ISCHEMIC STROKE AND MAJOR BLEEDING WHILE ON DIRECT ORAL ANTICOAGULANTS IN NAÏVE PATIENTS WITH ATRIAL FIBRILLATION: IMPACT OF RESUMPTION OR DISCONTINUATION OF ANTICOAGULANT TREATMENT. A population-based study

AIMS

We assessed the cumulative incidence of recurrent stroke, major bleeding and all-cause mortality associated with restarting antithrombotic treatment, in patients experiencing an anticoagulation-related event (stroke or major bleeding), occurred during anticoagulation therapy for AF.

METHODS AND RESULTS

We performed a retrospective population-based analysis on linked claims data of patients resident in the Veneto Region, treated with DOACs for AF and discharged (2013-2020) from the hospital for stroke, intracranial haemorrhage (ICH), and major bleeding. To adjust for competing risk of death and reduce confounding, we started the follow up after a 120-days blanking period, counting events in patients resuming oral anticoagulation versus those that did not. Risks of all-cause mortality, ischemic stroke (IS)intracranial haemorrhage (ICH), and other major bleeding events (MB) were estimated with multivariable Cox proportional hazard models and propensity score to adjust for differences in baseline characteristics. Overall, 1029 patients (mean age 77 years) were included in the final cohort: 23% experienced an IS, 18% an ICH, and 59% MB. Of these, 77% resumed anticoagulation. The cumulative incidence of events was significantly lower in patients resuming therapy. In the multivariable analysis considering age, sex and propensity score as covariates, resumption of anticoagulation significantly reduced the risk of a cumulative event (HR 0.45, 95%CI 0.35-0.57, p < 0.01). Stratifying for the index event, among patients with IS (92% resumed therapy), we observed a risk reduction of 81%; in patients with ICH (64% resumed therapy), we observed a risk reduction of 64% and for patients with MB (76% resuming therapy), we observed a risk reduction of 49%.

CONCLUSIONS

In patients with AF who experienced an anticoagulation-related event, resuming oral anticoagulation was associated with better outcomes for all-cause mortality and subsequent events as compared with patients who did not resume treatment.

Frailty and outcomes in octogenarians with atrial fibrillation treated with edoxaban: ESCAPE study

Background

Frailty is associated with significant morbidity and mortality among elderly adults. Whether frailty predicts adverse outcomes in patients treated with oral anticoagulants for stroke prevention in atrial fibrillation remains uncertain.

Purpose

To examine the impact of frailty in clinical outcomes in elderly patients with non-valvular atrial fibrillation treated with edoxaban.

Methods

This is an observational prospective single centre cohort study enrolling consecutive naïve to anticoagulation patients of age ≥80 years starting oral anticoagulation with edoxaban for stroke prevention in non-valvular atrial fibrillation and followed up for 2 years. At baseline, all patients were evaluated for frailty, comorbidities, medications, and stroke and bleeding risk factors. Frailty was assessed using the Survey of Health Ageing and Retirement in Europe Frailty Index (SHARE-FI) tool, a validated frailty measure centred on health resource utilisation, with the cohort stratified into non-frail, pre-frail and frail. The clinical outcomes were the cumulative incidence of stroke/systemic embolism, major bleeding, and clinically relevant non-major bleeding (CRNMB), and individual components part of the composite outcome.

Results

Among 160 patients who received edoxaban for stroke prevention in atrial fibrillation, 34% were frail, 20% pre-frail, 46% non-frail. The mean age of the cohort was 85±4 years and 58% were female. The mean CHA2DS2VASc score was 4±1. Mean Cockroft-Gault creatinine clearance (CrCl) was 52±17 mL/min, and edoxaban 30mg was administered to 59% of patients as per indications (weight ≤60 kg and/or, CrCl 15–50 ml/min). The follow up extended for 681±289 days. Primary endpoint occurred in 46 patients (28.7%; annualised rate 15.4%patient-years): 19 events occurred in non-frail, 9 in pre-frail, and 18 in frail patients (p=0.6). Stroke/systemic embolism occurred in 2.2%, major bleeding in 5.0%, and CRNM bleeding in 10.0% of patients. Frailty was not a predictor of the events part of the composite outcome (non-frail 5.4% vs pre-frail 0% vs frail 1.9%, p=0.27; non-frail 5.4% vs pre-frail 9.4% vs frail 1.9%, p=0.29; and non-frail 13.5% vs pre-frail 3.1% vs frail 9.3%, p=0.25; for stroke/systemic embolism, major bleeding, and CRNMB, respectively). Cumulative rate of events (Figure) did not differ in frail versus the rest (non-frail and pre-frail) of patients (p=0.521).

