The effect of nateglinide on the pharmacokinetics and pharmacodynamics of acenocoumarol

OBJECTIVE

The potential for a drug interaction was investigated between nateglinide, an oral antidiabetic agent, and acenocoumarol, an oral anticoagulant, as these drugs are primarily metabolized via CYP2C9.

METHODS

A two-period, randomized, double-blind, two-way crossover study design was employed to evaluate the effect of nateglinide on the pharmacokinetics and pharmacodynamics of acenocoumarol in 11 healthy male or female subjects. All subjects received either nateglinide 120 mg t.i.d. or placebo for 5 days in a crossover fashion and a single 10-mg dose of acenocoumarol on day 3. Plasma concentrations of R- and S-acenocoumarol and the anticoagulation parameters [prothrombin time (PT) and international normalized ratio of PT (PTINR)] were determined for 72 h following acenocoumarol administration. The pharmacokinetic and pharmacodynamic parameters of acenocoumarol were determined by noncompartmental analysis.

RESULTS

The mean (coefficient of variation (CV%)) area under the concentration-time curve (AUC(0-t)) of R-acenocoumarol in the presence and absence of nateglinide was 4217 (23%) and 3831 (24%) ng.h/ml, respectively. The corresponding values for S-acenocoumarol were 397 (20%) and 382 (23%), respectively. The mean (CV%) C(max) of R-acenocoumarol in the presence and absence of nateglinide was 304 (16%) and 316 (16%), respectively and the corresponding values for S-acenocoumarol were 142 (36%) and 141 (34%), respectively. The 90% confidence intervals indicated that exposure parameters, AUC(0-t) and C(max), of both R- and S-acenocoumarol were within the acceptable limits of 0.8-1.25. The mean (CV%) of area under the concentration-time curve of PT (AUC(PT)) following acenocoumarol administration in the presence and absence of nateglinide was 1170 (10%) and 1136 (8%), respectively. The corresponding AUC(INR) values were 104 (13%) and 99 (10%), respectively. Nateglinide co-administration has no influence on the PT or PTINR of acenocoumarol (p > 0.05).

CONCLUSION

Co-administration of nateglinide does not influence either the pharmacokinetics or the anticoagulant activity of R- and S-acenocoumarol in healthy subjects. This suggests that no dosage adjustments will be required when nateglinide and acenocoumarol are coadministered in clinical practice.

Coagulation monitoring and management of anticoagulation during cardiac assist device support

BACKGROUND

The incidence of clinically significant thromboembolic events due to the use of cardiac assist device systems remains high. Despite the considerable advances in cardiac assist device technology, the monitoring and management of the hypercoagulable coagulation status, resulting from foreign surfaces of the assist device system, altered rheologic conditions, and blood stasis in the recipient heart remain a challenge. Moreover septic complications and insufficient anticoagulation are responsible for thromboembolic events.

METHODS

In addition to standard coagulation analysis, functional coagulation tests were performed including the use of a thrombelastographic monitoring system (ROTEG) and a platelet function analyzer (PFA-100).

RESULTS

Severe biventricular ischemic heart failure developed in a 58-year-old man with acute myocardial infarction and he needed a biventricular assist device for a bridge to cardiac transplantation. Although the patient received acenocoumarol (Sintrom; Novartis Pharma, Vienna, Austria) and acetylsalicylic acid (Aspisol; Bayer AG, Leverkusen, Germany) as usual, ROTEG and the PFA-100 detected hypercoagulability while routine coagulation screening tests showed hypocoagulability. Moreover thrombus formation surrounding the canula of the left ventricular assist device was detected. Antithrombotic therapy with clopidogrel (Plavix) was initiated. Coagulation was closely monitored with modified thrombelastography and the PFA-100 to achieve sufficient but not overwhelming anticoagulation therapy. Three months after biventricular assist device implantation the patient underwent successful transplantation with no major blood loss.

CONCLUSIONS

Thrombelastography should be the standard form of monitoring in such patients to decrease the risk of thromboembolic events and prevent bleeding complications.

[Evaluation of an education program of patients undergoing oral anticoagulation treatment]

OBJECTIVE

To evaluate the therapeutic impact of an education program on patients undergoing oral anticoagulation treatment, within the hospital of Annecy (France).

MATERIAL AND METHODS

Groups of 10 patients were invited to participate to two meetings. The education was carried out by two nurses. Thanks to this prospective study, we compare the population before and after education in terms of treatment knowledge and stability.

RESULTS

Within 9 months 88 patients have been included, amongst which 55 have attended the two meetings. The average of correct answers to the knowledge evaluation questionnaire distributed before and after 6 months of education were, respectively, 6.63/12, 10.09/12 (P < 0.0001). Through INR controls within the 6 months preceding (424 controls) and the 6 months following the education (619 controls), we observe: an increase of the total INR average in therapeutic zone, from 45% to 61% (P < 0.0001); a decrease of the difference average per patient between the INR value observed and the one targeted: 0.54 before education, 0.40 after education (P = 0.0016); at last, the average phasing per patient under the therapeutic zone increases after education, from 49% to 65% (P < 0.001).

CONCLUSION

The education improves objectively the knowledge of patient undergoing AVK. If the size of patient sample is not large enough to prove any consequence on hemorrhagic or thrombotic complications, the education program still improves significantly the treatment stability.

