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Background— The Bleeding Academic Research Consortium (BARC) has recently proposed a unified definition of bleeding in patients receiving antithrombotic therapy. We investigated the relationship between bleeding events as defined by BARC and 1-year mortality in patients undergoing percutaneous coronary intervention (PCI) and assessed whether the BARC bleeding definition is superior to existing bleeding definitions in regard to mortality prediction in patients after PCI procedures. Methods and Results— This study represents a patient-level pooled analysis of 12 459 patients recruited in 6 randomized trials of patients undergoing PCI. Bleeding events were assessed with the use of BARC, Thrombolysis in Myocardial Infarction (TIMI), and Randomized Evaluation in PCI Linking Angiomax to Reduced Clinical Events (REPLACE-2) trial criteria. The primary outcome was 1-year mortality. Bleeding occurred in 1233 patients (9.9%) according to BARC (679 patients or 5.4% with BARC class ≥2 bleeding), in 374 patients (3.0%) according to TIMI, and in 491 patients (3.9%) according to REPLACE-2 criteria. There were 340 deaths (2.7%) over the first year after PCI. BARC class ≥2 bleeding was associated with a significant increase in 1-year mortality (adjusted hazard ratio 2.72; 95% confidence interval, 2.03–3.63). The predictivity of a multivariable model for 1-year mortality was significantly improved after inclusion of bleeding defined according to BARC to an extent comparable to that provided by TIMI and REPLACE-2 criteria. Conclusions— The present study demonstrated a close association between bleeding events defined according to BARC and 1-year mortality after PCI.

Background— Durable polymer coatings have been implicated in mid- and long-term adverse events after drug-eluting stent implantation. A polymer-free dual-drug sirolimus- and probucol-eluting stent and a new generation permanent polymer zotarolimus-eluting stent are recently developed technologies demonstrating encouraging results. Methods and Results— In a clinical trial with minimal exclusion criteria, we randomly assigned 3002 patients to treatment with sirolimus- and probucol-eluting stents versus zotarolimus-eluting stents. The trial was designed to demonstrate noninferiority of the sirolimus- and probucol-eluting stents. The primary end point was the combined incidence of cardiac death, target-vessel–related myocardial infarction, or target-lesion revascularization at 1-year follow-up. Follow-up angiography was scheduled at 6 to 8 months. The sirolimus- and probucol-eluting stent was noninferior to the zotarolimus-eluting stent in terms of occurrence of the primary end point (13.1% versus 13.5%, respectively, P noninferiority =0.006; hazard ratio=0.97, 95% confidence interval, 0.78 to 1.19; P superiority =0.74). The incidence of definite/probable stent thrombosis was low in both groups (1.1% versus 1.2%, respectively; hazard ratio=0.91 [95% confidence interval, 0.45 to 1.84], P =0.80). With regard to angiographic efficacy, there were no differences between the sirolimus- and probucol-eluting stent and the zotarolimus-eluting stent in terms of either in-segment binary angiographic restenosis (13.3% versus 13.4% respectively; P =0.95) or in-stent late luminal loss (0.31±0.58 mm versus 0.29±0.56 mm, respectively; P =0.46). Conclusion— In this large-scale study powered for clinical end points, a polymer-free sirolimus- and probucol-eluting stent was noninferior to a new generation durable polymer-based zotarolimus-eluting stent out to 12 months. Clinical Trial Registration— http://www.clinicaltrials.gov . Unique identifier NCT 00598533.

Vessel maturation involves recruitment of mural cells. Laminar shear stress is a major trigger for vessel maturation. However, the molecular mechanisms by which shear stress affects recruitment of pericytes are unclear. MicroRNAs are small non-coding RNAs, which post-transcriptionally control gene expression. Since shear stress regulates various miRs, we hypothesize that flow-induced miRs inhibit repulsive cues and facilitate mural cell coverage. Laminar shear stress for 72h induces the up-regulation of miR-27b (2.8±0.24-fold vs static, p To determine whether miR-27b controls pericyte recruitment, we tested the effect of endothelial miR-27b on adhesion of pericytes. Overexpression of miR-27b increased the adhesion of pericytes (p Taken together, our data demonstrate that shear stress regulate miR-27b, which targets Ang2 and semaphorins, thereby controlling pericyte adhesion and coverage in vitro and in vivo.