Conclusions

Frailty status was not a predictor of events among the elderly with atrial fibrillation treated with edoxaban. Anticoagulation with edoxaban is feasible in octogenarians even if frail.

Funding Acknowledgement

Type of funding sources: None.

P374 MANAGEMENT OF A HOSPITAL NURSING OFFICE FOR AF AND CONTROL OF DIRECT ORAL ANTICOAGULANT THERAPY IN THE COVID EMERGENCY PHASE

Anticoagulant therapy is the gold standard treatment in thromboembolic prevention in AF patients. Starting from the indications from the regional indications that give the therapeutic diagnostic path, a divisional clinic dedicated to the diagnosis and treatment of AF was born in our territory. The aim of the team (Cardiologists, Nurses, GPs, administrative secretariat) was to monitor the number of patients treated with DOACs through AIFA therapeutic plans; Verify adherence to regional guidelines, analysis of therapy adherence; Prepare a protocol for the management of complications and emergencies; Ensure that the departments and services authorized to prescribe NOA take charge, in collaboration with general practitioners who since June 2020 have become active prescribers and also actors in the follow–up of patients; Taking care of the training of the prescribers themselves and the education of patients through hospital meetings dedicated to guided counseling and, finally, monitoring the pharmaceutical expenditure of the NOA on the total prescription of the local health unit of competence in compliance with the regional indicators. In our hospital the pilot project started in 2017 (3726 currently in FU). In the three–year period 2017–19, an average of 700 therapeutic plans were collected for renewal / first prescription per year (58.3 plans / month) to be monitored in subsequent years. In the two–year period 2020–2021, which saw the difficulty of organizing activities due to the pandemic emergency, 903 and 790 PTs were analyzed with an average of 70 plans / month, keeping almost 75% of face to face visits compared to telemedicals set up in the pandemic context.

According to the data, therefore, there is a strong need for diagnostic and health assistance paths. Despite the emergency period and despite a framework in which territorial medicine could have helped the clinical and bureaucratic effort, no resistance to the care burden has occurred and on the contrary the constant increase in patients makes the complexity and difficulty of a correct clinical classification and management support for patients with AOC needs

Incidence of atrial fibrillation in an opportunistic screening campaign in a general practitioner setting: a prospective population study

Introduction

The detection of atrial fibrillation (AF) largely depends on the method used, thus the reported true rate of incident AF is controversial. The detection of symptomatic AF is straight forward in most cases, while it is unclear which strategies provide the best results for the detection of silent AF. Traditional methods like pulse palpation have a low accuracy and pulse guided ECG confirmation is not deemed cost-effective.

Purpose

The aim of the study was to detect the incidence symptomatic AF, using ECG, and opportunistic screening of silent AF, using an AF-detection capable automatic sphygmomanometer, in patients ≥65 years old in the general practitioner (GP) setting.

Methods

This was a population-based prospective cohort study of unselected general population referred for routine visits in 93 randomly selected GPs. Patients of both sexes of ≥65 years without previous diagnosis of AF were considered for the study. Each patient if symptomatic was directly referred to perform an ECG, otherwise if asymptomatic, underwent blood pressure monitoring with an AF-detection capable automatic sphygmomanometer followed by an ECG in case the device signaled AF.

Results

The final population comprised of 14987 individuals of ≥65 years old. The follow up extended to 16838 patient-years. The overall incidence of AF was 2.25% patient-years (95% CI 2.03–2.48). AF incidence was significantly higher in male (male/female ratio 1.29), overweight (BMI: 28.2 kg/m2 vs 27.0 kg/m2), older (79.1 vs 75.4 years old) individuals, with 44.9% belonging to the ≥80-year-old group. Other risk factors for incident AF were higher systolic BP measurements, history of stroke/TIA, congestive heart failure and chronic kidney disease. On multivariate analysis, age (annual increment), mitral valve disease, previous stroke and the number of annual visits (&gt;10), were independent predictors of incidental AF.

About 25% of cases were silent AF (0.56% patient-years, 95% CI 0.46–0.69) and were identified using the AF-detection capable automatic sphygmomanometer. Independent predictors of silent AF were age (per year increment), overweight (BMI &gt;28 kg/m2) and the number of visits (&gt;10) in the GPs' office.