Comparison of control and stability of oral anticoagulant therapy using acenocoumarol versus phenprocoumon

Variability in the control of oral anticoagulant therapy has been associated with a heightened risk of complications. We compared control of anticoagulation between two commonly used coumarins, phenprocoumon and acenocoumarol, and among anticoagulation clinics. All qualifying patients were managed at six regional anticoagulation clinics in the Netherlands. This retrospective cohort study compiled data during a three-year period from a computerised dosing and management system. Anticoagulation control was expressed as the percent of time within the therapeutic range and stability expressed as the time-weighted variance in the international normalised ratio (INR). Data were available for 22,178 patients of whom 72% were treated with acenocoumarol. INRs of patients who received phenprocoumon were within the therapeutic range 50% of the time compared with 43% for acenocoumarol (OR 1.32, 95% CI 1.24-1.41). Moreover, patients on phenprocoumon required 15% fewer monitoring visits and had more stable INR values. These observations were consistent for all six clinics. There were also sizable differences between the clinics with respect to control and stability of anticoagulation that were stable from year-to-year and were unrelated to the drug used. With its longer half-life of three to five days, phenprocoumon produces more stable anticoagulation than acenocoumarol and should generally be the drug of choice when these are the available choices. The differences observed among clinics suggest that certain clinics employ policies and practices resulting in better control of anticoagulation.

Acenocoumarol therapy in pediatric patients

To determine guidelines for administering and monitoring acenocoumarol therapy in children, 93 patients (median 5.1 years, range: 0.2-18 years) were prospectively evaluated over a 33-month period. The loading doses used were: <1 year, 0.20 mg x kg-1; >1-5 years, 0.09 mg x kg-1; 6-10 years, 0.07 mg x kg-1; 11-18 years, 0.06 mg x kg-1. In this study, the loading dose and the dose to achieve and maintain target therapeutic range (TTR) for acenocoumarol are age-dependent, with infants having the highest and teenagers having the lowest requirements. The use of a different loading dose according to age has allowed most of the children (80%) in all the age groups to achieve TTR in less than 1 week. No patients had serious bleeding or thrombotic complications. We conclude that there is an age-dependent response to acenocoumarol in pediatric patients. The implementation of an age-adjusted loading dose regimen reduces the length of hospitalization required to achieve effective anticoagulant therapy.

Extended oral anticoagulant therapy after a first episode of pulmonary embolism

BACKGROUND

The optimal duration of oral anticoagulant treatment after a first episode of pulmonary embolism remains uncertain.

OBJECTIVE

To evaluate the long-term clinical benefit of extending a 3-month course of oral anticoagulant therapy to 6 months (pulmonary embolism associated with temporary risk factors) or to 1 year (idiopathic pulmonary embolism) in patients with a first episode of pulmonary embolism.

DESIGN

Multicenter randomized study with independent, blinded assessment of the outcome events.

SETTING

19 Italian hospitals.

PATIENTS

326 patients who had had 3 months of oral anticoagulant therapy without experiencing recurrence or bleeding.

MEASUREMENTS

The primary study outcome was recurrence of symptomatic, objectively confirmed venous thromboembolism.

RESULTS

Among 165 patients assigned to extended anticoagulant therapy, 15 patients (9.1%) had a recurrence of venous thromboembolism (3.1% per patient-year; average follow-up, 34.9 months), as compared with 18 of 161 patients (11.2%) assigned to discontinue treatment (4.1% per patient-year; average follow-up, 32.7 months); the rate ratio was 0.81 (95% CI, 0.42 to 1.56). All but one of the recurrences occurred after anticoagulant treatment was discontinued. Nineteen recurrences (57.6%) were episodes of pulmonary embolism, two of which were fatal. Three major bleeding episodes were observed during extended anticoagulation (1.8%). Among patients with idiopathic venous thromboembolism, 11 of 90 patients assigned to extended anticoagulation and 11 of 91 patients assigned to discontinue treatment experienced a recurrence (relative risk, 0.99 [CI, 0.45 to 2.16]).

CONCLUSION

Patients with pulmonary embolism have a substantial risk for recurrence after discontinuation of oral anticoagulation, regardless of treatment duration. Physicians should try to identify patients who are at high risk for recurrent venous thromboembolism and are therefore potential candidates for indefinite oral anticoagulant therapy.

Impact of pre-treatment INR level on the effect of intravenous low dose vitamin K in patients with excessive anticoagulation

Administration of vitamin K is the common mode of treatment in excessively anticoagulated patients. However, patient's response to vitamin K varies, depending on the vitamin K dose and the route of administration. Another potential source of variation is the pre-treatment INR which has not been accounted for in most previous studies. In the present study the effect of baseline INR on the response to a single dose of intravenous vitamin K (0.5 mg) was studied in 95 episodes of excessively anticoagulated patients (n = 76). In 67 episodes of moderately excessive baseline INR (6-10) mean INR declined from 8.0 +/- 1.2 to 2.6 +/- 0.9 at 24 hours, 59/67 (88%) responding within the first 12 hours and not requiring a second dose. In contrast, in 28 episodes with highly excessive baseline INR (> 10) response was slower; mean INR declining from 13.6 +/- 2.7 to 4.0 +/- 2.1 at 24 hours. In 14/28 of these episodes, patients failed to respond to vitamin K in the first 12 hours and required a second vitamin K dose. We conclude that INR at presentation affects the response to vitamin K and that this INR value should be considered in determining appropriate vitamin K doses.

Age and First INR After Initiation of Oral Anticoagulant Therapy with Acenocoumarol Predict the Maintenance Dosage

BACKGROUND

This retrospective study was performed to develop a model to predict the maintenance dosage of the vitamin K antagonist acenocoumarol, based upon the first INR after a standard initial dosage regimen.

