Thrombotic Antiphospholipid Syndrome Research Articles

Predictors of adverse cardiac events in a large cohort of patients with antiphospholipid syndrome

Abstract Background Non-valvular cardiac disease in antiphospholipid syndrome (APS) has been modestly evaluated. Aim We wanted to assess the prevalence and evolution of major adverse cardiovascular events(MACE) in a cohort of APS patients. Material and Methods From a large cohort of 181 APS patients included in a study from 2011-2012.year data for the occurrence of MACE in 10 years of follow-up were evaluated in 82 patients (86.6% females, 62.2% with primary (PAPS), and 37.8% patients with APS associated with systemic lupus erythematosus (SLE) (sAPS)). At the inclusion in all patients, a transthoracic echocardiography study for the assessment of dimensions and functionality of the left and right heart along with valvular functions and morphology. Standard atherosclerotic risk factors prevalence was analyzed. Antiphospholipid antibodies(aPL) analysis included the detection of aCL (IgG/IgM), ß2GPI (IgG/IgM), and LA, and all patients were treated according to the valid guidelines by the rheumatologist. Data regarding the occurrence of new myocardial infarction (MI), cerebrovascular events (CVI), arterial and/or venous thrombosis, heart failure (HF), and cardiovascular death (considered as MACE) have been collected 10 years after inclusion. Results The prevalence of standard atherosclerotic risk factors was less than 40% in both study groups. Left ventricle ejection fraction(LVEF) was over 45% in more than 90% of patients in both groups (p=0.246) with valvular dysfunction present in 49% of PAPS and 58.1% of sAPS patients (p=0.426). 9.8% PAPS and 12.9% sAPS had coronary artery disease(CAD) (p=0.724) and HF was present in 7.8% PAPS and 3.2% sAPS (p=0.645). MACE occurred in 17.6% of PAPS and 22.6% of sAPS (p=0.585). The new MI occurred in 9.8% of PAPS and 9.7% of sAPS (p=1.000), CVI in 5.9% of PAPS and 3.2% of sAPS (p=1.000), HF in 5.9% of PAPS and 3.2% of sAPS (p=1.000) and cardiovascular death in 9.8% of PAPS and 12.9% of sAPS (p=0.724). New thrombotic events (arterial and/or venous) occurred in 15.7% of PAPS and 17.2% of sAPS (p=1.000). During the follow-up period, 66.7% of PAPS and 55.2% of SAPS (p=0.313) were treated with aspirin, 25.5% of PAPS and 25.0% of sAPS with warfarin, and chloroquine was administered in 46.8% of PAPS and 53.6% of sAPS (p=0.571). Age (p=0.008), gender (p=0.034), thrombotic APS (p=0.033), hypertension (p=0.003), diabetes mellitus (p=0.043), and cardiovascular manifestations present at the time of APS diagnosis (p=0.035), namely CAD (p=0.001) and HF (p=0.005) were significantly associated with 10y MACE. aPL type and category were not associated with 10y MACE. In a multivariate logistic model, age. hypertension, and HF were independent predictors for 10y MACE. Conclusions APS patients develop new cardiovascular events despite optimal medical therapy. Cardiovascular evaluation at the time of diagnosis and proper cardiologist follow-up with the rigorous treatment of standard atherosclerotic risk factors is of utmost importance.

How to treat patients with thrombotic antiphospholipid syndrome in 2024?

Antiphospholipid syndrome encompasses a range of clinical conditions, particularly thrombotic or obstetrical manifestations, associated with the presence of antiphospholipid antibodies. Managing thrombotic antiphospholipid syndrome in daily clinical practice can be challenging and requires thorough risk stratification and tailored treatment strategies. Primary prophylaxis focuses on improving traditional thrombosis risk factors and, in certain situations, may include low-dose aspirin and / or prophylactic anticoagulants (e.g., low-molecular-weight heparin). The treatment of thrombotic antiphospholipid syndrome primarily involves long-term anticoagulation with vitamin K antagonists. In some cases, a combination of vitamin K antagonists and low-dose aspirin, vitamin K antagonists with international normalized ratio target >3 or a switch to therapeutic doses of low-molecular-weight heparin might be employed. The use of hydroxychloroquine is essential for patients with secondary systemic lupus erythematosus and may be considered for patients with recurrent thrombosis. In other selected situations, the use of immunomodulatory agents can be considered.

Cell-bound complement activation products in antiphospholipid antibody-positive patients without other systemic autoimmune rheumatic diseases.