Background— CD40L-CD40 interactions induce inflammatory signals in cells of the vascular wall. We evaluated the effects of glycoprotein (GP) IIb/IIIa (α IIb β 3 ) engagement that occurs during platelet-endothelium interactions on CD40L surface exposure on platelets and initiation of proteolytic activity in human umbilical vein endothelial cells (HUVECs). Methods and Results— Transient (60-minute) adhesion of thrombin-prestimulated platelets enhanced HUVEC expression of urokinase-type plasminogen activator receptor and membrane type-1 matrix metalloproteinase (MT1-MMP) (reverse transcriptase–polymerase chain reaction, flow cytometry) and secretion of urokinase-type plasminogen activator, tissue-type plasminogen activator, and MMP-1 (ELISA) and induced proteolytic activity via MMP-2 and MMP-9 (gelatin zymography). These effects were abrogated by hindrance of physical platelet-endothelial contacts using transwell systems or inhibited by GRGDSP, mAbs anti–GP IIb/IIIa (7E3), anti-α v β 3 (LM609), or anti-CD40L (TRAP1). In addition, MMP-2 and MMP-9 were inhibited by specific GP IIb/IIIa antagonists tirofiban, lamifiban, or integrelin. On endothelial cells, induction of proteolytic activity by activated platelets was mimicked by CD40 engagement using soluble CD40L but not affected by antibody clustering of α v β 3 . On platelets, CD40L and CD62P exposure was enhanced on adhesion to HUVECs or immobilized fibrinogen and was abrogated by GRGDSP or LM609. In suspension, cross-linking of GP IIb/IIIa by fibrinogen plus secondary mAb upregulated CD40L surface exposure. Consistently, bivalent mAb 7E3 upregulated CD40L, whereas ligation of GP IIb/IIIa by soluble fibrinogen alone or monovalent Fab-fragment c7E3 had no effect. Conclusions— Platelet adhesion via GP IIb/IIIa upregulates CD40L and CD62P surface exposure. Proteolytic activity of HUVEC is induced by the concerted action of β 3 -integrin–mediated platelet adhesion and subsequent CD40L-induced signals in HUVECs. Effective anti–GP IIb/IIIa or anti-CD40L strategies might, therefore, contribute to plaque stabilization.

70-year-old white man was admitted to the Department of Vascular Surgery with a critical right forearm ischemia caused by acute thromboembolic occlusion and underwent operative embolectomy. Microbiological testing revealed colonization of the embolus with Staphylococcus lugdunensis and S. epidermidis. Because of pain in the lower thoracic spine, elevated C-reactive protein, and a recent history of spondylodiscitis with evidence of coagulase-negative Staphylococcus spp., the patient was transferred to the Department of Neurosurgery 16 days after vascular surgery. S. epidermidis was then isolated from blood cultures. The patient had a history of coronary heart disease with reduced left ventricular function, atrial fibrillation, diabetes mellitus, and hemodialysis resulting from diabetic nephropathy, as well as kidney transplantation and subsequent kidney transplant failure in 2000. The patient was taking no immunosuppressive medication at admission. He had had a transcatheter aortic valve (CoreValve, Medtronic) implanted 12 months before as a result of severe native valve stenosis (logistic EuroSCORE, 33.11% at the time of implantation). He was transferred to our echocardiography laboratory with persistently elevated levels of C-reactive protein. Three months before transthoracic and transesophageal echocardiography (Movies I and II in the online-only Data Supplement), he was negative for signs of prosthetic valve endocarditis (PVE). Two- and 3-dimensional transesophageal echocardiography now showed an elongated mass 3 cm in length floating around a longitudinal axis within the stent lumen of the prosthetic valve. Apparently, the mass was attached to the stent struts. In addition, there were signs of a paravalvular abscess at the noncoronary sinus (Figure 1 and Movies III through V in the online-only Data Supplement). Minor paravalvular regurgitation was present at the left coronary sinus. The native valves did not show any signs of endocarditic lesions. The peak velocity across the valve had increased by ≈140 cm/s (Figure 2). After echocardiographic diagnosis of PVE and initiation of calculated antibiotic therapy with vancomycin, gentamicin, and rifampicin, the patient was transferred to the Department of Cardiac Surgery. The infected valve was replaced by a porcine valve (Hancock II, Medtronic; diameter 25 mm) under extracorporeal circulation. Intraoperative findings confirmed massive lesions on the biological parts of the transcatheter valve consistent with PVE (Figure 3). Surprisingly, 3 to 4 stent struts had penetrated the aortic sinotubular junction close to the noncoronary sinus. The valve was

