A systematic comparison of novel and existing differential analysis methods for CyTOF data.

Cytometry techniques are widely used to discover cellular characteristics at single-cell resolution. Many data analysis methods for cytometry data focus solely on identifying subpopulations via clustering and testing for differential cell abundance. For differential expression analysis of markers between conditions, only few tools exist. These tools either reduce the data distribution to medians, discarding valuable information, or have underlying assumptions that may not hold for all expression patterns. Here, we systematically evaluated existing and novel approaches for differential expression analysis on real and simulated CyTOF data. We found that methods using median marker expressions compute fast and reliable results when the data are not strongly zero-inflated. Methods using all data detect changes in strongly zero-inflated markers, but partially suffer from overprediction or cannot handle big datasets. We present a new method, CyEMD, based on calculating the earth mover's distance between expression distributions that can handle strong zero-inflation without being too sensitive. Additionally, we developed CYANUS - CYtometry ANalysis Using Shiny - a user-friendly R Shiny App allowing the user to analyze cytometry data with state-of-the-art tools, including well-performing methods from our comparison. A public web interface is available at https://exbio.wzw.tum.de/cyanus/.

Immature Platelet Fraction Predicts Adverse Events in Patients With Acute Coronary Syndrome: the ISAR-REACT 5 Reticulated Platelet Substudy.

BACKGROUND: Immature or reticulated platelets are associated with impaired efficacy of antiplatelet drugs and adverse events in cardiovascular patients. Their role as a predictive biomarker in patients with acute coronary syndrome treated with potent P2Y12 receptor inhibitors is not fully understood. We aimed to prospectively evaluate reticulated platelets as a predictor of the primary end point of the ISAR-REACT 5 trial consisting of death, myocardial infarction, or stroke at 1 year in patients with acute coronary syndrome randomized to prasugrel or ticagrelor. METHODS: Immature platelet fraction (IPF) was assessed within 48 hours after randomization. Patients were divided based on the IPF median values: the IPFhigh group included patients with IPF>median and the IPFlow group included patients with IPF≤median. Platelet aggregation was assessed using the Multiplate Analyzer and was correlated to IPF. RESULTS: Five hundred seventy-seven patients were included in the study. IPF values in % (median [interquartile range]) within the first 48 hours did not differ between the two study groups: 3.6 (2.5-5.2)% in the prasugrel group and 3.6 (2.5-5.4)% in the ticagrelor group (P=0.882). The incidence of the primary end point was significantly higher in the IPFhigh (IPF>3.6%) group compared with the IPFlow (IPF≤3.6%) group: 13.0% versus 7.2% (HRadj, 1.74 [1.02-3.00]; P=0.044), independently from the assigned drug (Pint=0.159). No significant association between IPF and BARC 3 to 5 bleeding was observed. ADP-induced platelet aggregation correlated significantly with IPF in patients treated with prasugrel (r=0.22; P=0.005) while no correlation was detected in patients treated with ticagrelor (r=0.09; P=0.257). CONCLUSIONS: Independently from drug treatment, IPF was associated with the primary end point and therefore is a promising biomarker for the prediction of adverse cardiovascular events in patients with acute coronary syndrome treated with prasugrel or ticagrelor. REGISTRATION: https://www. CLINICALTRIALS: gov; Unique identifier: NCT01944800.

Platelet mass cytometry reveals dysregulation of prothrombotic pathways in essential thrombocythemia.

Thromboembolic events are common in patients with essential thrombocythemia (ET). However, the pathophysiological mechanisms underlying the increased thrombotic risk remain to be determined. Here, we perform the first phenotypical characterization of platelet expression using single-cell mass cytometry in six ET patients and six age- and sex-matched healthy individuals. A large panel of 18 transmembrane regulators of platelet function and activation were analyzed, at baseline and after ex-vivo stimulation with thrombin receptor-activating peptide (TRAP). We detected a significant overexpression of the activation marker CD62P (p-Selectin) (p = .049) and the collagen receptor GPVI (p = .044) in non-stimulated ET platelets. In contrast, ET platelets had a lower expression of the integrin subunits of the fibrinogen receptor GPIIb/IIIa CD41 (p = .036) and CD61 (p = .044) and of the von Willebrand factor receptor CD42b (p = .044). Using the FlowSOM algorithm, we identified 2 subclusters of ET platelets with a prothrombotic expression profile, one of them (cluster 3) significantly overrepresented in ET (22.13% of the total platelets in ET, 2.94% in controls, p = .035). Platelet counts were significantly increased in ET compared to controls (p = .0123). In ET, MPV inversely correlated with platelet count (r=-0.96). These data highlight the prothrombotic phenotype of ET and postulate GPVI as a potential target to prevent thrombosis in these patients.

