Thrombotic events associated with low baseline direct oral anticoagulant levels in atrial fibrillation: the MAS study.

ABSTRACT: Although effective and safe, treatment with direct oral anticoagulants (DOAC) in atrial fibrillation (AF) is still associated with thrombotic complications. Whether the measurement of DOAC levels may improve treatment efficacy is an open issue. We carried out the observational, prospective, multicenter Measure and See (MAS) study. Blood was collected 15 to 30 days after starting DOAC treatment in patients with AF who were followed-up for 1 year. Plasma samples were centralized for DOAC level measurement. Patients' DOAC levels were converted into drug/dosage standardized values to allow a pooled analysis in a time-dependent, competitive-risk model. The measured values were transformed into standardized values (representing the distance of each value from the overall mean) by subtracting the DOAC-specific mean value from the original values and dividing by the standard deviation. Trough and peak DOAC levels were assessed in 1657 and 1303 patients, respectively. In total, 21 thrombotic complications were recorded during 1606 years of follow-up (incidence of 1.31% of patients per year). Of 21 thrombotic events, 17 occurred in patients whose standardized activity levels were below the mean of each DOAC (0); the incidence was the highest (4.82% of patients per year) in patients whose standardized values were in the lowest class (-1.00 or less). Early measurement of DOAC levels in patients with AF allowed us to identify most of the patients who, having low baseline DOAC levels, subsequently developed thrombotic complications. Further studies are warranted to assess whether thrombotic complications may be reduced by measuring baseline DOAC levels and modifying treatment when indicated. This trial was registered at www.ClinicalTrials.gov as #NCT03803579.

Incidence and clinical outcomes of heparin-induced thrombocytopenia: 11 year experience in a tertiary care university hospital.

Heparin-induced thrombocytopenia (HIT) is a rare immuno-mediated adverse reaction with high thrombotic and mortality risk. To evaluate incidence and outcomes of HIT cases diagnosed at a tertiary care hospital from 2007 to 2018. A retrospective study was conducted. Patients with suspected HIT underwent 4Ts score assessment and anti-heparin PF4 IgG antibodies ELISA screening test. If the latter was positive, platelet aggregation test (PAT) was performed. If the latter was positive, any form of heparin was stopped, alternative anticoagulants were started and then overlapped with warfarin. HIT incidence was calculated by dividing HIT cases by the mean yearly number of admitted patients over 11 years. Follow-up was 90 days. Among 2125 screening tests, 96 (4.5%) were positive with confirmatory PAT in 82/90 (3.8% for missing data in 6). Median age was 75; 39 patients were surgical and 51 medical. The median 4Ts score was 5. Unfractionated heparin was employed in 34 (37%). HIT incidence was 0.16/1000/patient/years (95% CI: 0.12-0.23) in surgical and 0.15/1000/patient/years (95%: 0.12-0.20) in medical patients. HIT with thrombosis (HIT-T) was observed in 31 patients (0.05/1000/patient/years 95% CI: 0.04-0.1), with venous thromboses in 25 (80%). HIT without thrombosis was observed in 59 patients (0.1/1000 patient/years; 95% CI: 0.08-0.13, twofold vs HIT-T). All cause mortality was 25.5% (95% CI: 17.6-35.4), major bleeding 7.7% (95% CI:3.2-15.3), and thromboembolic complications 3.3% (95% CI:1.1-9.3). HIT is a rare event with high mortality, despite the use of non heparin anticoagulants.

Venous Thromboembolism in Women of Childbearing Age: Insights from the START Registry.

BACKGROUND: Women of childbearing age are exposed to venous thromboembolic risk mainly for pregnancy and use of oral contraceptives. The impact of risk factors (RF) on venous thromboembolism (VTE) in these circumstances is still unclear. AIM: In the context of START registry, we aimed to investigate the weight of a series of RF on the occurrence of pregnancy- or combined oral contraceptive (COC)-associated VTE. MATERIALS AND METHODS: We selected all women included in the START for VTE occurred between 18-42 years and compared those with a first or recurrent pregnancy/postpartum- (group A) or COC-VTE (group B) with those who had VTE outside these circumstances (group C). Final analysis included a cohort of 532 women. Follow-up data showed that there were no significant differences between the groups in terms of thrombotic and haemorrhagic complications. As for pregnancy-associated VTE, the overall outcome was good in terms of both maternal and fetal prognosis. RESULTS: In a binary model of logistic regression, correcting for potential confounders, VTE family history conferred a significant and independent higher risk of COC-VTE compared with group C. Similarly, comparison between group A and C documented that family history significantly affected the risk of pregnancy-associated VTE. VTE in the group C was significantly associated with older age. Lastly, smoke was a significant risk factor for pregnancy/postpartum VTE when group A and group B were compared. CONCLUSION: Present data suggest that in the setting of fertile women, family history of VTE has a greater role in predicting COC- and pregnancy/postpartum- VTE than outside these circumstances.

