[Prolongation of anti vitamin K treatment for 18 months versus placebo after 6 months treatment of a first episode of ideopathic pulmonary embolism: a mutlicentre, randomised double blind trail. The PADIS-EP Trial]. / Prolongation d'un traitement par antivitamine K pendant dix-huit mois versus placebo au décours d'un premier épisode d'embolie pulmonaire idiopathique traité six mois: un essai randomisé multicentrique en double aveugle. Essai "PADIS-EP".

BACKGROUND: After stopping a 3 to 6 months course of oral anticoagulation for a first episode of idiopathic venous thromboembolism (VTE), the risk of recurrent VTE is high (10% per year). In this setting, international guidelines recommend at least 6 months treatment. However, this recommendation is not satisfactory for the following reasons: (1) no randomized trial has compared 6 months to extended duration (2 years) anticoagulation; and (2), even though the frequency of recurrent VTE is similar after pulmonary embolism (PE) and deep vein thrombosis (DVT), the fatality rate of recurrent VTE after PE is higher than that after DVT. METHODS: A French multicentre double blind randomized trial. The main objective is to demonstrate, after a first episode of symptomatic idiopathic PE treated for 6 months using a vitamin K antagonist, that extended anticoagulation for 18 months (INR between 2 and 3) is associated with an increased benefit / risk ratio (recurrent VTE and severe anticoagulant-related bleeding) compared to placebo. The double blind evaluation is ensured using by active warfarin and placebo, and blinded INR. The protocol was approved by the ethics board of the Brest Hospital on the 7th of March 2006. For an alpha risk of 5% and a beta risk of 20%, the estimated sample size is 374 patients. EXPECTED RESULTS: This study has the potential to: (1) demonstrate that the benefit / risk ratio of extended anticoagulation for 18 months is higher than that observed with placebo in patients with a first episode of idiopathic PE initially treated for 6 months, during and after the treatment period; and (2) to validate or invalidate the contribution of isotope lung scans, lower limb Doppler ultrasound and D-Dimer at 6 months of treatment as predictors of recurrent VTE (medico-economic analysis included).

Control of oral anticoagulation in patients with the antiphospholipid syndrome--influence of the lupus anticoagulant on International Normalized Ratio. Groupe Méthodologie en Hémostase du Groupe d'Etudes sur l'Hémostases et la Thrombose.

The recommended therapeutic range of International Normalized Ratio (INR) for oral anticoagulant treatment in patients with the antiphospholipid syndrome remains controversial. As a part of this controversy, it has been suggested that lupus anticoagulants (LA) could interfere with the determination of prothrombin time, thus questioning the validity of monitoring the treatment of these patients using INR. To clarify this point, we compared the values of INR obtained in the plasmas of two groups of patients, one without LA (n = 47), and the other with LA (n = 43). INR were determined using 8 different thromboplastin reagents on the same automated coagulation instrument. Chromogenic factor X, which is supposed to be insensitive to the presence of LA, was also measured. The results are the following: provided INR was calculated using calibrated reference plasmas, there was no significant difference between INR values obtained with the 8 reagents, both in the non-LA and in the LA groups (CV: 5.9 and 6.7%. respectively). Closer examination revealed that INR results obtained with one reagent (the recombinant thromboplastin Innovin) diverged from those of the 7 others, leading to an overestimation of INR, to a very large extent in some instances. However this effect was restricted to a subset of the patient population with LA (6 out of 43). Finally, the relationship between INR (average value obtained using the 8 reagents) and factor X was identical in non-LA and in LA patient groups. We conclude that, provided the reagents which display the LA interference are identified and excluded for this purpose, the INR system is valid for monitoring oral anticoagulant treatment in patients with LA.

Quantification of lupus anticoagulants in clinical samples using anti-beta2GP1 and anti-prothrombin monoclonal antibodies.

