Challenges in the Monitoring of Therapeutic Plasma Exchange during Acute Heparin-Induced Thrombocytopenia in Adults under ECMO.

Therapeutic plasma exchange (TPE) has been proposed to remove heparin-induced thrombocytopenia (HIT) antibodies before planned thoracic surgery in patients with acute HIT and to allow brief re-exposure to heparin during surgery. In patients on extracorporeal membrane oxygenation (ECMO), simultaneous administration of TPE and alternative nonheparin anticoagulant therapies is challenging. We report 2 patients on ECMO with acute HIT who underwent repeated TPE to enable cardiothoracic surgery with the use of heparin. In both cases, serial monitoring of HIT antibody titer and heparin-induced platelet activation assay (HIPA) was performed. The effect of adding exogenous platelet factor 4 (PF4) in the HIPA was also tested. Negative anti-PF4/H IgG levels were achieved after 5 and 3 TPE sessions, respectively and patients could beneficiate from surgery with brief heparin re-exposure without any thrombotic complication. Negative HIPA results were obtained before negative anti-PF4/H IgG in one patient but remained positive in the other despite very low antibody titers. The addition of PF4 in HIPA led to more contrasted results for the two patients. Serial HIT screening including immunological and functional assays is necessary to closely monitor TPE in acute HIT patients on ECMO who require surgery. The addition of PF4 in HIPA could help detect clinically relevant platelet-activating antibodies and guide re-exposure to heparin.

Exacerbation of thrombo-inflammation by JAK2V617F mutation worsens the prognosis of cerebral venous sinus thrombosis.

Cerebral venous sinus thrombosis (CVST) is an uncommon venous thromboembolic event accounting for <1% of strokes resulting in brain parenchymal injuries. JAK2V617F mutation, the most frequent driving mutation of myeloproliferative neoplasms has been reported to be associated with worse clinical outcomes in patients with CVST. We investigated whether hematopoietic JAK2V617F expression predisposes to specific pathophysiological processes and/or worse prognosis after CVST. Using an in vivo mouse model of CVST, we analyzed clinical, biological and imaging outcomes in mice with hematopoietic-restricted Jak2V617F expression, compared to Jak2WT mice. In parallel, we studied a human cohort of JAK2V617F-positive or negative CVST. Early after CVST, mice with hematopoietic Jak2V617F expression had increased adhesion of platelets and neutrophils in cerebral veins located in the vicinity of CVST. On day 1, Jak2V617F mice had a worse outcome characterized by significantly more frequent and severe intracranial hemorrhages (ICH) and higher mortality rates. Peripheral neutrophil activation was enhanced, as indicated by higher circulating platelet-neutrophil aggregates, upregulated CD11b expression, and higher myeloperoxydase (MPO) plasma level. Concurrently, immunohistological and brain homogenates analysis showed higher neutrophil infiltration and increased blood-brain-barrier disruption. Similarly, JAK2V617F-positive CVST patients tended to present higher thrombotic burden and had significantly higher SII, a systemic thrombo-inflammatory marker, compared to JAK2V617F-negative patients. In mice with CVST, our study corroborates that Jak2V617F mutation leads to a specific pattern including increased thrombotic burden, ICH and mortality. The exacerbated thrombo-inflammatory response, observed both in mice and JAK2V617F-positive patients, could contribute to hemorrhagic complications.

Pancytopenia related to acquired sea-blue histiocytosis during chronic parenteral nutrition.

Bone marrow smear showing histiocytes (black arrow) containing sea blue granules stained with May-Grünwald Giemsa.

State of the art in cerebral venous sinus thrombosis animal models.

Cerebral venous sinus thrombosis (CVST) is an uncommon venous thromboembolic event accounting for less than 1% of strokes resulting in brain parenchymal injuries. Diagnosis and prognosis are still challenging due to highly variable clinical course and etiologies. Beyond thrombosis, different CVST-related parenchymal injuries may occur and include edema, ischemic strokes, and intra-cerebral hemorrhage (ICH; i.e., parenchymal/subdural hematomas, and subarachnoid hemorrhages), which are identified in 40%-60% of patients without clearly identified mechanisms. In this perspective, experimental animal models contribute to the understanding of initiation, propagation, and resolution of thrombosis, as well as brain-related damages. Last but not least, animal models may be useful to study new therapeutic approaches. In this review, we provide a comprehensive overview of CVST experimental models, focusing on their strengths, limits, and contribution to the current knowledge.

