Intra-Coronary Thrombolysis with Streptokinase or Lys-Plasminogen/Urokinase in Acute Myocardial Infarction: Effects on Recanalization and Blood Fibrinolysis

Forty-two patients with total occlusion of a coronary vessel were treated with intracoronary fibrinolytic agents. Four therapeutic protocols were compared: group I received streptokinase (SK) as a continuous infusion; group II and III received SK as a bolus at different doses and group IV received lysplasminogen (Pg) plus urokinase (UK); maximal doses were 350,000 IU of SK and 250,000 IU of UK plus 75 μK of Pg. Thrombolysis was assessed by coronary angiography. Coagulation studies were performed prior to, 15 min and 6 hr after the end of the thrombolytic treatment. Recanalization was achieved in 27 of the 31 SK-treated patients (87%) and in 7 of the 11 Pg-UK- treated patients (63.6%). The recanalization frequency was the same in the three SK-treated groups, even though when SK was administered as a bolus, the dose was significantly less than when administered on a continuous infusion. Although systemic fibrinolysis occurred in all 4 groups of patients, this effect was less pronounced in the UK-treated patients than in the three SK- treated groups. This study also shows that recanalization can be achieved with a dose of SK lower than the anti-SK antibody level. Haemorrhagic side effects were minimal in all patients studied. Severe defibrination is usually considered a risk of haemorrhage. These preliminary results suggest that bolus injection of SK or the use of UK plus lys-Pg can reduce the level of defibrination and thus the haemorrhagic risk.

French Multicentric Evaluation of Recombinant Tissue Factor (Recombiplastin) for Determination of Prothrombin Time

Recombiplastin, a recombinant a human tissue factor, elaborated by Ortho Diagnostic Systems, produced by Baculovirus and relipidated with highly purified phospholipids, was tested as a new reagent for determining prothrombin time (PT) in a French multicentric study. Its intralaboratory- performances, including sensitivity, repeatability, reproducibility and stability, were explored to establish whether its use would reduce the interlaboratory dispersion of PT values, and therefore improve the standardization of oral anticoagulant treatment.

The 9 university hospital hematology laboratories involved in this study used the same type of instrument (KC 10). For 10 consecutive days, they determined PTS on a normal plasma pool, plasma dilutions of 1/2, 1/3 and 1/8, 3 identical lyophilized calibrated plasmas, as well as plasmas from 20 normal subjects, 50 patients on oral anticoagulant therapy with Recombiplastin which has an International Sensitivity Index (ISI) of 1, and 2 commercial thromboplastin extracts (ISI #1 or 2). In the patients on anticoagulants, factors VII, X and V were measured when results were conflicting.

The intra and interlaboratory reproducibilities of Recombiplastin, calculated on the basis of either PTS expressed in seconds, or of the International Normalized Ratio (INR), were good, with coefficients of variation (CV) similar to those observed with the 5 other reagents used by the different laboratories (2% <CV <8%).

The stability of Recombiplastin was excellent, with no variation in PT after 72 h of incubation at 37° C.

A normal PT of 12 s was obtained with Recombiplastin, similar to the values found for the reagents with ISI #2. In the patients on anticoagulants, Recombiplastin gave the longest coagulation times (PTRecombipiastin = 64.2 s vs PTNeoPlastin = 32.8 s, and PTThromborel = 54.4 s). These results suggest that Recombiplastin is highly sensitive to the changes in coagulation induced by anticoagulants. Recombiplastin was more sensitive to factor VII deficiency than any of the other reagents, even those with ISI #1.

The coefficients of correlation between the INRS calculated on the basis of the PTS obtained with Recombiplastin and the INRS based on the PTS for other thromboplastins, were satisfactory (0.85 <R <0.95) but a breakpoint in the slope of the regression curves was observed when INR >4. This observation requires further investigation, particularly in connection with the exact ISI values for Recombiplastin and the other thromboplastins used in this study.

In conclusion, Recombiplastin is stable and sensitive and gives accurate reproducible results. However, the behavior of Recombiplastin is slightly different from that of the commercial reagents whether their ISI is 1 or 2, and its use did not reduce the interlaboratory dispersion of PT values.

Treatment of Hereditary Protein C Deficiency with Stanozolol

Five type I protein C deficient male patients received 5 mg stanozolol b.i.d. during 4 weeks. After four weeks of treatment plasma protein C activity increased from 0.42 to 0.74 U/ml and protein C antigen from 0.49 to 0.75 U/ml. This approximately 1.6 fold increase in plasma protein C was accompanied by an increase in factor II antigen (1.5 fold), factor V activity (1.6 fold), factor X antigen (1.1 fold), antithrombin III antigen (1.3 fold) and heparin cofactor II antigen (1.5 fold), while the concentration of factor VII, factor VIII, and factor IX activity, and of protein S antigen remained unchanged. Prothrombin fragment F1+2, measured in two patients, increased 1.3 fold. In addition to its effect on procoagulant and anticoagulant factors stanozolol had profibrinolytic effects, reflected in an increase in tPA activity and in the concentration of plasminogen. These data indicate that in type I protein C deficient patients stanozolol increases the concentrations of both procoagulant and anticoagulant factors and favours fibrinolysis. The efficacy of stanozolol in preventing thrombotic disease in type I protein C deficient patients, however, remains to be established. During the four weeks of stanozolol treatment no thrombotic manifestations were observed in the protein C deficient patients.

