Background:Immature platelet fraction (IPF) reflects thrombopoietic activity and platelet reactivity and has been associated with adverse cardiovascular outcomes. However, its prognostic value in patients undergoing primary percutaneous coronary intervention (PPCI) for ST-elevation myocardial infarction has not been systematically evaluated. Methods:We analyzed 1,713 consecutive PPCI patients from a prospective single-center registry (July 2019-April 2026). Patients were stratified into IPF tertiles: low (≤3.0%), mid (3.0-5.1%), and high (>5.1%). The primary endpoint was long-term all-cause mortality, estimated using the Kaplan-Meier method and compared by the log-rank test. All effect estimates were derived from multivariable Cox proportional hazards regression adjusted for age, ejection fraction, sex, hypertension, diabetes mellitus, chronic renal failure, and prior coronary artery disease. Prespecified sensitivity analyses comprised a 3-year truncated analysis and a postdischarge landmark analysis. Results:Among 1,713 PPCI patients (median age: 64 years, 20.9% female), median IPF was 4.2%. Over a median potential follow-up of 3.0 years, 233 deaths (13.6%) occurred. Kaplan-Meier estimated 3-year all-cause mortality increased stepwise across tertiles: 9.1, 10.2, and 18.2% in the low, mid, and high IPF groups, respectively (log-rank p < 0.001). In-hospital mortality showed a nonsignificant trend (2.1, 2.6, and 3.9%; p = 0.157). On multivariable Cox regression, IPF as a continuous variable was not independently associated with long-term mortality (hazard ratios [HR]: 1.039 per 1% increase, 95% confidence intervals [CI]: 0.998-1.081, p = 0.066), whereas the high IPF tertile was independently associated with a 51% higher hazard of death compared with the low tertile (HR: 1.51, 95% CI: 1.08-2.12, p = 0.017). The association persisted in the 3-year truncated analysis (HR: 1.78, 95% CI: 1.23-2.58, p = 0.002) and in the postdischarge landmark analysis (HR: 1.52, 95% CI: 1.04-2.21, p = 0.03). Conclusion:High admission IPF (>5.1%) was independently associated with increased long-term mortality after PPCI. Because IPF is automatically reported as part of the admission complete blood count at no additional cost, it may help identify patients who warrant closer postdischarge surveillance. However, external validation in independent cohorts is required before IPF can be incorporated into routine risk stratification.
Background:The prognostic significance of syncope in patients with acute pulmonary embolism (PE) remains uncertain. We assessed its association with early outcomes and explored whether distinct clinical phenotypes could be identified within this group. Methods:We analyzed a prospectively collected single-center cohort of patients with confirmed symptomatic PE diagnosed between 2010 and 2025, grouped by syncope at presentation. The primary outcome was a 30-day composite of all-cause mortality, major bleeding, and recurrent venous thromboembolism. Associations were estimated using inverse probability of exposure weighting. Estimand A balanced baseline confounders, whereas Estimand B additionally balanced measured markers of acute severity. Within the syncope subgroup, exploratory clustering used 13 baseline clinical variables. Results:Among 2,331 patients with PE, 329 (14.1%) presented with syncope. Under Estimand A, syncope was associated with a 14.0-percentage-point higher risk of the composite outcome (95% confidence interval [CI]: 9.0-19.6; risk ratio [RR]: 2.71, 95% CI: 2.02-3.52). Under Estimand B, the association was substantially attenuated, with a risk difference of 5.2 percentage points (95% CI: - 0.2 to 10.6; RR: 1.54, 95% CI: 0.98-2.19). A similar attenuation was observed for all-cause mortality and major bleeding. Exploratory clustering identified four phenotypes, none of which met the prespecified criteria for internal stability. Conclusion:In acute PE, syncope identifies patients at higher risk of early adverse outcomes. This association was substantially attenuated after accounting for measured acute severity, suggesting that syncope mainly marks a more severe initial presentation rather than carrying prognostic information independent of severity.