Conclusions

We found a higher than previously reported incidence of AF possibly due to capturing silent AF. This simple protocol, using an AF-capable automatic sphygmomanometer, might be feasible and easily implemented on the routine GP care where high rates of coverage can be achieved.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Veneto Region Italy

An in vitro model to mimic the thrombotic occlusion of small vessels in catastrophic antiphospholipid syndrome (CAPS)

Platelet activation and decrease in platelet count characterize the development of the most feared form of antiphospholipid syndrome (APS), i.e. catastrophic APS (CAPS). We aimed to assess if immuno-affinity purified anti-β2-glycoprotein I (aβ2GPI) antibodies enhance platelet activation inducing a significant flow obstruction in a platelet function analyzer (PFA). Affinity purified aβ2GPI antibodies were obtained from 13 triple positive patients with a strong lupus anticoagulant (LA) and high titers of IgG anticardiolipin antibodies (aCL) and IgG aβ2GPI. Platelet activation stimulated by adenosine diphosphate (ADP) in the presence or absence of aβ2GPI was measured by the expression of P-selectin on platelet surface using flow cytometry. P-selectin expression remained close to baseline when normal whole blood was incubated with aβ2GPI alone. When stimulated using aβ2GPI combined with ADP, P-selectin expression (28.42 ± 5.15% vs. 20.98 ± 3.94%, p = 0.0076) was significantly higher than ADP alone. Closure time of normal whole blood passed through the PFA was significantly shorter using affinity purified aβ2GPI than control IgG both in Col/ADP (160.1 ± 62.1 s vs. 218.6 ± 43.8 s; p = 0.021) and Col/EPI cartridges (149.5 ± 26.7 s vs. 186.9 ± 45.5 s; p = 0.030). Thus, platelet activation is enhanced by aβ2GPI antibodies with a consequent premature closure in a PFA, possibly resembling that in microcirculation in patients with CAPS.

P6515Balloon pulmonary angioplasty in patients with chronic thromboembolic pulmonary hypertension: a systematic review and meta-analysis

Introduction

Balloon pulmonary angioplasty (BPA) is a percutaneous treatment option for patients with chronic thromboembolic pulmonary hypertension (CTEPH) judged inoperable or with persistent symptoms after surgery.

Purpose

We performed a systematic review of the literature to better understand the effectiveness and safety of balloon pulmonary angioplasty.

Methods

PubMed and EMBASE were searched for studies reporting BPA results in patients with CTEPH. Differences in clinical and hemodynamic parameters including 6-minute walking distance, NYHA class, mean PAP, pulmonary vascular resistance, and cardiac output, before and after the procedure were analyzed. Weighted mean proportion and 95% confidence intervals (CIs) of adverse events were calculated.

Results

Of the 1084 potentially eligible studies, 13 were included in the final analysis, yielding on overall cohort of 676 patients. BPA was associated with a reduction in mean pulmonary artery pressure (median: from 43 to 30 mmHg), reduction in pulmonary vascular resistance (median: from 10.22 to 5.00 Woods Units), increase in cardiac index (median: from 2.45 to 2.72 l/min/m2), and improvement of 6-minute walking distance (median: from 328 to 442 meters). Estimated peri-procedural mortality was 2.2% of patients (95% CI 0.7–4.4) with a low risk of publication bias. Mortality rate tends to be higher in older studies and this is consistent with the progressive experience gathered by operators. Reperfusion and pulmonary vessel injuries occurred in 9.5% (95% CI 2.7–19.6) and 2.5% (95% CI 0.8–5.0) of the total BPA sessions, respectively, with on overall high risk of publication bias.

Haemodynamic parameters and 6-minute wal

Conclusions

Our findings suggest that BPA in CTEPH patients is an effective and safe treatment option in inoperable patients or patients with persistent-recurrent symptoms after surgery. Balloon pulmonary angioplasty might be considered as a second line-treatment in patients with chronic thromboembolic pulmonary hypertension not amenable for surgery.

P4671A well-defined subgroup of chronic thromboembolic pulmonary hypertension patients are positive for antiphospholipid antibodies

Introduction

Recurrent thromboembolism is a major risk factor for chronic thromboembolic pulmonary hypertension (CTEPH). Antiphospholipid antibodies (aPL) are a recognized risk factor for recurrent thromboembolism, however, their contribution to the development of CTEPH is currently unknown.

Purpose

The aim of this study was to evaluate the prevalence of antiphospholipid autoantibodies in a large cohort of consecutive patients with CTEPH.

Methods

Starting May 2013 to December 2018, 297 CTEPHpatients were consecutively enrolled. Diagnosis was confirmed with standardized right heart catheterization, 2D or/and 3D pulmonary angiography in all patients.All patients were also screened for thrombophilia including lupus anticoagulant IgG/IgM anticardiolipin antibodies and IgG/IgM aβ2GPI antibodies. Clinical and demographic characteristics, laboratory profile and hemodynamic data were compared between patients with aPL positive and aPL negative laboratory profiles.