Recurrences and bleeding during extended treatment of patients with venous thromboembolism: results of the international, prospective, observational WHITE study.

BACKGROUND: Little data are available on real-life long-term treatments after a venous thromboembolism (VTE), and on recurrent VTE or bleeds events during treatments. METHODS: We investigated the complications occurring during follow-up (FU) in VTE patients who had received the treatment decisions given by the clinical centers, active in 7 countries (China, Czechia, Poland, Portugal, Russia, Slovakia, Tunisia), which participated in the international, prospective, observational WHITE study. RESULTS: FU information was collected in 1004 patients, recruited by 62 clinical centers (17 centers did not participate in FU collection). Extended treatments were proposed to 811 patients: direct oral anticoagulants (DOACs) (475), sulodexide (202), antiplatelet agents (73), vitamin K antagonists (VKAs) (45), low molecular weight heparin (LMWH) (16). All specific treatments were stopped in the remaining 193 patients. Patients who during FU used treatments different than those prescribed by the local investigators (263) or for other causes (26) were excluded from analysis. 50 primary events occurred throughout 1044 years FU in 715 patients, 4.8 incidence (×100 patient-years) [3.8 for recurrences, and 0.96 for bleeding (major or clinically relevant)]. Primary event incidence differed according to treatments (LMWH=33.3, antiplatelets =7.6, VKAs = 6.1, DOACs = 4.7, sulodexide = 4.2, all treatment stopped = 2.5), and differed across the involved countries. CONCLUSIONS: DOACs were the most used drugs for extended treatments. Overall, the rate of primary events during FU was low. The investigators identified patients at low risk of recurrence and high bleeding risk. Sulodexide use for secondary prevention deserves further studies.

Thrombotic burden, D-dimer levels and complete compression ultrasound for diagnosis of acute symptomatic deep vein thrombosis of the lower limbs.

BACKGROUND: Diagnostic algorithms for deep vein thrombosis (DVT) include D-dimer for its high negative predictive value, thus reducing the need for imaging. Small thrombi may be associated with low D-dimer levels, increasing false negatives. AIM: To assess the sensitivity and thus the false negative rates of standard and age-adjusted D-dimer cut offs for isolated distal DVT (IDDVT) in outpatients. MATERIALS AND METHODS: We enrolled consecutive outpatients with suspected DVT of the lower limbs referring to our vascular emergency department from 2009 to 2018. Patients underwent D-dimer testing (STA, Stago, cut-off: 500 µg/L), pretest clinical probability (PTP) evaluation and complete compression ultrasonography. Follow-up was 3 months. RESULTS: Among 3948 patients (M:1554-39%, median age 69), 486 proximal DVTs (12.3%) and 348 IDDVTs (8.8%) were diagnosed. Median D-dimer was higher in proximal than IDDVT (3960 vs 1400 µgr/L; p = 0.001). The false negative rate of the standard D-dimer cut-off was 2% (95%CI: 0.8-3.2%) for proximal DVT and 14.7% (95% CI: 11-81%) for IDDVT. The false negative rate of the age-adjusted cut-off was 4.9% (3-7%) for proximal DVT and 19.5% (95% CI: 15.4-24.7%) for IDDVT. CONCLUSIONS: Small calf thrombi are associated with low D-dimer levels, and age-adjusted D-dimer may be below the cut-off more frequently in subjects with IDDVT than standard cut-off D-dimer, although such D-dimer levels might exclude IDDVT that require treatment.

Influence of clinical presentation, site, and extent of venous thrombosis on decision about duration of anticoagulation: Data from the international, prospective, observational WHITE study.