The objective of this study was to analyze complement activation in antiphospholipid antibody (aPL)-positive patients without other systemic autoimmune rheumatic diseases, using C3/C4 and cell-bound complement activation products (CB-CAPs) (B-lymphocytes [BC4d], erythrocytes [EC4d], and platelets [PC4d]). Persistently aPL-positive patients with or without aPL-related clinical manifestations (thrombotic APS [TAPS], microvascular APS [MAPS], obstetric APS, thrombocytopenia [TP], and/or hemolytic anemia [HA]) were enrolled in a single center study. Blood and clinical data were collected at baseline; a subgroup of patients completed 6- or 12-month follow-up. At baseline, 4/31 (13%) patients had decreased C3/C4, while 7/29 (24%) had elevated BC4d, 11/33 (33%) EC4d, and 12/32 (38%) PC4d. Based on different aPL profiles, all patients with decreased C3/C4 or elevated BC4d, EC4d, and PC4d had triple aPL or isolated lupus anticoagulant positivity. Based on different aPL clinical phenotypes, the number of patients with strongly positive EC4d and PC4d were proportionally higher in those with MAPS/TP/HA, compared to TAPS or no APS. Compared to baseline, the frequencies of BC4d, EC4d, and PC4d positivity were not significantly different in the subgroup of patients during their 6- or 12-month follow-up. There was a weak correlation between C3/C4 and CB-CAPs, especially for PC4d. In summary, complement activation in aPL-positive patients varies based on aPL profiles and clinical phenotypes. Given the higher percentage of aPL-positive patients with abnormal CB-CAPs, compared to C3/C4, and the poor inverse correlation between CB-CAPs and C3/C4, our study generates the hypothesis that CB-CAPs have a role in assessing disease activity and thrombosis risk in aPL-positive patients.

Clinical outcomes of patients receiving long-term fondaparinux for thrombotic antiphospholipid syndrome.

Vitamin-K antagonists (VKA) are considered the first-line anticoagulants for thrombotic antiphospholipid syndrome (TAPS), particularly with triple positivity or arterial events. However, thrombotic recurrence remains high despite anticoagulation and other clinical issues may arise. Long-term parenteral anticoagulants may therefore be considered, however little is known about the viability of fondaparinux in this setting. We describe the efficacy and safety of long-term fondaparinux for TAPS (>3-months duration) treated at a single centre in the UK. Clinical features and the outcomes of recurrence and bleeding were reviewed using electronic patient records. 46 patients were identified with history of either venous or arterial TAPS and a total 175 patient-years using fondaparinux (median duration 2.7 years/patient (IQR 1.4-4.8)). 43 (93%) had VKA as first-line anticoagulation with a median duration of 6.5 years (IQR 4.0 - 9.8). All patients received fondaparinux as second-to fourth-line anticoagulation.Thrombosis recurrence occurred in 1 (1%) patient (0.6 events/100-patient years). Major, clinically relevant non-major (CRNM) or minor bleeding occurred in 2 (7%), 5 (10.9%) and 8 (17.4%) patients respectively. Major/CRNM bleeding rates were 1.1 and 2.9 events/100-patient-years. Age >65years was associated with bleeding (p = .047) and concurrent antiplatelets were associated with major/CRNM bleeding (p = .011). Logistic regression showed increasing age was associated with bleeding (OR = 1.097, p = .009). We suggest that fondaparinux may be used for TAPS when VKA is not appropriate. Thrombotic recurrence was infrequent, and the number of major bleeding events appeared comparable to conventional therapies.

Thrombotic antiphospholipid syndrome: Recurrent thromboses

Thrombotic antiphospholipid syndrome (APS) is a condition affecting young people in whom a thromboembolic event occurs in the presence of circulating antiphospholipid antibodies (aPL).The aim of this study was the evaluation of the incidence of recurrent thrombosis and its risk factors in antiphospholipid syndrome.Material and methods. The retrospective study included 98 patients with aPL who were followed up at the institute from 2014 to 2023, of whom 66 (67%) were women and 32 (33%) were men. Of the 98 patients with aPL, 48 (49%) had a diagnosis of systemic lupus erythematosus (SLE). Antiphospholipid antibodies (aPL), including antibodies to cardiolipin (IgG/IgM aCL), antibodies to ß2-glycoprotein 1 (IgG/IgM aß2GP1), antibodies to ß2-glycoprotein IgG against domain 1 (IgG aß2GP1-D1), antibodies to phosphatidylserine/prothrombin complex (IgG/ IgM aPS/PT) and other thrombotic risk factors. aPL was assessed by enzyme-linked immunosorbent assay (ELISA) and chemoluminescence assay (CHLA).Results. Thrombosis recurrence was reported in 62 (63%) of 98 patients, and 36 (35%) did not. The main cause of recurrent thrombosis was treatment with direct oral anticoagulants (DOACs). 24 (38.7%) of 62 patients with recurrent thrombosis were treated with DOACs, the duration of which ranged from 6 to 24 months. The next most common cause of recurrent thrombosis was the lack of continuous anticoagulant therapy in 20 (32.5%) of the patients. In 17 (27.4%) of the patients, the recurrence occurred while they were still taking warfarin. In 10 (41.7%) of the 24 patients, the recurrent thrombosis was arterial in origin. This was associated with recurrent cerebral circulation problems. The level of positivity did not matter, but all had triple IgG aPL positivity. 5 had lupus anticoagulant (LA) at the onset of the disease before anticoagulant use. IgG aPS/PT was most important in association with recurring thrombosis in the ELISA: 45 (72.6%) of 62 patients with recurring thrombosis were positive for IgG aPS/PT, compared with 19 (52.8%) of 36 patients without recurring thrombosis. The detection of all aPL was more frequent in CHMA than in ELISA. However, the definition of aPL in ELISA is recommended according to the latest classification criteria. Triple IgG positivity for aCL of IgG aß2GP1, IgG aß2GP1-D1 and CHMA remained a risk factor for recurrent thrombosis and increased the risk of recurrence more than threefold. Obesity was a risk factor for recurrent thrombosis, with a 5-fold increased risk of recurrent thrombosis in obese compared to non-obese patients (p=0.01).Conclusions. Recurrent thrombosis in APS is largely associated with IgG aCL, IgG aß2GP1, IgG aß2GP1-D1, IgG aPS/PT. Triple IgG aPL positivity in any combination significantly increased recurrent thrombosis risk.The presence of any type of aPL IgG in both ELISA and CHLA influenced the recurrence rate of thrombosis in APS.Obesity was a significant risk factor for recurrent thrombosis.