[Venous thromboembolism and pregnancy]

Venous thromboembolism (VTE) is a major cause of maternal morbidity and mortality during or early after pregnancy. Prior VTE or family history of VTE, clinical or biological risk factors increased the risk of pregnancy-related VTE. Defining the risk of VTE before or at the beginning of pregnancy is necessary to propose the best prevention. However, the management is not standardized between physicians, centres and countries. Current guidelines for prophylaxis and treatment of VTE are discussed in this review.

Skin necrosis due to fluindione treatment: a rare but serious complication

In the setting of protein C deficiency, skin necrosis, which occurs most often at the initial phase of oral anticoagulants therapy, is a rare side effect. Six cases have previously been reported in the literature. In this case report, we present a protein C deficient 42-year-old woman who was being treated for venous thrombosis. Five days after the initiation of oral anticoagulant treatment, she developed extensive skin necrosis on her left calf, followed by a painful leg ulcer. The pathogenesis underlying skin necrosis caused by anticoagulation therapy is still not clear. Despite only a few cases being reported in the literature, it is important to recognise this complication since adequate therapeutic approaches leading to a stable anticoagulation state may prevent it.

[Pregnancy and venous thromboembolism. North-American and European guidelines. American College of Chest Physicians]

Guidelines concerning the prevention and treatment of pregnancy-associated venous thromboembolism (VTE) have been elaborated by the American College of Chest Physicians and published in Chest in 2008. In this review, they have been compared with European guidelines and discussed taking into account the papers published since 2008.Most recommendations are of low grade of evidence because randomized studies are lacking during pregnancy and many reflect guidelines proposed by experts. The decisions on the most appropriate prophylaxis, dose to be administered and moment of pregnancy for starting prophylaxis are often decided case by case after careful assessment of the risk of pregnancy-associated VTE, on one hand, and the risk for the mother, on the other.Risk factors (age >or= 35, obesity, history of VTE with or without sequellae, in vitro fertilization)or thrombophilia have to be taken into account. Scores have been proposed to improve standardisation and evaluation of the risk of VTE and they should be validated.

[Arterial and venous thrombosis in lung cancer]

We report the case of a 61-year old man in whom a deep venous thrombosis was the presenting feature of disseminated lung carcinoma. A few days later, an arterial thrombosis occurred necessitating amputation. Within a few weeks, the lung cancer progressed dramatically and the patient died. While the association between venous thrombosis and cancer is well known, the relationship between cancer and arterial thrombosis has been less explored. This observation allows discussion of the pathophysiological and clinical aspects of this association, as well as the implications for patient care.

The adolescent and adult form of cobalamin C disease: clinical and molecular spectrum

BACKGROUND

Cobalamin C disease is the most common inborn error of cobalamin metabolism with an autosomal recessive mode of inheritance and mutations within the MMACHC gene. Clinical features, including systemic, haematological and neurological abnormalities, usually occur in the first year of life. Adolescent and adult onset presentations are rare.

METHODS

We report on the clinical, molecular and imaging features in three patients aged 40, 42 and 42 years at the last follow-up. We examine these cases together with eight previously described cases to determine the clinical and molecular features of the disease in adults.

RESULTS

Mean age at onset of clinical symptoms was 26 years; clinical features included predominant neurological disturbances and thromboembolic complications. White matter abnormalities on brain MRI were sometimes observed. Most patients (eight of nine patients investigated) were compound heterozygotes for the 271dupA mutation and a missense mutation. Intramuscular or intravenous hydroxycobalamin therapy stopped the progression of the disease and resulted in a better clinical outcome and favourable biological status in 7/9 treated cases, while the two untreated patients died quickly.

CONCLUSIONS

As cobalamin C disease and related disorders of homocysteine metabolism are treatable conditions, homocysteinaemia should be included in the investigations of patients with progressive neurological deterioration, unexplained psychiatric disturbances or recurrent thromboembolic events.

Rituximab alone or in association with corticosteroids in the treatment of acquired factor VIII inhibitors: report of two cases

Acquired haemophilia is a factor VIII (FVIII) deficiency due to autoantibodies directed against FVIII that can be responsible for severe haemorrhage. The therapeutic approach, in addition to the treatment of bleeding episodes with clotting factor infusion, relies on corticosteroids (CS), cyclophosphamide (CYC), and/or high-dose intravenous immunoglobulins (IVIg). However, the efficacy of IVIg is limited, and CS and CYC may cause a number of adverse effects. Recently, rituximab has been proposed, alone or in combination with CS and immunosuppressants in a small number of patients with acquired anti-FVIII antibodies with a good efficacy. We report here on two patients, aged 74 and 81, respectively, who developed acquired haemophilia, with high titre FVIII inhibitors and severe haemorrhage, in the absence of a detectable cause. Both of them received rituximab as a first line therapy with a marked and prolonged efficacy.