BACKGROUND: Low attention has generally been dedicated to the influence of clinical presentation, extent of venous thrombosis and presence of residual vein obstruction (RVO) on the decision about the duration of secondary prophylaxis after a first venous thromboembolism (VTE). AIM: This study aimed at investigating the role of the mentioned VTE characteristics on the therapeutic decision using the information collected in the international, prospective, observational WHITE study. RESULTS: 1240 patients were recruited by 79 clinical centers in 7 countries (China, Czechia, Poland, Portugal, Russia, Slovakia, and Tunisia). 35 patients had as index event a pulmonary embolism (PE) without a deep vein thrombosis (DVT), and all continued anticoagulation. We focused on the 1205 subjects with DVT. The treatment decision differed among countries; altogether, more than 85% of patients with proximal (with or without distal) DVT continued a prophylactic treatment with anticoagulants, or antithrombotics; 34% of patients with isolated distal DVT stopped treatment, and more than 85% of patients with a PE associated to a DVT continued treatment. At multivariable analysis, the presence of proximal DVT, signs of post-thrombotic syndrome (PTS), residual vein obstruction (RVO), maintenance <180 days and concomitant diseases was associated with increased probability to continue secondary prophylaxis. CONCLUSION: The presentation as proximal DVT (with or without PE) or isolated PE influenced the treating physicians' decision in favor of extension of secondary prophylaxis, together with the presence of concomitant diseases and local conditions which may increase the risk of post-thrombotic syndrome.

Unprovoked or provoked venous thromboembolism: not the prevalent criterion to decide on anticoagulation extension in clinical practice of various countries-the prospective, international, observational WHITE study.

The decision on treatment after a first venous thromboembolism (VTE) to prevent recurrences may be influenced by many factors. The prospective, observational, WHITE study aimed to analyze how this issue was tackled in every-day clinical practice in various countries, which have sensibly different socio-economic conditions and healthcare systems. Doctors active in 79 Internal or Vascular clinical centers in 7 countries (China, Czechia, Poland, Portugal, Russia, Slovakia, and Tunisia) enrolled VTE patients after the maintenance treatment phase. The present report analyzed information, collected in the central database, regarding the baseline characteristics, index events, type and duration of anticoagulant therapy and decision on post-maintenance treatment. From April 2018 to December 2020, 1240 patients were enrolled, 58% with an unprovoked index event. Direct oral anticoagulants (DOACs) were used in > 85% of all cases in China, Poland, Portugal, Russia and Czechia, in 52% in Slovakia and in no patient in Tunisia. The maintenance anticoagulation lasted in average approximately 6 months. Altogether, anticoagulation was stopped in 20%, extended in about 50%, regardless of whether the event was unprovoked or provoked and shifted to antithrombotics (mainly sulodexide or aspirin) in the remaining patients. In conclusion, some differences in VTE patient management were found between countries. The provoked/unprovoked nature of the index event, instead, was not the prevalent criterion to drive the decision on extension of anticoagulation, without large variations between countries. DOACs were the most widely used anticoagulant drugs, whereas > 25% of patients received antithrombotic drugs instead of anticoagulants as extended treatment.

Anticoagulation Duration After First Venous Thromboembolism: Real-Life Data From the International, Observational WHITE Study.

BACKGROUND: International guidelines recommend at least three months anticoagulation in all patients after acute venous thromboembolism (VTE) and suggest those with unprovoked events be considered for indefinite anticoagulation if the risk of recurrence is high and the risk of bleeding during treatment non-high. Other authors have recently argued against using a dichotomy unprovoked/provoked events to decide on anticoagulation duration and suggest instead using overall risk factors present in each patient as the basis for deciding. AIM: This sub-analysis of the WHITE study aimed at assessing the reasons for the treatment decisions taken by doctors in different countries. RESULTS: 1240 patients were recruited in 7 countries (China, Czechia, Poland, Portugal, Russia, Slovakia, and Tunisia). Anticoagulation was extended in 51.7% and 49.3% of patients with unprovoked or provoked events (n.s.); stopped in 15.4% versus 28.9% (P < .0001), and changed to antithrombotic drugs (sulodexide or aspirin) in 32.9% versus 21.8% (P < .0001). In the 430 subjects with isolated distal deep vein thrombosis (IDDVT) anticoagulation was stopped in 34.4%, continued in 37.0% (mainly those with post-thrombotic syndrome [PTS]) and switched to antithrombotics in the balance. High risk of recurrence was the most prevalent reason (>83% of cases) given to continue anticoagulation, regardless of nature and site of the index events, followed by risk of bleeding and presence of PTS signs. CONCLUSION: On average, attending physicians estimated the risk of recurrence in real life conditions, and the consequent therapeutic decision, using all the information available, not limiting to the location or nature of the index event.