Results

Overall, 297 consecutive patients with CTEPH were assessed for aPLs. Of these, 23 patients (7.7%) resulted positive for laboratory tests exploring aPL. Among patients with positive aPL, profile 17 (74%) were positive for all three test exploring aPL (LA+, aCL+, aB2GPI+). When compared to CTEPH patients without aPL test positivity, those positive for aPL were significantly younger (30.0 vs 55.6 years, p<0.0001), had a positive history of pulmonary embolism (95.6% vs 65.7%, p=0.003), deep venous thrombosis (78.3% vs 41.9%, p=0.0008) and were more frequently affected by other autoimmune diseases (43.5% vs 2.9%, p<0.0001). Moreover, positive aPL patients showed better hemodynamics on right heart catheterization, had more proximal lesions, and had more frequently level I and II surgical classification (82.6% vs 40.5%, p=0.0002) on pulmonary angiography.

Conclusions

These findings suggest that young patients with pulmonary embolism should be assessed for aPLs to guide anticoagulation therapy and prevent recurrences. Additionally, younger age, more proximal lesions and less severe hemodynamic profiles make majority patients with APS good candidates for PEA surgery.

458Real world persistence with direct oral anticoagulants in anticoagulation naive patients with atrial fibrillation

Introduction

Anticoagulation therapy is central for the management of stroke in patients with non-valvular atrial fibrillation (NVAF). Persistence with oral anticoagulation is essential to prevent thromboembolic complications.

Purpose

To assess persistence levels of DOACs and look for possible predictors of treatment discontinuity in NVAF patients.

Methods

We performed a population-based retrospective cohort study in the Veneto Region (north-eastern Italy, about 5 million inhabitants) using the regional health system databases. Naïve patients initiating direct oral anticoagulants (DOACs) for stroke prevention in NVAF from July 2013 to September 2017 were included in the study. Patients were identified using Anatomical Therapeutic Chemical (ATC) codes, excluding other indications for anticoagulation therapy using ICD-9CM codes. Treatment persistence was defined as the time from initiation to discontinuation of the therapy. Baseline characteristics and comorbidities associated to the persistence of therapy with DOACs were explored by means of Kaplan-Meier curves and assessed through Cox regression.

Results

Overall, 17920 patients initiated anticoagulation with DOACs in the study period. Most patients were older than 74 years old, while gender was almost equally represented. Comorbidities included hypertension (72%), diabetes mellitus (17%), congestive heart failure (9%), previous stroke/TIA (20%), and prior myocardial infarction (2%). After one year, the persistence to anticoagulation treatment was 82.7%, while the persistence to DOAC treatment was 72.9% with about 10% of the discontinuations being due to switch to VKAs. On multivariate analysis, factors negatively affecting persistence were female gender, younger age (<65 years), renal disease and history of bleeding. Conversely, persistence was better in patients with hypertension, previous cerebral ischemic events, and previous acute myocardial infarction.

Persistence to DOAC therapy

Conclusion

This real-world data show that within 12 months, one out of four anticoagulation-naïve patients stop DOACs, while one out of five patients stop anticoagulation. Efforts should be made to correct modifiable predictors and intensify patient education.

Lupus anticoagulant identifies two distinct groups of patients with different antibody patterns

BACKGROUND

Whether antibodies directed to β2-Glycoprotein I (aβ2GPI) are responsible for LA activity is not well defined. However, in the absence of such antibodies the molecule responsible for LA phenomenon is unknown.

OBJECTIVE

The aim of this study was the biochemical identification of the target antigen epitope of aPL responsible of LA activity in the absence of aβ2GPI antibodies together with the biological and clinical characteristics of these patients in comparison with classical triple positive patients.

PATIENTS/METHODS

A comparison of patients with LA without (LA+/aβ2GPI-) and those with (LA+/aβ2GPI+) associated aβ2GPI antibodies was performed. Size exclusion chromatography and analytical chromatography were used to identify the molecule with LA activity in patients LA+/aβ2GPI-.

RESULTS AND CONCLUSIONS

Analytical size-exclusion chromatography revealed a peak of 996Kd with LA activity perfectly overlapping that of IgM anti phosphatidylserine/prothrombin (aPS/PT) antibodies. Similarly, all the 25 LA+/aβ2GPI- patients were positive for aPS/PT antibodies. LA+/aβ2GPI- compared to 33 LA+/aβ2GPI+ patients turned out to be significantly older, with a lower rate of previous thromboembolic events and a weaker LA activity. Search for aPS/PT and aβ2GPI antibodies in patients with LA is useful to identify two subgroups of LA at different risk of thromboembolic events.

Thrombocytopenia in high-risk patients with antiphospholipid syndrome

Essentials The prevalence of thrombocytopenia in patients with antiphospholipid syndrome is not well defined. We studied triple positive patients with antiphospholipid syndrome and its catastrophic variant. Prevalence of thrombocytopenia was 6% and 100% in patients who developed the catastrophic form. In triple positive patients thrombocytopenia is low and platelets drop during the catastrophic form.