Abstract Thrombus formation in atrial fibrillation mostly occurs in the left atrial appendage (LAA). LAA closure (LAAC) seems logical to reduce thrombo-embolic AF-related stroke. Early device trials, which predominantly compared LAAC against oral anticoagulant (OAC) with warfarin, showing after 5 years less bleeding and possibly similar ischemic stroke rates with LAAC. New trials (CHAMPION-AF, OPTION, CLUSTER-AF and ASAP TOO) comparing LAAC versus direct OACs, or standard of care for the OAC-intolerant, have reported apparently discordant results, most probably related to the patient phenotype than LAAC itself. Recent meta-analyses, which include new trials have shown that overall, LAAC is followed by less clinically-relevant bleeding but more ischemic but not total strokes. Longer follow-up offsetting penalties related to the implant procedure, more expert implantation and reduced device-related thrombosis should increase the comparative value of LAAC. Meanwhile, LAAC offers therapeutic relief for OAC-intolerant patients or for those wh, understand the outcomes of LAAC and prefer device rather than medical therapy. A change in guideline recommendations should now be considered.
BACKGROUND:Sublingual estradiol is increasingly used for gender-affirming hormone therapy (GAHT), but its chronic hemostatic effects remain insufficiently characterized. OBJECTIVES:To compare hemostatic changes between oral estradiol plus cyproterone acetate (CPA) with divided-dose sublingual estradiol monotherapy in treatment-naive transgender women. METHODS:In this prospective, non-randomized study, 30 treatment-naïve transgender women received oral estradiol 2 mg once daily plus CPA 10 mg daily (n=15) or sublingual estradiol 0.5 mg four times daily without an anti-androgen (n=15) for 6 months. Free Protein S antigen, Protein C, thrombin generation assay (TGA), and thromboelastography (TEG) were assessed at baseline and 6 months. RESULTS:Free Protein S antigen decreased in all participants receiving sublingual estradiol (median change, -22%; p<0.001), compared with a smaller, heterogeneous change with oral estradiol plus CPA (median change, -4.2%; p=0.099). At 6 months, median free Protein S antigen was 77% versus 106%, respectively (p=0.003). After adjustment for baseline Protein S and age, sublingual treatment remained associated with lower 6-month levels (B=-15.8; p<0.001). TGA lag time decreased by a median of 19% in the sublingual group, but the between-group difference was not significant after correction (adjusted p=0.063).TEG maximum amplitude increased modestly with oral estradiol plus CPA and differed between groups after correction (adjusted p=0.009), although values remained within physiological ranges. No thrombotic events occurred. CONCLUSIONS:The two GAHT protocols were associated with different laboratory hemostatic patterns, including a reduction in free Protein S antigen with sublingual estradiol. These findings warrant further evaluation in larger mechanistic studies.
Background:Von Willebrand factor (VWF) and its primary molecular regulator, ADAMTS13, play an important role in hemostasis. Their dysfunction has been increasingly linked to numerous bleeding, thrombotic, and inflammatory conditions. Murine bleeding models are widely used to study their role and assess therapeutic efficacy of targeted agents. Despite this, no review has systematically identified and compared bleeding models proven to involve VWF or ADAMTS13 in vivo. This scoping review addresses this gap by identifying models, associated outcomes, and evaluating methodological inconsistencies that may impact translatability. Methods:A comprehensive literature search was conducted to identify studies using murine models of hemostasis from inception to October 2024. Two reviewers independently screened articles and extracted data on mouse characteristics, bleeding induction methods, and VWF or ADAMTS13-related findings. Results:A total of 35 studies published between 1997 and 2024 were included; 40.0% utilized C57BL/6J mice and 40.0% of models used both sexes. Fourteen (40.0%) studies did not report the mouse supplier, and 20.0 and 80.0% did not report the age and weight of mice, respectively. Most studies (91.4%) used the tail tip transection model, 5.7% employed saphenous vein bleed, and 5.7% performed tail vein transection. Key methodological variations pertained to bleeding quantification, maximum observation time, and length of tail tip removed. Conclusion:This review highlights that most studies assessing VWF-related hemostasis use a single model, but there is methodological variability, limiting reproducibility and translational relevance. Standardized protocols and collaborative efforts to establish consensus guidelines are urgently needed to improve cross-study comparisons to strengthen preclinical therapeutic testing.