MATERIAL AND METHODS

Outpatients with atrial fibrillation ( n = 284) and initial regimens of 6-4 or 6-4-2 mg acenocoumarol on day 1, 2 and 3, respectively, were included. The maintenance dosage of the period 3-6 months after the installment was related to the first INR after those standard initial dosage regimens, because in that period the INR was 76% of the time within the therapeutic range and therefore considered suitable to perform the analysis.

RESULTS

A clear relation was found between the first INR, the maintenance dosage and the age. A model that predicts the maintenance dosage immediately after the standard initial dosage and based on the first INR and adjusted for age, has been developed, according to the formula: required dosage = 5.03-1.65 * ln (first INR) - 0.01 * age.

CONCLUSION

We have developed a formula to predict the maintenance dosage of acenocoumarol. With this formula it is possible to install this maintenance dosage and thus achieve oral anticoagulant therapy within the therapeutic range at an earlier stage. This will have to be shown in a prospective study.

Pharmacokinetic study of the digoxin-acenocoumarol interaction in rabbits

A study was carried out to evaluate the potential pharmacokinetic interaction between digoxin and acenocoumarol. The binding of digoxin to rabbit cardiac tissue homogenates was assessed in vitro, using the equilibrium dialysis technique. An increase in the first-order constant (p<0.05) and a reduction in the partition coefficient in the equilibrium situation (p<0.001) of digoxin were observed when the cardiac homogenates were previously treated with acenocoumarol. In the in vivo study, the kinetics of digoxin administered in single and multiple dosage regimens were compared in control rabbits and in rabbits treated simultaneously with acenocoumarol. Kinetic analysis of the results was performed using Non-linear Mixed Effects Modeling (NONMEM). In the presence of acenocoumarol, the population distribution volume (Vd) of digoxin was increased by 40-60%, no differences being found as regards the elimination clearance. Also, joint administration of both drugs led to a reduction in digoxin concentrations in the heart (p<0.01) at the end of the dosage regimen. Both sets of results point to the hypothesis of a hitherto unreported possible pharmacokinetic interaction between the two drugs affecting the distribution process. This interaction could lead to lower plasma digoxin levels, in view of the increased Vd, and a possible reduction in the therapeutic effect, owing to the decrease in affinity and in concentration in heart tissue.

Low rate of bleeding and thrombotic complications of oral anticoagulant therapy independent of age in the real-practice of an anticoagulation clinic

Over past years, there has been a world-wide increase in oral anticoagulant treatment (OAT). This study was aimed at evaluating the efficacy and safety of OAT managing in a real-practice situation. Nine hundred and three consecutive unselected patients referred for the control of OAT to the Anticoagulation Clinic of the University of Florence were studied. The total follow-up period was 1679 patient-years. The rate of total, major and fatal bleeding events was 5.0, 1.1 and 0.06 per 100 patient-years, respectively. In patients with a target International Normalized Ratio (INR) > or = 3, a significantly higher rate of bleeding (P = 0.02) with respect to patients with a target INR < 3 was observed. The rate of all thrombotic events was 3.8 per 100 patient-years. The rate of major and fatal thrombotic events were 2.4 and 0.4 per 100 patient-years, respectively. At INR >/= 4.5 the rate of bleeding was significantly higher (P = 0.005) than at lower INR. At INR < 2 the rate of all thrombotic events was significantly higher (P = 0.00001) with respect to more elevated intensities of anticoagulation. A low incidence of complications may be obtained even in elderly outpatients on OAT followed at an anticoagulation clinic.

[Prevention of postoperative bleeding in patients taking oral anticoagulants. Effects of tranexamic acid]

INTRODUCTION

We present a prospective clinical study on use of tranexamic acid mouthwashes in patients taking oral anticoagulants and who have to undergo minor ambulatory oral surgery, without modifying their anticoagulant therapy.

MATERIAL AND METHODS

Forty patients (18 men and 22 females) aged from 42 to 81 were studied from April 2000 to December 2002. All patients were under the same anticoagulant, vitamin K antagonist, (Sintrom) for different pathologies. The anticoagulant therapy was not modified neither before nor after surgery. More than 70 oral procedures were carried out under local anesthesia. The International Normalized Ratio of prothrombin time (INR) was<=4. Tranexamic acid 5% (Exacyl) mouthwashes were prescribed during and after surgery.

RESULTS

All the patients were followed up during 2 weeks after surgery. There were no postoperative bleedings.

DISCUSSION

Use of tranexamic acid mouthwashes under a specific protocol is an efficient, reliable and economic method in preventing postoperative bleeding in patients under oral anticoagulant therapy.

Compliance and stability of INR of two oral anticoagulants with different half-lives: a randomised trial

The aim of the study was to assess the respective roles of the half-life of elimination of oral anticoagulants and patient education as causes of instability of anticoagulation level in patients on oral anticoagulant therapy. Patients were randomised to receive either warfarin (long half-life) or acenocoumarol (short half-life) and either intensive or standard education, according to a factorial design. Instability of oral anticoagulant therapy was evaluated by the percentage of INRs and the time within the target range, and the variability between successive measurements. Compliance was assessed by means of electronic pill bottles. Eighty-six patients were included. Apart from the variability index, instability was similar between groups. Correlations between compliance and instability were observed only in the acenocoumarol group. No difference was found between the education groups. In patients starting oral anticoagulant therapy, dose determination may be the most important factor contributing to instability.

Low molecular weight heparin (nadroparine) versus oral anticoagulant (acenocoumarol) in the long-term treatment of deep venous thrombosis: comparison of efficacy, safety and hospitalisation period in 105 patients

OBJECTIVE

To evaluate and compare the efficacy and safety of low molecular weight heparin (LMWH) (nadroparine) and acenocoumarol in the treatment of deep venous thrombosis (DVT).