Impact of COVID-19 on thrombus composition and response to thrombolysis: Insights from a monocentric cohort population of COVID-19 patients with acute ischemic stroke.

BACKGROUND: Resistance to fibrinolysis, levels of procoagulant/antifibrinolytic neutrophil extracellular traps (NETs), and the severity of acute ischemic stroke (AIS) are increased by COVID-19. Whether NETs are components of AIS thrombi from COVID-19 patients and whether COVID-19 impacts the susceptibility of these thrombi to thrombolytic treatments remain unknown, however. OBJECTIVES: We aimed to characterize AIS thrombi from COVID-19 patients by immunohistology and to compare their response to thrombolysis to that of AIS thrombi from non-COVID-19 patients. PATIENTS/METHODS: For this monocentric cohort study, 14 thrombi from COVID-19 AIS patients and 16 thrombi from non-COVID-19 patients, all recovered by endovascular therapy, were analyzed by immunohistology or subjected to ex vivo thrombolysis by tissue-type plasminogen (tPA)/plasminogen. RESULTS: COVID-19 AIS thrombi were rich in neutrophils and contained NETs, but not spike protein. Thrombolysis assays revealed a mean resistance profile to tPA/plasminogen of COVID-19 AIS thrombi similar to that of non-COVID-19 AIS thrombi. The addition of DNase 1 successfully improved thrombolysis by potentiating fibrinolysis irrespective of COVID-19 status. Levels of neutrophil, NETs, and platelet markers in lysis supernatants were comparable between AIS thrombi from non-COVID-19 and COVID-19 patients. CONCLUSIONS: These results show that COVID-19 does not impact NETs content or worsen fibrinolysis resistance of AIS thrombi, a therapeutic hurdle that could be overcome by DNase 1 even in the context of SARS-CoV-2 infection.

Heparin-induced Thrombocytopenia Diagnosis: A Retrospective Study Comparing Heparin-induced Platelet Activation Test to 14 C-serotonin Release Assay.

Laboratory confirmation of heparin-induced thrombocytopenia (HIT) is of crucial importance and remains challenging and relies on platelet functional assays highlighting the presence of heparin-dependent platelet-activating antibodies in patient serum or plasma. Platelet functional assays using washed platelets include the 14 C-serotonin release assay (SRA), usually described as the gold standard, and the heparin-induced platelet activation assay (HIPA). Since its first comparison with SRA there has been no additional published study regarding HIPA diagnostic performances compared with SRA. Aim of our retrospective study was to compare the concordance between HIPA and SRA in HIT suspected-patients with positive anti-PF4/heparin antibodies between October 2010 and October 2015. Fifty-five HIT-suspected patients who beneficiated from both HIPA and SRA were included. Positive and negative percent agreements were 83.8% (95% CI 68.0-93.8%) and 66.7% (95% CI 41.0-86.7%), respectively. Overall percent agreement was 78.2% (95% CI 65.0-92.2%). Agreement was higher in patients who underwent cardiopulmonary bypass with extracorporeal circulation circuit for cardiac surgery. We also confirm that the use of a minimum of 2 platelet donors to establish positive HIT diagnosis and 4 platelet donors to exclude HIT diagnosis allows obtaining a good agreement with SRA. Although HIPA and SRA were performed with different platelet donors and in different laboratories, HIPA had a good positive agreement with SRA for HIT diagnosis, showing that HIPA is a useful functional assay that does not require radioactivity and could be developed worldwide to improve HIT diagnosis.

A Novel Mouse Model for Cerebral Venous Sinus Thrombosis.

Cerebral venous sinus thrombosis (CVST) is an uncommon cause of stroke resulting in parenchymal injuries associated with heterogeneous clinical symptoms and prognosis. Therefore, an experimental animal model is required to further study underlying mechanisms involved in CVST. This study is aimed at developing a novel murine model suitable and relevant for evaluating injury patterns during CVST and studying its clinical aspects. CVST was achieved in C57BL/6J mice by autologous clot injection into the superior sagittal sinus (SSS) combined with bilateral ligation of external jugular veins. Clot was prepared ex vivo using thrombin before injection. On days 1 and 7 after CVST, SSS occlusion and associated-parenchymal lesions were monitored using different modalities: in vivo real-time intravital microscopy, magnetic resonance imaging (MRI), and immuno-histology. In addition, mice were subjected to a neurological sensory-motor evaluation. Thrombin-induced clot provided fibrin- and erythrocyte-rich thrombi that lead to reproducible SSS occlusion at day 1 after CVST induction. On day 7 post-CVST, venous occlusion monitoring (MRI, intravital microscopy) showed that initial injected-thrombus size did not significantly change demonstrating no early spontaneous recanalization. Microscopic histological analysis revealed that SSS occlusion resulted in brain edema, extensive fibrin-rich venular thrombotic occlusion, and ischemic and hemorrhagic lesions. Mice with CVST showed a significant lower neurological score on post-operative days 1 and 7, compared to the sham-operated group. We established a novel clinically CVST-relevant model with a persistent and reproducible SSS occlusion responsible for symptomatic ischemic and hemorrhagic lesions. This method provides a reliable model to study CVST physiopathology and evaluation of therapeutic new regimens.