Hematological features and alternate diagnoses in critically ill thrombotic antiphospholipid syndrome patients.

Severe thrombotic antiphospholipid syndrome (APS) frequently affects the kidney, heart, and central nervous system. The precise frequency, clinical picture, differential diagnoses, and outcome of APS-related hematological involvement are lacking, especially in patients requiring ICU admission. This study aimed to describe the hematological manifestations associated with critically ill thrombotic APS patients and catastrophic antiphospholipid syndrome. This French, national, multicenter, retrospective study, conducted, from January 2000 to September 2018, included all APS patients admitted to 24 participating centers' ICUs with any new thrombotic manifestation. The prevalence of hematological manifestations and their associated outcomes were studied. One hundred and thirty-four patients, female 72%, median [IQR] age 45 [34-56] years, with 152 episodes were included. Anemia was present in 95% of episodes and thrombocytopenia in 93%. The lowest values for hemoglobin and platelets were 7.1 [6.3-8.8] g/dL and 38 [21-60] g/L, respectively. The lowest platelet count below 20g/L was significantly associated with a higher in-ICU mortality rate (50%, p < 0.0001). A thrombotic microangiopathy syndrome (TMA) syndrome was seen in 16 patients (12%) and was associated with higher in-hospital mortality (p = 0.05). Median ADAMTS-13 levels were 44% [27-74]. Anti-ADAMTS13 antibodies were tested in 11 patients and found negative in all. A suspicion of heparin-induced thrombocytopenia (HIT) was raised in 66 patients but only four patients were classified as definite HIT. Disseminated intravascular coagulation (DIC) was seen in 51% of patients. Thrombocytopenia is very frequent in severe APS patients and may be related to TMA, HIT, or DIC. Deciphering the mechanisms of thrombocytopenia is decisive in CAPS patients. Key Points • Thrombocytopenia is the hallmark laboratory finding in CAPS. • A complete thrombotic microangiopathy pattern is infrequent in CAPS patients. • Alternate diagnoses of CAPS, especially heparin-induced thrombocytopenia, need to be adequately investigated.

Rethinking the use of direct oral anticoagulants for secondary thromboprophylaxis in patients with thrombotic antiphospholipid syndrome.

Patients with thrombotic antiphospholipid syndrome (APS) are at high risk for recurrent thrombosis, and indefinite anticoagulation is recommended. Patients with APS merit indefinite anticoagulation, and vitamin K antagonists (VKAs) have historically been the standard treatment. Direct oral anticoagulants (DOACs) present an appealing alternative to VKAs. Due to their pharmacokinetic and pharmacodynamic characteristics, DOACs offer advantages over VKAs, namely the lack of need for laboratory monitoring, the usage of a fixed dosage, and the absence of significant interaction with dietary components and drugs. The efficacy and safety of DOACs in patients with APS have been studied in four phase II/III clinical trials (three with rivaroxaban and one with apixaban). These studies showed DOACs' inferiority compared to VKAs in preventing recurrent thrombosis. Recurrence was significantly greater in patients with arterial thrombotic events and a triple positivity for antiphospholipid antibodies. No differences were observed in the incidence of venous thromboembolism between both groups. Major bleeding was similar in patients treated with DOACs or VKAs. Several observational studies have reported similar results. This review aims to analyse the existing evidence on the efficacy and safety of DOACs for secondary prevention in patients with APS.

Recurrent thrombotic events in pediatric antiphospholipid syndrome: A systematic review and meta-analysis

BackgroundPediatric antiphospholipid syndrome (APS) is one of the most common acquired hypercoagulable states in children, yet it remains poorly characterized. ObjectivesTo perform a systematic review and meta-analysis of the pooled incidence of thrombotic recurrence in this population (primary outcome), exploring the effect of age, APS type (primary vs. secondary to autoimmune diseases), and type of index thrombotic event. Secondary outcomes included the incidence of bleeding events and mortality. Materials and methodsThe MEDLINE, EMBASE, and COCHRANE databases were searched for studies reporting outcomes of cohorts of children aged ≤18 years with thrombotic APS as defined by the revised Sydney classification criteria. ResultsA total of 1011 studies were identified; of those, 9 were included in the final analysis (352 patients). The pooled incidence proportion of thrombosis recurrence was 0.27 [0.18–0.37], with an overall follow-up duration of a median of 2.7 to 5.8 years or a mean of 2.6 to 6.1 years. The estimate did not change meaningfully according to APS type (0.30 [0.18–0.46] for primary APS vs. 0.29 [0.19–0.42] for autoimmune APS), nor when the index thrombotic event was venous vs. arterial (0.30 [0.20–0.41] vs. 0.27 [0.27–0.51], respectively). The incidence of bleeding events was not reported in these studies. The incidence proportion of mortality was estimated at 0.07 [0.04–0.11] over the follow-up period, with 8/10 of the reported deaths directly associated with recurrent thrombotic events. ConclusionsThe incidence of thrombotic recurrence in children with APS is high and requires attention to evaluate anticoagulation management in this population.