SUMMARY

Background Thrombocytopenia is the most common non-criteria hematological feature in patients with antiphospholipid syndrome (APS). This condition is more common in patients with catastrophic APS (CAPS). Objectives To evaluate the prevalence of thrombocytopenia in a large series of high-risk patients with APS, and to assess the behavior of the platelet count during CAPS. Methods/Patients This was a cross-sectional study in which we analyzed the platelet counts of a homogeneous group of high-risk APS patients (triple-positive). Six of these patients developed a catastrophic phase of the disease, and the platelet count was recorded before the acute phase, during the acute phase, and at recovery. Results The mean platelet count in 119 high-risk triple-positive patients was 210 × 109 L-1 . With a cut-off value for thrombocytopenia of 100 × 109 L-1 , the prevalence of thrombocytopenia was 6% (seven patients). No difference between primary APS and secondary APS was found. In patients who suffered from CAPS, a significant decrease from the basal count (212 ± 51 × 109 L-1 ) to that at the time of diagnosis (60 ± 33 × 109 L-1 ) was observed. The platelet count became normal again at the time of complete remission (220 ± 57 × 109 L-1 ). A decrease in platelet count always preceded the full clinical picture. Conclusions This study shows that, in high-risk APS patients, the prevalence of thrombocytopenia is low. A decrease in platelet count was observed in all of the patients who developed the catastrophic form of the disease. A decrease in platelet count in high-risk APS patients should be considered a warning signal for disease progression to CAPS.

The role of platelets in antiphospholipid syndrome

Despite extensive research, the pathogenesis of antiphospholipid syndrome (APS) remains obscure in many aspects. However, it is widely accepted that thrombosis is the result of a hypercoagulable state caused by antibodies directed against β2-glycoprotein I (β2-GPI), a protein whose physiological role is unknown. Although underestimated, platelets may be involved in APS and its thrombotic manifestations, especially arterial, in several ways. Thrombocytopenia is the most relevant non-criteria manifestation of APS, possibly caused by direct binding of anti-β2-GPI antibodies or anti-β2-GPI-β2-GPI complexes. On the other hand, platelets may have a key role in APS-related thrombosis due to the presence of multiple receptors that can interact with anti-β2-GPI antibodies (especially apolipoprotein E receptor 2' (apoER2') and glycoprotein Ibα (GPIbα)) with consequent release of different procoagulant mediators such as thromboxane B2, platelet factor 4 (PF4), and platelet factor 4 variant (CXCL4L1). The aim of this review is to put together evidence on the possible role of platelets in APS and to stimulate further research on the issue.

Laboratory testing for antiphospholipid syndrome

This is a practical report on laboratory tests for the diagnosis of antiphospholipid syndrome (APS). After a general definition of APS, this study deals with appropriateness and timing in requesting the determination of antiphospholipid (aPL) antibodies. Lupus anticoagulant (LAC), anticardiolipin (aCL), and anti β2-glycoprotein I (aβGPI) are the mandatory tests to be performed, while other tests are not yet validated for clinical use. Interpretation of results is an important discussed issue that implies a close liaison between clinical pathologists and clinicians. Finally, a personal definition of APS according to aPL antibody profile closes the manuscript.

Efficacy and safety of rivaroxaban vs warfarin in high-risk patients with antiphospholipid syndrome: Rationale and design of the Trial on Rivaroxaban in AntiPhospholipid Syndrome (TRAPS) trial

Background

New oral anticoagulants may simplify long-term therapy in conditions requiring anticoagulation. Rivaroxaban is a direct factor Xa inhibitor that has been extensively studied and is now approved for the prevention and therapy of a number of thromboembolic conditions.

Objective and methods

This is a multicentre, randomized, open-label, study that will evaluate if Rivaroxaban 20 mg od (or 15 mg od in patients with moderate renal insufficiency) is non-inferior to warfarin (INR target 2.5), for the prevention of thromboembolic events, major bleeding and death in high risk (triple positive) patients with antiphospholipid syndrome. Secondary endpoints will assess the incidence of any individual component of the composite end point. An external adjudication committee will evaluate all suspected outcome events. This will be a unique trial, as it will enrol the biggest homogenous cohort of high risk APS individuals.

Conclusion

The methods and the study design should be appropriate to achieve study results that are both scientifically valid and relevant to clinical practice.

Antiphospholipid syndrome: antibodies to Domain 1 of β2-glycoprotein 1 correctly classify patients at risk

BACKGROUND

Determination of lupus anticoagulant (LA), anticardiolipin (aCL) and β2-Glycoprotein 1 (aβ2GP1) antibodies is mandatory to classify patients with antiphospholipid syndrome (APS) into risk categories.