Essential thrombocythemia (ET) is a rare disease characterized by an increased number of platelets in the blood. As a complication, many of these patients develop a blood clot, which can be life-threatening. So far, the reason behind the higher risk of blood clots is unclear. In this study, we analyzed platelet surface markers that play a critical role in platelet function and platelet activation using a modern technology called mass cytometry. For this purpose, blood samples from 6 patients with ET and 6 healthy control individuals were analyzed. We found significant differences between ET platelets and healthy platelets. ET platelets had higher expression levels of p-Selectin (CD62P), a key marker of platelet activation, and of the collagen receptor GPVI, which is important for clot formation. These results may be driven by a specific platelet subcluster overrepresented in ET. Other surface markers, such as the fibrinogen receptor GPIIb/IIIa CD41, CD61, and the von Willebrand factor receptor CD42b, were lower expressed in ET platelets. When ET platelets were treated with the clotting factor thrombin (thrombin receptor-activating peptide, TRAP), we found a differential response in platelet activation compared to healthy platelets. In conclusion, our results show an increased activation and clotting potential of ET platelets. The platelet surface protein GPVI may be a potential drug target to prevent abnormal blood clotting in ET patients.

JCAD promotes arterial thrombosis through PI3K/Akt modulation: a translational study.

AIMS: Variants of the junctional cadherin 5 associated (JCAD) locus associate with acute coronary syndromes. JCAD promotes experimental atherosclerosis through the large tumor suppressor kinase 2 (LATS2)/Hippo pathway. This study investigates the role of JCAD in arterial thrombosis. METHODS AND RESULTS: JCAD knockout (Jcad-/-) mice underwent photochemically induced endothelial injury to trigger arterial thrombosis. Primary human aortic endothelial cells (HAECs) treated with JCAD small interfering RNA (siJCAD), LATS2 small interfering RNA (siLATS2) or control siRNA (siSCR) were employed for in vitro assays. Plasma JCAD was measured in patients with chronic coronary syndrome or ST-elevation myocardial infarction (STEMI). Jcad-/- mice displayed reduced thrombogenicity as reflected by delayed time to carotid occlusion. Mechanisms include reduced activation of the coagulation cascade [reduced tissue factor (TF) expression and activity] and increased fibrinolysis [higher thrombus embolization episodes and D-dimer levels, reduced vascular plasminogen activator inhibitor (PAI)-1 expression]. In vitro, JCAD silencing inhibited TF and PAI-1 expression in HAECs. JCAD-silenced HAECs (siJCAD) displayed increased levels of LATS2 kinase. Yet, double JCAD and LATS2 silencing did not restore the control phenotype. si-JCAD HAECs showed increased levels of phosphoinositide 3-kinases (PI3K)/ proteinkinase B (Akt) activation, known to downregulate procoagulant expression. The PI3K/Akt pathway inhibitor-wortmannin-prevented the effect of JCAD silencing on TF and PAI-1, indicating a causative role. Also, co-immunoprecipitation unveiled a direct interaction between JCAD and Akt. Confirming in vitro findings, PI3K/Akt and P-yes-associated protein levels were higher in Jcad-/- animals. Lastly, as compared with chronic coronary syndrome, STEMI patients showed higher plasma JCAD, which notably correlated positively with both TF and PAI-1 levels. CONCLUSIONS: JCAD promotes arterial thrombosis by modulating coagulation and fibrinolysis. Herein, reported translational data suggest JCAD as a potential therapeutic target for atherothrombosis.

Blood Coagulation Disorders in Heart Failure: From Basic Science to Clinical Perspectives.