Comparison of clinical and serological features in thrombotic antiphospholipid syndrome patients, with and without associated systemic lupus erythematosus, followed for up to 42 years: A single centre retrospective study.

To assess the impact of concomitant systemic lupus erythematosus (SLE) on the clinicopathological manifestations of thrombotic antiphospholipid syndrome (APS). This single-centre, retrospective study compared clinical and antiphospholipid antibody (aPL) data from 118 patients, 58 with SLE-associated APS (SLE-APS), and 60 with primary APS. Median follow-up was 13.9 (IQR 7.7-19.3) and 8.6years (3.5-10.6) for the SLE-APS cohort and PAPS cohort, respectively. Age at diagnosis of APS was lower in the SLE-APS cohort (mean 35.9 vs PAPS: 46.7years; p < 0.05). Distribution of aPL subtypes was similar across cohorts. 198 thrombotic events were identified overall (index plus recurrent), with venous thromboembolism (VTE) and arterial thrombosis each occurring in just over half of patients in both cohorts. Microvascular thrombosis (12.1% vs 0%), and a mixed (any combination of venous, arterial and microvascular) thrombotic phenotype (19.0% vs 6.7%, p = 0.05) were more prevalent in SLE-APS patients. Recurrent thrombosis incidence rates (∼0.5 events/10-patient years), and Kaplan-Meier recurrence-free survival after index thrombosis, were similar. In the PAPS cohort, only: (i) triple-aPL-positivity was associated with a significantly higher recurrent thrombosis event rate (incidence rate ratio 2.22, p = 0.03) and lower recurrence-free survival after first thrombosis (log-rank test p = 0.01); (ii) lupus anticoagulant (LA)-positivity was associated with higher prevalance of arterial thrombosis (RR 2.69, p = 0.01), and lower prevlance of VTE (RR 0.48, p < 0.001), versus LA-negativity. Concomitant SLE does not appear to modify long-term recurrent thrombosis risk, or aPL phenotypes, in patients with APS. Triple-aPL-positivity and LA-positive status may have less influence on thrombotic outcomes in patients with SLE-APS compared to PAPS.

Obstetric antiphospholipid syndrome carries an increased lifetime risk for obstetric and thrombotic complications—a population-based study

BackgroundAntiphospholipid syndrome (APS) can present with either a thromboembolic event (thrombotic APS, TAPS) or an obstetric complication (obstetric APS, OAPS). Data on long-term complications in the different APS phenotypes are limited. ObjectivesWe aimed to compare obstetric history, antiphospholipid antibody profiles, obstetric and thromboembolic complications, and pregnancy outcomes between TAPS and OAPS. MethodsThis retrospective cohort study included women who delivered singleton pregnancies between 1998 and 2020. One hundred sixteen thousand four hundred nine women were included, resulting in 320,455 deliveries. Among the included patients, 71 were diagnosed with APS, 49 were classified as OAPS, and 22 as TAPS. The demographics, obstetric, neonatal, and thrombotic outcomes were compared among TAPS, OAPS, and the general obstetric population. ResultsOAPS patients had an increased risk of thrombotic events compared with the general obstetric population (odds ratio [OR] 18.0; 95% CI, 8.7-37.2). In pregnancies following the diagnosis of APS, despite standard antithrombotic treatment, OAPS patients exhibited an elevated risk of placenta-related and neonatal complications compared with the general obstetric population (late fetal loss [adjusted OR {aOR}, 15.3; 95% CI, 0.5-27.5], stillbirth [aOR, 5.9; 95% CI, 2.2-15.4], placental abruption [aOR, 4.8; 95% CI, 1.5-15.3], preeclampsia [aOR, 4.4; 95% CI, 2.5-7.7], fetal growth restriction [aOR, 4.3; 95% CI, 8.5-27.5], small for gestational age neonate [aOR, 4.0; 95% CI, 2.4-6.6], and low Apgar scores [Apgar'1: aOR, 2.6; 95% CI, 1.3-10.4; Apgar'5: aOR, 3.7; 95% CI, 1.3-10.4]). TAPS patients exhibited increased risk of preeclampsia (aOR, 3.1; 95% CI, 1.2-8). ConclusionOAPS patients exhibit a heightened risk of thrombotic events compared with the general obstetric population. Despite treatment, OAPS and TAPS still presented obstetric complications. These findings, after confirmation in prospective studies, need to be taken into consideration when planning the treatment approach for these patients.