METHODS

A retrospective study of the case notes of 105 patients (68 men) with established DVT who had been hospitalised during a 6-year period in a university hospital department.

RESULTS

Among 105 patients, 65 received nadroparine and the remaining intravenous unfractionated heparin (UH) as initial treatment. Twenty-seven patients out of 65 continued their treatment with nadroparine and the remaining 78 patients (38 initially treated with LMWH and 40 with UH) with acenocoumarol. The average hospital stay for those on LMWH treatment was 2.2 +/- 1.4 days in comparison to 6.4 +/- 1.2 days for those treated with acenocoumarol (p < 0.001). During the home-based phase of treatment, 14 patients were re-admitted to hospital for recurrent DVT; ten and four of those treated with acenocoumarol and LMWH, respectively (p = NS). Haemorrhagic complications occurred in 12 of the patients who received acenocoumarol and in one of those on LMWH (p = NS).

CONCLUSIONS

The patients who received LMWH had a significantly lower duration of hospitalisation than those who received acenocoumarol. There were no significant differences between the administration of LMWH and acenocoumarol in terms of efficacy or safety in patients with DVT.

Low incidence of hemorrhagic complications of oral anticoagulant therapy in patients with atrial fibrillation in the daily practice of an anticoagulation clinic

BACKGROUND

Over the last years, the use of oral anticoagulant treatment (OAT) has increased dramatically, principally for the prevention of embolic stroke in patients with atrial fibrillation. This study was aimed at evaluating the efficacy and safety of the management of OAT in a real-practice situation.

METHODS

Nine hundred and three consecutive unselected patients, 250 of whom with atrial fibrillation, referred for the control of OAT to the Anticoagulation Clinic of the University of Florence were studied. The total follow-up period was 1679 patient-years.

RESULTS

The rate of major bleeding events was 0.8 per 100 patient-years in atrial fibrillation patients. In patients with a target INR > or = 3 a significantly higher rate of bleeding (p = 0.02) with respect to patients with a target INR < 3 was observed.

CONCLUSIONS

A low incidence of complications may be obtained even in elderly atrial fibrillation patients on OAT followed in an Anticoagulation Clinic specifically devoted to this management.

[Oral anticoagulation with vitamin K antagonists]

Coumarins are broadly employed in clinical practice and should therefore belong to the group of 'well known' drugs. The present review will deal with some concepts of anticoagulant therapy: the role of vitamin K in the synthesis of functional coagulation factors, some clinically relevant pharmacokinetic aspects of coumarins, the management of oral anticoagulant therapy with special emphasis on the laboratory monitoring, and the most frequent complication, bleeding.

Pharmacogenetics of acenocoumarol: cytochrome P450 CYP2C9 polymorphisms influence dose requirements and stability of anticoagulation

BACKGROUND AND OBJECTIVES

Cytochrome P4502C9 (CYP2C9) is the main enzyme implicated in coumarinic metabolism. Variant alleles, CYP2C9*2 and CYP2C9*3, have been related to decreased enzymatic activity, but their clinical relevance in acenocoumarol metabolism has not been established. We investigated CYP2C9 polymorphisms in relation to acenocoumarol dose requirement, stability of anticoagulation and bleeding.

DESIGN AND METHODS

CYP2C9 genotyping was performed in 325 acenocoumarol-treated patients (INR target between 2.0 and 3.0) and in an additional group of 84 patients with repeated bleeding.

RESULTS

Patients with the wild-type CYP2C9*1/*1 genotype (n=169) required a higher maintenance dose of acenocoumarol (17.1 8.7 mg/week) than did patients with the CYP2C9*2 (14.6 6.4 mg/week, p<0.05, N=97) or the CYP2C9*3 allele (11.2 6.2 mg/week, p<0.001, n=59). Out of 170 patients requiring a low-dose of acenocoumarol (<or= 2 mg/day), 27.1% carried the CYP2C9*3 allele, while among the patients requiring higher doses, 8.4% had CYP2C9*3 (OR=4.77, 95% CI = 2.40-9.48, p<0.001 vs. 2C9*1/*1 patients). In the multivariate analysis, independent predictive variables for low-dose acenocoumarol requirements were age >70 years (OR=3.73, 95%CI=2.29-6.08, p<0.001), and the CYP2C9*3 allele (OR=4.75, 95%CI=2.36-9.55, p <0.001). Carriers of CYP2C9*3 spent less time within the therapeutic range (64.7 23.1%) than did patients with the CYP2C9*1/*1 genotype (75.1 22.0%, p<0.01), and more frequently had an INR >4.5 at the initiation of treatment (43.9% vs.11.6%, p<0.001), but did not show repeated bleeding more frequently (19.0% vs.15.5%, p=NS).

INTERPRETATION AND CONCLUSIONS

CYP2C9*3 is related to lower acenocoumarol dose requirements, a higher frequency of over-anticoagulation at the initiation of therapy and an unstable anticoagulant response.

[Acenocoumarol (Sintrom) and fluinidione (Previscan) in pediatrics after cardiac surgical procedures]

PATIENTS AND METHODS

Between 1997 and 2001, 150 children (one month to 16 years of age) were treated with oral anticoagulants after cardiac surgery (Fontan's operations and congenital heart diseases without valvulopathy: 62%, valvular prosthesis: 20%, arrhythmia: 4.6%, thrombosis: 4%, other: 9.4%). They were first treated by either unfractionated heparin (49%) or nadroparin (51%), then by acenocoumarol (n1 = 114) or fluindione (n2 = 36) until steady state.