Pulmonary vascular obstruction index (PVOI), assessed using the Qanadli index on computed tomography pulmonary angiography (CTPA) at pulmonary embolism (PE) diagnostic, has been associated with recurrence after unprovoked PE, but its complexity limits routine use. We aimed to evaluate simplified semiquantitative (Sq) measures of initial PVOI for predicting recurrent PE after anticoagulation discontinuation.This post hoc analysis, based on the double-blind, randomized PADIS-PE trial where patients with a first unprovoked PE initially treated during 6 months were allocated to receive either an additional 18-month warfarin or placebo, was restricted on the 180 patients who had PE diagnosed by CTPA. Initial PVOI was assessed using four methods: Qanadli score, modified Qanadli score, anatomical-based SqPVOI1, and lobe-based SqPVOI2. Accuracy and associations with recurrent PE were evaluated using area under the curve (AUC) analysis and Cox regression models.Among the 180 included patients (mean age 66.2 ± 16.5 years; 45.2% female), recurrent PE occurred in 42 patients (36-month median follow-up). Accuracy was comparable across the four PVOI scores, with AUCs ranging from 0.70 to 0.74. All scores showed comparable ability to predict recurrent PE. When using the anatomical-based SqPVOI1, recurrence risk increased progressively with more proximal thrombus location: compared with segmental artery involvement (36-month cumulative incidence, 10.5%; n = 76), risk was 2- to 3-fold with lobar artery involvement (HR 2.90, 95%CI, 1.20-7.05, p = 0.005; 36-month cumulative incidence, 25.6%; n = 63) and 4- to 5-fold increased risk (HR 4.59, 95%CI, 1.85-11.42, p = 0.001; 36-month cumulative incidence, 46.8%; n = 41) with main pulmonary artery involvement.Simplified anatomical assessment of PVOI showed prognostic information comparable to quantitative indices. Further prospective validation is needed.
Patients with acute coronary syndrome (ACS) who have concurrent high ischemic and high bleeding risk are common after percutaneous coronary intervention (PCI), yet evidence guiding P2Y12 inhibitor selection remains limited. We compared ticagrelor and clopidogrel in ACS patients meeting OPT-BIRISK dual high-risk criteria after drug-eluting stent (DES) implantation.We retrospectively analyzed a single-center PCI registry. ACS patients undergoing new-generation DES implantation (March 2019-March 2022) who met both high ischemic and high bleeding risk criteria were classified by discharge P2Y12 inhibitor. Propensity score overlap weighting was adjusted for confounding. The primary endpoint was 12-month net adverse clinical events (NACE): all-cause death, myocardial infarction, stroke, or Bleeding Academic Research Consortium (BARC) type 3 or 5 bleeding.The final cohort comprised 20,213 dual high-risk patients (ticagrelor, 4,563 [22.6%]; clopidogrel, 15,650 [77.4%]). NACE was similar between groups (4.58% vs. 5.21%; adjusted hazard ratio [aHR], 1.05; 95% confidence interval [CI], 0.89-1.23; p = 0.568). Ticagrelor was not associated with reduced ischemic events (aHR, 0.90; 95% CI, 0.72-1.12; p = 0.333) but with higher BARC type 3 or 5 bleeding (2.17% vs. 1.57%; aHR, 1.39; 95% CI, 1.08-1.77; p = 0.009). In exploratory subgroup analysis, ticagrelor was associated with higher NACE in patients aged 75 years or older (p-Value for interaction = 0.04).In dual high-risk ACS patients undergoing DES implantation, discharge ticagrelor-based dual antiplatelet therapy was associated with higher bleeding risk without reducing NACE or ischemic events compared with clopidogrel. These observational findings support individualized P2Y12 inhibitor selection and warrant prospective confirmation.