Predictors of damage accrual and its impact on health-related quality of life of thrombotic antiphospholipid syndrome: Independent validation of the damage index for antiphospholipid syndrome (DIAPS).

We aim to independently assess the validity of the damage index for antiphospholipid syndrome (DIAPS) in thrombotic antiphospholipid syndrome (APS) patients by exploring the prevalence and risk factors of organ damage and evaluating its impact on health-related quality of life (HR-QoL). Cross-sectional study including all thrombotic APS patients (Sydney criteria) attending a Portuguese tertiary centre. Damage was assessed using the DIAPS, and HR-QoL using the 3- and 5-level EuroQol HR-QoL (EQ-D5-3L and 5L), and Visual Analogue Scale (VAS) applied via a phone questionnaire. Spearman's correlation between DIAPS and the HR-QoL scales was performed. Risk factors for damage accrual and HR-QoL impairment were explored using univariate and multivariate logistic regression. Among the 108 patients (female, 65.7%; white, 90.7%; primary APS, 75.9%; median disease duration, 6years), damage (DIAPS≥1) developed in 48.2% of patients (mean ± SD DIAPS, 3.08 ± 1.83). DIAPS's neuropsychiatric domain was the most affected (24.2%), followed by the peripheral vascular domain (20.3%). No clinical, demographic nor laboratory parameters were significantly associated with damage. Regarding HR-QoL, pain/discomfort, anxiety/depression and usual activities domains were the most frequently impaired in both scales. DIAPS's domains correlated similarly with the EQ-5D-3L and 5L scales' individual domains. Female sex, medical disorders, secondary APS and type of presenting thrombosis (arterial) increased the risk of HR-QoL impairment. Total DIAPS was associated with higher odds of mobility, self-care and pain/discomfort impairment in both EQ-5D-3L and 5L scales but lost its independent risk in multivariable analysis. This external validation of DIAPS reinforces the ability of the score to correlate with HR-QoL while also highlighting risk factors for HR-QoL impairment other than damage accrual.

Insight into antiphospholipid syndrome: the role and clinical utility of neutrophils extracellular traps formation

Antiphospholipid syndrome (APLS) is a systemic immune dysregulation distinguished by repetitive complications and pregnancy loss in the absence of definite etiology. Most research focuses on the laboratory detection and clinical features of APLS, but its precise etiology remains to be deeply explored. NETosis is a newly developed theory in the pathophysiology of APLS which may serve as the missing bridge between coagulation and inflammation reaching the disease progression and severity. We aimed in this study to navigate the prognostic role of NETosis in thrombotic APLS. Our study included 49 newly diagnosed APLS patients (both 1ry and 2ry) who met clinical and laboratory criteria as per the international consensus statement on the update of the classification criteria for definite APLS and were sub-classified according to the occurrence of thrombotic events in thrombotic and non-thrombotic types. In addition, 20 sex and age-matched reactive subjects and 20 sex and age-matched healthy volunteer controls were enrolled. NETosis formation was assessed by measuring serum Myeloperoxidase (MPO) and Histones level using the enzyme-linked immunosorbent assay (ELISA) technique. Both MPO and Histones levels were able to discriminate among APLS cases from normal controls, showing significant cutoffs of > 2.09 ng/ml for MPO and > 1.45 ng/ml for Histones (AUC values were 0.987and 1.000, respectively). These values can be used as predictors for NETosis pathophysiology in APLS patients. Additionally, these markers demonstrated a significant association with several prognostic indicators, including thrombosis, higher PT and INR, and lower hemoglobin (Hb) levels which are supposed to be ameliorated by using NETs inhibitors. In conclusion, we suggest that measuring NETosis markers, MPO, and Histones, in the early course of APLS using proposed cutoff values will facilitate the timely initiation of anti-NETosis therapy and improve the overall prognosis, particularly for patients with thrombotic APLS.

Low recurrent thrombosis rates in single positive antiphospholipid syndrome regardless of type of anticoagulation

Thrombotic antiphospholipid syndrome (TAPS) is characterized by thrombosis and persistently positive tests for antiphospholipid antibodies or lupus anticoagulant (LAC). Triple-positive APS has the highest risk of recurrent thrombosis, but no studies have focused on recurrent thrombosis in patients with single-positive TAPS. We conducted a retrospective cohort study of patients with single-positive TAPS diagnosed at Lifespan Health System, Rhode Island, to determine the rates and risk factors for recurrent thrombosis. Between January 2001 and April 2022, 128 patients were assessed who had single-positive APS (LAC = 98, aCL = 21, aβ2GPI = 9) and who had been followed for a total of 1453.8 patient-years (median follow-up 3.04 years). The initial antithrombotic regimen was warfarin in 44 %, a direct oral anticoagulant (DOAC) in 34 %, enoxaparin in 2 %, and no antithrombotic therapy or antiplatelet therapy only in 20 %. Recurrent thrombosis occurred in 16 (12.5 %) with a recurrent thrombosis rate of 3.08 per 100 patient-years. Systemic lupus erythematosus was the only variable significantly associated with recurrent thrombosis in a model adjusted for age, sex, body mass index, and type of positive APS test. All 16 patients with recurrent thrombosis were initially treated with warfarin, and, at the time of recurrent thrombosis, 13 patients remained on warfarin and three were off anticoagulation. In conclusion, the recurrent thrombosis rate in single-positive APS is low, and not all patients with a single-positive test may need indefinite anticoagulation with warfarin. Larger prospective studies are required to confirm this finding and establish optimal anticoagulation regimens for low-risk TAPS.