Quantification of lupus anticoagulant (LA) in clinical samples is hampered by the lack of a suitable standard of activity. We evaluated the use of mAbs displaying LA activity for this purpose. As most patient samples contain both beta2Glycoprotein I (beta2GP1) and prothrombin dependent LA, a combination of two mAbs, one of each specificity, was added to normal plasma in a concentration from 0 to 60 microg/ml. Eight assay systems using different reagents and instruments were used. The calibration curves were linear for all but one, with marked differences between the responsiveness to each mAb. A panel of plasmas from 69 patients with persistent LA diagnosed using the SSC-ISTH criteria was tested. An antiphospholipid syndrome (APS) was present in 40, whereas 29 were asymptomatic. LA activities of individual plasmas varied between assays (p < 10(-4)), but homogeneous subgroups were identified. In a majority of samples, LA activity displayed a prothrombin-dependent profile, with a variable contribution of beta2GP1-dependent activity. The latter was associated to beta2GP1 antibodies detected by solid-phase immunoassay. By using 3 dilute Russell viper venom time assays, higher LA titers were found in APS, compared to asymptomatic patients (p <0.05).

Decision analysis for use of platelet aggregation test, carbon 14-serotonin release assay, and heparin-platelet factor 4 enzyme-linked immunosorbent assay for diagnosis of heparin-induced thrombocytopenia.

The value of the platelet aggregation test, carbon 14-labeled serotonin release assay (SRA), and heparin-platelet factor 4 enzyme-linked immunosorbent assay (H-PF4 ELISA) for the diagnosis of heparin-induced thrombocytopenia was evaluated by studying blood samples from 100 patients with suspected heparin-induced thrombocytopenia, and categorized into 4 clinical groups: unlikely (n = 22), possible (34), probable (36), and definite (8) thrombocytopenia. Results of the platelet aggregation test were positive in 40 of 44 patients with probable or definite heparin-induced thrombocytopenia (sensitivity 91%) and in 5 of 22 unlikely to have heparin-induced thrombocytopenia (specificity 77%). The SRA exhibited sensitivity of 88% and negative predictive value of 81%, close to those values for the platelet aggregation test; specificity and positive predictive value were 100%. The sensitivity of the heparin-PF4 ELISA was 97%, with specificity 86%, and a positive correlation was recorded between the level of antibodies to H-PF4 and clinical score (P = 0.66). When ELISA was used with the platelet aggregation test or SRA, positive predictive value and specificity were 100% when both tests yielded positive results, and negative predictive value was 100% when both tests yielded negative results. A biologic flow chart was designed that presented a choice based on the results of the platelet aggregation test or SRA in association with ELISA, and enabled more accurate and specific identification of heparin-induced thrombocytopenia.

Comparative study of the fibrinolytic system in human fetuses and in pregnant women.

Levels of major parameters of fibrinolysis were measured in 50 normal human fetuses between 19 and 39 weeks of gestation and compared to those of 50 healthy normal pregnant women and 30 adult controls. In fetuses, euglobulin clot lysis time (ECLT) was significantly shortened, plasminogen level was low and histidine-rich glycoprotein undetectable. While t-PA and u-PA levels were slightly lower than in adult controls, a significant decrease in PAI activity was demonstrated and no PAI-2 could be detected in fetal plasma. In contrast with these findings, the fibrinolytic equilibrium of pregnant women exhibited a prolonged ECLT and a strong increase in both PAI activity and PAI-2 antigen levels, while only a moderate elevation in u-PA and t-PA levels was measured.

Levels and plasma distribution of free and C4b-BP-bound protein S in human fetuses and full-term newborns.

Levels and plasma distribution of protein S were measured on umbilical cord plasmas from 25 normal full-term newborns and 25 normal fetuses which were between 20 and 31 weeks of gestation. Fetal blood samples were obtained by direct puncture of the umbilical vein under high resolution real-time ultrasound. Total and Free protein S levels were found to be lower in all fetuses and newborns as compared to normal adults. The calculated ratio Total protein S/Free protein S and crossed immunoelectrophoresis patterns indicate that protein S circulates essentially in the free form in fetuses and newborns. These data may be explained by the low levels of C4b-binding protein observed at these stages of development.