Abstract Introduction Treatment initiation or intensification to prevent exacerbation of chronic obstructive pulmonary disease (COPD) is based on the identification of patients with high exacerbation risk. The commonly used high-risk category of at least 2 moderate or 1 severe exacerbation within the prior 12 months has limited supporting evidence. We aimed to test the discriminative accuracy and assess the clinical utility of various COPD exacerbation categories for predicting future exacerbations. Methods In the COPDGene and NOVELTY cohorts, for each 1-year and 2-year recall periods, we estimated 6 distinct categories of exacerbation frequencies: ≥1 moderate (M1), ≥2 moderate (M2), ≥1 severe (S1), ≥1 moderate and ≥1 severe (M1andS1), ≥1 moderate or ≥ 1 severe (M1orS1), and ≥2 moderate or ≥ 1 severe (M2orS1), each ascertained in 3 ways: within 1 year, in each of 2 consecutive years (suffix E), and over a rolling combined 2-year period (suffix R). We used the area under the receiver operating characteristic curve (AUC) and decision curve analysis to evaluate the discriminative accuracy and clinical utility of these 18 categories for predicting the occurrence of M2orS1 (current standard) in the subsequent year. Results In COPDGene (n = 3,035), for the prediction of future M2orS1, baseline M1orS1R had the highest AUC (0.69, 95%CI 0.67-0.71) vs. baseline M2orS1 (0.66, 95%CI 0.64-0.67; Δ = 0.03;p<0.001). In NOVELTY (n = 3,080), M1orS1R category had the highest AUC (0.87, 95%CI 0.85-0.88) vs. M2orS1 (0.75, 95%CI 0.72-0.77, Δ = 0.12;p<0.001). Decision curve analysis demonstrated that the two-year rolling patterns provided the highest clinical utility across a clinically relevant treatment threshold range of 5% to 30% (Figure). M1orS1R also had the highest AUC for predicting any exacerbation (M1orS1) in both COPDGene (AUC = 0.68, 95%CI 0.66-0.70) and in NOVELTY (AUC = 0.86, 95%CI 0.85-0.88). Conclusions At least 1 moderate or 1 severe exacerbation over the previous 2 years has the highest discrimination and confers the highest clinical utility for predicting high COPD exacerbation risk. Overall, the combination of higher performance of various exacerbation history patterns in terms of their statistical (AUC) and clinical utility (net benefit) indicates that using a two-year recall and a lower threshold for high-risk classification (any moderate/severe events) is superior to the current standard of care. This abstract is funded by: This work was supported by NHLBI R01 HL151421 (SPB and AN), U01 HL089897 and U01 HL089856, by NIH contract 75N92023D00011, and by a Team Grant from the Canadian Institutes of Health Research (PHT 178432). COPDGene is also supported by the COPD Foundation through contributions made to an Industry Advisory Board that has included AstraZeneca, Bayer Pharmaceuticals, Boehringer Ingelheim, Genentech, GlaxoSmithKline, Novartis, Pfizer, and Sunovion. The NOVELTY study was funded by AstraZeneca.
Currently, no sensitive, widely available, rapid turnaround assays to measure the effect on coagulation of direct oral anticoagulants exist.The point-of-care ClotChek (Perosphere Technologies Inc.) coagulometer was developed to address this unmet need with high sensitivity and precision. This proof-of-concept study aimed to determine normal clotting time in healthy, non-anticoagulated subjects; summarize clotting times at trough and peak drug concentrations in patients taking apixaban and rivaroxaban; and identify cut-points that maximize both sensitivity and specificity for predicting whether an individual is meaningfully anticoagulated.In 141 normal subjects, the mean clotting time was 244.2 ± 25.8 seconds (median 244.0 seconds; range 183-296 seconds). In 39 patients on apixaban, mean clotting times were 293.9 ± 32.5 seconds at trough and 323.1 ± 27.9 seconds at peak. In 42 patients on rivaroxaban, mean clotting times were 287.8 ± 44.9 seconds at trough and 380.4 ± 41.2 seconds at peak. Strong positive correlations are seen between the anticoagulant drug response determined by the assay and anticoagulant drug levels for apixaban (Spearman's rho = 0.74, p < 0.0001) and for rivaroxaban (Spearman's rho = 0.82, p < 0.0001). ClotChek clotting times showed good sensitivity and specificity to identify meaningful anticoagulation (>75 ng/mL) among patients taking apixaban (AUC = 0.91, 83% sensitivity, 86% specificity) or rivaroxaban (AUC = 0.96, 91% sensitivity, 90% specificity). Similar results were seen using the lower threshold of >30 ng/mL.These results require clinical validation in further studies but suggest that the ClotChek assay could aid physicians at the point of care in making therapeutic decisions in patients with adverse events associated with oral factor Xa inhibitors.