D-Dimer Levels, Constitutional Thrombophilia, and Venous Thrombosis Prediction: Clinical Aspects and Implications

The negative predictive value of D-dimers in the diagnosis of a recent venous thromboembolism (VTE) episode is well established. The plasma level of D-dimer is usually increased in hypercoagulable states. The measurement of D-dimer could be of clinical interest in patients with constitutional thrombophilia as there is no close relationship between the clinical expression and the genotype indicating the existence of a hypercoagulable state. Moreover, the predictive value of D-dimer testing in patients with thrombophilia has been questioned. The review of the literature and results of a recent study of our group are presented. Decreased levels of D-dimer are observed in patients receiving an oral anticoagulant treatment versus untreated patients. In contrast, no significant difference was observed between those with and those without thrombophilia among treated or untreated patients. Patients with constitutional thrombophilia are supposed to have an increased risk of postoperative VTE. The review of the existing literature could not confirm this opinion but this could be due to the fact that most patients receive a prophylactic treatment. Thus, there is an indirect evidence of its efficacy in these patients.

Potential use of D-dimer measurement in patients treated with oral anticoagulant for a venous thromboembolic episode

AIM

We compared the level of plasma D-dimer in patients with previous venous thromboembolism (VTE), receiving or not oral anticoagulant treatment (OAT) and investigated its predictive value for the risk of VTE recurrence after OAT withdrawal.

METHODS

We have studied 149 patients, 81 receiving oral anticoagulants and 68 after treatment interruption. Patients with known causes of D-dimer increase were excluded. D-dimer measurements were performed by Vidas analyzer (bioMérieux, France).

RESULTS

A significantly lower D-dimer plasma level was found in patients under OAT than in untreated patients, 197+/-134 ng/ml versus 399+/-239 ng/ml, respectively (p<0.001). This decrease was similar in the different age populations and whether the patient had thrombophilia (n=84) or not. There was no correlation between INR and D-dimer levels. During a mean follow-up of 30 months, no recurrence occurred in patients under OAT versus 7 untreated patients. Among them, 3 had a D-dimer below 500 ng/ml, and 3 others had a level above 500 ng/ml. The last patient was not tested.

CONCLUSION

The physician should be informed of the decrease of D-dimer under OAT, since the usual cut-off of 500 ng/ml used for deep vein thrombosis (DVT) exclusion is probably lower in such treated patients. It has been recently proposed that normal D-dimer level had a high negative predictive value for VTE recurrence when this dosage was performed 3 months after OAT interruption. The small number of recurrences observed in our study with an available result of D-dimer measured more than 3 months after OAT discontinuation does not allow a definite

Markers of activated coagulation in patients with factor V Leiden and/or G20210A prothrombin gene mutation

The activated protein C (APC) resistance phenotype associated with an abnormal factor V Leiden (FVL), and the G20210A prothrombin gene mutation are the most common findings in patients with venous thromboembolism (VTE). In a group of 210 patients, we compared the levels of markers of coagulation activation in carriers of FVL (71 heterozygous, 30 homozygous), G20210A prothrombin mutation (88 heterozygous) or both mutations combined (21 heterozygous), in order to assess whether these markers allow identification of a group of patients with a higher risk of thrombosis; they were also compared to normal values. A total of 143 patients had a personal history of VTE and 67 were asymptomatic. None of them had other hereditary causes of thrombophilia or an antiphospholipid syndrome. None were currently treated with either anticoagulant or hormonal treatment. Pregnant women were excluded. No significant difference between the four groups of patients could be found in the levels of F1+2, TAT and DDI. Levels were all significantly higher than the control values (p<0.05). The levels of F1+2 and TAT were similar in patients with or without a history of VTE, regardless of the type of mutation. DDI levels were significantly higher in patients with a history of VTE than in asymptomatic subjects (443+/-248 vs. 333+/-222 ng/ml, p=0.02) but with only 57% sensitivity and specificity. In conclusion, our study confirms the hypercoagulable state found in mutation carriers and points out the inability of F1+2 and TAT assays to identify a group of subjects at higher risk of thrombosis, within carriers of genetic risk factors. Although the sensitivity and specificity of DDI assay are low, high DDI concentrations tend to be associated with the risk of VTE.

[Treatment of deep venous thrombosis by low molecular weight heparins. Comments on the recommendations of the North American Consensus]

LMW heparins have recently come into use in North America for treatment of venous thrombosis. Their first line recommendation is a major innovation of the last north american consensus conference on antithrombotics published in Chest at the beginning of 2001. This recommendation is grade 1A regarding its advantageous benefit-risk ratio. An earlier oral vitamine K antagonist treatment and a more regular nomogram use allow to reduce the relay duration and to obtain more often the targeted INR. The more predictable anticoagulant response with weight-based doses induces a simplified anti-Xa activity survey limited to renal dysfunction and obese or less than 50 Kg body weight persons but a regular platelet count remains mandatory. Several questions need to be discussed: once or twice daily subcutaneous injection use and treatment duration which seem related to the persistence of triggering factors, the variety of thrombophilia and comorbidity conditions. Due to a greater evidence-based medicine, the antithrombotic strategy becomes more related to a closer evaluation of the individual thrombotic risk level.