RESULTS

The retrospective analysis of data (age, body weight, international normalized ratio, loading and maintenance doses, time to achieve the steady state) led to the building of a dosage nomogram usable in pediatrics.

CONCLUSION

We demonstrated that the mean maintenance dose depended on age and weight. After three years, that dose (mg/kg) was getting close to adult values; it was higher before three years of age, especially before 12 months (p < 0.01), and very variable from a child to another. The recommended loading dose should be as close as possible to the effective maintenance dose: within that cohort, about 0.14 and 0.05 (acenocoumarol) or 1.1 and 0.40 mg kg-1 day-1 (fluindione), before 12 months and after three years respectively.

Extended venous thromboembolism prophylaxis after total hip replacement: a comparison of low-molecular-weight heparin with oral anticoagulant

BACKGROUND

Oral anticoagulants and low-molecular-weight heparin are both recommended for venous thromboembolism prophylaxis after total hip replacement. To date, these regimens have not been compared by means of clinical end points in the extended prophylaxis setting.

METHODS

We randomly assigned 1279 patients 3 days after total hip replacement surgery to fixed-dose subcutaneous low-molecular-weight heparin (reviparin sodium, 4200 anti-Xa IU) or adjusted-dose oral anticoagulant (international normalized ratio, 2-3; acenocoumarol) for a 6-week period. The primary end point was the failure rate, defined as the combined clinical events of a confirmed symptomatic thromboembolic event, a major hemorrhage, or death. All patients were followed up throughout the study interval. The primary objective was to compare the observed cumulative failure rate in the low-molecular-weight heparin vs oral anticoagulant group.

RESULTS

In the intent-to-treat population, objectively documented symptomatic thromboembolic events occurred in 15 (2.3%) of 643 patients vs 21 (3.3%) of 636 patients receiving low-molecular-weight heparin or oral anticoagulants, respectively (P =.30; 95% confidence interval for the difference, -0.8% to 2.8%). Major bleeding occurred in 9 (1.4%) of 643 patients vs 35 (5.5%) of 636 patients receiving low-molecular-weight heparin or oral anticoagulants, respectively (P =.001). The failure rate was 24 (3.7%) of 643 patients compared with 53 (8.3%) of 636 patients who received low-molecular-weight heparin or oral anticoagulants (P =.001).

CONCLUSIONS

A significantly higher benefit-risk ratio was observed for patients undergoing elective hip replacement who received extended out-of-hospital prophylaxis with low-molecular-weight heparin vs acenocoumarol. Low-molecular-weight heparin prophylaxis was at least as effective as oral anticoagulants, but with a marked improvement in safety.

Relationship between international normalized ratio values, vitamin K-dependent clotting factor levels and in vivo prothrombin activation during the early and steady phases of oral anticoagulant treatment

BACKGROUND AND OBJECTIVES

In vitro studies have shown that the rate of prothrombin activation is linearly related to the concentration of factor II (FII) in the assay system, suggesting a key role of prothrombin levels in the expression of the antithrombotic activity of oral anticoagulant treatment (OAT). We investigated the in vivo relationship between prothrombin activation and vitamin K-dependent clotting factor levels during the early and steady phases of OAT in patients and in healthy volunteers.

DESIGN AND METHODS

The changes in international normalizezd ratio (INR) and in the plasma levels of FVII, FX, FII, protein C (PC) and prothrombin fragment 1.2 (F1+2) induced by OAT were monitored over 9 days in 10 patients not on heparin starting warfarin after heart valve replacement (HVR) and in 9 healthy volunteers submitted to an 8-day course of warfarin treatment. FII and F1+2 plasma levels were also measured in 100 patients on stable oral anticoagulant treatment with INRs ranging from 1.2 to 6.84.

RESULTS

Because HVR patients had subnormal FVII, FX and FII levels after surgery, INR values > 2.0 were attained already 24 hours after the first warfarin dose. In healthy volunteers, INR values greater than 2.0 were first observed after 72 hours. Nadir levels of FVII, PC, FX and FII were reached between 40 and 88 hours in HVR patients and between 72 and 192 hours in healthy volunteers. The FII apparent half-disappearance time (t/2) was 99 hours in HVR patients and 115 hours in healthy volunteers (p = ns). In HVR patients there was no normalization of initially elevated F1+2 levels until day 7 with an apparent t/2 of 132 hours. In healthy volunteers, a decrease to subnormal F1+2 levels was observed by day 8 of treatment (apparent t/2 = 107 hours). In both HVR patients and healthy volunteers, FII and PC levels were independent predictors of the changes in F1+2 levels (p = 0.0001). In patients on stable OAT, only FII levels were independent predictors of the variation in F1+2 levels (p = 0.0001).

INTERPRETATION AND CONCLUSIONS

During the early phase of oral anticoagulant treatment in vivo prothrombin activation is a function of the balance between FII and PC levels and is not significantly prevented until nadir levels of FII are obtained. This provides an explanation for the requirement of overlapping heparin and oral anticoagulant treatment for at least 48 hours after the achievement of therapeutic INR values in patients with thromboembolic diseases. In addition, in vivo prothrombin activation is a function of FII levels rather than INR values also in patients on stable oral anticoagulant treatment.

Role of oral anticoagulation and inoue balloon mitral valvulotomy in presence of left atrial thrombus: a prospective serial transesophageal echocardiographic study

BACKGROUND AND AIMS OF THE STUDY

Left atrial (LA) and/or left atrial appendage (LAA) thrombi are often found in patients with rheumatic mitral stenosis (MS). The fate of these thrombi on optimal oral anticoagulation, and the feasibility of balloon mitral valvulotomy (BMV) is not well established. The study aims were to assess the efficacy of oral anticoagulation in the resolution/organization of these thrombi, and the feasibility and safety of Inoue BMV in these patients.