Modeling Large Vessel Occlusion Stroke for the Evaluation of Endovascular Therapy According to Thrombus Composition.

More than 40% of endovascular therapy (EVT) fail to achieve complete reperfusion of the territory of the occluded artery in patients with acute ischemic stroke (AIS). Understanding factors influencing EVT could help overcome its limitations. Our objective was to study the impact of thrombus cell composition on EVT procedures, using a simulation system for modeling thrombus-induced large vessel occlusion (LVO) in flow conditions. In an open comparative trial, we analyzed the behavior of size-standardized platelet-rich and red blood cells (RBC)-rich thrombi during simulated stent retriever-mediated EVT procedures. Sixteen simulated EVT procedures were performed (8 RBC- vs. 8 platelet-rich thrombi). Platelet-rich thrombi were associated with a higher number of stent retriever passes (p = 0.03) and a longer procedure duration (p = 0.02) compared to RBC-rich thrombi. Conversely, RBC-rich thrombi released more embolic fragments than platelet-rich thrombi (p = 0.004). Both RBC-rich and platelet-rich thrombi underwent drastic compaction after being injected into the in vitro circulation model, and histologic analyses showed that these EVT-retrieved thrombi displayed features comparable to those previously observed in thrombi from patients with AIS patients having LVO, including a marked structural dichotomy between RBC- and platelet-rich areas. Our results show that the injection of in vitro-produced thrombi in artificial cerebrovascular arterial networks is suitable for testing recanalization efficacy and the risk of embolization of EVT devices and strategies in association with thrombus cell composition.

Measuring beta-galactose exposure on platelets: Standardization and healthy reference values.

BACKGROUND: Correct diagnosis of the cause of thrombocytopenia is crucial for the appropriate management of patients. Hyposialylation/desialylation (characterized by abnormally high ß-galactose exposure) accelerates platelet clearance and can lead to thrombocytopenia. However, the reference range for ß-galactose exposure in healthy individuals has not been defined previously. OBJECTIVE: The objective of the present study was to develop a standardized assay of platelet ß-galactose exposure for implementation in a clinical laboratory. METHODS: ß-Galactose exposure was measured in platelet-rich plasma by using flow cytometry and Ricinus communis agglutinin (RCA). A population of 120 healthy adults was recruited to study variability. RESULTS: We determined an optimal RCA concentration of 12.5 µg/mL. The measure was stable for up to 4 hours (mean fluorescence intensity [MFI]-RCA: 1233 ± 329 at 0 hour and 1480 ± 410 at 4 hours). The platelet count did not induce a variation of RCA and the measure of RCA was stable when tested up to 24 hours after blood collection (MFI-RCA: 1252 ± 434 at day 0 and 1140 ± 297 24 hours after blood sampling). To take into account the platelet size, results should be expressed as RCA/forward scatter ratio. We used the assay to study variability in 120 healthy adults, and we found that the ratio is independent of sex and blood group. CONCLUSION: We defined a normal range in a healthy population and several preanalytical and analytical variables were evaluated, together with positive and negative controls. This assay may assist in the diagnosis of thrombocytopenic diseases linked to changes in ß-galactose exposure.

Neuron-Specific Enolase Levels in Adults Under Venoarterial Extracorporeal Membrane Oxygenation.