European Concerted Action on Anticoagulation (ECAA): multicentre international sensitivity index calibration of two types of point-of-care prothrombin time monitor systems

A multicentre modified World Health Organization (WHO)-type international sensitivity index (ISI) calibration has been performed at 10 European Concerted Action on Anticoagulation (ECAA) national laboratories using non-citrated whole-blood on two point-of-care test (POCT) prothrombin time (PT) monitor systems, CoaguChek Mini and TAS PT-NC, using single lots of test cards/strips. The relevant species (human and rabbit) WHO international reference preparations (IRPs) were tested with the manual PT technique on citrated plasma from the same blood donations. The ISI was calculated from the slope of the orthogonal regression line relating log PT (POCT) to log PT (IRP). The mean ISI of the CoaguChek Mini system was 1.75 and 1.13 with the prothrombin time non-citrated Thrombolytic Assessment System (TAS PT-NC). With the CoaguChek Mini system, seven out of 10 calibrations exceeded the current 3% WHO recommended limit for the coefficient of variation (CV) of the slope with conventional PT testing, whereas with the TAS PT-NC system, it was eight out of 10. All the POCT calibrations had a CV of the slope <5%. It is suggested that this level of precision be adopted as the limit of acceptability of calibration of these monitor systems. In these circumstances, the modified WHO-type ISI calibration appeared to be satisfactory for the POCT whole-blood monitors.

[Influence of oral anticoagulant treatment on D-dimers levels]

The usefulness of D-dimers determination for the exclusion of deep vein thrombosis (DVT) has been extensively studied. The persistence of high levels of D-dimers has also been suggested as a marker of hypercoagulability in rare studies and might be used to identify patients at risk for recurrent DVT. We have studied the influence of oral anticoagulant treatment in 149 patients, 17 to 84 year-old, with a history of venous thromboembolism; 81 received oral anticoagulant treatment, 68 did not. Patients with known reasons for high level of D-dimers such as cancer were excluded. Thrombophilia was found in 84 patients. D-dimers measurements were performed by ELFA technique using Vidas (bioMérieux, France) analyzer. A significantly lower level of D-dimers was observed in patients under oral anticoagulant compared to patients without this treatment, 197 +/- 134 mug/L versus 399 +/- 239 mug/L, respectively (p < 0.001). A level upper the normal value (500 mug/L) was found in only 3 patients out of 81 receiving an oral anticoagulant treatment as compared with 21 of the 68 patients without treatment. This decrease of D-dimers in patients receiving oral anticoagulants was the same in the different age populations. There was no correlation between INR and D-dimers levels in this study. The clinician should be informed of the decrease of D-dimers in patients treated with anticoagulants. The decrease of D-dimers plasma level during oral anticoagulant treatment suggest that D-dimers concentration in plasma is an indirect marker of reduced clotting activity in vivo.

Heparin-induced thrombocytopenia: laboratory diagnosis and management

Heparin-induced thrombocytopenia (HIT), a drug-induced immunohaematological adverse reaction, is a rare but potentially very severe condition. The main problem for this complex syndrome is its recognition and management, which should be as early as possible to avoid the development of life-threatening complications. Most studies have reported heterogeneous populations of patients with other diseases that potentially induce thrombocytopenia. There is no gold standard diagnostic criteria, and we have established a score with anamnestic criteria that allows us to evaluate the likelihood of HIT. In clinical practice, the diagnosis is based on the analysis of clinical features and laboratory tests. Platelet aggregation test (PAT) and an ELISA test (heparin platelet-induced antibodies) are generally performed by expert laboratories to confirm the occurrence of HIT. In our experience, both tests are concordant in the majority of patients. PAT seems to correlate better with the clinical features while ELISA appears more specific. Regarding their limits, both are complementary in the determination of HIT diagnosis coupled to the clinical score system. The treatment often requires a multidisciplinary approach. Danaparoid (Orgaran) or lepirudin (Refludan) are the two alternative treatments for HIT patients with marketing approval. To avoid further exposure to heparin, every HIT patient should carry a written document that confirms the immunoallergy.

A noninvasive diagnostic strategy including spiral computed tomography in patients with suspected pulmonary embolism

We conducted a study to evaluate a noninvasive strategy including spiral computed tomography (CT) in patients with suspected pulmonary embolism (PE). We systematically performed spiral CT, ventilation/perfusion lung scanning, and D-dimer (DD) measurement (VIDAS test), and in some cases (with a normal CT with nondiagnostic lung scan and increased DD) performed venous ultrasonography (US) on 247 consecutive patients with clinically suspected PE in our hospital. Patients in whom PE was deemed absent were not given anticoagulants. All patients were followed for 3 mo. The prevalence of PE in the 228 patients who could be evaluated was 42% (96 of 228). PE was confirmed by spiral CT in 73% of the patients, by a high-probability lung scan in 4%, and by findings on US in 23%. PE was ruled out by a normal lung scan in 14% of the patients, by a normal DD concentration (< 500 ng/ml) in 31%, by an obvious differential diagnosis on spiral CT in 18%, by a similar prior lung scan in 11%, and by the combination of normal spiral CT findings, a nondiagnostic lung scan, a DD concentration > 500 ng/ml, and normal US in 26%. Pulmonary angiography was performed in only two patients, both of whom had a normal spiral CT scan and a high-probability lung scan, and was normal. The 3-mo risk of thromboembolism in patients not given anticoagulants, based on the results of the diagnostic protocol, was 1.7% (95% confidence interval: 1.5 to 2.3%). There were no deaths. The noninvasive strategy of combining spiral CT, lung scanning, DD measurement, and in some cases US, in patients with suspected PE yielded a definite diagnosis in 99% of patients, and appeared to be safe.