Background:Elevated factor VIIa-antithrombin (FVIIa-AT) complex levels reflect enhanced tissue factor (TF)-driven coagulation activation and have been reported in atrial fibrillation (AF) recently. We hypothesized that elevated FVIIa-AT levels characterize patients with spontaneous echo contrast (SEC). Methods:We studied 131 AF patients (median age: 70 years; median CHADS-VASc score: 4 [2-5]); all but one were anticoagulated. Transesophageal echocardiography was performed to assess SEC and left atrial appendage thrombus (LAAT). FVIIa-AT complexes, fibrin clot permeability (K s), clot lysis time (CLT), and endogenous thrombin potential (ETP) were measured. Results:SEC was detected in 35 patients (27%), including eight (6%) with concomitant LAAT. The patients with SEC had 30% higher FVIIa-AT levels, compared with the remainder (p < 0.0001). FVIIa-AT levels correlated positively with AF duration (r = 0.38), CLT (r = 0.41), and ETP (r = 0.34; all p < 0.0001), but not with demographic, stroke risk or other clinical variables, except for permanent AF (+15%, p < 0.0001) and heart failure (HF; +11%, p = 0.02). Eighty-two percent of patients with SEC were in the highest FVIIa-AT quartile (≥178 pM), characterized by higher plasminogen activator inhibitor-1 (+14%) levels, reduced K s (-12%), and prolonged CLT (+33%; all p ≤ 0.02). In multivariable analysis, HF (OR: 9.00, 95% CI: 1.81-44.67) and FVIIa-AT concentration (OR per 10 pM increase: 2.40, 95% CI: 1.66-3.47) independently predicted SEC. Conclusion:This study is the first to link elevated FVIIa-AT levels, reflecting TF-pathway activation, with SEC and/or LAAT in anticoagulated AF patients, particularly in the presence of HF, suggesting a potential contribution of TF-mediated coagulation activation and impaired fibrinolysis in this phenomenon.
Background:Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is caused by autoantibody-mediated deficiency of ADAMTS13 activity, leading to formation of platelet-rich microthrombi. The inhibitory effect of caplacizumab on von Willebrand factor (VWF)-platelet interactions and its rapid kinetics were characterized. Material & Methods:Post hoc analyses of caplacizumab dosing were performed using data from the phase 1 healthy volunteers (NCT03172208) trial and phase 2 TITAN (NCT01151423)/phase 3 HERCULES (NCT02553317) trials of patients with iTTP. The time course for inhibition of VWF activity was analyzed using the VWF ristocetin cofactor activity (VWF:RCo) assay. Results:Most healthy volunteers with intravenous (IV) dosing (15/16 [94%]) and half of participants (8/16) with subcutaneous dosing achieved VWF:RCo activity suppression < 20% with caplacizumab at 1 hour; all participants achieved VWF:RCo suppression < 20% at 3 hours. A majority of patients with iTTP achieved VWF:RCo activity suppression < 20% postfirst IV caplacizumab dose in TITAN at 5 to 10 minutes (8/11 [72.7%]) and almost all in HERCULES at day 2 (62/64 [96.9%]); suppression was maintained throughout the first 5 weeks, with return to baseline values by the first visit after discontinuation (follow-up period day 3 in TITAN and day 7 in HERCULES). In a combined analysis of TITAN and HERCULES, median (IQR) change in VWF:RCo activity from baseline to day 2 was 90.2% (119.5, 61.5) in the caplacizumab group and 12.6% (20.0, 33.8) in the placebo group. Conclusion:This post hoc analysis demonstrated the pharmacodynamics of the rapid inhibitory effect of caplacizumab on VWF-platelet interaction (i.e., VWF:RCo suppression < 20%) that does not appear to be impacted by TPE in patients with iTTP.
Background:In patients with unprovoked venous thromboembolism (VTE), indefinite anticoagulation is recommended to prevent recurrence but may expose some patients to unnecessary long-term bleeding risk. Current clinical scores and biomarkers have limited discriminative performance, do not capture the time-dependent nature of VTE, and do not incorporate patients' perspectives or support shared decision-making. Objectives:To develop and validate time-dependent, multicomponent risk prediction scores and socio-anthropological scales (TDMI) integrated in a shared decision-making process to optimize long-term anticoagulation management after unprovoked VTE. Methods:MORPHEUS is an international, multidisciplinary research programme conducted in eight European countries. The TDMI will combine clinical, biological, imaging, and pharmacological biomarkers with socio-anthropological scales reflecting patients' lived experiences, preferences, and perceptions of risk. Candidate components will be identified through systematic literature review, Delphi consensus, qualitative interviews with patients and physicians, and pooled analyses of large prospective European VTE cohorts including clinical outcomes, biobanks, and imaging data. Dynamic, multi-level, time-dependent prediction models for recurrent VTE and anticoagulant-related bleeding will be derived using advanced statistical and machine-learning approaches. The clinical effectiveness and acceptability of TDMI integrated in a shared decision-making process will be evaluated in a stepped-wedge cluster randomized trial enrolling 2,400 patients with a first unprovoked VTE. Results:The TDMI is expected to improve individualized risk stratification, reduce unnecessary extended anticoagulation, lower bleeding complications, and improve patient satisfaction, treatment adherence, and quality of life. Conclusion:The MORPHEUS project will support personalized anticoagulation decisions and improve long-term outcomes in patients after unprovoked VTE.
