Impact of pulmonary hypertension on outcomes after TEER in patients suffering from mitral regurgitation.

AIM: Data on associations of invasively determined hemodynamic parameters with procedural success and outcomes in patients suffering from mitral regurgitation (MR) undergoing transcatheter edge-to-edge repair of the mitral valve (M-TEER) is limited. METHODS AND RESULTS: We enrolled 239 patients with symptomatic MR of grade 2 + , who received M-TEER. All patients underwent extensive pre-interventional invasive hemodynamic measurements via right heart catheterization (mean pulmonary arterial pressure (mPAP), systolic- (PAPsys) and diastolic pulmonary arterial pressure (PAPdia), pulmonary arterial wedge pressure (PAWP), a-wave, v-wave, pulmonary vascular resistance (PVR), transpulmonary pressure gradient (TPG), cardiac index (CI), stroke volume index (SVI)). mPAP and PAWP at baseline were neither associated with procedural success, immediate reduction of MR, nor residual MR after 6 months of follow-up. The composite outcome (All-cause mortality (ACM) and/or heart failure induced rehospitalization (HFH)) and HFH differed significantly after M-TEER when stratified according to mPAP, PAWP, PAPdia, a-wave and v-wave. ACM was not associated with the afore mentioned parameters. Neither PVR, TPG, CI nor SVI were associated with the composite outcome and HFH, respectively. In multivariable analyses, PAWP was independently associated with the composite outcome and HFH. PVR and SVI were not associated with outcomes. CONCLUSION: PAWP at baseline was significantly and independently associated with HFH and might serve as a valuable parameter for identifying patients at high risk for HFH after M-TEER. ACM and procedural success were not affected by pulmonary arterial pressure before M-TEER. We suggest that the post-capillary component of PH serves as the driving force behind the risk of HFH.

Mitral Valve Transcatheter Edge-to-Edge Repair: 1-Year Outcomes From the MiCLASP Study.

BACKGROUND: Mitral transcatheter edge-to-edge repair (M-TEER) is a guideline-recommended treatment option for patients with severe symptomatic mitral regurgitation (MR). Outcomes with the PASCAL system in a post-market setting have not been established. OBJECTIVES: The authors report 30-day and 1-year outcomes from the MiCLASP (Transcatheter Repair of Mitral Regurgitation with Edwards PASCAL Transcatheter Valve Repair System) European post-market clinical follow-up study. METHODS: Patients with symptomatic, clinically significant MR were prospectively enrolled. The primary safety endpoint was clinical events committee-adjudicated 30-day composite major adverse event rate and the primary effectiveness endpoint was echocardiographic core laboratory-assessed MR severity at discharge compared with baseline. Clinical, echocardiographic, functional, and quality-of-life outcomes were assessed at 1 year. RESULTS: A total of 544 patients were enrolled (59% functional MR, 30% degenerative MR). The 30-day composite major adverse event rate was 6.8%. MR reduction was significant from baseline to discharge and sustained at 1 year with 98% of patients achieving MR ≤2+ and 82.6% MR ≤1+ (all P < 0.001 vs baseline). One-year Kaplan-Meier estimate for survival was 87.3%, and freedom from heart failure hospitalization was 84.3%. Significant functional and quality-of-life improvements were observed at 1 year, including 71.6% in NYHA functional class I/II, 14.4-point increase in Kansas City Cardiomyopathy Questionnaire score, and 24.2-m improvement in 6-minute walk distance (all P < 0.001 vs baseline). CONCLUSIONS: One-year outcomes of this large cohort from the MiCLASP study demonstrate continued safety and effectiveness of M-TEER with the PASCAL system in a post-market setting. Results demonstrate high survival and freedom from heart failure hospitalization, significant and sustained MR reduction, and improvements in symptoms, functional capacity, and quality of life.

Machine learning insights into thrombo-ischemic risks and bleeding events through platelet lysophospholipids and acylcarnitine species.