Pseudo-homozygous activated protein C resistance due to coinheritance of heterozygous factor V Leiden mutation and type I factor V deficiency. Variable expression when analyzed by different activated protein C resistance functional assays.

The laboratory diagnosis of activated protein C (APC) resistance is based on a weak anticoagulant response to APC using a chronometric procedure confirmed in almost all cases by molecular diagnosis of the FV Leiden mutation. A recently-developed Xa-based assay (Accelerimat, Biomerieux) was compared with two different activated partial thromboplastin time (APTT)-based procedures (Coatest APC resistance and Modified Coatest, Chromogenix) in 115 patients with a personal or familial history of thrombotic disease, or both, being studied for the FV Leiden mutation. Our results confirmed the improvement in specificity for the FV Leiden mutation when the APTT-based assay was performed after dilution of samples in FV-deficient plasma (Modified Coatest). However, five patients who were heterozygous for the FV Leiden mutation appeared to be homozygous when tested by both APTT-based assays. These patients, belonging to three different families, had a FV type I deficiency with FV plasma levels between 43 and 64%. In contrast, the Xa-based method was not influenced by the decrease in plasma FV levels. Thus, this procedure is more specific than APTT-based assays to predict the genotype status of the FV Leiden mutation.

Increased plasma fibrinolysis and tissue-type plasminogen activator/tissue-type plasminogen activator inhibitor ratios after ethanol withdrawal in chronic alcoholics.

The effects of alcohol withdrawal on fibrinolysis were studied in 10 middle-aged male chronic alcoholics institutionalized for withdrawal therapy. All patients were sampled on admission [day 1 (D1)] and 21 days after alcohol withdrawal [day 22 (D22)]. The overall plasma fibrinolytic capacity (OFC) was assayed by measuring the ability of patient plasma to generate D-dimers from a standardized fibrin clot, and tissue-type plasminogen activator (t-PA) and t-PA inhibitor (PAI-1) levels were assayed together with serum cholesterol, triglyceride and cholesterol fractions. At D22, the OFC significantly increased in seven patients [D1 = 10 +/- 0.7 microg/h (mean +/- SD), D22 = 17 +/- 7.4 microg/h; P < 0.01], while t-PA and PAI-1 levels decreased in all patients but two (t-PA: D1 = 16.6 +/- 5 ng/ml, D22 = 10.2 +/- 3.8 ng/ml; P < 0.001; and PAI-1: D1 = 46 +/- 39 ng/ml, D22 = 21 +/- 28 ng/ml; P < 0.01). This study clearly demonstrates an increase in overall fibrinolytic activity after alcohol withdrawal, which is mainly due to a decrease in PAI-1 levels. These changes induced by alcohol abstinence might provide clear benefit by reducing the risk of thromboembolic events and particularly of stroke associated with elevated PAI-1 levels described in heavy drinkers.

Comparative evaluation of five different methods for the measurement of plasma factor II levels in carriers of the 20210A prothrombin variant.

The common genetic G to A variation of the prothrombin gene is associated with elevated levels of prothrombin [factor II (FII)] and is recognized as a risk factor for thrombosis. To determine whether one type of assay for plasma FII measurement was more efficient than other assays in displaying high FII levels in 20210A carriers, we compared five methods of measuring FII levels [i.e. an enzyme-linked immunosorbent assay (ELISA), a standard clotting assay, and three chromogenic methods using three different activators: Ecarin, Oxyuranus, and Textarin] in 30 G20210A patients and 30 G20210G controls. Plasma concentrations of factor X and factor VII + factor X were also determined by a clotting procedure. Functional assays were found to be equally efficient in demonstrating significantly higher FII levels in 20210A carriers than in non-carriers (P < 0.0001). With ELISA, the difference observed was less significant (P < 0.005). The specificity of every assay increased with FII cut-off levels; when a cut-off of 115% was applied, sensitivities of functional assays were between 73 and 93%, while sensitivities of ELISA declined dramatically to 33%. FII/factor X and FII/factor VII + factor X ratios were significantly higher in 20210A carriers (P < 0.0001). In conclusion, functional assays are preferentially required for measurements of FII levels in carriers of the 20210A variant.