Heart failure (HF) is a clinical syndrome that is divided into 3 subtypes based on the left ventricular ejection fraction. Every subtype has specific clinical characteristics and concomitant diseases, substantially increasing risk of thromboembolic complications, such as stroke, peripheral embolism and pulmonary embolism. Despite the annual prevalence of 1% and devastating clinical consequences, thromboembolic complications are not typically recognized as the leading problem in patients with HF, representing an underappreciated clinical challenge. Although the currently available data do not support routine anticoagulation in patients with HF and sinus rhythm, initial reports suggest that such strategy might be beneficial in a subset of patients at especially high thromboembolic risk. Considering the existing evidence gap, we aimed to review the currently available data regarding coagulation disorders in acute and chronic HF based on the insight from preclinical and clinical studies, to summarize the evidence regarding anticoagulation in HF in special-case scenarios and to outline future research directions so as to establish the optimal patient-tailored strategies for antiplatelet and anticoagulant therapy in HF. In summary, we highlight the top 10 pearls in the management of patients with HF and no other specific indications for oral anticoagulation therapy. Further studies are urgently needed to shed light on the pathophysiological role of platelet activation in HF and to evaluate whether antiplatelet or antithrombotic therapy could be beneficial in patients with HF. LAY SUMMARY: Heart failure (HF) is a clinical syndrome divided into 3 subtypes on the basis of the left ventricular systolic function. Every subtype has specific clinical characteristics and concomitant diseases, substantially increasing the risk of thromboembolic complications, such as stroke, peripheral embolism and pulmonary embolism. Despite the annual prevalence of 1% and devastating clinical consequences, thromboembolic complications are not typically recognized as the leading problem in patients with HF, representing an underappreciated clinical challenge. Although the currently available data do not support routine anticoagulation in patients with HF and no atrial arrhythmia, initial reports suggest that such a strategy might be beneficial in a subset of patients at especially high risk of thrombotic complications. Considering the existing evidence gap, we aimed to review the currently available data regarding coagulation problems in stable and unstable patients with HF based on the insight from preclinical and clinical studies, to summarize the evidence regarding anticoagulation in HF in specific patient groups and to outline future research directions to establish the optimal strategies for antiplatelet and anticoagulant therapy in HF, tailored to the needs of an individual patient. In summary, we highlight the top 10 pearls in the management of patients with HF and no other specific indications for oral anticoagulation therapy.

Role of Reticulated Platelets in Cardiovascular Disease.

Human platelets differ considerably with regard to their size, RNA content and thrombogenicity. Reticulated platelets (RPs) are young, hyper-reactive platelets that are newly released from the bone marrow. They are larger and contain more RNA compared to older platelets. In comparison to more mature platelets, they exhibit a significantly higher thrombogenicity and are known to be elevated in patients with an increased platelet turnover such as, diabetics and after acute myocardial infarction. Several studies have shown that RPs correlate with an insufficient antiplatelet response to aspirin and specific P2Y12 receptor inhibitors. In addition, RPs are promising novel biomarkers for the prediction of adverse cardiovascular events in cardiovascular disease. However, the reason for RPs intrinsic hyper-reactivity and their association with ischemic events is not completely understood and the biology of RPs is still under investigation. We here present a structured review of preclinical and clinical findings concerning the role of RPs in cardiovascular disease.

Association of immature platelets with perioperative complications in neurosurgery.

Immature platelets are newly formed platelets with an increased prothrombotic potential. This study evaluates whether immature platelets are associated with relevant complications in neurosurgical patients. Data were obtained in the frame of a prospectively conducted observational study exploring the association between immature platelets and major cardiovascular events after surgery. Immature platelet fraction (IPF) and H-IPF (highly fluorescent immature platelet fraction) were measured preoperatively and postoperatively at the neurosurgical ward (24-72 hours after surgery). Therapy-relevant complications after surgery were stratified using the Clavien-Dindo Grade (CDG >2) as primary outcome. Data were analyzed in 391 neurosurgical patients. While preoperatively there were no differences in IPF or H-IPF, patients with higher therapy-complication grades had higher values post-op compared to patients with lower grade complications (≤2 CDG). Cut-off values identified by receiver operating characteristic curve analysis revealed that there were significantly more patients with H-IPF ≥0.95% in the group with serious complications (CDG >2) [odds ratio OR (95% confidence interval CI) = 2.06 (1.09-3.9), p = .025], whereas this association was not present for the IPF cutoff value. In a multivariate model, H-IPF≥0.95% was independently associated with serious complications after surgery [OR (95% CI) = 1.97 (1.03-3.78), p = .041]. These findings suggest that H-IPF is associated with surgical complications and may improve risk stratification of neurosurgical patients (clinicaltrials.gov: NCT02097602, registration date: 27/03/2014).