Coronary artery disease (CAD) often leads to adverse events resulting in significant disease burdens. Underlying risk factors often remain inapparent prior to disease incidence and the cardiovascular (CV) risk is not exclusively explained by traditional risk factors. Platelets inherently promote atheroprogression and enhanced platelet functions and distinct platelet lipid species are associated with disease severity in patients with CAD. Lipidomics data were acquired using mass spectrometry and processed alongside clinical data applying machine learning to model estimates of an increased CV risk in a consecutive CAD cohort (n = 595). By training machine learning models on CV risk measurements, stratification of CAD patients resulted in a phenotyping of risk groups. We found that distinct platelet lipids are associated with an increased CV or bleeding risk and independently predict adverse events. Notably, the addition of platelet lipids to conventional risk factors resulted in an increased diagnostic accuracy of patients with adverse CV events. Thus, patients with aberrant platelet lipid signatures and platelet functions are at elevated risk to develop adverse CV events. Machine learning combining platelet lipidome data and common clinical parameters demonstrated an increased diagnostic value in patients with CAD and might improve early risk discrimination and classification for CV events.

Apixaban versus Aspirin for Embolic Stroke of Undetermined Source.

Apixaban versus Aspirin for Embolic StrokeIn a trial of 352 patients with embolic stroke of undetermined source, 5 mg of apixaban administered twice daily was compared with 100 mg of aspirin administered once daily for the prevention of recurrent ischemic strokes. At 12 months, 13.6% of patients given apixaban had new ischemic lesions on magnetic resonance imaging compared with 16.0% of patients given aspirin, and the rates of clinically relevant bleeding were also comparable.

Optimal Antithrombotic Strategies in Cardiogenic Shock.

Cardiogenic shock (CS) represents a critical condition with a high mortality rate. The most common cause of CS is coronary artery disease, and patients typically present with myocardial infarction, necessitating immediate treatment through percutaneous coronary intervention (PCI) and often requiring mechanical circulatory support. CS is associated with a prothrombotic situation, while on the other hand, there is often a significant risk of bleeding. This dual challenge complicates the selection of an optimal antithrombotic strategy. The choice of antithrombotic agents must be personalized, taking into consideration all relevant conditions. Repeated risk assessment, therapeutic monitoring, and adjusting antithrombotic therapy are mandatory in these patients. This review article aims to provide an overview of the current evidence and practical guidance on antithrombotic strategies in the context of CS.

Outcomes of patients undergoing edge-to-edge mitral valve repair with the Edwards PASCAL transcatheter valve repair system under conscious sedation.

BACKGROUND: The development of the PASCAL transcatheter valve repair system for treating mitral regurgitation (MR) greatly extends therapeutic options. AIMS: To assess the safety, efficacy, and time efficiency of the PASCAL system in transcatheter edge-to-edge repair (TEER) under conscious sedation (CS). METHODS: This is a retrospective, two-center, German registry study consisting of 211 patients who underwent TEER using the PASCAL system under CS. The endpoints were to assess (1) technical, device, and procedural success as per Mitral Valve Academic Research Consortium (MVARC), (2) conversion rate to general anesthesia (GA), (3) hospital length of stay (LoS), (4) New York Heart Association (NYHA) class, and (5) MR compared to baseline at 30-day. RESULTS: A total of 211 patients with a mean age of 78.4 ± 8.9 years, with 51.4% being female and 86.7% belonging to NYHA functional class III/IV and EuroSCORE II 6.3 ± 4.9%, were enrolled. Procedural success attained was 96.9%, and six patients (2.8%) required conversion from CS to GA. At 30 days follow-up, a significant improvement in MR was found in 96 patients (54.2%) patients with 0/1 grade MR and 45 patients (29.5%) were in NYHA functional class III + IV. Moreover, TEER under CS has a short hospital LoS (6.71 ± 5.29 days) and intensive care unit LoS (1.34 ± 3.49 days) with a 2.8% mortality rate. CONCLUSIONS: Performing TEER with the PASCAL system under CS resulted in appreciable (96.9%) procedural success with low mortality and is a safe and promising alternative to GA with positive clinical outcomes.