Background:Current guidelines recommend indefinite oral anticoagulant (OAC) therapy for atrial fibrillation (AF) patients with stroke risk factors, regardless of catheter ablation (CA) outcomes. However, these recommendations are largely based on nonrandomized evidence, and the long-term anticoagulation strategy for patients after successful CA for AF remains uncertain. Objective:To evaluate the efficacy and safety of discontinuing OAC versus continuing OAC in AF with successful CA. Methods:We searched PubMed, Embase, and major conference proceedings from inception to November 2025 to identify eligible randomized controlled trials (RCTs). Pooled effect estimates were calculated as risk differences (RDs) with 95% confidence intervals (CIs). Results:A total of 2,324 patients were included across three RCTs, with the mean age ranging from 63 to 67 years, 71.4% were men, and the average CHA2DS2-VASc score was approximately 2. Among patients with successful CA, OAC discontinuation was not associated with a significant increase in the risks of stroke, ischemic stroke, stroke or systemic embolism, transient ischemic attack, and all-cause death. In contrast, continued OAC was associated with significantly higher risks of major bleeding (RD: 1.0%, 95% CI: 0.2-1.7), intracranial bleeding (RD: 0.6%, 95 CI: 0.0-1.1), minor bleeding (RD: 2.2%, 95% CI: 0.2-4.1), and clinically relevant nonmajor bleeding (RD: 2.5%, 95% CI: 1.2-3.9). No statistically significant difference was observed in gastrointestinal bleeding between groups. Conclusion:In patients with AF and moderate baseline stroke risk after successful CA, discontinuation of OAC was associated with a lower risk of bleeding complications and was not associated with a statistically significant increase in thromboembolic events. These findings are primarily applicable to patients with moderate stroke risk and should not be extrapolated to higher-risk populations.
Introduction:Glanzmann thrombasthenia (GT) and GT-like phenotype represent inherited platelet disorders caused by defects in platelet glycoprotein αIIbβ3 (encoded by ITGA2B and ITGB3) or RASGRP2- and FERMT3-mediated platelet intracellular signaling, respectively. While globally rare, prevalence of these bleeding phenotypes is notably higher in regions with high consanguinity, including Pakistan, with limited data on GT-associated variants. Compared with traditional diagnostic approaches, next-generation sequencing (NGS) offers comprehensive detection of known and novel variants, enhancing diagnostic accuracy in genetically heterogeneous disorders like GT. Methods:This study investigated the mutational spectrum of GT and GT-like phenotype in 67 patients from 55 unrelated Pakistani families using a targeted gene panel. Variant annotation and pathogenicity assessments were performed using established guidelines. Structural modeling and molecular dynamics simulations were used to predict the functional consequences of select novel variants. Results:A total of 21 distinct variants were identified (15 in ITGA2B and 6 in ITGB3), achieving an 87.3% diagnostic yield. In all, 10 were novel, including missense, frameshift, splice-site, and copy number variants (CNVs). Two recurrent ITGA2B frameshift variants suggested possible founder effect. Analysis of RASGRP2 revealed two novel homozygous variants in GT-like cases. A genotype-phenotype association analyses suggested a severe bleeding diathesis in GT patients harboring truncating mutations in an age-dependent manner, and clinical diversity among GT patients with same genetic variant. Conclusion:This study expands the mutational spectrum of GT and GT-like bleeding diathesis in Pakistani population, identifying novel and recurrent mutations, which highlights the diagnostic value of NGS.
Tissue factor pathway inhibitor (TFPI) is an important determinant of thrombin generation in patients with deficiency in factor (F)VIII, FIX, and FXI. As such, anti-TFPI monoclonal antibodies such as concizumab have been developed to treat hemophilia A (HA) and B (HB).The objective of this study is to generate single-domain antibodies (sdAbs) as a novel class of pharmacological agents blocking TFPI and increasing thrombin generation in the plasma of patients with severe HA, HB, and FXI deficiency.A large synthetic library of sdAbs was generated and selected by phage-display on recombinant human TFPIα (rhTFPIα). Anti-TFPI sdAbs were screened on their ability to promote thrombin generation. Their binding to the Kunitz (K1, K2, K3) domains of TFPIα were measured by enzyme-linked immunosorbent assay. Their effects on the inhibitory activity of rhTFPIα toward FXa and TF/FVIIa complex were tested in purified systems. Thrombin generation was measured on plasmas from patients with severe HA, HB, or FXI-deficiency spiked with the anti-TFPI sdAbs.A total of 14 out of 188 screened sdAbs specifically bound to rhTFPIα, and two of them (26E5 and 26E8) targeted the K1 domain of TFPI and increased thrombin generation in the plasma of patients with HA. Both sdAbs impaired the ability of rhTFPIα to inhibit FXa and TF/FVIIa, in the absence and presence of their physiological modulators (protein S and FXa, respectively). These sdAbs efficiently increased thrombin generation in HB and FXI-deficient plasmas.Our large synthetic library could be used for readily generating diverse and functionally relevant anti-TFPI sdAbs that may be therapeutically attractive.