Can complement activation be the missing link in antiphospholipid syndrome?

APS is an autoimmune disorder with life-threatening complications that, despite therapeutic advantages, remains associated with thrombotic recurrences and treatment failure. The role of complement activation in APS pathogenesis is increasingly recognised, specifically in obstetric APS. However, its exact role in thrombotic APS and on the severity of the disease is not yet fully elucidated. Further mechanistic studies are needed to delineate the role of complement activation in the various APS clinical manifestations with aim to identify novel markers of disease severity, together with clinical trials to evaluate the efficacy of complement inhibition in APS. This could ultimately improve risk stratification in APS, patient tailored targeted therapy with complement inhibition identified as an adjunctive treatment. This article reviews current findings and challenges about complement activation in APS, discusses the potential role of platelet mediated complement activation in this setting and provides an overview on clinical implications and current therapeutics.

7-year follow-up atherosclerotic plaque progression in patients with antiphospholipid syndrome versus diabetes mellitus and healthy controls.

Patients with antiphospholipid syndrome (APS) carry a substantial burden of cardiovascular disease and subclinical atherosclerosis. We aimed to assess a 7-year follow-up atherosclerotic plaque progression in APS patients vs diabetes mellitus (DM) and healthy controls (HC). Eighty-six patients with thrombotic APS, 86 with DM and 86 HC (all age- and sex-matched) who underwent a baseline ultrasound of carotid and femoral arteries were invited for a 7-year follow-up ultrasonography examination. We compared atherosclerosis progression among the three groups and examined determinants of plaque progression in APS patients. Sixty-four APS patients (75% females, 43.8% with primary APS), 58 patients with DM and 66 HC were included in the 7-year ultrasound re-evaluation. New plaque was detected in 51.6%, 36.2% and 25.8% of APS, DM and HC subjects, respectively. After adjusting for traditional cardiovascular risk factors (CVRFs) and baseline plaque presence, APS patients showed a 3-fold (OR = 3.07, p= 0.007) higher risk for atherosclerosis progression vs HC and 2-fold (OR = 2.25, p= 0.047) higher risk than DM patients. In multivariate analysis in the APS group, plaque progression was independently associated with systemic lupus erythematosus (SLE) co-existence (OR = 7.78, p= 0.005) and number of CVRFs (OR = 3.02, p= 0.002), after adjusting for disease-related parameters and CVRF-related medications. Sustained low-density lipoprotein target attainment reduced plaque progression risk (OR = 0.34, p= 0.021). Half of APS patients develop new atherosclerotic plaques over a 7-year follow-up, having a three-times higher risk vs HC. Concomitant SLE and number of traditional CVRFs are associated with plaque progression, supporting the need for thorough CVRF assessment and control.

Platelets and Thrombotic Antiphospholipid Syndrome

Antiphospholipid antibody syndrome (APS) is an autoimmune disorder characterised by thrombosis and the presence of antiphospholipid antibodies (aPL): lupus anticoagulant and/or IgG/IgM anti-β2-glycoprotein I and anticardiolipin antibodies. APS carries significant morbidity for a relatively young patient population from recurrent thrombosis in any vascular bed (arterial, venous, or microvascular), often despite current standard of care, which is anticoagulation with vitamin K antagonists (VKA). Platelets have established roles in thrombosis at any site, and platelet hyperreactivity is clearly demonstrated in the pathophysiology of APS. Together with excess thrombin generation, platelet activation and aggregation are the common end result of all the pathophysiological pathways leading to thrombosis in APS. However, antiplatelet therapies play little role in APS, reserved as a possible option of low dose aspirin in addition to VKA in arterial or refractory thrombosis. This review outlines the current evidence and mechanisms for excessive platelet activation in APS, how it plays a central role in APS-related thrombosis, what evidence for antiplatelets is available in clinical outcomes studies, and potential future avenues to define how to target platelet hyperreactivity better with minimal impact on haemostasis.

The prevalence and incidence of thrombotic primary antiphospholipid syndrome in adults aged 18–49 years: A population-based study in a mountain community in northern Italy

ObjectiveTo estimate prevalence and incidence of thrombotic Primary Antiphospholipid Syndrome (PAPS) in the general population aged 18–49 years. MethodsThe study was carried out in Valtrompia, a valley in northern Italy, in 2011–2015. The identification of PAPS cases leveraged three integrated sources: 1) Rheumatology Unit at the University Hospital; 2) General Practitioners; 3) hospital discharge codes of patients admitted for thrombotic events. ResultsPrevalence and incidence were estimated as 22.9 (95% C.I. 11.4–41.0) and 5.0 (2.6–8.7) cases per 100,000 individuals, respectively. The estimates were 28.3 and 4.8, and 17.2 and 5.1 in males and females, respectively. The type of disease onset was mainly of arterial type in men and venous in women. ConclusionsThrombotic PAPS was found to be a rare disease in this population-based study. Prevalence and incidence were not significantly different between males and females aged 18–49 years, but a different type of onset was observed.