Prevention of cerebral thromboembolism by oral anticoagulation with dabigatran after pulmonary vein isolation for atrial fibrillation: the ODIn-AF trial.

BACKGROUND AND OBJECTIVES: Long-term oral anticoagulation (OAC) following successful catheter ablation of atrial fibrillation (AF) remains controversial. Prospective data are missing. The ODIn-AF study aimed to evaluate the effect of OAC on the incidence of silent cerebral embolic events and clinically relevant cardioembolic events in patients at intermediate to high risk for embolic events, free from AF after pulmonary vein isolation (PVI). METHODS: This prospective, randomized, multicenter, open-label, blinded endpoint interventional trial enrolled patients who were scheduled for PVI to treat paroxysmal or persistent AF. Six months after PVI, AF-free patients were randomized to receive either continued OAC with dabigatran or no OAC. The primary endpoint was the incidence of new silent micro- and macro-embolic lesions detected on brain MRI at 12 months of follow-up compared to baseline. Safety analysis included bleedings, clinically evident cardioembolic, and serious adverse events (SAE). RESULTS: Between 2015 and 2021, 200 patients were randomized into 2 study arms (on OAC: n = 99, off OAC: n = 101). There was no significant difference in the occurrence of new cerebral microlesions between the on OAC and off OAC arm [2 (2%) versus 0 (0%); P = 0.1517] after 12 months. MRI showed no new macro-embolic lesion, no clinical apparent strokes were present in both groups. SAE were more frequent in the OAC arm [on OAC n = 34 (31.8%), off OAC n = 18 (19.4%); P = 0.0460]; bleedings did not differ. CONCLUSION: Discontinuation of OAC after successful PVI was not found to be associated with an elevated risk of cerebral embolic events compared with continued OAC after a follow-up of 12 months.

Stratification of hypertension and SARS-CoV-2 infection by quantitative NMR spectroscopy of human blood serum.

BACKGROUND: Diagnostic approaches like the nuclear magnetic resonance spectroscopy (NMR) based quantification of metabolites, lipoproteins, and inflammation markers has helped to identify typical alterations in the blood serum of COVID-19 patients. However, confounders such as sex, and comorbidities, which strongly influence the metabolome, were often not considered. Therefore, the aim of this NMR study was to consider sex, as well as arterial hypertension (AHT), when investigating COVID-19-positive serum samples in a large age-and sex matched cohort. METHODS: NMR serum data from 329 COVID-19 patients were compared with 305 healthy controls. 134 COVID-19 patients were affected by AHT. These were analyzed together with NMR data from 58 hypertensives without COVID-19. In addition to metabolite, lipoprotein, and glycoprotein data from NMR, common laboratory parameters were considered. Sex was considered in detail for all comparisons. RESULTS: Here, we show that several differences emerge from previous NMR COVID-19 studies when AHT is considered. Especially, the previously described triglyceride-rich lipoprotein profile is no longer observed in COVID-19 patients, nor an increase in ketone bodies. Further alterations are a decrease in glutamine, leucine, isoleucine, and lysine, citric acid, HDL-4 particles, and total cholesterol. Additionally, hypertensive COVID-19 patients show higher inflammatory NMR parameters than normotensive patients. CONCLUSIONS: We present a more precise picture of COVID-19 blood serum parameters. Accordingly, considering sex and comorbidities should be included in future metabolomics studies for improved and refined patient stratification. Due to metabolic similarities with other viral infections, these results can be applied to other respiratory diseases in the future.

The functionality of our human body is driven by a large number of small molecules, called metabolites. These metabolites can be associated with health but also disease conditions. In this study, we used a technology called nuclear magnetic resonance spectroscopy (NMR) to determine metabolite and protein concentrations in the blood of acutely-infected COVID-19 patients and compared these results with disease severity and clinical laboratory data. We particularly focus on patients with the very common cardiovascular condition, arterial hypertension (AHT), and important factors such as sex, age and medication. Our findings provide a more detailed insight into COVID-19 and which individuals are at higher risk for more severe disease.