We thank Drs Vranckx and Valgimigli for their interest in our article1 related to validation of the Bleeding Academic Research Consortium (BARC) definition of bleeding in patients with coronary artery disease undergoing percutaneous coronary intervention.2 In the article, and in this response, we share the same opinion with Drs Vranckx and Valgimigli regarding the need to validate the BARC-proposed bleeding definition criteria in prospective studies. Although compiled and proposed by a highly experienced group of researchers in investigating bleeding complications (as an end point in various trials …

Background: Platelets play a key role in haemostasis and in the pathophysiology of various diseases including arterial thrombosis. Glycoprotein (GP)VI, the major platelet collagen receptor, mediates platelet activation and firm adhesion to collagen structures exposed at sites of vascular injury. Here, we determined the effects of specific activation of GPVI on the human platelet proteome by two-dimensional differential in-gel electrophoresis (2D-DIGE) and mass spectrometry. Methods and Results: Platelets from healthy human donors were isolated and purified. Platelets were stimulated with an activating monoclonal antibody specific for GPVI, or control IgG. Platelet proteins were subjected to 2D-DIGE with extensive software-assisted image analysis. Subsequent identification of the differentially abundant proteins was carried out by MALDI TOF/TOF MS and LC ESI-MS/MS. We identified 8 differentially regulated proteins associated with cell signaling, metabolism, organization and rearrangement of the cytoskeleton, and membrane trafficking. Differentially abundant proteins included pleckstrin, beta-centractin, src substrate cortactin, charged multivesicular body protein 3, aldose reductase and protein disulfide isomerase-associated 3 precursor. Conclusion: Specific platelet activation via GPVI results in the differential regulation of several proteins. The results provide further insight into the mechanisms that underlie platelet activation through the GPVI receptor, which may help to identify novel pharmacological targets.

Background: Pathological fibrin formation is a predominant cause for arterial thrombosis, triggering myocardial infarction and stroke. Tissue factor (TF), which is expressed by vascular endothelium and cell-derived microparticles, is a central trigger of intravascular fibrin generation. In intact blood vessels, TF is only minimally active, and the coagulation system is down-regulated. In contrast, TF is rapidly stimulated following endothelial disruption. However, the molecular mechanisms that trigger fibrin formation via regulation of TF activation are largely undefined. Methods and Results: Here, we have identified a novel pathway that leads to TF activation in vitro and contributes to intravascular coagulation in vivo. We show that the protein disulfide isomerase (PDI) induces disulfide formation of the Cys186/Cys209 pair located in the extracellular domain of TF. In vitro, PDI-mediated disulfide formation led to profound activation of TF. In vivo, we found that PDI is not present in the intact vessel wall, but becomes abundantly expressed following vessel damage. We show that injured smooth muscle cells and adherent/activated platelets are the major cellular sources of PDI at sites of vascular injury. We then assessed fibrin formation following injury of the common carotid artery using intravital microscopy. We observed that PDI-blockade strongly reduced fibrin formation by approximately 45– 60%. Likewise, intravenous infusion of PDI significantly enhanced TF-dependent fibrin formation. Together, this implies that PDI initiates coagulation in vitro and also during arterial thrombosis in vivo. Notably, PDI did not act on platelets to trigger intravascular coagulation. Correspondingly, PDI blockade also inhibited fibrin formation, when platelet adhesion was prevented using a function-blocking anti-GPVI antibody. Conclusion: These findings reveal for the first time in vivo that the thiol isomerase PDI is a major molecular trigger of blood coagulation, which is exposed after vessel injury and converts TF into its functionally active form. Hence, PDI represents a promising novel target for the treatment of pathologic fibrin formation in patients with thrombotic disorders.