DOAC plasma levels measured by chromogenic anti-Xa assays and HPLC-UV in apixaban- and rivaroxaban-treated patients from the START-Register.

INTRODUCTION: To measure direct factor Xa inhibitor (apixaban, edoxaban, rivaroxaban) concentrations, dedicated chromogenic anti-Xa assays are recommended as suitable methods to provide rapid drug quantification. Moreover, the high-performance liquid chromatography with ultraviolet detection (HPLC-UV) is reported as a reliable quantitative technique. We investigated seven anti-Xa assays and an HPLC-UV method for measurement of apixaban and rivaroxaban levels in patients enrolled in the START-Register. METHODS: A total of 127 apixaban and 124 rivaroxaban samples were tested by HPLC-UV and the following anti-Xa assays: Biophen DiXaI and Heparin LRT (Hyphen BioMed), Berichrom and Innovance Heparin (Siemens), STA-Liquid Anti-Xa (Stago Diagnostics), Technochrom anti-Xa (Technoclone), and HemosIL Liquid Anti-Xa (Werfen). Each method was performed in one of the participating laboratories: Bologna, Cremona, Florence, and Padua. RESULTS: Our data confirmed the overestimation of apixaban and rivaroxaban levels by the antithrombin-supplemented anti-Xa method (Berichrom). Performances and reproducibility of the six anti-Xa assays not supplemented with antithrombin and the HPLC-UV method were good, with limits of quantification from 8-39 ng/mL (apixaban) and 15-33 ng/mL (rivaroxaban). The six chromogenic methods showed good concordances with the quantitative HPLC-UV [bias: -26.9-22.3 ng/mL (apixaban), -11.3-18.7 ng/mL (rivaroxaban)]. Higher bias and wider range between limits of agreement were observed at higher concentrations [<100 ng/mL: bias -21.3-4.1 ng/mL (apixaban) and -6.2-3.8 ng/mL (rivaroxaban); >200 ng/mL: bias -42.2-36.8 ng/mL (apixaban) and -20.1-68.9 ng/mL (rivaroxaban)]. CONCLUSION: Overall, the anti-Xa assays not supplemented with antithrombin and the HPLC-UV method proved to be suitable for apixaban and rivaroxaban quantification.

An in vitro study to investigate the interference of enoxaparin on plasma levels of direct oral factor Xa inhibitors measured by chromogenic assays.

INTRODUCTION: Co-administration of enoxaparin and a direct oral factor Xa inhibitor (xabans: apixaban, edoxaban, rivaroxaban) could give rise to the problem of overlapping the anti-Xa activity when measuring direct oral anticoagulant (DOAC) levels. We aimed to evaluate in vitro the degree of the interference of increasing enoxaparin concentrations on xaban plasma levels measured by different chromogenic anti-Xa assays with drug-specific calibrators and controls. METHODS: Seven plasma samples were spiked with apixaban, edoxaban, or rivaroxaban at fixed concentration, and enoxaparin at increasing concentrations (0, 0.125, 0.250, 0.50, 1.0, 1.50, and 2.0 IU/mL). The evaluated chromogenic assays were as follows: Biophen DiXaI and Biophen Heparin LRT (Hyphen BioMed), Berichrom Heparin and Innovance Heparin (Siemens), STA-Liquid Anti-Xa (Stago Diagnostics), Technochrom anti-Xa (Technoclone), and HemosIL Liquid Anti-Xa (Werfen). RESULTS: The presence of enoxaparin caused increased DOAC levels, with over-estimation depending on the anti-Xa assay and on the heparin concentration in the sample. The smallest over-estimation was in the sample with enoxaparin 0.125 IU/mL and the greatest in the sample with enoxaparin 2.0 IU/mL (0%, 3.1%, and 7.4% vs 583.8%, 526.1%, and 415.2% for apixaban, edoxaban, and rivaroxaban, respectively). Biophen DiXaI showed lower interference compared to other methods (maximum over-estimation in the presence of enoxaparin 2.0 IU/mL: 56.4% dosing rivaroxaban by Biophen DIXaI vs 583.8% dosing apixaban by Berichrom Heparin). CONCLUSION: The presence of enoxaparin interferes with xabans measurement by chromogenic anti-Xa assays causing falsely elevated DOAC levels, the over-estimation being dependent on the anti-Xa assay and on the heparin concentration in the sample.