Thrombus architecture is influenced by the antiplatelet loading treatment in patients with acute myocardial infarction.

BACKGROUND: Intracoronary thrombus formation is a main cause of acute myocardial infarction triggered by platelet activation. However, there are no data on the impact of different treatment strategies with antiplatelet agents before percutaneous coronary intervention (PCI) on histological characteristics of thrombus formation. OBJECTIVE: In this study, we investigate the impact of preinterventional administration of the P2Y12-inhibitors clopidogrel and prasugrel on thrombus composition, highlighting significant changes associated with the antiplatelet pre-treatment. METHODS: We prospectively enrolled 104 consecutive patients with ST-segment elevation myocardial infarction (STEMI) undergoing immediate PCI and thrombus aspiration by immunohistochemical staining along with RNA-sequencing employing Nanostring analysis. Fifty-two patients were treated with either prasugrel loading (60 mg) or clopidogrel loading (600 mg) prior to PCI, respectively. RESULTS: In Patients with STEMI, intracoronary thrombus architecture was significantly altered between patients pre-treated with prasugrel when compared to clopidogrel. Fibrin content of thrombi was significantly decreased (41.8 % versus 66.7 %, p = 0.009) after pre-treatment with prasugrel compared to clopidogrel. Furthermore, levels of MPO positive cells in intracoronary thrombi were significantly decreased in patients with prasugrel pre-treatment (90.5 versus 201.1, p = 0.014) indicating an association of antiplatelet pre-treatment and the inflammatory responses during thrombus formation. Most strikingly, we observed significant differences among both pre-treatment groups regarding altered RNA expression and signaling pathways of thrombo-inflammatory processes within the thrombotic material, which were independently associated with antiplatelet strategies. CONCLUSIONS: Our study elucidates the impact of antiplatelet pre-treatment on thrombus remodeling and architecture, thereby lowering the risk of recurrent adverse cardiovascular events in prasugrel-treated patients.

[Thromboembolic diseases from a cardiological point of view]. / Thromboembolische Erkrankungen aus kardiologischer Sicht.

Thromboembolic disease is associated with a high mortality. It can be divided into two groups: embolism from a venous and embolism from an arterial side. This article gives an overview on thromboembolic disease (with a focus on pulmonary embolism and ischemic stroke) from a cardiologist's perspective.The therapeutic options for acute pulmonary embolism range from anticoagulation to fibrinolysis to interventional recanalization and surgery. The deciding factor for choice of therapy is the risk of early death. Besides clinical parameters, laboratory markers like cardiac troponin and right ventricular function on echocardiography or CTPA (computed tomography pulmonary angiography) are used to determine the early mortality risk. In hemodynamically instable patients, immediate thrombolysis is required, whereas patients with intermediate and low risk can be treated with anticoagulation. Interventional recanalization is currently being studied in patients at risk for development of CTEPH (chronic thromboembolic pulmonary hypertension) or an intermediate risk of early mortality.In ischemic stroke, early interdisciplinary workup involving a cardiologist is paramount. Post stroke screening should include monitoring for arrythmias (especially atrial fibrillation) and transthoracic echocardiography as well as sonography of extra- and intracranial arteries. If no embolic source can be detected (embolic stroke of undetermined source), transesophageal echo can be helpful to detect intracardiac shunts like patent foramen ovale (PFO) or intracardiac tumors. Post stroke care includes secondary prevention measures like risk factor modification and lipid lowering therapy as well as anticoagulation. In high risk for paradoxical embolization, interventional PFO closure can be performed. Interventional closure of the left atrial appendage (LAA) can be discussed in patients with both high thromboembolic and bleeding risk.

Platelet miRNAs: differential expression in coronary artery disease and associations with course of left ventricular systolic function.