Thrombosis recurrence and major bleeding in non-anticoagulated thrombotic antiphospholipid syndrome patients: Prospective study from antiphospholipid syndrome alliance for clinical trials and international networking (APS ACTION) clinical database and repository (“Registry”)

BackgroundLong-term anticoagulant therapy is generally recommended for thrombotic antiphospholipid syndrome (TAPS) patients, however it may be withdrawn or not introduced in routine practice. ObjectivesTo prospectively evaluate the risk of thrombosis recurrence and major bleeding in non-anticoagulated TAPS patients, compared to anticoagulated TAPS, and secondly, to identify different features between those two groups. Patients/MethodsUsing an international registry, we identified non-anticoagulated TAPS patients at baseline, and matched them with anticoagulated TAPS patients based on gender, age, type of previous thrombosis, and associated autoimmune disease. Thrombosis recurrence and major bleeding were prospectively analyzed using Kaplan-Meier method and compared using a marginal Cox's regression model. ResultsAs of June 2022, 94 (14 %) of the 662 TAPS patients were not anticoagulated; and 93 of them were matched with 181 anticoagulated TAPS patients (median follow-up 5 years [interquartile range 3 to 8]). The 5-year thrombosis recurrence and major bleeding rates were 12 % versus 10 %, and 6 % versus 7 %, respectively (hazard ratio [HR] 1.38, 95 % confidence interval [CI] 0.53 to 3.56, p = 0.50 and HR 0.53; 95 % CI 0.15 to 1.86; p = 0.32, respectively). Non-anticoagulated patients were more likely to receive antiplatelet therapy (p < 0.001), and less likely to have more than one previous thrombosis (p < 0.001) and lupus anticoagulant positivity (p = 0.01). ConclusionFourteen percent of the TAPS patients were not anticoagulated at recruitment. Their recurrent thrombosis risk did not differ compared to matched anticoagulated TAPS patients, supporting the pressing need for risk-stratified secondary thrombosis prevention trials in APS investigating strategies other than anticoagulation.

Cytokine Profiling in Antiphospholipid Syndrome Demonstrates Persistent Immune Dysregulation and a Procoagulant Phenotype

Background: The antiphospholipid syndrome (APS) is an autoimmune thromboinflammatory disease characterized by thrombosis and the persistent detection of antiphospholipid antibodies (aPL). The rate of recurrent thrombosis in APS is between 3 and 24% despite standard of care anticoagulation with a vitamin K antagonist, suggesting a persistent prothrombotic milieu in APS which may be driven by altered cytokine signaling. Objective: To test the hypothesis that cytokine signaling is dysregulated in APS and contributes to thrombotic risk, we profiled cytokine levels in patients with thrombotic APS and healthy individuals. Methods: We measured a panel of 46 serum cytokines using the Meso Scale Discovery electrochemiluminescent platform, a validated measurement system that provides linear readouts of analytes over several logs of concentration, in 21 APS patients and 12 healthy individuals. All APS patients met the Revised Sapporo Criteria for thrombotic APS. Measurements were performed in triplicate and the log2 transformed averages were analyzed, setting significance at a FDP-adjusted p value of &amp;lt;0.05, while controlling for age and sex. Cytokine values were correlated with clinical history and antibody isotype profile. Results: Our cohort was 67% female and 85% identified as white. All APS patients had thrombotic disease: 57% with history of VTE, 19% with ATE, and 24% with both VTE and ATE. 14% had catastrophic APS. 67% were triple-positive for anti-cardiolipin (aCL), anti-β2 glycoprotein 1 (aβ2GP1), and lupus anticoagulant (LAC). 10% had isolated IgM isotypes of aCL or aβ2GP1. We found significantly elevated levels of TNF-α, IL-6, IL-7, IL-8, IL-10, IL-16, IL-12/IL-23p40, soluble VCAM-1, soluble ICAM-1, PIGF, SAA and CRP and significantly decreased levels of IL-17genB, IL-22 and IL-31 in APS compared with healthy controls (Figure 1). Cytokine levels were measured a median of 5 months (1-240) from the last thrombotic event, demonstrating persistence of the inflammatory response. To determine if cytokine levels were predictive of thrombotic risk, we correlated the number and pattern of positive aPL isotypes and LAC with cytokine levels. We found that TNF-α, IL-8, IL-10, sVCAM-1, sICAM-1, VEGF, IL-7, IL-12/IL-23p40, IL-4, IL-6, IL-16, PIGF, IL-23 and IL-17A each correlated with aPL positivity, with higher levels in triple-positive APS, and the highest levels observed in patients positive for all five measured antibody isotypes (aCL IgG, IgM, IgA; aβ2GP1 IgG, IgM) plus the functional LAC (Figure 2). IL-31 level inversely correlated to the number of positive aPL tests. A sub-analysis of cytokines in patients with isolated IgM aCL or aβ2GP1 antibodies with or without LAC showed significantly increased levels of TNF-α compared to healthy controls, and did not differ from APS patients with other patterns of aPL positivity. This suggests that a similar proinflammatory or procoagulant background is present in patients with isolated antiphospholipid IgM antibodies as those with IgG. Discussion: The sustained differences in cytokine levels measured in APS patients suggests a picture of ongoing immune dysregulation and compensation capable of driving vascular cell activation, and tipping the hemostasis balance into thrombosis. We find upregulation of proinflammatory cytokines, such as TNF-α and IL-6, capable of activating endothelial cells and triggering amplification loops leading to chemokine and acute phase reactant release, cell adhesion molecule expression, recruitment of leukocytes, and accumulation of complement and coagulation proteins, with the net effect of driving inflammation and thrombosis. Decreased levels of IL-17, IL-22 and IL-31 are indicative of dysregulation of the Th17 CD4+ T cell response, which has been implicated in autoimmune pathogenesis. The correlation of cytokine levels with triple or greater aPL positivity suggests a model for advancing risk stratification and has utility as a biomarker of thrombosis. Our study, although limited by size, represents one of the most extensive profiling of cytokines in thrombotic APS.