We recently discovered that fibrin interacts with the endothelial cell receptor N-cadherin and identified specific amino acid residues in N-cadherin that are critical for this interaction. However, the functional significance of this interaction has remained unclear.Given the structural and functional similarities between N-cadherin and vascular endothelial cadherin, we hypothesized that the interaction of fibrin with N-cadherin may contribute to fibrin-dependent angiogenesis. The primary objective of this study was to test this hypothesis.To test our hypothesis, we first knocked out N-cadherin in immortalized human microvascular endothelial cells (HMEC-1) using CRISPR technology, generating N-cadherin-knockout cells lacking this receptor. Our experiments using a fibrin gel angiogenesis assay revealed that fibrin promoted the formation of capillary-like structures by wild-type HMEC-1 cells, as expected. In contrast, fibrin had no effect on the N-cadherin-knockout cells. These findings highlight the critical role of N-cadherin in fibrin-dependent angiogenesis and suggest that the interaction of fibrin with N-cadherin may contribute to this process. To validate this suggestion, we mutated the amino acid residues in N-cadherin of HMEC-1 that are critical for fibrin binding, generating HMEC-1 cells expressing mutant N-cadherin. Experiments using these mutant cells, using the same angiogenesis assay, produced results nearly identical to those observed with the N-cadherin-knockout cells. Specifically, fibrin did not stimulate angiogenesis in the mutant HMEC-1 cells expressing mutant N-cadherin lacking fibrin-binding ability, thereby providing direct confirmation of our hypothesis.Our study establishes the functional role of the interaction between fibrin and endothelial N-cadherin, demonstrating that this interaction promotes fibrin-dependent angiogenesis.
Abstract:Antiphospholipid antibodies (aPL) are a heterogeneous group of autoantibodies that target phospholipids and phospholipid-binding proteins, and are identified clinically by anticardiolipin, anti-β2-glycoprotein I, or lupus anticoagulant assays. While aPL are a well-established mediator of thrombosis through both proinflammatory and prothrombotic pathways, the role of aPL in arrhythmogenesis including atrial fibrillation (AF) and their association with AF-related thromboembolic outcomes remains poorly defined. In small observational studies, testing positive for aPL has been reported in up to 20% of patients with AF and has been associated with a higher risk of ischemic stroke and other thromboembolic events. In this mini-review, in addition to sharing a succinct summary on prevalence and pathogenicity of aPL in various vascular and thrombotic conditions, we specifically summarize the existing body of literature investigating the association between aPL and AF prevalence and clinical outcomes. Furthermore, we describe the rationale and study design of the TaPL-AF (Thrombophilia with aPL in Atrial Fibrillation) study, an ongoing investigation leveraging Mass General Brigham (MGB) Biobank data to provide evidence on the incidence and prognostic relevance of aPL positivity in AF and explore the impact of aPL on the effectiveness of direct oral anticoagulants in preventing thromboembolic events. These efforts aim to define the clinical relevance of aPL in AF, including their potential role in refining thromboembolic risk stratification and guiding anticoagulation strategies.