OBJECTIVES: We aimed to determine if elevations in serum neuron-specific enolase are associated with brain injury and outcomes in adults who require venoarterial extracorporeal membrane oxygenation. DESIGN: Prospective observational study. SETTING: Two ICUs of a university hospital, Paris, France. PATIENTS: Consecutive adult patients treated with venoarterial extracorporeal membrane oxygenation for refractory cardiogenic shock or in-hospital refractory cardiac arrest. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Serum sampled 1, 3, and 7 days after venoarterial extracorporeal membrane oxygenation cannulation was stored at -80°C and neuron-specific enolase concentrations were measured in batches at the end of the study. The association between neuron-specific enolase concentrations and outcomes (28-d mortality and poor outcome, defined by a score of 4-6 on the modified Rankin scale at 90 d) were explored by multivariable logistic regression, with neuron-specific enolase concentrations dichotomized according to median values. One-hundred three patients were included, of whom 26 (25%) received preextracorporeal membrane oxygenation cardiopulmonary resuscitation. Median (interquartile range) day-1, day-3, and day-7 neuron-specific enolase serum concentrations were 37 µg/L (26-51 µg/L), 25 µg/L (19-37) µg/L, and 22 µg/L (17-31 µg/L). After adjustment for Simplified Acute Physiology Score II, preextracorporeal membrane oxygenation cardiopulmonary resuscitation, and Sepsis Organ Failure Assessment score at time of cannulation, a day-3 neuron-specific enolase greater than 25 µg/L remained independently associated with 28-day mortality (adjusted odds ratio, 4.98; 95% CI, 1.86-13.32) and poor outcome at 90 days (adjusted odds ratio, 4.63; 95% CI, 1.81-11.84). A day-3 neuron-specific enolase threshold greater than 80 µg/L had a 100% specificity for prediction of both mortality (95% CI, 92-100%) and poor functional outcome (95% CI, 89-100%). In a subset of patients who underwent brain CT, neuron-specific enolase concentrations were significantly higher in patients diagnosed with stroke, as compared with those without stroke. CONCLUSIONS: In adult patients under venoarterial extracorporeal membrane oxygenation, day-3 serum neuron-specific enolase concentrations are independently associated with short-term mortality and poor functional outcomes. These findings deserve validation in a multicenter setting.

Obstetrical outcome and treatments in seronegative primary APS: data from European retrospective study.

OBJECTIVE: To compare characteristics, pregnancies and treatments during pregnancies of seronegative and seropositive antiphospholipid syndrome (APS), to analyse factors associated with obstetrical outcome. PATIENTS AND METHODS: Inclusion criteria were: (1) thrombotic and/or obstetrical APS (Sydney criteria); (2) absence of conventional antiphospholipid antibodies (APL); (3) at least one persistent non-conventional APL among IgA anticardiolipin antibodies, IgA anti-B2GPI, anti-vimentin G/M, anti-annexin V G/M, anti-phosphatidylethanolamine G/M and anti-phosphatidylserine/prothrombin G/M antibodies. The exclusion criteria were: (1) systemic lupus erythematosus ( SLE) or SLE-like disease; and (2) other connective tissue disease. RESULTS: A total of 187 women (mean 33±5 years) with seronegative APS were included from 14 centres in Austria, Spain, Italy, Slovenia and France and compared with 285 patients with seropositive APS. Seronegative APS has more obstetrical rather than thrombotic phenotypes, with only 6% of venous thrombosis in comparison to seropositive APS. Cumulative incidence of adverse obstetrical events was similar in seronegative and seropositive APS patients, although higher rates of intrauterine deaths (15% vs 5%; p=0.03), of preeclampsia (7% vs 16%, p=0.048) and lower live birth term (36±3 vs 38±3 weeks of gestation; p=0.04) were noted in seropositive APS. The cumulative incidence of adverse obstetrical events was significantly improved in treated versus untreated seronegative APS (log rank<0.05), whereas there was no difference between patients who received aspirin or aspirin-low-molecular weighted heparin combination. CONCLUSION: Several non-criteria APL can be detected in patients with clinical APS features without any conventional APL, with various rates. The detection of non-criteria APL and thus the diagnosis of seronegative APS could discuss the therapeutic management similar to seropositive APS, but well-designed controlled studies are necessary.

Functional Fibrinolysis Assays Reveal Different Mechanisms underlying Plasminogen Dysfunction in Ligneous Conjunctivitis.