[Heparin-induced thrombopenia: significance and difficulties of precise identification of the immunologic mechanism]

Heparin-induced thrombocytopenia (HIT) is a drug induced immunohematologic adverse reaction which is a rare but potentially very severe accident. Its diagnosis is important for epidemiologic and drug surveillance studies and in order to decide the most appropriate treatment. Its importance is enhanced since there is no gold standard diagnostic criteria. In clinical practice the diagnosis is based on a group of criteria related to clinical events and laboratory tests. We have established a score based on anamnestic criteria which allowed us to evaluate and compare two different laboratory tests: a platelet aggregation test (PAT) and a test for the detection of heparin dependent antibodies (Heparin Platelet Induced Antibodies or HPIA). The functional test PAT which is commonly used in expert laboratories detects antibodies inducing platelet aggregation in the presence of heparin. The HPIA test more recently developed is an ELISA test which detects antibodies directed at heparin-platelet factor 4 complexes. The relative value of theses two methods for the diagnosis of HIT is not well documented. We have analysed the results of these two tests in 273 consecutive patients with a suspicion of HIT. The results were concordant in 70% of patients. In selecting the patients with the lowest and the highest probability of HIT according to the score, PAT was found a more sensitive and HPIA a more specific test than the other. At low probability PAT is more often positive than HPIA 18% and 9% respectively. No test is 100% reliable, the specificity being limited for both tests since in about 20% of cases one or both tests are negative contrasting with a highly probable HIT. In this last group of patients, PAT was more frequently positive (86%) than HPIA (72%). Both tests are negative in 6% of patients suggesting the existence of presently unknown antigenic targets. Considering a group of 19 patients with a high probability of HIT, we have found antibodies against IL-8 or NAP-2 in only 7 patients. The discrepancy between a HPIA positive and a PAT negative encountered in 8% of patients may be explained by the existence of IgA or IgM immunoglobulins since in contrast to IgG they are unable to promote platelet aggregation via the CD32 platelet membrane receptor. This work suggests than neither test is 100% reliable and that they play a complementary role in the diagnosis of HIT. The potential advantage of using both tests should be confirmed in complementary studies

Acquired hemophilia due to factor VIII inhibitors in 34 patients

BACKGROUND

Acquired hemophilia is a rare disease caused by the development of auto-antibodies against factor VIII.

SUBJECTS AND METHODS

We studied the characteristics and outcomes of 34 patients (19 women and 15 men) with acquired hemophilia from 1980 to 1997.

RESULTS

The mean age of the patients was 61 years (range, 22-93 years). An underlying disease was observed in 18 (53%) patients: 5 patients had cancer, 4 an autoimmune disorder, 2 a dermatologic disorder, 3 asthma, 3 were postpartum, and 1 had an adverse reaction to ampicillin. Factor VIII level was <5% in 30 (90%) patients; factor VIII antibodies were elevated (>10 Bethesda units) in 23 (69%) patients. Bleeding requiring transfusions was reported in 25 (75%) patients. Human factor VIII was given to 14 patients and porcine factor VIII to 5. Six patients received prothrombin complex concentrates and one desmopressin. Several immunosuppressive treatments were used, mainly corticosteroids, cyclophosphamide, and intravenous immunoglobulin. Bleeding stopped in all but one patient within 2 weeks. Most patients achieved complete remission, although two relapses were observed subsequently.

CONCLUSION

This large study helps to clarify the presentation and clinical course of acquired hemophilia. Prospective studies are needed to determine the efficacy of treatment.

A single genetic origin for the common prothrombotic G20210A polymorphism in the prothrombin gene

The polymorphism G20210A in the 3' untranslated region of the prothrombin gene is associated with an increased level of factor II activity and confers a twofold to fivefold increase in the risk for venous thromboembolism. Among Caucasian populations, the prevalence of factor II G20210A heterozygotes is 1% to 6%, whereas in non-Caucasian populations it is very rare or absent. The aim of the present study was to discern whether factor II G20210A originated from a single or recurrent mutational events. Allele frequencies of four dimorphisms spanning 16 of 21 kb of the factor II gene were determined in 133 unrelated Caucasian subjects of Jewish, Austrian, and French origins who bore factor II G20210A (10 homozygotes and 123 heterozygotes) and 110 Caucasian controls. Remarkable differences in the allele frequencies for each dimorphism were observed between the study groups (P = .0007 or less), indicating strong linkage disequilibrium and suggesting a founder effect. Indeed, a founder haplotype was present in 68% of 20210A mutant alleles and only in 34% of 20210G normal alleles (P < .0001). These data strongly support a single origin for factor II G20210A that probably occurred after the divergence of Africans from non-Africans and of Caucasoid from Mongoloid subpopulations.