BACKGROUND: MicroRNAs are paramount in post transcriptional gene regulation. We investigated platelet miRNAs in patients with CAD and examined potential associations with course of left ventricular ejection fraction (LVEF%). MATERIALS AND METHODS: In a first cohort, 62 MiRNAs were measured in platelets of 100 patients suffering from CAD. Expression profiles of individuals with chronic coronary syndrome (CCS) and MI were compared (CCS n = 67, MI n = 33). Also, associations between miRNA profiles and change in left ventricular ejection fraction (LVEF%) were investigated. In a second cohort of patients suffering from CCS (n = 10), MI (n = 11) or no CAD (n = 13), we measured miRNA expression in platelets, platelet supernatant and serum. This was carried out before and after in vitro platelet activation with CRP. RESULTS: Platelet miRNAs 103a-3p and 155-5p demonstrated higher expression in patients with CCS then in individuals with MI. Furthermore, multiple miRNAs were significantly higher expressed in matched controls compared to MI patients. 8 miRNAs showed higher expression in patients with improving LVEF% after a 1-year follow-up. In our second cohort, we found higher concentrations of 6 miRNAs in the platelet supernatant of patients with CCS, MI and no CAD after in vitro platelet activation. Most of these miRNAs showed a higher abundance in serum of MI patients as compared to CCS. CONCLUSION: Several miRNAs show higher expression in platelets of CCS compared to MI. After in vitro platelet activation, a release of multiple miRNAs out of the thrombocyte was observed. Furthermore, upregulation of serum miRNAs was found in MI patients when compared to CCS patients and individuals without CAD. Hence, platelets could present a source of upregulated circulating miRNAs in MI and additionally affect course of LVEF%.

Management of patients on antithrombotic therapy with severe infections: a joint clinical consensus statement of the ESC Working Group on Thrombosis, the ESC Working Group on Atherosclerosis and Vascular Biology, and the International Society on Thrombosis and Haemostasis.

Patients with severe infections and a pre-existing indication for antithrombotic therapy, i.e. antiplatelet agents, anticoagulant drugs, or their combinations, require integrated clinical counselling among coagulation, infectious disease, and cardiology specialists, due to sepsis-induced coagulopathy that frequently occurs. Bacterial and viral pathogens constitute an increasing threat to global public health, especially for patients with ongoing antithrombotic treatment who have a high risk of thrombotic recurrences and high susceptibility to severe infections with increased morbidity and mortality. Similarly, sepsis survivors are at increased risk for major vascular events. Coagulopathy, which often complicates severe infections, is associated with a high mortality and obligates clinicians to adjust antithrombotic drug type and dosing to avoid bleeding while preventing thrombotic complications. This clinical consensus statement reviews the best available evidence to provide expert opinion and statements on the management of patients hospitalized for severe bacterial or viral infections with a pre-existing indication for antithrombotic therapy (single or combined), in whom sepsis-induced coagulopathy is often observed. Balancing the risk of thrombosis and bleeding in these patients and preventing infections with vaccines, if available, are crucial to prevent events or improve outcomes and prognosis.

De-escalation or abbreviation of dual antiplatelet therapy in acute coronary syndromes and percutaneous coronary intervention: a Consensus Statement from an international expert panel on coronary thrombosis.

Conventional dual antiplatelet therapy (DAPT) for patients with acute coronary syndromes undergoing percutaneous coronary intervention comprises aspirin with a potent P2Y purinoceptor 12 (P2Y12) inhibitor (prasugrel or ticagrelor) for 12 months. Although this approach reduces ischaemic risk, patients are exposed to a substantial risk of bleeding. Strategies to reduce bleeding include de-escalation of DAPT intensity (downgrading from potent P2Y12 inhibitor at conventional doses to either clopidogrel or reduced-dose prasugrel) or abbreviation of DAPT duration. Either strategy requires assessment of the ischaemic and bleeding risks of each individual. De-escalation of DAPT intensity can reduce bleeding without increasing ischaemic events and can be guided by platelet function testing or genotyping. Abbreviation of DAPT duration after 1-6 months, followed by monotherapy with aspirin or a P2Y12 inhibitor, reduces bleeding without an increase in ischaemic events in patients at high bleeding risk, particularly those without high ischaemic risk. However, these two strategies have not yet been compared in a head-to-head clinical trial. In this Consensus Statement, we summarize the evidence base for these treatment approaches, provide guidance on the assessment of ischaemic and bleeding risks, and provide consensus statements from an international panel of experts to help clinicians to optimize these DAPT approaches for individual patients to improve outcomes.