Comparative double-blind study of two dosage regimens of low-molecular weight heparin in elderly patients with a fracture of the neck of the femur.

A randomized double-blind study comparing the efficacy and safety of two different dosage regimens of a low-MW heparin, Enoxaparin (Lovenox) 20 mg twice (group A) or 40 mg once (group B), was carried out in 103 elderly patients with a fracture of the neck of the femur. Distal and proximal thrombosis occurred in 18.3% of patients in group A and in 10.4% in group B. No major hemorrhagic complication was observed, except for two hematomas in each group. This trial suggests that a total daily dose of 40 mg of Enoxaparin can be effective in the prevention of deep vein thrombosis in elderly surgically treated patients and does not involve a major risk of bleeding.

The white clot syndrome or heparin associated thrombocytopenia and thrombosis (WCS or HATT) (26 cases).

The Authors report a new iatrogenic complication of preventive or curative standard heparinotherapy. This so called "white clot syndrome" or "Heparin associated thrombocytopenia and thrombosis" is an anatomico-clinical entity characterized by severe, multiple, recurrent, arterial and/or venous thromboembolic accidents which are sometimes fatal. They appear, paradoxically, under heparin treatment and are concomitant with thrombocytopenia (generally less than 100 10(9)/l). Antiplatelet immunoallergic phenomena, via type IgG antibodies, induced by heparin, are the most commonly admitted in physiopathology; however they remain controversial. Treatment of "WCS" includes urgent suppression of standard heparin, administration of antivitamin K, or the new generation of low molecular weight heparin. This series presents 26 cases of HATT treated by LMWH (CY 216 CHOAY). Severe complications must be surgically cured. Prevention of WCS or HATT is mandatory by the systematic survey of platelet count during heparinotherapy.

Hemostasis development in the lamb fetus and neonate.

Fetal and neonatal lamb hemostasis were studied from the 60th day of pregnancy to birth. Platelet counts and blood coagulation, as assessed by tests such as recalcification time and thromboelastography, were similar in fetuses, neonates, and adult sheep. The values of coagulation factors were low, ie, vitamin K-dependent Factors II, VII, IX, and X remained unchanged (30 and 40% of adult reference values) until the last 10 days of gestation, and then increased until birth (40 to 60%). Values of fibrinogen and Factor V followed a similar pattern, although their activities became identical to adult values at birth. Also, we measured values of protein C and antithrombin III, which are synthesized by the liver. The importance of hepatic failure and fetal vitamin K deficiency were discussed. Factors VIII and XII activities increased gradually during pregnancy to reach adult values at birth. Fetal fibrinolytic activity increased. This could not be explained by the values of tissue-type plasminogen activator (it was not detectable) or by the presence of its fast-acting inhibitor, whose concentration did not decrease.

[Treatment of acute pulmonary embolism with a low molecular weight heparin by the intravenous route. Study of the optimal dosage]. / Traitement des embolies pulmonaires aiguës par une héparine de bas poids moléculaire par voie intraveineuse. Recherche de la posologie optimale.