BACKGROUND: Ligneous conjunctivitis (LC) is a rare disorder associated with plasminogen deficiency characterized by chronic fibrin deposits in the eyelids. All patients with plasminogen deficiency do not develop LC, whose underlying mechanisms remain unknown. OBJECTIVE: We investigated whether fibrinolytic activity was correlated with phenotype and/or genotype in patients suffering from LC and their relatives. METHODS: Plasminogen activity/antigen levels and PLG mutations were determined in 10 patients with LC, 17 of their asymptomatic relatives, and 10 healthy individuals used as a control group. Plasma fibrinolytic activity was evaluated using three different assays: (1) tissue-plasminogen activator (t-PA) front lysis, (2) cell-based urokinase-dependent euglobulin clot lysis (ECLT) at the surface of corneal cells, and (3) urokinase-dependent plasminogen activation. RESULTS: Plasminogen activity varied from <10 to 40% in patients, 36 to 105% in relatives, and >80% in control healthy individuals. Homozygous K19E mutation was associated with normal antigenic plasminogen levels. In front-lysis experiments, all patients had a lower fibrinolysis rate as compared with their relatives and to control individuals. The cell-based ECLT and plasminogen activation assay demonstrated that urokinase-mediated fibrinolysis was not impaired in patients with homozygous K19E mutation compared with the other mutants. CONCLUSION: We confirm that plasminogen levels fail to predict LC occurrence. In these conditions, t-PA clot lysis front is useful to predict clinical outcome in plasminogen deficiency. Moreover, we provide evidence that occurrence of LC overlaps quantitative and qualitative plasminogen deficiencies. The homozygous K19E mutation is associated with isolated impaired t-PA-mediated fibrinolysis compared with other mutants.

Interferon Alpha Therapy Increases Pro-Thrombotic Biomarkers in Patients with Myeloproliferative Neoplasms.

Myeloproliferative neoplasms (MPN) are associated with an increased risk of arterial and venous thrombosis. Pegylated-interferon alpha (IFN) and hydroxyurea (HU) are commonly used to treat MPN, but their effect on hemostasis has not yet been studied. The aim of our study was to determine whether IFN and HU impact the biological hemostatic profile of MPN patients by studying markers of endothelial, platelet, and coagulation activation. A total of 85 patients (50 polycythemia vera and 35 essential thrombocythemia) were included: 28 treated with IFN, 35 with HU, and 22 with no cytoreductive drug (non-treated, NT). Von Willebrand factor, shear-induced platelet aggregation, factor VIII coagulant activity (FVIII:C), fibrinogen, and thrombin generation with and without exogenous thrombomodulin were significantly higher in IFN-treated patients compared to NT patients, while protein S anticoagulant activity was lower. In 10 patients in whom IFN therapy was discontinued, these hemostatic biomarkers returned to the values observed in NT patients, strongly suggesting an impact of IFN therapy on endothelial and coagulation activation. Overall, our study shows that treatment with IFN is associated with significant and reversible effects on the biological hemostatic profile of MPN patients. Whether they could be associated with an increased thrombotic risk remains to be determined in further randomized clinical studies.

Microfluidic Modeling of Thrombolysis.

Objective- Despite the high clinical relevance of thrombolysis, models for its study in human flowing blood are lacking. Our objective was to develop a microfluidic model for comparative evaluation of thrombolytic therapeutic strategies. Approach and Results- Citrated human blood was supplemented with 3,3'-dihexyloxacarbocyanine iodide and Alexa Fluor 647 fibrinogen conjugate, recalcified, and perfused for 3 to 4 minutes at venous or arterial wall shear rate in microfluidic flow chambers coated with collagen and tissue factor to generate nonocclusive fluorescent thrombi. A second perfusion was performed for 10 minutes with rhodamine-6G-labeled citrated whole blood, supplemented or not with r-tPA (recombinant tissue-type plasminogen activator), fluorescein isothiocyanate-conjugated r-tPA, and Alexa Fluor 568 plasminogen conjugate. Plasminogen and r-tPA bound to preformed thrombi and r-tPA caused a concentration-dependent decrease in thrombus fibrin content (up to 50% reduction at 15 µg/mL r-tPA) as assessed by fluorescence microscopy. Fibrinolysis was confirmed by measurement of D-dimers in the output flow. Remarkably, despite ongoing fibrinolysis, new platelets continued to be recruited to the thrombus under lysis. Under the arterial condition, combining r-tPA with hirudin enhanced fibrinolysis but did not prevent the recruitment of new platelets, which was, however, prevented by antiplatelet agents (ticagrelor or the GPVI [glycoprotein VI]-blocking antigen-binding fragment 9O12). Conclusions- Our microfluidic thrombolysis model is suitable for studying thrombolysis and testing the efficacy of drugs used in combination with r-tPA. Real-time analysis of fibrin and platelets during r-tPA-mediated fibrinolysis at arterial or venous flow conditions showed that platelets continue to accumulate during fibrinolysis. Such platelet accumulation may impair r-tPA-mediated recanalization.