METHODS

All consecutive patients with severe MS and a mitral valve suitable for BMV, but found to have LA/LAA thrombus on transesophageal echocardiography (TEE) between January 1999 and January 2001 were included. Anticoagulation was carried out with oral nicoumalone; the INR was maintained at 2.5-3.5. Follow up TEE was performed at intervals of two months for a maximum of six months. BMV using the Inoue balloon technique was performed as soon as possible after resolution or organization of thrombus.

RESULTS

Sixty-six patients with MS (41 females, 25 males, mean age 33.1+/-10.4 years) and LA thrombus on TEE were studied. Thrombi were categorized into three groups: type I, thrombi localized to LAA (n = 36; 54.6%); type II, LAA thrombi protruding just beyond the LAA mouth (n = 22; 33.3%); and type III, LAA thrombi extending into the LA cavity (n = 8; 12.1%). Mean thrombus size was 27.6+/-9.1 mm (range: 15-35 mm). Complete resolution was seen in 22 patients (33.3%), and organization in 38 (57.6%). No significant change was observed in six patients (9.1%). Resolution was most common in the first two months, and in type I thrombi (41.7%, 27.2% and 12.5% in type I, II and III thrombi, respectively). BMV was performed in 90.9% of patients, and was uneventful in all. BMV was performed in the presence of organized thrombus in 63% of patients.

CONCLUSION

Anticoagulant therapy is effective in resolution and/or organization of LA thrombi in patients with MS. Six months' duration of anticoagulation appears optimal. BMV using the Inoue balloon technique can be performed safely after resolution or organization of thrombus, with no additional risk of complication.

Low dose oral vitamin K to reverse acenocoumarol-induced coagulopathy: a randomized controlled trial

Low dose oral vitamin K rapidly reverses warfarin-associated coagulopathy. Its effect in patients receiving acenocoumarol is uncertain. We compared the effect of withholding acenocoumarol and administering 1 mg oral vitamin K with simply withholding acenocoumarol in asymptomatic patients presenting with INR values between 4.5 and 10.0. The primary end-point of the study was the INR value on the day following randomisation. We found that patients receiving oral vitamin K had more sub-therapeutic INR levels than controls (36.6% and 13.3%, respectively; RR 1.83, 95% confidence interval 1.16, 2.89) and a lower, but non-significant, proportion of INR values in range (50% and 66.6%, respectively) on the day following randomisation. After 5 +/- 1 days, there were more patients with an INR value in range in the vitamin K group than in controls (74.1% and 44.8%, respectively). There were no clinical events during 1 month follow-up. We conclude that the omission of a single dose of acenocoumarol is associated with an effective reduction of the INR in asymptomatic patients presenting with an INR value of 4.5 to 10.0. Furthermore, the use of a 1 mg dose of oral vitamin K results in an excessive risk of over-reversal of the INR.

Effect of low-dose aspirin on the international normalized ratio variability in patients with mechanical heart valve prostheses

An increased risk of bleeding is associated with a more intense oral anticoagulation, a greater international normalized ratio (INR) variability and the use of aspirin. We studied the INR variability of patients (n = 121) with modern heart valves who had been prospectively randomized to receive acenocoumarol at a targeted INR of 2.4-3.6 plus aspirin 100 mg/day or acenocoumarol alone at the same dosage, to evaluate whether aspirin influences variability and thus the risk of bleeding. Variability was similar in patients with no events regardless of the use of aspirin. A statistically significantly higher variability was observed in patients with bleeding events independently of the use of aspirin. Nevertheless, the concomitant use of aspirin in patients with a high variability should be monitored closely and thoroughly.

[Oral anticoagulant treatment: practical aspects and significance of anticoagulant clinics]

Vitamin K antagonists (VKA) decrease the synthesis of the active forms of four coagulation factors (factors II, VII, IX, X) and three inhibitors (proteins C, S, Z). There are VKA having a short half life (Sintrom, Pindione) and VKA having a long half life (Apegmone, Previscan, Coumadine). The treatment is monitored by the INR which in the majority of the indications must range between two and three. The first INR is usually performed 36 to 72 h after starting the treatment. There are a number of drug interactions. The rate of major bleedings range from 1.1 to 4.9 for 100 patient-year according to the published studies. Since around 600,000 patients are treated by VKA in our country, the absolute number of serious bleeding is high (> or = 17,000 per year). Anticoagulant clinics are structures aimed to instruct the patient and to advise the general practitioner to monitor the treatment, using computer assisted methods. It has been reported that these structures reduce the incidence of bleeding and of thrombotic events by 3 to 4 times.