What is the context?Immature platelets are newly formed platelets with a higher thrombotic potential and play an important role in atherothrombotic events.Higher levels of immature platelets were observed in patients with acute coronary syndrome or stroke.Lately, the focus in immature platelet research shifted from observation to outcomes. Immature platelets were identified as independent predictors of major cardiovascular events in cardiologic patients with coronary artery disease. Besides, an association between immature platelets and major cardiovascular events was described in surgical patients after non-cardiac surgery.What is new?This study builds on these findings and extends the focus to perioperative complications after neurosurgery.The data were obtained prospectively in the frame of an observational clinical trial exploring the association of immature platelets and major cardiovascular events in general. Data measured in the neurosurgical cohort of that study (391 neurosurgical patients) were analyzed in the present work.Within the limitations of our study, our analyses suggest that the postoperative IPF (immature platelet fraction) and H-IPF (highly fluorescent immature platelet fraction) values, which were measured at the neurosurgical ward after surgery are both associated with higher therapy-relevant complication grades (>2 according to Clavien-Dindo Grade), whereas preoperatively obtained values were not.What is the impact?This is the first study showing a relationship between immature platelets and therapy-relevant perioperative complications in neurosurgical patients. It could be a pilot trial for varied scientific questions including risk stratification of neurosurgical patients.

Duration of antiplatelet therapy after complex percutaneous coronary intervention in patients at high bleeding risk: a MASTER DAPT trial sub-analysis.

AIM: To assess the effects of 1- or ≥3-month dual antiplatelet therapy (DAPT) in high bleeding risk (HBR) patients who received biodegradable-polymer sirolimus-eluting stents for complex percutaneous coronary intervention (PCI) and/or acute coronary syndrome (ACS). METHODS AND RESULTS: In the MASTER DAPT trial, 3383 patients underwent non-complex (abbreviated DAPT, n = 1707; standard DAPT, n = 1676) and 1196 complex (abbreviated DAPT, n = 588; standard DAPT, n = 608) PCI. Co-primary outcomes at 335 days were net adverse clinical events [NACE; composite of all-cause death, myocardial infarction, stroke, and bleeding academic research consortium (BARC) 3 or 5 bleeding events]; major adverse cardiac or cerebral events (MACCE; all-cause death, myocardial infarction, and stroke); and Types 2, 3, or 5 BARC bleeding. Net adverse clinical events and MACCE did not differ with abbreviated vs. standard DAPT among patients with complex [hazard ratio (HR): 1.03, 95% confidence interval (CI): 0.69-1.52, and HR: 1.24, 95% CI: 0.79-1.92, respectively] and non-complex PCI (HR: 0.90, 95% CI: 0.71-1.15, and HR: 0.91, 95% CI: 0.69-1.21; Pinteraction = 0.60 and 0.26, respectively). BARC 2, 3, or 5 was reduced with abbreviated DAPT in patients with and without complex PCI (HR: 0.64; 95% CI: 0.42-0.98, and HR: 0.70; 95% CI: 0.55-0.89; Pinteraction = 0.72). Among the 2816 patients with complex PCI and/or ACS, NACE and MACCE did not differ and BARC 2, 3, or 5 was lower with abbreviated DAPT. CONCLUSION: In HBR patients free from recurrent ischaemic events at 1 month, DAPT discontinuation was associated with similar NACE and MACCE and lower bleeding rates compared with standard DAPT, regardless of PCI or patient complexity. CLINICAL TRIAL REGISTRATION: This trial is registered with ClinicalTrials.gov, number NCT03023020, and is closed to new participants, with follow-up completed.

Transcription Factor MAFF (MAF Basic Leucine Zipper Transcription Factor F) Regulates an Atherosclerosis Relevant Network Connecting Inflammation and Cholesterol Metabolism.

