the pharmacodynamic response to antiplatelet medication. High on-treatment platelet reactivity (HTPR) to clopidogrel has been reported to partially account for the enhanced risk of death and cardiovascular events in CKD patients. Objective To investigate the antiplatelet effects of aspirin in patients with CKD. METHODS: We conducted a cross-sectional study in 116 patients on permanent aspirin medication. The pharmacodynamic response to aspirin was determined by arachidonic acid-induced thromboxane formation. RESULTS: HTPR to aspirin was more frequent in patients with impaired renal function (47% vs. 22%; odds ratio, 3.16; 95% confidence interval [CI], 1.34-7.41; P = 0.008). The pharmacodynamic response to aspirin was impaired in patients with moderate/severe CKD (92; interquartile range [IQR], 282 ng mL(-1) ) as compared to patients with normal/mildly reduced renal function (36; IQR, 100 ng mL(-1) ; difference in medians, 57; CI, 5-110 ng mL(-1) ; P = 0.013). Bivariate Pearson analysis showed residual thromboxane formation to be correlated with glomerular filtration rate (R = -0.303; R(2) = 0.092; P = 0.001). Patients with CKD were older and more frequently female. Multivariate linear regression analysis revealed that the correlation was independent of age (R = -0.314; R(2) = 0.082; P = 0.002) and gender (R = -0.305; R(2) = 0.077; P = 0.006). CONCLUSION: Renal function is correlated with pharmacodynamic response to aspirin. Patients with CKD have an increased risk of impaired antiplatelet effects of aspirin. Larger trials are needed to assess the clinical impact of this finding and investigate the optimal antithrombotic regimen in CKD patients.

Release of sphingosine-1-phosphate from human platelets is dependent on thromboxane formation.

BACKGROUND: Platelets release the immune-modulating lipid sphingosine-1-phosphate (S1P). However, the mechanisms of platelet S1P secretion are not fully understood. OBJECTIVES: The present study investigates the function of thromboxane (TX) for platelet S1P secretion during platelet activation and the consequences for monocyte chemotaxis. METHODS: S1P was detected using thin-layer chromatography in [(3)H]sphingosine-labeled platelets and by mass spectrometry. Monocyte migration was measured in modified Boyden chamber chemotaxis assays. RESULTS: Release of S1P from platelets was stimulated with protease-activated receptor-1-activating peptide (PAR-1-AP, 100 µM). Acetylsalicylic acid (ASA) and two structurally unrelated reversible cyclooxygenase inhibitors diclofenac and ibuprofen suppressed S1P release. Oral ASA (500-mg single dose or 100 mg over 3 days) attenuated S1P release from platelets in healthy human volunteers ex vivo. This was paralleled by inhibition of TX formation. S1P release was increased by the TX receptor (TP) agonist U-46619, and inhibited by the TP antagonist ramatroban and by inhibitors of ABC-transport. Furthermore, thrombin-induced release of S1P was attenuated in platelets from TP-deficient mice. Supernatants from PAR-1-AP-stimulated human platelets increased the chemotactic capacity of human peripheral monocytes in a S1P-dependent manner via S1P receptors-1 and -3. These effects were inhibited by ASA-pretreatment of platelets. CONCLUSIONS: TX synthesis and TP activation mediate S1P release after thrombin receptor activation. Inhibition of this pathway may contribute to the anti-inflammatory actions of ASA, for example by affecting activity of monocytes at sites of vascular injury.

Procalcitonin as a diagnostic tool in lower respiratory tract infections and tuberculosis.