Abstract Rationale Prolonged mechanical ventilation (MV) occurs in approximately 14% of post lung transplant patients and is associated with increased mortality. The AeroPace temporary transvenous diaphragmatic neurostimulation (TTDN), a novel FDA-approved device, has been shown to shorten MV duration by an average of 2.8 days (Lungpacer Medical, PA). In the RESCUE3 study, the AeroPace patient were weaned 34% faster by day 30 or 43% faster per protocol. We describe our single-center experience using TTDN in lung transplant recipients requiring prolonged MV and extracorporeal membrane oxygenation (ECMO). Methods Between June and August 2021, patients with difficulty weaning from MV following lung transplantation at the University of Florida were identified under the Emergency Use Authorization (EUA) program during the COVID-19 pandemic. The AeroPace TTDN subclavian catheter was placed at bedside. Each TTDN session delivered 60 electrical stimulations, administered once or twice daily during volume-controlled or pressure-support ventilation. Therapy was continued until successful liberation from MV or for a maximum of 30 days. Results Three patients underwent TTDN therapy. Case 1: A 55-year-old man underwent bilateral orthotopic lung transplantation (BOLT) for drug-induced fibrotic lung disease, complicated by primary graft dysfunction requiring veno-venous (VV) ECMO and six months of MV. After 30 days of TTDN and subsequent automatic tube compensation (ATC) trials, he was successfully liberated from MV. Case 2: A 48-year-old woman received BOLT for COVID-19-related respiratory failure complicated by multiple episodes of hospital-acquired pneumonia. TTDN was initiated one month post-transplant, leading to successful liberation after six sessions. Case 3: A 55-year-old man underwent lung-kidney transplantation for COVID-19-associated respiratory failure requiring VV ECMO. TTDN was started two weeks post-transplant, while still on ECMO. Patient was weaned from MV after nine days of therapy. All patients tolerated TTDN without complications related to catheter placement or stimulation. Conclusion This case series is the first to report the use of TTDN in post-lung transplant patients with prolonged MV. TTDN was well tolerated and may facilitate earlier ventilator liberation by mitigating diaphragmatic atrophy associated with prolonged MV. Further prospective studies are warranted to evaluate its efficacy in improving post-transplant outcomes. This abstract is funded by: None
Abstract Rationale Cardiopulmonary exercise testing (CPET) provides objective metrics of aerobic fitness and ventilatory efficiency that may influence competitive performance in elite soccer. This study compared ergospirometric profiles between a team that reached the tournament finals and a team eliminated before the final stage in the Ecuadorian professional league, focusing on VO2max and ventilatory efficiency, and explored their associations with peak exercise outputs. Methods Retrospective cohort of 40 professional players evaluated during pre-competition screening (Team A—finalists: n = 20; Team B—non-finalists: n = 20). Standardized ramp bicycle CPET was conducted to volitional exhaustion following ATS/ACCP recommendations. Variables included VO2max (mL/kg/min), ventilatory thresholds (VT1, VT2), VE/VCO2 slope, oxygen pulse (O2/HR), respiratory exchange ratio (RER), peak minute ventilation (VE), peak workload, peak heart rate, and test duration. Comparisons employed two-sample tests with equal-variance checks; effect sizes were expressed as Cohen’s d. Correlations between CPET indices and mechanical or electrophysiologic performance markers were examined across all subjects. A two-sided α of 0.05 was predefined. Ethics approval: institutional waiver for secondary use of de-identified performance records. Results The two groups were comparable in age, body composition, and training exposure. Mean VO2max was 61.6 ± 8.1 in finalists and 62.6 ± 9.0 mL/kg/min in non-finalists (d = 0.12). VE/VCO2 slope averaged 21.7 ± 2.3 versus 22.1 ± 3.6, and O2 pulse 154.6 ± 10.8 versus 156.2 ± 11.9 for finalists and non-finalists, respectively; between-team differences were not statistically significant. Peak workload (319 ± 61 vs 315 ± 28 W), heart rate (185 ± 5 vs 193 ± 5 bpm), RER (1.18 ± 0.24 vs 1.22 ± 0.13), and duration (12.3 ± 1.2 vs 12.8 ± 1.3 min) were likewise similar. Across all players, VO2max correlated positively with peak workload and O2 pulse, whereas VE/VCO2 showed an inverse relationship with performance, consistent with established ventilatory efficiency principles. Conclusions Among these Ecuadorian elite squads, CPET profiles were broadly comparable; reaching the tournament finals was not associated with superior VO2max or ventilatory efficiency. Nonetheless, player-level data reaffirm that higher VO2max and O2 pulse predict superior peak mechanical output, supporting CPET as a practical tool for monitoring readiness and individualizing conditioning. These findings emphasize within-team physiological stratification, targeted aerobic development (e.g., VO2 at VT2), and standardized reporting using effect sizes with confidence intervals. Future multicenter studies integrating match-tracking analytics could clarify how aerobic fitness interacts with tactical execution to influence competitive outcomes. This abstract is funded by: NO FUNDING