BACKGROUND: Coronary artery disease (CAD) is a multifactorial condition with both genetic and exogenous causes. The contribution of tissue-specific functional networks to the development of atherosclerosis remains largely unclear. The aim of this study was to identify and characterize central regulators and networks leading to atherosclerosis. METHODS: Based on several hundred genes known to affect atherosclerosis risk in mouse (as demonstrated in knockout models) and human (as shown by genome-wide association studies), liver gene regulatory networks were modeled. The hierarchical order and regulatory directions of genes within the network were based on Bayesian prediction models, as well as experimental studies including chromatin immunoprecipitation DNA-sequencing, chromatin immunoprecipitation mass spectrometry, overexpression, small interfering RNA knockdown in mouse and human liver cells, and knockout mouse experiments. Bioinformatics and correlation analyses were used to clarify associations between central genes and CAD phenotypes in both human and mouse. RESULTS: The transcription factor MAFF (MAF basic leucine zipper transcription factor F) interacted as a key driver of a liver network with 3 human genes at CAD genome-wide association studies loci and 11 atherosclerotic murine genes. Most importantly, expression levels of the low-density lipoprotein receptor (LDLR) gene correlated with MAFF in 600 CAD patients undergoing bypass surgery (STARNET [Stockholm-Tartu Atherosclerosis Reverse Network Engineering Task]) and a hybrid mouse diversity panel involving 105 different inbred mouse strains. Molecular mechanisms of MAFF were tested in noninflammatory conditions and showed positive correlation between MAFF and LDLR in vitro and in vivo. Interestingly, after lipopolysaccharide stimulation (inflammatory conditions), an inverse correlation between MAFF and LDLR in vitro and in vivo was observed. Chromatin immunoprecipitation mass spectrometry revealed that the human CAD genome-wide association studies candidate BACH1 (BTB domain and CNC homolog 1) assists MAFF in the presence of lipopolysaccharide stimulation with respective heterodimers binding at the MAF recognition element of the LDLR promoter to transcriptionally downregulate LDLR expression. CONCLUSIONS: The transcription factor MAFF was identified as a novel central regulator of an atherosclerosis/CAD-relevant liver network. MAFF triggered context-specific expression of LDLR and other genes known to affect CAD risk. Our results suggest that MAFF is a missing link between inflammation, lipid and lipoprotein metabolism, and a possible treatment target.

Long term follow-up after balloon expandable covered stents implantation for management of transcatheter aortic valve replacement related vascular access complications.

OBJECTIVES: To report the experience of a high-volume center with balloon-expandable (BE) stents implantation to manage vascular complications after transcatheter aortic valve replacement (TAVR). BACKGROUND: Despite increased operator experience and better devices, vascular complications after TAVR are still a major issue and covered stent implantation is often required. METHODS: We retrospectively collected baseline and procedural data about 78 consecutive patients who underwent BE stent implantation to manage a vascular complication after transfemoral TAVR. Primary endpoints were technical success, incidence of new-onset claudication and need for vascular interventions during long-term follow-up. Secondary endpoints included length of hospitalization, in-hospital and 30-day mortality, and major postoperative complications. RESULTS: BE stents implantation to manage vascular complications after TAVR was successfully performed in 96.2% of the cases, with bailout surgery required in two cases. One patient suffered in-hospital death. Predischarge Doppler Ultrasound revealed no cases of in-stent occlusion or fracture. At a median follow-up of 429 days (interquartile range, 89-994 days), no cases of symptomatic leg ischemia were reported and only one patient experienced new-onset claudication. CONCLUSIONS: Our experience showed good periprocedural and long-term results of BE covered stent implantation to manage vascular complication after TAVR. Their great radial outward force may guarantee effective hemostasis without necessarily being associated with stent deformation/fracture resulting in restenosis or further interventions. More research is needed to define the role of BE covered stents in this setting.

Mass cytometry of platelet-rich plasma: a new approach to analyze platelet surface expression and reactivity.

Mass cytometry (CyTOF) is a new technology that allows the investigation of protein expression at single cell level with high resolution. While several protocols are available to investigate leukocyte expression, platelet staining and analysis with CyTOF have been described only from whole blood. Moreover, available protocols do not allow sample storage but require fresh samples to be obtained, processed, and measured immediately. We provide a structured and reproducible method to stain platelets from platelet-rich plasma to study thrombocyte protein expression and reactivity using mass cytometry. With our method, it is possible to acquire a large number of events allowing deep bioinformatic investigation of platelet expression heterogeneity. Integrated in our protocol is also a previously established freezing protocol that allows the storage of stained samples and to delay their measurement. Finally, we provide a structured workflow using different platelet stimulators and a freely available bioinformatic pipeline to analyze platelet expression. Our protocol unlocks the potential of CyTOF analysis for studying platelet biology in health and disease.