OBJECTIVES

To measure relevant antibodies, considered to be those of the IgG isotype directed towards β2GP1 and particularly those directed to Domain 1 (Dm1) of the molecule.

PATIENTS/METHODS

In this cross-sectional study we measured IgG aβ2GP1-Dm1 by a chemiluminescent immunoassay in a group of individuals initially positive for IgG aβ2GP1 and classified as triple (LAC+, IgG aCL+, IgG aβ2GP1+, n = 32), double (LAC-, IgG aCL+, IgG aβ2GP1+, n = 23) or single positive (LA-, IgG aCL-, IgG aβ2GP1+, n = 10).

RESULTS AND CONCLUSION

Geometric mean and standard deviation expressed as chemiluminescent units (CU) in triple, double and single positive groups were 273.0 ± 6.2, 18.2 ± 9.6 and 4.4 ± 2.2, respectively. The geometric mean obtained in 40 healthy subjects was 2.0 ± 2.0. Mean CU values were significantly different among groups and with respect to values found in 40 healthy subjects (P < 0.0001). Positive values of IgG aβ2GP1-Dm1 (above 14.2 CU) were found in 45 individuals while 20 individuals (20/65 = 30.8%) positive for IgG aβ2GP1 were negative for IgG aβ2GPI-Dm1. There was a significant association between positive IgG aβ2GP1-Dm1 and thromboembolic events (P = 0.001). Positive and negative values of IgG aβ2GP1-Dm1 were consistently confirmed after 12 weeks, with only three low positive values being negative after 12 weeks. In conclusion, IgG aβ2GP1-Dm1 seems a robust and reproducible test that in association with the classic tests may be useful in clinical practice in identifying individuals at high risk of developing thromboembolic events.

Confirmation of initial antiphospholipid antibody positivity depends on the antiphospholipid antibody profile

BACKGROUND

The revised classification criteria for the antiphospholipid syndrome state that antiphospholipid (aPL) antibodies (lupus anticoagulant [LAC] and/or anticardiolipin [aCL] and/or anti-β2 -glycoprotein I [aβ2 GPI] antibodies) should be detected on two or more occasions at least 12 weeks apart. Consequently, classification of patient risk and adequacy of treatment may be deferred by 3 months.

OBJECTIVES

In order to early classify patient risk, we evaluated whether aPL positivity confirmation is related to aPL antibody profiles.

PATIENTS AND METHODS

Consecutive patients referred to our center who were initially positive in one or more tests exploring the presence of aPL were tested after 3 months. During a 4-year period, 225 patients were initially positive in one or more tests, and 161 were available for confirmation after 3 months. Patients were classified as triple-positive (n = 54: LAC(+) , aCL(+) , aβ2 GPI(+) , same isotype), double-positive (n = 50: LAC(-) , aCL(+) , aβ2 GPI(+) , same isotype) and single-positive (n = 53: LAC or aCL or aβ2 GPI antibodies as the sole positive test).

RESULTS

Among subjects with triple positivity at initial testing, 98% (53 of 54) had their aPL profile confirmed after 12 weeks. The double-positive and single-positive groups had data confirmed in 42 of 50 (84%) and 23 of 57 (40%) subjects, respectively.

CONCLUSIONS

Our results show that high-risk subjects with triple-positive aPL profiles are identified early, at the time of the initial screening tests.

Secondary prevention in thrombotic antiphospholipid syndrome

Secondary prevention of venous thromboembolism in antiphospholipid syndrome (APS) is usually made using vitamin K antagonists (VKAs) to maintain an international normalized ratio (INR) between 2.0 and 3.0. The optimal intensity of anticoagulation was determined in two prospective randomized controlled trials, both excluding the benefit of more intense anticoagulation. The same regimen is also recommended in patients with APS and arterial thromboembolism as aspirin does not appear to protect against recurrences. The duration of treatment is usually indefinite because of a substantial risk of recurrence.

Circulating β2 glycoprotein I-IgG anti-β2 glycoprotein I immunocomplexes in patients with definite antiphospholipid syndrome

Beta2-glycoprotein I (β(2)GPI), a relevant antigen in Antiphospholipid Syndrome (APS), binds anionic macromolecules including heparin (Hep). A possible formation of ternary complexes between β(2)GPI, antibodies and Hep in APS is thus possible. The aim of this study was to evaluate Hep-β(2)GPI interaction in patients with APS. The affinity of Heps of different length, including unfractionated Hep (UFH), low-molecular weight Hep (enoxaparin) and pentasaccharide (fondaparinux), to human β(2)GPI was estimated by fluorescence spectroscopy, yielding dissociation constant (K(d)) values of 1.1, 24.0 and 89.4 µM, demonstrating that the longer UFH binds to β(2)GPI far more tightly than the shorter ones. Plasma and protein G-purified IgGs from eight patients with APS (i.e. five with thromboembolic disease and three with catastrophic APS), were fractionated by affinity chromatography using a Hep (UFH)-bound column, eluted with a linear NaCl gradient. For each chromatographic analysis, fractions were collected in the whole NaCl gradient and tested by ELISA for the presence of β(2)GPI and anti-β(2)GPI IgG. The results of Hep-affinity chromatography and ELISAs concurrently indicate that either β(2)GPI and anti-β(2)GPI IgG elute from the Hep column in the same chromatographic peak, at a retention time identical to that of the purified, isolated β(2)GPI, thus suggesting that circulating immunocomplexes containing β(2)GPI are present in patients with APS.