Thrombin generation and intracranial atherosclerotic disease in patients with a transient ischaemic attack.

BACKGROUND: Intracranial atherosclerotic disease (ICAD) is responsible for at least 10% of transient ischaemic attacks (TIA). Thrombin generation has been shown to be associated with several atherosclerotic conditions and may be relevant in the pathogenesis of TIA from ICAD. OBJECTIVE: To evaluate the association between thrombin generation and ICAD in patients with TIA. MATERIALS AND METHODS: Consecutive patients with confirmed diagnosis of TIA by vascular neurologist were enrolled. Within 24h from diagnosis, all the patients underwent: blood samples including thrombin generation search, electrocardiography, brain CT scan, blood pressure (BP) measurement, supra-aortic echo-Doppler, transcranial Doppler (TCD) and standard echocardiogram. Thrombin generation was measured as endogenous thrombin potential (ETP) in platelet-rich plasma (PRP) and in platelet-poor plasma (PPP), in the presence and in the absence of thrombomodulin (TM). RESULTS: 120 patients (male 52.5%), aged 69±16years were enrolled. Ten patients on warfarin treatment had significantly lower ETP than the others. Among the remaining, ETP in the presence or absence of TM did not differ according to TOAST classification aetiology (large vessel vs. cardioembolic vs. lacunar vs. others). In PRP, ETP was similar in patients with ICAD and in those without (1748±160 vs. 1851±36nM·min, p=0.393), whereas, ETP measured in presence of thrombomodulin was higher in patients with than in those without ICAD (2045±99 vs. 1715±41nM·min, p=0.011). In PPP, ETP was similar in patients with ICAD and in those without, whereas thrombin peak was higher in patients with ICAD than in those without both in the presence (165±17 vs. 130±5nM, p=0.036) and in the absence of TM (178±19 vs. 142±5nM, p=0.037). CONCLUSION: ETP measured in presence of TM is enhanced in patients with ICAD, supporting that thrombomodulin-protein C pathways is relevant in TIA from ICAD. These hypothesis-generating data suggest that thrombin generation may be relevant in cerebral ischaemia from intracranial disease, and justify larger studies.

Diagnostic Accuracy of a New d-Dimer Assay (Sclavo Auto d-Dimer) for Exclusion of Deep Vein Thrombosis in Symptomatic Outpatients.

In patients presenting non-high clinical pretest probability (PTP), a negative d-dimer can exclude venous thromboembolism without imaging tests. However, each d-dimer assay should be validated in prospective studies. We evaluated an automated d-dimer immunoassay using the Sclavo Auto d-dimer (Sclavo Diagnostics Int, Sovicille, Italy) provided by Dasit Diagnostica (Cornaredo, Milan, Italy). Three hundred two consecutive outpatients suspected of leg deep vein thrombosis (DVT) with non-high PTP were included. The Sclavo Auto d-dimer assay was evaluated on 2 analyzers (Sysmex CA-7000 and Sysmex CS-2100; Sysmex Corporation, Kobe, Japan, provided by Dasit). The cutoff value (200 ng/mL) was established a priori. Prevalence of DVT was 11.9%. Since no false-negative patients were detected, the sensitivity and negative predictive values (NPVs) were 100% (sensitivity = CA-7000: 100% [95% confidence interval, CI: 93.3-100], CS-2100: 100% [95% CI: 93.3-100]; NPV = CA-7000: 100% [95% CI: 97.9-100], CS-2100: 100% [95% CI: 98.0-100]). Specificity was 65.4% (95% CI: 59.4-71.1) and 69.2% (95% CI: 63.3-74.7) for CA-7000 and CS-2100, respectively. Specificity increased when a higher cutoff value (234 ng/mL) was used for patients aged ≥60 years without compromising the safety. Assay reproducibility was satisfactory at concentrations near the cutoff value (total coefficient of variations <10%). In conclusion, the Sclavo Auto d-dimer assay was accurate when used for DVT diagnostic workup in outpatients with non-high PTP. Based on its high sensitivity and NPV, it can be used as a stand-alone test in outpatients with non-high PTP. Given its high specificity, the number of patients in whom further imaging techniques can be avoided increased, improving the yield of the test.

Measurement of factor XIII (FXIII) activity by an automatic ammonia release assay using iodoacetamide blank-procedure: no more overestimation in the low activity range and better detection of severe FXIII deficiencies.