Biomarkers for the risk of thrombosis in pancreatic adenocarcinoma are related to cancer process.

BACKGROUND: Venous thrombo-embolic events (VTE) frequently occur in patients with pancreatic ductal adenocarcinoma (PDAC) and contribute to high morbidity and mortality. OBJECTIVES: To determine whether VTE biomarkers are related to cancer, inflammation or precancerous states and to assess their relevance to predict VTE in PDAC. PATIENTS AND METHODS: We compared VTE biomarkers in patients with PDAC (n = 42), intraductal papillary mucinous neoplasm of the pancreas (IPMN, n = 48) or chronic pancreatitis (n = 50). PDAC patients were followed-up for 6 months. RESULTS: Factor VIII, D-dimers, von Willebrand factor, free tissue factor pathway inhibitor and microvesicle-tissue factor (MV-TF) activity were higher in PDAC patients compared to patients with IPMN or chronic pancreatitis. PDAC patients with metastasis presented higher D-dimers and MV-TF activity compared to patients with localized lesions, but elevation of D-dimers was dependent on tumor size. In multivariate analysis, elevated D-dimers (≥2.16 µg/mL) or MV-TF activity (≥2.37 pg/mL) were significant risk factors for VTE in PDAC patients, after adjustment for age and sex (HR 4.9 [1.0-23.1] or HR 10.5 [1.5-72.4], mean [interquartile range], respectively). Cumulative probability of VTE at 6 months was higher in patients with elevated D-dimers (56.3% vs 15.6%, p = 0.009) and in patients with high MV-TF activity (74.3% vs 21.7%, p = 0.01). CONCLUSIONS: VTE biomarkers including D-dimers and MV-TF activity are not related to inflammation but rather to cancer process and dissemination. D-dimers and MV-TF activity are associated to future VTE in PDAC patients and could help identify patients who could benefit from thromboprophylaxis.

Non-conventional antiphospholipid antibodies in patients with clinical obstetrical APS: Prevalence and treatment efficacy in pregnancies.

OBJECTIVES: To describe the prevalence of non-conventional APL in patients with obstetrical APS without conventional APL and the impact of treatment on pregnancy outcome. METHODS: Patients with clinical obstetrical criteria were tested for anti-phosphatidylethanolamine (aPE) IgG/M, anti-prothrombin/phosphatidylserine (anti-PS/PT) IgG/M, and anti-annexin V IgG. Pregnancy losses rates were compared between APS, non-conventional APS, and non-APL and in untreated pregnancies to treated ones for each group. RESULTS: Using the cutoffs (ROC), 65/96 (68%) patients have been considered as non-conventional APS and compared to 83 APS and 31 patients without APL. The obstetrical history in non-conventional APS did not differ in comparison to confirmed APS. The frequencies of anti-annexin V IgG antibodies tended to be more frequent in non-conventional APS (88% versus 73%; p = 0.06), and those of anti-PE IgG and M were similar. The anti-PS/PT IgG and M antibodies were more frequent in confirmed APS than in non-conventional APS (63% and 37% versus 4% and 5%, respectively, p < 0.0001). Overall, 261 pregnancies in patients with non-conventional APS were compared with 81 pregnancies of confirmed APS and 132 pregnancies from non-APL group. Out of 474, 136 (29%) patients have been treated during pregnancies, and treatment significantly increased the rate of live birth (26% in untreated versus 72% in treated pregnancies, p < 0.0001). In univariate analyses, treatment effect on pregnancy losses was similar in patients with APS and non-conventional APS, with odds ratio at 3.3 (95% CI: 1.8-6.1) and 6.9 (95% CI: 3.9-12.3) (p = 0.49) and significantly more important for the 2 APS groups pooled versus non-APL group [OR at 1.9 (95% CI: 1.1-3.5) for non-APL group versus 5.3 (95% CI: 3.5-8.1) for APS groups, p = 0.0025]. CONCLUSION: In this study, 68% of patients with clinical criteria for obstetrical APS seronegative for conventional APL have non-conventional APL. These patients have a significant decrement of pregnancy losses if they receive treatment for APS during their pregnancy.