Sorting and magnetic-based isolation of reticulated platelets from peripheral blood.

Reticulated Platelets (RPs) are large, RNA-rich, prothrombotic and hyperactive platelets known to be elevated in high-risk populations such as diabetics and patients with acute coronary syndrome. High levels of RPs correlate with mortality and adverse cardiovascular events in patients with coronary artery disease as well as with an insufficient antiplatelet response to thienopyridines and aspirin after percutaneous coronary interventions, making them an appealing drug target. However, processing of platelets is challenging and no specific marker for RPs exists. Until now, the gold standard laboratory-based method to study them is based on the flow cytometric measurement of their cell size and their RNA-content with the fluorescent dye Thiazole Orange (TO). Nevertheless, standardized protocols for staining and processing of RPs are missing and the existing techniques were not applied for cell sorting. We provide here a structured and reproducible method to detect, isolate and collect RPs from peripheral blood by RNA-specific staining with TO implementing several platelet inhibitors as well as magnetic labeling allowing sufficient cell recovery and deep biological investigation of these platelets.

Influence of diagnosis of venous thromboembolism on immature platelets, absolute platelet count and platelet aggregation over time.

The extent of the involvement of platelets in venous thromboembolisms (VTE) is still not fully understood. Immature platelets are large, RNA-rich, prothrombotic platelets. They are involved in arterial thromboembolisms and are associated with adverse cardiovascular events. Their role in VTE has not been investigated before. The aim of this study was to assess different platelet parameters including immature platelet fraction (IPF), immature platelet count (IPC), absolute platelet count and platelet aggregation (PA) over time in patients with VTE at time of diagnosis, as well as at 3-10 days and at 90-110 days after diagnosis. 50 healthy volunteers similar in age and sex to patients served as controls at diagnosis. IPF was measured by the Sysmex XE-5000 analyzer, PA was assessed using the Multiplate analyzer. Diagnosis of VTE had no relevant effect on IPF and IPC whereas absolute platelet count and PA were significantly decreased compared to controls. In the course of VTE, IPF decreased significantly, whereas IPC, absolute platelet count and PA increased. In conclusion, VTE was associated with relevant changes of the absolute platelet count and PA at diagnosis, as well as changes in IPF and IPC over time reflecting a relevant and measurable platelet consumption in VTEs.

Plasma Soluble Glycoprotein VI, Platelet Function, Bleeding, and Ischemic Events in Patients Undergoing Elective Percutaneous Coronary Intervention.

BACKGROUND AND AIMS: Glycoprotein VI (GPVI) is the major platelet-specific collagen receptor. GPVI shedding with generation of soluble GPVI (sGPVI) is an endogenous feedback mechanism preventing platelet overstimulation. sGPVI has not been investigated in patients with chronic coronary syndrome (CCS) undergoing percutaneous coronary intervention (PCI), especially regarding its potential value as a predictor of ischemic and bleeding risk. METHODS: Baseline plasma sGPVI levels were available in 318 patients with CCS undergoing PCI. Platelet function was assessed by measuring both adenosine diphosphate (ADP) and collagen-induced platelet aggregation. Co-primary endpoints were a composite of death or myocardial injury at 48 hours after PCI, and Bleeding Academic Research Consortium (BARC) type 1 to 5 bleeding at 30 days. RESULTS: There was no significant correlation between sGPVI and platelet function at baseline or at 48 hours after PCI and loading with antiplatelet drugs. Baseline plasma sGPVI levels were not associated with the ischemic risk: the incidence of the ischemic endpoint was 25.0% in the lower, 22.9% in the middle, and 26.7% in the upper sGPVI tertile (p = 0.82). There was a significant nonlinear relationship between sGPVI and the risk of bleeding: the incidence of the bleeding endpoint was 11.8% in the lower, 12.6% in the middle, and 26.4% in the upper sGPVI tertile (p = 0.006). CONCLUSION: In patients with CCS undergoing PCI, plasma levels of sGPVI did not correlate with ADP- or collagen-induced platelet aggregation. Patients with higher baseline levels of sGPVI may carry an increased risk of bleeding at 30 days after PCI but no excess risk of ischemic events.

Reticulated Platelets Predict Cardiovascular Death and Adverse Events in Coronary Artery Disease: A Systematic Review and Meta-analysis.