Monitoring heparin therapy using activated partial thromboplastin time--results of a multicenter trial establishing the therapeutic range for SILIMAT, a reagent with high sensitivity to heparin

APTT is widely used for laboratory monitoring of treatment with unfractionated heparin (UFH). However, since its sensitivity to heparin varies significantly from one reagent to another, the therapeutic range had to be defined for each brand of APTT reagent. As an example, SILIMAT (bio-Mérieux) is a new APTT reagent containing rabbit brain phospholipids and micronized silica as an activator. Since its high sensitivity to heparin has been previously reported, a multicenter trial was carried out in an attempt to define the therapeutic range of APTT performed using this new reagent. For that purpose, 170 blood samples drawn for routine coagulation testing from 170 different patients treated with UFH were analyzed. A single batch of two different APTT reagents were used on KC10 coagulometers: SILIMAT and Automated APTT (Organon-Teknika) whereas the anti-Xa activity was evaluated by a chromogenic substrate-based assay. The same methodology was used in all the centers. In order to obtain a plasma anti-Xa activity within the therapeutic range i.e. between 0.30 and 0.70 IU/ml, the APTT ratios were found between 1.90 and 5.40 for SILIMAT, which corresponded to clotting times of the patients plasma between 63 and 178 s. The APTT ratios were significantly lower when evaluated using Automated APTT (between 1.70 and 4.10), with clotting times between 53 and 127 s. In addition, a good correlation was found between the Anti-Xa activity and APTT for both reagents (r > 0.65). However, it is not possible to make recommendations regarding the therapeutic ranges without restrictions. Although about 70% of the patients with an anti-Xa activity between 0.30 and 0.70 IU/ml had an APTT in the above defined ranges, the degree of concordance between the two assays is not absolute. Actually more than 30% of the patients had discordant anti-Xa activity and APTT and more than a quarter of the patients included in the above defined therapeutic range for APTT had an anti-Xa activity outside the 0.30-0.70 IU/ml range, whatever the reagent used. In conclusion, to define the therapeutic ranges of APTT using the recommended method is practicable but some critical points could be raised, suggesting that a better method is awaited in order to improve the standardization.

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.

Frequency of the 20210 G-->A mutation in the 3'-untranslated region of the prothrombin gene in 35 cases of cerebral venous thrombosis

BACKGROUND AND PURPOSE

A novel sequence variation in the 3'-untranslated region of the prothrombin (factor II) gene (nucleotide 20210 G-->A) has been recently described as a risk factor for deep vein thrombosis and pulmonary embolism. It is found in approximately 1% to 4% of healthy subjects. We studied the frequency of this factor II variant in patients with cerebral venous thrombosis.

METHODS

The 20210A allele of the prothrombin gene was studied after DNA extraction, polymerase chain reaction amplification, and HindIII digestion in 35 patients with magnetic resonance imaging or angiographically confirmed cerebral venous thrombosis (23 women and 12 men, aged 11 to 71 years).

RESULTS

Two patients (5.7%) had the 20210A allele of the prothrombin gene. Both had other risk factors for thrombosis (use of oral contraceptives and of intrathecal steroids).

CONCLUSIONS

The 20210A allele of the prothrombin gene in association with other prothrombic factors may increase the risk of cerebral venous thrombosis, but case-control studies will be necessary to clarify these associations.

Leiden factor V mutation in four patients with small bowel infarctions

The Leiden factor V mutation is observed in 20% of unexplained lower limb venous thromboses and involves substitution of the arginine residue at position 506 by glutamine (R506Q). It is known to decrease the anticoagulant activity of activated protein C. This case report describes 4 cases of small bowel infarction (SBI) associated with the presence of this mutation. Two cases of arterial and 2 cases of venous SBI were observed. Extensive assessment excluded the usual causes of SBI and plasma hypercoagulation syndrome (antithrombin III, protein C, and protein S deficiency and myeloproliferative syndrome). An abnormal resistance to activated protein C was observed. Molecular analysis consisting of polymerase chain reaction amplification and digestion with MnlI showed that 2 patients were heterozygous and 2 were homozygous for the R506Q mutation. Despite familial history of thrombosis in only 1 patient, first- and second-degree relatives of 2 patients also had the presence of the mutation. Examination for the presence of abnormal resistance to activated protein C should be part of the etiological assessment of SBI. Its presence may warrant consideration of long-term anticoagulant therapy, especially for patients with shortened small bowel who are treated by home parenteral nutrition with deep venous access.