The diagnostic significance of procalcitonin concentrations in lower respiratory tract infections and tuberculosis is not known. A prospective analysis was, therefore, performed in patients with acute exacerbation of chronic bronchitis (AECB), community-acquired pneumonia (CAP), hospital-acquired pneumonia (HAP) and tuberculosis and their procalcitonin levels compared with those of patients with noninfectious lung diseases (controls). In addition, standard inflammatory parameter data were collected. A prospective clinical study was performed with four different groups of patients and a control group that consisted of patients with noninfectious lung diseases. A total of 129 patients were included: 25 with HAP, 26 CAP, 26 AECB, 27 tuberculosis, and 25 controls. C-reactive protein level, blood cell counts and procalcitonin concentration were evaluated on the first day after onset of clinical and inflammatory symptoms prior to treatment. The median procalcitonin concentrations in HAP, CAP, AECB and tuberculosis were not elevated in relation to the cut-off level of 0.5 ng x mL(-1). In the HAP group, in four of five patients who subsequently died, procalcitonin concentrations of >0.5 ng x mL(-1) were found. In acute lower respiratory infections, such as HAP, CAP and AECB, significantly elevated levels were found in comparison to the control group, but below the usual cut-off level. No differences were observed between tuberculosis and the control group. Relative to the current cut-off level of 0.5 ng x mL(-1), procalcitonin concentration is not a useful parameter for diagnosis of lower respiratory tract infections. However, compared to the control group, there were significantly elevated levels in patients with hospital-acquired pneumonia, community-acquired pneumonia and acute exacerbation of chronic bronchitis below the current cut-off level, which should be further investigated.

[Kallikrein concentration in mixed saliva after contraceptive administration or postmenopausal hormone replacement]. / Zur Kallikreinkonzentration im Vollspeichel nach Kontrazeptivagabe oder postmenopausaler Hormonsubstitution.

BACKGROUND: The aim of our study was to evaluate the premise (Jenzano 1992) that estrogen influences the female mixed saliva kallikrein level (MSK). METHODS: We estimated the MSK level from woman between the ages of 17 and 39 with (n = 20) and without (20) contraceptive medication (at least an one year treatment) and postmenopausal women between the ages of 47 and 65 with (n = 20) and without (n = 22) hormonal substitution. Kallikrein was estimated by means of the cleavage of the chromogenic tripeptide Val-Leu-Arg-p-nitranilide (SIGMA) and absorbance measuring of p-nitraniline at 405 nm. RESULTS: A Wilcoxon test was conducted for statistical analysis. The MSK level decreases significantly (p = 0.000) under contraceptive medication (estrogen component: synthetic ethinyl-estrogen). However the MSK level of postmenopausal women showed no significant alteration (p = 0.158) after hormone substitution (estrogen component: natural estrogen). The finding may be due to the weaker effect of the estrogen used in post-menopausal hormone therapy. CONCLUSIONS: Our results demonstrate that estrogenic substances affect salivary kallikrein levels.

PIP: The premise that estrogen influences mixed saliva kallikrein (MSK) levels (i.e., that there is a correlation between markedly increased MSK levels and decreasing estrogen levels) in peri- and postmenopausal women was evaluated. 20 women aged 17-37 years (median age, 21 years) using contraceptives and 20 women aged 17-39 years (median age, 24 years) not using contraceptives, as well as 22 postmenopausal women aged 47-64 years (median age, 57 years) not using hormonal substitution and 20 postmenopausal women aged 47-65 years (median age, 56 years) using hormonal substitution were studied. For contraception, one-phase preparations containing synthetic ethinyl estradiol of 0.02-0.05 mg were used. For postmenopausal hormonal substitution, combination preparations containing 2 mg of natural estradiol and containing 1-2 mg of estradiol valerate were utilized. Kallikrein was estimated by means of the enzymatic cleavage of the chromogenic tripeptide DL-Val-Leu-Arg-p-nitranilide (SIGMA) and photometric absorbance measurement of released p-nitraniline at 405 nm. The specificity of the method of measurement for glandular kallikrein was accomplished by the use of SBTI (Soybean Trypsin Inhibitor: SIGMA T 9003). The MSK level decreased very significantly for those using contraceptives (0.02-0.05 mg of ethinyl estradiol). However, the MSK level of postmenopausal women showed no significant alteration after hormonal substitution (natural estrogen). The salivary kallikrein level changes measured demonstrate that contraceptives that contain a synthetic estrogen as estrogenic component very significantly affect kallikrein concentration.