Initiation of oral anticoagulant therapy in orthopedic and surgical patients: an algorithm compared with routine dosing

Oral anticoagulant therapy is initiated in most hospitals in The Netherlands by clinicians who routinely dose oral anticoagulants (without using an algorithm). This may explain the low proportion of patients leaving the hospital stabilized. To test this hypothesis this study compared the dosing of acenocoumarol in orthopedic and surgical patients using an algorithm with routine dosing. Because of the routine administration of low molecular weight heparin for at least the first 5 days of acenocoumarol therapy, the study focused on supratherapeutic INR-values during this period. The study included 103 patients and was performed on orthopedic surgery and general surgery wards of a Dutch hospital over 5 months. The patients received acenocoumarol as an oral anticoagulant to prevent venous thromboembolism after general of orthopedic surgery. Patients were randomized into a group routinely dosed by physicians (n=54) and a group dosed using a dosing algorithm (n=49). A patient was defined as stable if he had two consecutive INR values within the range of 2-3 during hospitalization with the first (of the two consecutive INR values within range) having been measured on day 5 or later. The groups did not differ significantly in proportion of patients stabilized, time to stabilization, or length of hospitalization. In the first period (days 1-5) the routine dosing group had significantly more INR values above therapeutic range than the algorithm group, while the algorithm group had more INR values below the therapeutic range. There were two bleeding episodes in the routine dosing group and none in the algorithm group. Despite the lack of differences in stabilization between the two groups, this study suggests an advantage of dosing acenocoumarol using an algorithm in a study population consisting of prophylactically treated, mostly elderly orthopedic patients. The algorithm provides a safe dosing schedule for elderly postoperative patients who use low molecular weight heparin and NSAIDs concomitantly and are thus at high risk for bleeding complications.

Treatment with vitamin K antagonists: frequency of indications and appropriateness of continuation

To prevent venous and arterial thrombosis vitamin K antagonists (VKA) are the treatment of choice for many indications. It is important to balance the benefits and the potential hazards of this treatment. An effective way to prevent unnecessary bleeding during VKA treatment is to stop treatment when the indication is no longer present. In this study, we analyze the distribution of indications in a randomly selected group of 250 patients starting VKA treatment at the Amsterdam Thrombosis Service. The proportion of patients still treated after one year of follow-up was also investigated. The distribution of the indications among patients starting VKA therapy was approximately 50% for venous thromboembolism treatment and prophylaxis, and approximately 50% for prophylaxis of arterial thrombosis. After one year of follow-up, 164 (65.6%) of the 250 patients had stopped VKA therapy. Reasons for stopping included: no indication for continuing VKA treatment, e.g. end of treatment, prophylaxis or restoration of sinus rhythm (137 patients); death (17) and other reasons (10). Six (2.4%; 95% CI: 0.9-5.1%) patients had a questionable indication for long-term treatment, and 9 (3.6%, 95% CI: 1.6-6.7%) patients had no clear indication for continued VKA treatment. We conclude that in the setting of the Amsterdam Thrombosis Service, only a small proportion of patients is treated with long-term VKA therapy without a valid indication after 1 year.

Platelet aggregation in different antithrombotic regimens. Possible proaggregant effect of low level oral anticoagulation

Few trials have studied platelet activity during oral anticoagulation and all show a tendency for platelet aggregation to increase. This adverse effect has also been shown in some patients treated with unfractionated heparin, the so-called white clot syndrome. We studied platelet aggregation in patients with atrial fibrillation enrolled in the NASPEAF study and receiving antiaggregant, anticoagulant and both treatments.

METHODS

15 healthy control subjects (group C) and 99 patients were enrolled, the latter receiving 4 different antithrombotic regimens for platelet aggregation: group 1, 600 mg of the antiplatelet drug triflusal; group 2, anticoagulation for an INR of 2-3; and both treatments with 2 different levels of anticoagulation, mean INR of 1.85 (group 3) and of 2.15 (group 4). The same amounts of the agonists ADP, arachidonic acid and collagen were used in all tests. For statistical analysis we used the interval in min, from the addition of the agonist to the beginning of aggregation and the % of aggregation at 5 and 8 min.

RESULTS

After arachidonic acid was given, the interval to the beginning of aggregation was shorter in group 2 than in group C: 0.6 +/- 0.21 and 1.1 +/- 1.2, and in both was significantly shorter than in the other three receiving antiplatelet drugs alone: group 1 = 1.58 +/- 1.4 or combined with anticoagulants: group 3 = 1.7 +/- 1.7 and group 4 = 2.4 +/- 2.1. The % of aggregation at 5 min, in groups C, 2, 1, 3 and 4 was respectively 48 +/- 24, 43.2 +/- 19, 29.6 +/- 17, 34.8 +/- 22 and 23.2 +/- 22.5. The data showed significantly increased platelet activity in groups C and 2 compared to groups 1, 3 and 4. Group 3 with a low anticoagulation level (mean INR = 1.85) showed a tendency to greater platelet activity than group 1 and 4 with p value = 0.08.

CONCLUSIONS

The antiplatelet drug triflusal alone or combined with a therapeutic level of anticoagulation effectively reduces platelet aggregation and is not influenced by anticoagulant treatment. A low level of anticoagulation (INR < 2) shows a tendency to increase platelet activity.

Low adjusted-dose acenocoumarol therapy in sickle cell disease: a pilot study

Vasoocclusion is a continuous process in sickle cell disease (SCD) and accumulates to significant end organ damage, mostly irrespective of the occurrence of manifest acute vasoocclusive events. As there are indications that reversing the hypercoagulable state may be of clinical benefit in sickle cell patients, we performed a randomized, double blind, placebo-controlled, cross-over pilot study to assess the efficacy and safety of low-adjusted dose acenocoumarol therapy (International Normalized Ratio: 1.6-2.0) in SCD. Treatment consisted of either acenocoumarol or placebo for 14 weeks, after which treatment was discontinued for a period of five weeks. Then, patients initially on acenocoumarol received placebo (and vice versa) for 14 weeks. Therapy efficacy was assessed by comparing the frequency of vasoocclusive complications, the occurrence of bleeding, and clotting activation between acenocoumarol and placebo treatment of each individual patient. Twenty-two patients (14 homozygous [HbSS] and 8 double heterozygous sickle-C [HbSC]; aged 20-59 years) completed the entire study. Acenocoumarol treatment did not result in a significant reduction of acute vasoocclusive events (three painful crises during acenocoumarol, five painful crises during placebo). There was a marked reduction of the hypercoagulable state (depicted by a decrease in plasma levels of prothrombin F1.2 fragments [P = 0.002], thrombin-antithrombin complexes [P = 0.003], and D-dimer fragments [P = 0.001]) without the occurrence of major bleeding. Even though no clinical benefit (pertaining to the frequency of painful crises) was detected in this pilot study, the value of low adjusted-dose acenocoumarol for preventing specific events (such as strokes) and as a long-term treatment of sickle cell patients should be subject of further study.