Circulating Platelets in Thrombotic Antiphospholipid Syndrome Display High Procoagulant Activity and Surface Complement Deposition: Correlation with Thrombotic Risk

Background Antiphospholipid syndrome (APS) is characterized by circulating antiphospholipid antibodies (aPL) accompanied by arterial and/or venous thrombosis, and/or recurrent pregnancy loss. It commonly affects young women in whom it dramatically increases their risk of myocardial infarction, ischemic stroke, deep vein thrombosis and pulmonary embolism. Although the thrombotic risk associated with aPL is established, the underlying mechanisms are still incompletely defined and there are no definitive predictive biomarkers. As a result the management of APS involves indefinite anticoagulation. Increased activation of vascular cells, including platelets is considered to underlie the pathogenesis of APS, and may be mediated in some cases by complement. There is a considerable crosstalk between platelets and complement at various levels during thrombosis. First, activated complement proteins stimulate platelets through their cognate receptors on the platelet surface, and genetic deficiency of complement proteins in mice leads to decreased platelet responsiveness. Second, platelets secrete complement proteins into the medium upon activation. Third, agonist-stimulated platelets contribute to activation of both the classical and alternative pathways of the complement cascade. Hence, we sought to investigate the association between the complement-platelet axis and the prothrombotic pathology observed in APS. Methods Venous blood was drawn from patients with APS and healthy controls, and washed human platelets were prepared by differential centrifugation. Platelets either remained unstimulated or were treated with thrombin (0.1, 0.25, 0.5 U/ml) for 5 min and then labelled with FITC-PAC1, PE-anti-CD62P antibody, Alexa Fluor 488-anti-C4d conjugate, PE-Annexin V, Mitotracker Red, MitoSOX Red, Fluo4-AM, Rhod2-AM, Cell Event Green Caspase 3/7 detection reagent and FITC-IETD-FMK for 30 min in the dark, and then analyzed by flow cytometry to measure integrin activation, P-selectin expression (α-granule secretion), complement C4d binding, phosphatidylserine (PS) exposure, mitochondrial membrane potential, mitochondrial ROS, cytosolic calcium, mitochondrial calcium, caspase 3/7 activity (apoptosis) and caspase 8 activity (extrinsic apoptosis pathway), respectively. Platelet markers were correlated with complement binding and clinical characteristics of APS patients including number of thrombotic events and circulating levels of aPL. Results Thrombin-induced platelet integrin activation and P-selectin expression were identical in APS patients and healthy controls. However, platelets isolated from APS patients had significantly higher procoagulant activity (PS exposure) as well as complement C4d binding in both unstimulated and thrombin-stimulated states compared to healthy controls. There was a strong positive correlation between platelet PS exposure and C4d binding in APS patients, but not healthy individuals, suggesting a role for complement activation in formation of procoagulant platelets in APS. A subset of APS patients with high platelet procoagulant activity (PS exposure &amp;gt; mean + 2SD observed in healthy individuals) had lower mitochondrial membrane potential and increased mitochondrial calcium transients compared to healthy individuals, suggesting mitochondrial permeability transition pore (mPTP)-driven PS exposure. Another subset of APS patients with PS exposing platelets showed caspase activation indicating apoptosis. Platelet PS exposure and C4d binding correlated strongly with the number of thrombotic events as well as levels of circulating aPL, which identifies complement-induced procoagulant platelets as predictors and possible underlying mechanisms for thrombosis in APS. Conclusion Our preliminary studies suggest that PS-exposing platelets are generated in APS by multiple mechanisms including agonist-induced mPTP formation and apoptosis-associated caspase activation. Platelet PS exposure in APS is positively correlated with C4d binding, suggesting a role for complement activation in driving platelet procoagulant activity. Complement activation and PS exposure on platelets are strong predictors of thrombotic risk in APS and could serve as promising targets for novel antithrombotic agents in APS management.