BACKGROUND: The pro-thrombotic immature or reticulated platelets (RPs) are known to be elevated in high-risk patients and in different pathological settings. It has been shown that RPs correlate with an insufficient antiplatelet response to antiplatelet agents. RPs are emerging novel predictors of adverse cardiovascular events in cardiovascular disease. This study, using the totality of existing evidence, evaluated the prognostic role of RPs in patients with coronary artery disease. METHODS: We performed a systematic review and meta-analysis including trials of acute and chronic coronary syndrome reporting clinical outcomes according to RPs levels in the peripheral blood. We compared patients with elevated RPs (RPshigh) to patients without elevated RPs (RPslow). Odds ratios (ORs) and 95% CIs were used as metric of choice for treatment effects with random-effects models. The primary endpoint was major adverse cardiovascular and cerebrovascular events (MACCE). Secondary endpoints were cardiovascular death, myocardial infarction, ischemic stroke, urgent coronary revascularization and bleedings. RESULTS: A total of 7 studies, including 2213 patients, were included. The risk for MACCE was significantly higher in RPshigh compared to RPslow patients (OR 2.67 [1.87; 3.81], I2 = 43.8%). RPshigh were associated with cardiovascular death (OR 2.09 [1.36; 3.22], I2 = 40.4%). No associations for RPshigh were detected with the other singular components of MACCE: myocardial infarction (OR 1.73 [0.89; 3.38] I2 = 60.5%) and stroke (OR 1.72 [0.59; 4.96] I2 = 21%). The risk of bleeding did not differ between groups(OR 0.58 [0.15; 2.22] I2 = 86.1%). CONCLUSION: Elevated RPs are significantly associated with increased risk of cardiovascular events and cardiovascular death.

Hutchinson-Gilford progeria syndrome mice display accelerated arterial thrombus formation and increased platelet reactivity.

INTRODUCTION: Hutchinson-Gilford Progeria Syndrome (HGPS) is an ultra-rare premature aging genetic disorder caused by a point mutation in the lamin A gene, LMNA. Children with HGPS display short lifespans and typically die due to myocardial infarction or ischemic stroke, both acute cardiovascular events that are tightly linked to arterial thrombosis. Despite this fact, the effect of the classic HGPS LMNA gene mutation on arterial thrombosis remains unknown. METHODS: Heterozygous LmnaG609G knock-in (LmnaG609G/+) mice, yielding an equivalent classic mutation observed in HGPS patients (c.1824C>T; pG608G mutation in the human LMNA gene) and corresponding wild-type (WT) control littermates underwent photochemically laser-induced carotid injury to trigger thrombosis. Coagulation and fibrinolytic factors were measured. Furthermore, platelet activation and reactivity were investigated. RESULTS: LmnaG609G/+ mice displayed accelerated arterial thrombus formation, as underlined by shortened time to occlusion compared to WT littermates. Levels of factors involved in the coagulation and fibrinolytic system were comparable between groups, while LmnaG609G/+ animals showed higher plasma levels of thrombin-antithrombin complex and lower levels of antithrombin. Bone marrow analysis showed larger megakaryocytes in progeric mice. Lastly, enhanced platelet activation upon adenosine diphosphate, collagen-related peptide, and thrombin stimulation was observed in LmnaG609G/+ animals compared to the WT group, indicating a higher platelet reactivity in progeric animals. CONCLUSIONS: LMNA mutation in HGPS mice accelerates arterial thrombus formation, which is mediated, at least in part, by enhanced platelet reactivity, which consequently augments thrombin generation. Given the wide spectrum of antiplatelet agents available clinically, further investigation is warranted to consider the most suitable antiplatelet regimen for children with HGPS to mitigate disease mortality and morbidity.

Coagulation Disorders and Thrombotic Complications in Heart Failure With Preserved Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is associated with multiple cardiovascular and noncardiovascular comorbidities and risk factors which increase the risk of thrombotic complications, such as atrial fibrillation, chronic kidney disease, arterial hypertension and type 2 diabetes mellitus. Subsequently, thromboembolic risk stratification in this population poses a great challenge. Since date from the large randomized clinical trials mostly include both patients with truly preserved EF, and those with heart failure with mildly reduced ejection fraction, there is an unmet need to characterize the patients with truly preserved EF. Considering the significant evidence gap in this area, we sought to describe the coagulation disorders and thrombotic complications in patients with HFpEF and discuss the specific thromboembolic risk factors in patients with HFpEF, with the goal to tailor risk stratification to an individual patient.