Vitamin K metabolism in a patient resistant to vitamin K antagonists

We investigated various pharmacokinetic and pharmacodynamic parameters in a 63-year-old man, resistant to warfarin, fluindione, acenocoumarol and phenprocoumon. Daily doses of up to 30 mg of the long-acting phenprocoumon yielded a drug concentration of 85 mg/l (usual range 1-5 mg/l) but the international normalized ratio remained around 1. The plasma half-life of phenprocoumon was approximately 350 h (normal 120-150 h). Thus, the resistance was not due to malabsorption or to an accelerated metabolism of the drug. The level of vitamin K1 (1,202 ng/l) was insufficient to induce resistance. Decarboxyprothrombin concentrations were low, demonstrating that the gamma-carboxylation of the precursors of the vitamin K-dependent coagulation factors was not effectively reduced. The concentration of vitamin K epoxide, normally increased under oral anticoagulation, correlated to the vitamin K concentration (r2 = 0.77) but the quotient epoxide/vitamin K remained 4-fold lower than that of 22 warfarin-sensitive patients, suggesting an absence of blockade of the vitamin K reductase by phenprocoumon. This resistance to all the molecular forms of the vitamin K antagonists is most likely due to a reduced affinity of the drugs to a mutant vitamin K reductase.

[Multigenic thrombophilia: genetic anomaly of factor II and mutation of factor V Leiden. Study in a French family]

BACKGROUND

A genetic variation of the prothrombin (factor II) gene, a G to A transition at nucleotide position 20210, was recently found in patients with familial thrombophilia (predisposition to venous thrombosis). It seems to be frequent in patients with the factor V Leiden mutation. We report a family with the factor V Leiden and/or the genetic variation of prothrombin in 3 members.

CASE REPORT

The patient had repeated episodes of deep vein thromboses starting at the age of 30 during the 4th pregnancy. She is a heterozygous carrier of both the factor V Leiden nutation and the prothrombin mutation 20210 A. She has 4 asymptomatic children, aged 28 to 32 and 3 of them have been explored: one son has the prothrombin mutation, one daughter the factor V Leiden and one has none of them.

DISCUSSION

This case report illustrates the polygenic nature of thrombophilia which may explain the heterogeneity of clinical expression observed in isolated congenital abnormalities, especially in factor V Leiden mutation.

[Comparison of two groups of 22 women homozygous or heterozygous for factor V Leiden mutation]

Clinical characteristics of thrombophilia associated with heterozygous mutation of factor V are well characterized. In contrast, they are not well documented in homozygous subjects who are rare. Moreover, estroprogestative intake and pregnancy are important precipitating factors of venous thromboembolism in women with factor V mutation. In order to determine difference in clinical expression between homo and heterozygous subjects, two groups of 22 age matched women were compared. A modified technique for the diagnosis of activated protein C resistance has been used, and its great specificity and sensitivity has been confirmed. In these two small series of patients, a greater severity of clinical profile was not clearly evident. However, recurrences and thrombosis during pregnancy were more frequent in homozygous than in heterozygous women. However, the differences did not reach significance. Molecular markers of hypercoagulable states were not regularly increased even in homozygous untreated patients, but they were more often increased in untreated than in treated patients. In contrast, to other varieties of thrombophilia, homozygous mutation of factor V may be associated with a minor clinical severity suggesting the role of environmental factors and/or still unknown molecular alterations.

[Value of plasma D-dimer assays in the diagnosis of venous thromboembolism]

The diagnostic usefulness of measuring plasma D-dimers using the ELISA method and the latex agglutination test has been prospectively evaluated in 117 patients hospitalized for suspicion of acute venous thrombo-embolism (AVTE): pulmonary embolism was suspected in 80 patients and the remaining 37 had a suspicion of deep vein thrombosis of the lower limbs. The diagnosis of AVTE was confirmed in 50% of the patients, all of whom underwent gold standard invasive investigation i.e. pulmonary angiography and/or contrast venography. The sensitivity, specificity, negative predictive value and positive predictive value of a D-dimers plasma concentration exceeding 500 ng/ml for the diagnosis of AVTE were respectively 98, 58, 97 and 70% when using the ELISA method, and 86, 71, 84 and 75% when using the latex assay. In 47 patients whose lung scans yielded abnormalities of indeterminate probability of pulmonary embolism, the sensitivity of the ELISA method was very high (94%), but that of latex assay was low (67%). Our results demonstrate that measuring the plasma D-dimers by the latex assay should not be used in the diagnosis of AVTE. On the other hand, the ELISA method might be of great interest in the diagnostic strategy of AVTE, as a normal concentration of D-dimers rules out almost definitely the diagnosis of AVTE, and hence, spares from performing invasive investigations.

[Severe hemorrhagic complications during treatment with low molecular weight heparin. Apropos of 2 cases]

Two cases of fatal bleeding in patients treated with low molecular weight heparin for deep vein thrombosis are reported. Risk factors for bleeding were: severe underlying disease (cancer in one case, morbid obesity and cardiac failure in the other), age over 80 years and worsening of renal insufficiency in both cases, recent surgical procedure in one case. Anti-Xa activity was beyond the therapeutic range at the time of bleeding in both cases. The usefulness of biologically monitoring the treatment of deep vein thrombosis with low molecular weight heparin is discussed.