Experimental studies on rabbits have shown that CY 222, a low molecular weight heparin (mean: 2.500 daltons), has the anti-thrombosis properties of heparin but reduces the risk of haemorrhage in optimal doses of 1.000 AXa IC (Institut Choay) units/kg/day. The safety and effectiveness of CY 222 were tested in 47 patients presenting with a less than 5 days' old pulmonary embolism. The patients were divided into three groups according to dosage: group I (n = 16) received 500 AXa ICu/kg/day; group II (n = 17), 750 AX ICu/kg/day, and group III (n = 14), 1.000 AXa ICu/kg/day. The drug was administered by continuous intravenous infusion during 10 days. Its effectiveness was assessed from the Miller index calculated on conventional pulmonary angiograms on days 0, 5 and 10. On the 10th day of treatment, the percentage of revascularization was similar in all three groups (group I 65.9 +/- 9.9 p. 100; group II 71 +/- 6.8 p. 100; group III 68 +/- 8.5 p. 100), but the improvement was significantly more rapid in group III patients. Embolism recurred in 5 cases (2 in group I, 1 in group II, 2 in group III) and was fatal in 1 case (group I). Haemorrhagic complications were noted in 3 cases (group III patients). Except for thromboelastography, all coagulation tests were unmodified by CY 222. The anti Xa and the (very low) anti IIa activities of the drug were directly related to the doses administered.(ABSTRACT TRUNCATED AT 250 WORDS)

[Preliminary study of the use of low-molecular weight heparin to prevent thrombotic risk]. / Etude préliminaire à l'utilisation des héparines de bas poids moléculaire en prévention du risque thrombotique.

This study involved two stages: In vitro study. Three LMWHs, CY 216-CY 222 (Choay) and PK 10169 (Pharmuka), were compared to standard heparin, SH (Choay), and to a high-molecular-weight heparin, HAF (Choay), which particularly revealed a dissociation of anti-Xa (++) and anti-IIa (+) activities for the LMWHs: (table: see text) In vivo study. Healthy volunteers. Subcutaneously injections of PK 10169 or CY 222 according to various protocols (rythm of injections, dosage). For both LMWHs, the dissociation of anti-Xa and anti-IIa activities reoccurs in vivo. A peak of anti-Xa effect was observed 3 to 4 hours after the injections. The duration period of this activity is about 12 hours. The importance of the global platelet tests HT and TEG (modified for the highest doses) should be noted. Study of haemorrhagic tendencies in patients with slight thrombotic risk. From this preliminary study, protocols with CY 216, CY 222 and PK 10169 are proposed for the prevention of thrombotic risk in orthopaedic surgery (injections at 12-hour intervals).

[Association of D-dimer and helicoidal thoracic scanner for diagnosis of pulmonary embolism. Prospective study of 106 ambulatory patients]. / Association D-dimères et scanner thoracique hélicoïdal pour le diagnostic d'embolie pulmonaire. Etude prospective chez 106 patients ambulatoires.

OBJECTIVE: Ventilation/perfusion pulmonary scintigraphy (PS), the current mainspring in the diagnosis of pulmonary oedema (PE), is frequently non-conclusive. The objective of this study was to determine, prospectively, the diagnostic value of the association of D-dimers and helicoidal thoracic scanner (HTS) in a continuous series of ambulatory adults with suspected PE and admitted to a cardiologic emergency unit. METHODS: Exclusion criteria were as follows: symptoms or clinical signs of seventy, contraindication for HTS and/or on pulmonary angiography, curative anticoagulant therapy for more than 48 hours, history of PE less than 3 months before or the impossibility of conducting all the examinations with 48 hours. All the patients underwent determination of D-dimers by rapid ELISA test, HTS and 2 reference examinations, venous Doppler of the lower limbs and a PS, completed by pulmonary angiography if the PS did not permit diagnosis and the venous Doppler was negative. RESULTS: One hundred and six patients were selected over a recruitment period of 18 months. The prevalence of PE was of 45% (48/106). Forty-four of the 48 PE of the series were central form. HTS was considered dubious in 10 patients (10.4%, PE+ n = 2, PE- n = 8). The results of D-dimers were negative in only 34.5% patients without PE (20/58). Pulmonary angiography was necessary in 15 patients. The negative and positive predictive values of D-dimers were respectively of 100 and 55.8% (48/86) and those of HTS respectively 100 (46/46) and 92% (46/50). CONCLUSION: The diagnostic strategy of clinical suspicion of PE, starting with determination of D-dimers by rapid ELISA test followed by helicoidal thoracic scanner in the case of a positive result, was particularly effective in this series of patients with a high prevalence of PE. These results must be confirmed in a larger series and in a general emergency unit.