Interpretation of laboratory data and need for reference laboratories

A single positive laboratory test among those exploring the presence of antiphospholipid antibodies is not associated with thromboembolic events and does not identify patients with antiphospholipid syndrome. On the other hand, more than one laboratory test positive, and in particular all three tests positive, is strongly associated to thromboembolic events and identifies high risk patients. Triple positivity is in fact related to the presence of a specific anti-β2-glycoprotein I (anti-Domain I) antibody, also able to prolong coagulation tests. Monoclonal antibodies against Domain I with Lupus Anticoagulant activity might be candidate material for standardization of antiphospholipid assays. Much work remains to be done in this field.

Antiphospholipid syndrome: critical analysis of the diagnostic path

Antiphospholipid syndrome (APS) is diagnosed in the presence of vascular thrombosis or pregnancy morbidity occurring in patients with circulating antiphospholipid antibodies (lupus anticoagulant [LA] and/or IgG/IgM anticardiolipin [aCL] and/or IgG/IgM anti-beta2glycoprotein I [abeta2GPI] antibodies). Each test may identify different autoantibodies; a single test makes the diagnosis possible when positive on two or more occasions at least 12 weeks apart. However, single test positivity may be unrelated to pathogenic antibodies, which are now considered to be a subclass of abeta2GPI antibodies directed against the domain I of this protein. Conversely, all three positive tests identify a single class of abeta2GPI antibodies, thus identifying high-risk patients with APS.

Prevalence and significance of anti-prothrombin (aPT) antibodies in patients with Lupus Anticoagulant (LA)

OBJECTIVE

Anti-prothrombin (aPT) antibodies have been found in Lupus Anticoagulant (LA) positive patients. Their prevalence and relative contribution to thromboembolic risk in LA-positive patients is not well defined. The aim of this study was to determine their presence and association with thromboembolic events in a large series of patients with confirmed LA.

METHODS

Plasma from LA-positive patients was collected at Thrombosis Centers and sent to a reference central laboratory for confirmation. Positive plasma was tested using home-made ELISA for the presence of aPT and anti-beta(2)GPI antibodies.

RESULTS

LA was confirmed in 231 patients. Sixty-one of 231 (26%, 95%CI 22-33) LA positive subjects were positive for IgG aPT and 62 (27%, 95% CI 21-33) were positive for IgM aPT antibodies. Clinical features of Antiphospholipid Syndrome (APS) were not associated with the presence of IgG aPT [43 APS in 61 (70%) positive and 109 APS in 170 (64%) negative IgG aPT subjects, p=ns] or IgM aPT. Rate of positivity of IgG and IgM a beta(2)GPI was significantly higher than that of IgG and IgM aPT. Clinical events accounting for APS occurred in 97 of 130 (75%) IgG a beta(2)GPI positive and in 55 of 101 (54%) IgG a beta(2)GPI negative patients (OR 2.4, 95% CI 1.4 to 4.3, p=0.002). No significant association with clinical events in patients positive for both IgG aPT and IgG a beta(2)GPI as compared to those positive for one or another test was found. When patients negative for both IgG aPT and IgG a beta(2)GPI (LA positive only) were compared with remaining patients, a significantly lower association with clinical events was found (OR=0.4, 95% CI: 0.2 to 0.7, p=0.004).

CONCLUSIONS

As compared to IgG a beta(2)GPI, the prevalence of IgG aPT in patients with LA is significantly lower and not associated with the clinical features of APS.

Clinical course of high-risk patients diagnosed with antiphospholipid syndrome

BACKGROUND

The characteristics and the clinical course of antiphospholipid syndrome (APS) in high-risk patients that are positive for all three recommended tests that detect the presence of antiphospholipid (aPL) antibodies have not been described.

METHODS

This retrospective analysis of prospectively collected data examined patients referred to Italian Thrombosis Centers that were diagnosed with definite APS and tested positive for aPL [lupus anticoagulant (LA), anti-cardiolipin (aCL), and anti-beta2-glycoprotein I (beta2GPI) antibodies]. Laboratory data were confirmed in a central reference laboratory.