Implantation of contemporary transcatheter aortic valves in small aortic annuli: the international multicentre TAVI-SMALL 2 registry.

BACKGROUND: Treatment of aortic stenosis in patients with small annuli is challenging and can result in prosthesis-patient mismatch (PPM). AIMS: We aimed to compare the forward flow haemodynamics and clinical outcomes of contemporary transcatheter valves in patients with small annuli. METHODS: The TAVI-SMALL 2 international retrospective registry included 1,378 patients with severe aortic stenosis and small annuli (annular perimeter <72 mm or area <400 mm2) treated with transfemoral self-expanding (SEV; n=1,092) and balloon-expandable valves (BEV; n=286) in 16 high-volume centres between 2011 and 2020. Analyses comparing SEV versus BEV and supra-annular (SAV; n=920) versus intra-annular valves (IAV; n=458) included inverse probability of treatment weighting (IPTW). The primary endpoints were the predischarge mean aortic gradient and incidence of severe PPM. The secondary endpoint was the incidence of more than mild paravalvular leak (PVL). RESULTS: The predischarge mean aortic gradient was lower after SAV versus IAV (7.8±3.9 vs 12.0±5.1; p<0.001) and SEV versus BEV implantation (8.0±4.1 vs 13.6±4.7; p<0.001). Severe PPM was more common with IAV and BEV when compared to SAV and SEV implantation, respectively, (8.8% vs 3.6%; p=0.007 and 8.7% vs 4.6%; p=0.041). At multivariable logistic regression weighted by IPTW, SAV protected from severe PPM regardless of its definition. More than mild PVL occurred more often with SEV versus BEV (11.6% vs 2.6%; p<0.001). CONCLUSIONS: In small aortic annuli, implantation of SAV and SEV was associated with a more favourable forward haemodynamic profile than after IAV and BEV implantation, respectively. More than mild PVL was more common after SEV than BEV implantation.

Leukocytes carrying Clonal Hematopoiesis of Indeterminate Potential (CHIP) Mutations invade Human Atherosclerotic Plaques.

Background: Leukocyte progenitors derived from clonal hematopoiesis of undetermined potential (CHIP) are associated with increased cardiovascular events. However, the prevalence and functional relevance of CHIP in coronary artery disease (CAD) are unclear, and cells affected by CHIP have not been detected in human atherosclerotic plaques. Methods: CHIP mutations in blood and tissues were identified by targeted deep-DNA-sequencing (DNAseq: coverage >3,000) and whole-genome-sequencing (WGS: coverage >35). CHIP-mutated leukocytes were visualized in human atherosclerotic plaques by mutaFISH™. Functional relevance of CHIP mutations was studied by RNAseq. Results: DNAseq of whole blood from 540 deceased CAD patients of the Munich cardIovaScular StudIes biObaNk (MISSION) identified 253 (46.9%) CHIP mutation carriers (mean age 78.3 years). DNAseq on myocardium, atherosclerotic coronary and carotid arteries detected identical CHIP mutations in 18 out of 25 mutation carriers in tissue DNA. MutaFISH™ visualized individual macrophages carrying DNMT3A CHIP mutations in human atherosclerotic plaques. Studying monocyte-derived macrophages from Stockholm-Tartu Atherosclerosis Reverse Networks Engineering Task (STARNET; n=941) by WGS revealed CHIP mutations in 14.2% (mean age 67.1 years). RNAseq of these macrophages revealed that expression patterns in CHIP mutation carriers differed substantially from those of non-carriers. Moreover, patterns were different depending on the underlying mutations, e.g. those carrying TET2 mutations predominantly displayed upregulated inflammatory signaling whereas ASXL1 mutations showed stronger effects on metabolic pathways. Conclusions: Deep-DNA-sequencing reveals a high prevalence of CHIP mutations in whole blood of CAD patients. CHIP-affected leukocytes invade plaques in human coronary arteries. RNAseq data obtained from macrophages of CHIP-affected patients suggest that pro-atherosclerotic signaling differs depending on the underlying mutations. Further studies are necessary to understand whether specific pathways affected by CHIP mutations may be targeted for personalized treatment.