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.

Interventional Removal of LV Thrombus in a Patient With Cardiogenic Shock and Transitory Ischemic Attack.

We discuss a 38-year-old bodybuilder who had cardiogenic shock and multiorgan failure. The patient developed significant speech disorders resulting from thromboembolism of a huge, volatile left ventricular thrombus. Because of inoperability and the threat of severe ischemic stroke, the thrombus was removed with a snare and application of a cerebral embolic protection device. (Level of Difficulty: Advanced.).

Platelet versus plasma CXCL14, coronary artery disease, and clinical outcomes.

Background: Platelets express CXCL14, while platelet-derived CXCL14 induces monocyte chemotaxis and exerts an angiostatic effect on endothelial cells. Objectives: This study investigated both platelet surface-associated and circulating levels of CXCL14 in patients with heart disease and associations of this chemokine with myocardial function and outcomes in patients with coronary artery disease (CAD). Methods: This prospective study enrolled 450 patients with symptomatic heart disease. Platelet surface-associated and plasma CXCL14 levels were analyzed. All patients were followed up for 360 days for a primary composite outcome consisting of all-cause mortality, myocardial infarction, and/or ischemic stroke. Secondary outcomes consisted of the single events of all-cause mortality or myocardial infarction. Results: Baseline platelet-associated but not circulating CXCL14 levels were significantly lower in patients with chronic coronary syndrome (mean fluorescence intensity logarithmized, 1.35 ± 0.35) when compared to those with acute coronary syndrome (1.47 ± 0.38) and without CAD (1.51 ± 0.40). Platelet CXCL14 levels were significantly lower (1.37 ± 0.37 vs 1.48 ± 0.39) and circulating CXCL14 levels were significantly higher (lg, 2.88 ± 0.20 pg/mL vs 2.82 ± 0.26 pg/mL) in patients with normal baseline left ventricular ejection fraction (LVEF) when compared to those with impaired LVEF. Low baseline circulating CXCL14 (hazard ratio, 2.33; 1.00-5.46) but not platelet CXCL14 was associated with worse outcome in patients with CAD. Conclusion: Platelet-associated and circulating CXCL14 levels show differential regulation in patients with and without CAD. Although platelet-associated CXCL14 increased and circulating CXCL14 decreased with impairment of LVEF, only lower circulating CXCL14 upon admission was associated with worse prognosis in patients with CAD.

Platelets regulate ischemia-induced revascularization and angiogenesis by secretion of growth factor-modulating factors.

In ischemic tissue, platelets can modulate angiogenesis. The specific factors influencing this function, however, are poorly understood. Here, we characterized the complement anaphylatoxin C5a-mediated activation of C5a receptor 1 (C5aR1) expressed on platelets as a potent regulator of ischemia-driven revascularization. We assessed the relevance of the anaphylatoxin receptor C5aR1 on platelets in patients with coronary artery disease as well as those with peripheral artery disease and used genetic mouse models to characterize its significance for ischemia and growth factor-driven revascularization. The presence of C5aR1-expressing platelets was increased in the hindlimb ischemia model. Ischemia-driven angiogenesis was significantly improved in C5aR1-/- mice but not in C5-/- mice, suggesting a specific role of C5aR1. Experiments using the supernatant of C5a-stimulated platelets suggested a paracrine mechanism of angiogenesis inhibition by platelets by means of antiangiogenic CXC chemokine ligand 4 (CXCL4, PF4). Lineage-specific C5aR1 deletion verified that the secretion of CXCL4 depends on C5aR1 ligation on platelets. Using C5aR1-/-CXCL4-/- mice, we observed no additional effect in the revascularization response, underscoring a strong dependence of CXCL4 secretion on the C5a-C5aR1-axis. We identified a novel mechanism for inhibition of neovascularization via platelet C5aR1, which was mediated by the release of antiangiogenic CXCL4.