RESULTS

One hundred and sixty patients were enrolled in this cohort study. The qualifying events at diagnosis were venous thromboembolism (76 cases; 47.5%), arterial thromboembolism (69 cases; 43.1%) and pregnancy morbidity (11 cases; 9.7%). The remaining four patients (2.5%) suffered from catastrophic APS. The cumulative incidence of thromboembolic events in the follow-up period was 12.2% (95% CI, 9.6-14.8) after 1 year, 26.1% (95% CI, 22.3-29.9) after 5 years and 44.2% (95% CI, 38.6-49.8) after 10 years. This was significantly higher in those patients not taking oral anticoagulants as compared with those on treatment (HR=2.4 95% CI 1.3-4.1; P<0.003). Major bleeding associated with oral anticoagulant therapy was low (0.8% patient/years). Ten patients died (seven were cardiovascular deaths).

CONCLUSIONS

Patients with APS and triple positivity for aPL are at high risk of developing future thromboembolic events. Recurrence remains frequent despite the use of oral anticoagulants, which significantly reduces the risk of thromboembolism.

Lower versus standard intensity oral anticoagulant therapy (OAT) in elderly warfarin-experienced patients with non-valvular atrial fibrillation

It has been observed that elderly patients with nonvalvular atrial fibrillation (NVAF) benefit from standard [an international normalised ratio (INR) goal of 2.0-3.0] oral anticoagulant treatment (OAT). The hypothesis that lower-intensity anticoagulation therapy can offset the higher bleeding risk in this population has never been tested in an 'ad hoc' clinical trial. Patients over 75 years of age with NVAF were randomised to receive warfarin to maintain the INR at 1.8 (range 1.5-2.0) or at a standard target of 2.5 (range 2.0-3.0). There were 135 patients in the low-intensity and 132 in the standard-intensity groups. During a mean follow-up lasting 5.1 years, 59 primary outcome events (thromboembolism and major haemorrhage) were recorded, 24 (3.5 per 100 patient-years) in the low-intensity group and 35 (5.0 per 100 patient-years) in the standard-intensity group (HR=0.7, 95% CI 0.4-1.1, p=0.1). The reduction in the primary endpoint was mainly due to a diminution in major bleedings (1.9 vs. 3.0 per 100 patient-years; HR=0.6, 95% CI 0.3-1.2, p=0.1). The median achieved INR value was 1.86 in the low-intensity and 2.24 in the standard-intensity group (p<0.001). The frequency of INR testing was 26.1 +/- 13.5 vs. 24.3 +/- 11.6 days, p<0.0001). In this exploratory study we observed a low rate of stroke and major bleeding in elderly patients (>75) being managed in an anticoagulation clinic for primary stroke prevention with low-intensity anticoagulation (INR 1.5-2.0). However, further trials are needed to confirm the hypothesis generated by the present study.

Standardized low-molecular-weight heparin bridging regimen in outpatients on oral anticoagulants undergoing invasive procedure or surgery: an inception cohort management study

BACKGROUND

Bridging therapy with low-molecular-weight heparin is usually recommended in patients who must stop oral anticoagulants before surgical or invasive procedures. To date, there is no universally accepted bridging regimen tailored to the patient's thromboembolic risk. This prospective inception cohort management study was designed to assess the efficacy and safety of an individualized bridging protocol applied to outpatients.

METHODS AND RESULTS

Oral anticoagulants were stopped 5 days before the procedure. Low-molecular-weight heparin was started 3 to 4 days before surgery and continued for 6 days after surgery at 70 anti-factor Xa U/kg twice daily in high-thromboembolic-risk patients and prophylactic once-daily doses in moderate- to low-risk patients. Oral anticoagulation was resumed the day after the procedure with a boost dose of 50% for 2 days and maintenance doses afterward. The patients were followed up for 30 days. Of the 1262 patients included in the study (only 15% had mechanical valves), 295 (23.4%) were high-thromboembolic-risk patients and 967 (76.6%) were moderate- to low-risk patients. In the intention-to-treat analysis, there were 5 thromboembolic events (0.4%; 95% confidence interval, 0.1 to 0.9), all in high-thromboembolic-risk patients. There were 15 major (1.2%; 95% confidence interval, 0.7 to 2.0) and 53 minor (4.2%; 95% confidence interval, 3.2 to 5.5) bleeding episodes. Major bleeding was associated with twice-daily low-molecular-weight heparin administration (high-risk patients) but not with the bleeding risk of the procedure.

CONCLUSIONS

This management bridging protocol, tailored to patients' thromboembolic risk, appears to be feasible, effective, and safe for many patients, but safety in patients with mechanical prosthetic valves has not been conclusively established.