BACKGROUND: Laboratory investigation with specific factor XIII (FXIII) assays plays a crucial role in diagnosis of FXIII deficiency. According to the International Society on Thrombosis and Hemostasis (ISTH), it is necessary a blank sample with iodoacetamide, provided by the kit or locally prepared, when the ammonia release assays are used, to avoid FXIII activity overestimation. METHODS: In this study we set up a modification of the Berichrom FXIII chromogenic assay, in which iodoacetamide was added by the BCS analyzer in the reaction mixture of the blank sample, without modifications of the original reagents. We analyzed 100 plasma samples of outpatients with clinical symptoms suggestive of a bleeding diathesis (20 samples had FXIII activity <20%). RESULTS: In all samples blank subtraction significantly reduced FXIII activity, mostly in the low activity range group (from 10.1% to 2.4%, p<0.0001). In this group correction with iodoacetamide also increased the agreement with the immunoassay and allowed FXIII activity measure up to 0%. CONCLUSIONS: Despite the low number of samples included in the study, the described automatic procedure seemed to decrease FXIII activity overestimation and, especially for low activity range samples (<20%), to improve the agreement between FXIII activity and concentration. Our data suggested that iodoacetamide correction could allow the detection of severe FXIII deficiencies (activity <5%) otherwise undiagnosed using the original method.

Rivaroxaban in the Treatment of Heparin-Induced Thrombocytopenia.

Heparin-induced thrombocytopenia (HIT) is a prothrombotic condition and it is associated with increased in vivo thrombin generation that needs to be treated with non-heparin anticoagulants such as direct thrombin inhibitors (DTIs). DTIs require parenteral administration and are associated with a non negligible risk of major bleeding. We describe a case of HIT treated with rivaroxaban, a direct oral factor Xa inhibitor which could be used to inhibit the generation of thrombin, instead of DTIs. A 68 year-old man with a thrombosis confined to the internal gastrocnemius and soleal veins developed HIT during enoxaparin 80 mg twice a day. Enoxaparin was stopped and rivaroxaban 20 mg once a day was started. Platelet count returned to base line after 6 days from enoxaparin withdrawal. After 3 months rivaroxaban was stopped and the patient had an uneventful course. This case report supports the hypothesis that rivaroxaban may be candidate for treatment of HIT, and larger studies are justified.

D-dimer for the diagnosis of upper extremity deep and superficial venous thrombosis.

BACKGROUND: D-dimer role is well established in the diagnostic work-up for lower limb deep vein thrombosis (DVT), however it has not been formally tested for clinically suspected upper extremity DVT and/or superficial vein thrombosis (SVT). AIM: To ascertain D-dimer diagnostic accuracy for upper extremity DVT and/or SVT. STUDY DESIGN: We performed a single centre management study in outpatients referred by emergency or primary care physicians for clinically suspected upper extremity DVT. All patients underwent D-dimer testing (cut-off value: ≤500 ng/mL), and a B-mode and color Doppler ultrasonography examination. In case of either technical problems or anatomical barriers, ultrasonography was repeated after 5-7 days. All patients were followed up for three months for the occurrence of symptomatic DVT and/or SVT and/or pulmonary embolism. RESULTS: We enrolled 239 patients (F: 63.6%; mean±SD age: 58.3±16.8). At the initial diagnostic work-up, DVT was detected in 24 (10%) patients while SVT in 35 (14.6%) patients. During follow-up, one upper extremity DVT was found. D-dimer levels were higher in patients with DVT than in those without. Sensitivity and specificity of D-dimer for DVT were 92% (95%CI: 73-99%) and 60% (95%CI: 52-67%) respectively, with a negative predictive value of 98% (95%CI: 93-100%), whereas for SVT they were 77% (95%CI: 59-89%) and 60% (95%CI: 52-67%) respectively, with a negative predictive value of 93% (95%CI: 86-97%). CONCLUSIONS: D-dimer has a negative predictive value ≥93% for excluding DVT in symptomatic outpatients and it can be a useful test in the diagnostic work-up of suspected upper extremity DVT.

D-dimer, FVIII and thrombotic burden in the acute phase of deep vein thrombosis in relation to the risk of post-thrombotic syndrome.