Background: Arterial (AT) and venous thromboses (VT) are the major causes of morbidity in industrialized countries. While the critical contribution of platelets to AT has been recognized, the molecular and cellular mechanisms that trigger the development of VT are not yet fully understood. Methods: We established a novel model of VT, where thrombus formation occurs after venous stasis in the absence of mechanical endothelial injury. In contrast to published models, our approach closely resembles the triggers that lead to VT in humans. The molecular and cellular events in VT were assessed using intravital and electron microscopy. In particular, we evaluated the differential contribution of platelets (pts) and leukocytes (lcs) to AT and VT. Results: We found that in AT pts adhere rapidly, whereas only few lcs are recruited. The loss of platelet P-Selectin reduced lc accumulation during AT, was associated with thrombus destabilization, but had no effect on pt adhesion/aggregation. The loss of GPIIb led to a complete lack of pt adhesion/aggregation in AT. While AT largely depends on pts, lc adhesion was the prominent initial phenomenon during VT and involved both P-selectin and Mac-1. P-Selectin−/− as well as Mac-1−/− mice showed a massive reduction in lc accumulation. The lack of P-Selectin was accompanied by a reduction of the thrombus size 48 hours after stasis and was only marginally reduced in Mac 1−/− mice, indicating that lc rolling is sufficient to promote VT. The expression of tissue factor by lcs played a pivotal role for VT. Accordingly, mice with reduced TF expression showed a dramatic reduction in venous thrombus size. In addition to TF-bearing lcs, pts were recruited to the vessel wall early in VT. Pt accumulation involved both the fibrinogen and the vWF receptor and was virtually abolished in mice lacking GPIIb or GPIbα. To our surprise, we observed that pts do not accumulate during VT but play a functional role. Reduced pt adhesion in mice lacking either GPIIb, GPIbα, or VWF was associated with a significant reduction in venous thrombus size. Conclusion: Together, we show that VT, unlike AT depends on the concerted action of both lcs and pts. Hence, targeting pt activation and adhesion might provide a promising strategy in the prophylaxis and treatment of VT.

Background— The membrane-bound chemokine fractalkine (CX 3 CL1) is expressed on various cell types such as activated endothelial cells and has been implicated in the inflammatory process of atherosclerosis. The aim of the present study was to dissect the role of fractalkine in leukocyte recruitment to inflamed endothelium under arterial shear forces. Methods and Results— With the use of immunofluorescence and laminar flow assays, the present study shows that human umbilical vein endothelial cells stimulated with tumor necrosis factor-α and interferon-γ abundantly express CX 3 CL1 and promote substantial leukocyte accumulation under arterial flow conditions. In the presence of high shear, firm adhesion of leukocytes to inflamed endothelial cells is reduced by ≈40% by a function-blocking anti-fractalkine antibody or by an antibody directed against the fractalkine receptor (CX 3 CR1). With the use of intravital video-fluorescence microscopy we demonstrate that inhibition of fractalkine signaling attenuates leukocyte adhesion to the atherosclerotic carotid artery of apolipoprotein E–deficient mice, which suggests that the CX 3 CL1-CX 3 CR1 axis is critically involved in leukocyte adhesion to inflamed endothelial cells under high shear forces both in vitro and in vivo. Surprisingly, platelets were strictly required for fractalkine-induced leukocyte adhesion at high shear rates. Correspondingly, specific inhibition of platelet adhesion to inflamed endothelial cells also significantly reduced leukocyte accumulation. We show that both soluble and membrane-bound fractalkine induces platelet degranulation and subsequent surface expression of P-selectin, which thereby promotes direct platelet-leukocyte interaction. Conclusion— Fractalkine expressed by inflamed endothelial cells triggers P-selectin exposure on adherent platelets, which thereby initiates the local accumulation of leukocytes under arterial shear, an essential step in the development of atherosclerotic lesions.

Background— The platelet glycoprotein (GP) IIb/IIIa integrin binds to fibrinogen and thereby mediates platelet aggregation. Here, we addressed the role of GP IIb for platelet adhesion and determined the relevance of platelet GP IIb for the processes of atherosclerosis and cerebral ischemia-reperfusion (I/R) injury. Methods and Results— GP IIb −/− mice were generated and bred with ApoE −/− animals to create GP IIb −/− ApoE −/− mice. Platelet adhesion to the mechanically injured or atherosclerotic vessel wall was monitored by in vivo video fluorescence microscopy. In the presence of GP IIb, vascular injury and early atherosclerosis induced platelet adhesion in the carotid artery (CA). In contrast, platelet adhesion was significantly reduced in the absence of GP IIb integrin ( P +/+ ApoE −/− or GP IIb −/− ApoE −/− mice. Interestingly, the absence of GP IIb attenuated lesion formation in CA and AA, indicating that platelets, via GP IIb, contribute substantially to atherosclerosis. Next, we assessed the implication of GP IIb for cerebral I/R injury. We observed that after occlusion of the middle cerebral artery, the cerebral infarct size was drastically reduced in mice lacking GP IIb compared with wild-types. Conclusions— These findings show for the first time in vivo that GP IIb not only mediates platelet aggregation but also triggers platelet adhesion to exposed extracellular matrices and dysfunctional endothelial cells. In a process strictly involving GP IIb, platelets, which are among the first blood cells to arrive at the scene of endothelial dysfunction, contribute essentially to atherosclerosis and cerebral I/R injury.