Retinal arterial occlusion associated with resistance to activated protein C

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Diagnosis and clinical characteristics of inherited activated protein C resistance

The diagnostic strategies and clinical characteristics of thrombophilia associated with heterozygous or homozygous factor V Leiden mutation have been determined according to the literature and to a personal study in 51 families. Factor V mutation was present in the 51 propositi and in 84 out of 125 family members (81 heterozygous, 3 homozygous). Venous thrombosis was observed in all the propositi, in 17 of the 84 family members with the mutation and in 6 of the 41 with a normal APC resistance test and no mutation. An associated protein C or protein S deficiency was present in 5 families (10%). The most frequent clinical manifestations were superficial or deep vein thrombosis and/or pulmonary embolism, but also thrombosis at an unusual site (cerebral, mesenteric or central retinal vein). A causal relationship is frequently difficult to demonstrate. A precipitating factor was observed in 84% of cases and a recurrent thrombotic episode occurred in 50% of propositi. The risk of thrombosis associated with pregnancy was high in the post-partum period, especially in homozygous women. In the 28 homozygous subjects, markers of coagulation activation were frequently elevated in untreated patients. Finally, the efficacy of anticoagulant treatment is suggested but the long period often observed between treatment interruption and a recurrence does not militate in favour of long term treatment.

Coagulation studies, factor V Leiden, and anticardiolipin antibodies in 40 cases of cerebral venous thrombosis

BACKGROUND AND PURPOSE

Cerebral venous thrombosis (CVT) is an infrequent condition with a large variety of causes. However, in 20% to 35% of cases, no cause is found. We studied coagulation parameters, including activated protein C resistance associated with factor V gene mutation (factor V Leiden) and anticardiolipin antibodies, in a large series of patients with CVT with or without identified cause or risk factor.

METHODS

Forty patients (30 women and 10 men) aged 19 to 71 years (mean age, 36.2 years) with CVT diagnosed by angiography and/or MRI were studied 1 to 18 years after thrombosis. No known cause was found in 10 idiopathic cases. Coagulation studies included the following tests: fibrinogen, antithrombin, protein C, protein S, plasminogen, anticardiolipin antibodies, activated protein C resistance, and factor V Leiden.

RESULTS

Six cases of thrombophilia (15%) were found: 1 protein C deficiency, 1 protein S deficiency, and 4 activated protein C resistance with heterozygous factor V Leiden mutation (10%). Only 1 case (protein S deficiency) was found in the group of 10 patients with idiopathic CVT. In the other 5, there was another cause or risk factor. Three patients (8%) had increased anticardiolipin antibodies: 1 with systemic lupus and 2 with primary antiphospholipid syndrome; 2 of these 3 patients also had factor V Leiden mutation.

CONCLUSIONS

Although present in a number of CVT cases, acquired (anticardiolipin) or congenital varieties of thrombophilia (factor V Leiden being the most frequent) are almost invariably associated with other predisposing factors. This suggests that (1) these abnormalities should be looked for in patients with CVT, whether a cause is found or not, and (2) their presence should not deter the search for other potential causes. The detection of such abnormalities has major practical consequences on the long-term management of patients to prevent further thrombotic episodes.

[Value of an extensive biological study in venous or arterial thromboses]

OBJECTIVES

The aim of this work is to study the signification of an extensive biological evaluation in patients with "unexplained" thrombosis. We studied 78 patients with more than one arterial and/or venous thromboembolic event.

METHODS

Fifty-four patients were admitted for unexplained deep venous thrombosis (group I, n = 19, 9 men and 10 women) and/or arterial thrombosis (group II, n = 35, 21 men and 14 women). A third group (group III) included 24 patients (13 men, 11 women) known to have a pathologic state which can lead to a thrombotic event.

RESULTS

The patients in both groups I and II had, more often than normal subjects, a high level of homocysteinemia (26% vs 3%, p < 0.001), anti-beta 2 glycoprotein 1 (18.5% vs 3%, p < 0.001) and antiphospholipid antibodies (13% vs 3%, p < 0.02). We also found a significant association between an increase of erythrocytic aggregation and arterial thrombosis (group II). In the third group, for both arterial (n = 14) and venous (n = 10) thrombosis, we found a high level of anticardiolipin antibodies (25% vs 3%, p < 0.001), anti-beta 2 glycoprotein 1 antibodies (12.5% vs 3%, p < 0.05) and abnormal erythrocytic aggregation (16.5% vs 3%, p < 0.01). In these 3 groups the other studied parameters (Lp(a), platelet aggregation, cryoglobulin, cryofibrinogen, antinuclear antibodies, anticytoplasm antibodies, plasma and urine immunoelectrophoresis, protein C, protein S, antithrombin III, plasminogen) were not different from levels observed in normal subjects.

CONCLUSION

An extensive biological analysis, including plasma homocystein level, anticardiolipin antibodies, anti-beta 2 glycoprotein 1 antibodies and a study of the erythrocytic aggregation would appear to be of value in patients presenting recurrent arterial or venous thromboembolic events. Specific therapy can be applied in case of abnormal results continued anticoagulant therapy for anticardiolipin and anti-beta 2 glycoprotein 1 antibodies, and a vitamin therapy for increased homocysteinemia.