BACKGROUND: Post-thrombotic syndrome (PTS) is the most common complication of deep vein thrombosis (DVT), but few data are available on the risk factors for PTS. AIMS: To assess whether the time-course of D-dimer, FVIII, and thrombotic burden are related to PTS development. METHODS: Patients (n=59) with proximal DVT of the lower limbs (age 64; range:20-88years; male 56%) were enrolled on the day of diagnosis (D0) and all received heparin for 5-7days, overlapped and followed by vitamin K antagonists (VKA) for 3months. Whole-leg compression ultrasound examination was conducted on D0 and 7 (D7), 30 (D30), and 90 (D90) days afterwards, when blood samples were also taken for D-dimer (STA Liatest) and FVIII (chromogenic assay) testing. Thrombotic burden was defined at each time point according to a score, which considered thrombosis extent and occlusion degree. Villalta score was evaluated at D30, D90, and D180. RESULTS: At D90, 12 patients developed PTS (Villalta score ≥5) and the median Villalta score was 1 (IQR 0.3-3.0) and was not correlated with either D-dimer or FVIIII time course. At D180, 13 patients had PTS and they had similar thrombotic score at D0, D30 to those without PTS, but higher at D90 (7.6±5.1 vs. 3.2±3.6; p=0.011). Thrombotic score at D90 was correlated with Villalta score at D90 (rho=0.374, p=0.009) and at D180 (rho=0.436, p=0.006). CONCLUSIONS: Thrombotic burden after 90days of VKA is correlated with PTS.

Influence of proband's characteristics on the risk for venous thromboembolism in relatives with factor V Leiden or prothrombin G20210A polymorphisms.

In family studies, the risk for venous thromboembolism (VTE) in relatives with factor V Leiden (FVL) or G20210A prothrombin (PT20210A) gene polymorphisms may differ according to genotype and clinical presentation of the proband. To address this hypothesis, a retrospective cohort family study was carried out on 192 kindreds with at least one member with homozygous FVL or PT20210A, for a total of 886 relatives. The proband of the family was heterozygous in 68 and homozygous or with both polymorphisms in 124 kindreds. Twenty-three probands were asymptomatic, 11 had had arterial thrombosis, 7 obstetrical complications, and 151 venous thrombosis (122 VTE and 29 superficial vein thrombosis). The incidence of VTE (per 1000 patient-years) in relatives was higher when the proband had heterozygous rather than homozygous polymorphism (1.25 [95% confidence interval (CI), 0.73-1.91] vs 0.44 [0.19-0.78]) and when the proband had had VTE instead of other or no clinical manifestations (0.95 [0.57-1.42] vs 0.50 [0.19-0.96]). Compared with relatives belonging to kindreds with homozygous probands without VTE, the adjusted hazard ratio of VTE for relatives selected from kindreds with heterozygous probands with VTE was 4.14 (95% CI, 1.17-14.71). The genotype and clinical presentation of the proband influence the risk for VTE in relatives with FVL or PT20210A.

Age and gender specific cut-off values to improve the performance of D-dimer assays to predict the risk of venous thromboembolism recurrence.

The Prolong study shows that continuing vitamin K antagonists (VKA) in patients with abnormal D-dimer (evaluated by a qualitative assay, Clearview Simplify D-dimer) results in a significant reduction of venous thromboembolism (VTE) recurrence. The present study retrospectively analyzes a subgroup of patients enrolled in the Prolong study with a view to calculate cut-off values for six quantitative D-dimer methods to predict the risk of VTE recurrence. We measured D-dimer levels by VIDAS D-dimer Exclusion (bioMerieux), STA Liatest D-dimer (DiagnosticaStago), HemosIL D-dimer and HemosIL D-dimer HS (Instrumentation Laboratory), Innovance D-dimer (Siemens) and AutoDimer (Trinity Biotech) in frozen plasma aliquots sampled 30 ± 10 days after VKA cessation in 390 patients enrolled in the Prolong study. During follow-up (562.7 years), 28 patients had recurrent VTE (7.2%, 5.0% person-years). Since D-dimer levels are positively correlated with age and significantly lower in men, we calculated method-specific cut-off values according to age and gender. The HRs for VTE recurrence calculated using method-specific cut-off values based on age and gender are higher than those using cut-off values indicated by the manufacturers for VTE exclusion in symptomatic outpatients. These data suggest that method-specific cut-off values calculated according to patient age and gender can be more accurate in identifying patients at a higher risk for VTE recurrence. These method-specific cut-off values are being evaluated in the ongoing prospective management multicenter DULCIS study.