The effect of acenocoumarol on hemorheological parameters

The effect of acenocoumarol on hemorheological variables was measured in 35 non-valvular chronic atrial fibrillation patients before starting oral anticoagulant therapy (basal) and one and two months after beginning treatment (INR-2,3). Fibrinogen increased significantly from the basal situation: 332+/-99 mg/dl to 386+/-96 mg/dl in the second month (p<0.05). However, this small increase in fibrinogen is not large enough to mediate other rheological changes, and whole blood filterability, blood viscosity, plasma viscosity and erythrocyte deformability and aggregability remained unchanged after treatment. These results suggest that acenocoumarol does not affect rheological parameters and can therefore be used as a "neutral drug" for rheological studies in cardiovascular patients under oral anticoagulant therapy.

Three months versus one year of oral anticoagulant therapy for idiopathic deep venous thrombosis. Warfarin Optimal Duration Italian Trial Investigators

BACKGROUND

In patients with idiopathic deep venous thrombosis, continuing anticoagulant therapy beyond three months is associated with a reduced incidence of recurrent thrombosis during the period of therapy. Whether this benefit persists after anticoagulant therapy is discontinued is controversial.

METHODS

Patients with a first episode of idiopathic proximal deep venous thrombosis who had completed three months of oral anticoagulant therapy (with warfarin, in 97 percent of the cases and acenocoumarol in 3 percent) were randomly assigned to the discontinuation of oral anticoagulants or to their continuation for nine additional months. The primary study outcome was recurrence of symptomatic, objectively confirmed venous thromboembolism during at least two years of follow-up.

RESULTS

The primary intention-to-treat analysis showed that of 134 patients assigned to continued oral anticoagulant therapy, 21 had a recurrence of venous thromboembolism (15.7 percent; average follow-up, 37.8 months), as compared with 21 of 133 patients assigned to the discontinuation of oral anticoagulant therapy (15.8 percent; average follow-up, 37.2 months), resulting in a relative risk of 0.99 (95 percent confidence interval, 0.57 to 1.73). During the initial nine months after randomization (after all patients received three months of therapy), 1 patient had a recurrence while receiving oral anticoagulant therapy (0.7 percent), as compared with 11 of the patients assigned to the discontinuation of oral anticoagulant therapy (8.3 percent; P=0.003). The incidence of recurrence after the discontinuation of treatment was 5.1 percent per patient-year in patients in whom oral anticoagulant therapy was discontinued after 3 months (95 percent confidence interval, 3.2 to 7.5 percent; average interval since discontinuation, 37.2 months) and 5.0 percent per patient-year in patients who received an additional 9 months of oral anticoagulant therapy (95 percent confidence interval, 3.1 to 7.8 percent; average interval since discontinuation, 29.4 months). None of the recurrences were fatal. Four patients had non-fatal major bleeding during the extended period of anticoagulant therapy (3.0 percent).

CONCLUSIONS

In patients with idiopathic deep venous thrombosis, the clinical benefit associated with extending the duration of anticoagulant therapy to one year is not maintained after the therapy is discontinued.

Abrupt versus gradual withdrawal of vitamin K antagonist treatment in patients with venous thromboembolic disease: assessment of hypercoagulability and clinical outcome

BACKGROUND

It is yet unclear whether vitamin K antagonist treatment should be stopped abruptly or gradually after an episode of venous thromboembolism. The mode of withdrawal might influence a potential development of a hypercoagulable state, which could influence the risk for recurrent disease.

METHODS

We prospectively studied 37 consecutive patients in whom acenocoumarol was discontinued either abrupt (18) or gradually (19) (2/3 and 1/3 of the initial dose for one week). Blood sampling was performed at various time points up to 18 days after complete withdrawal and was analysed for INR, prothrombin fragment F1 + 2 and D-dimer. All patients were clinically followed-up for the assessment of the association between hypercoagulability and occurrence of disease such as recurrent venous thromboembolism or malignancy.

RESULTS

An approximately fourfold increase was observed (median increase from 0.3 to 1.3 nmol/l) in the F1 + 2 levels after both abrupt and gradual withdrawal and in the D-dimer concentrations in the abrupt withdrawal group (0.10 to 0.44 mg/l), while those in whom acenocoumarol was discontinued gradually showed a less pronounced increase of the D-dimer levels (0.11 to 0.29 mg/L) (not significant). During follow-up one recurrent venous thromboembolic event occurred in each group, and a diagnosis of cancer was made four times. All these patients had the highest D-dimer concentrations measured in the entire study group.

CONCLUSIONS

This study indicates the potential for a hypercoagulable state after acenocoumarol discontinuation, which was not prevented by tapering the acenocoumarol dose. D-dimer, measured 2 to 3 weeks after acenocoumarol withdrawal, might be an important tool to identify patients at risk for recurrent venous thromboembolism and/or for the presence of an underlying malignancy.

Spontaneous cervical epidural hematoma associated with oral anticoagulant therapy

A 54-year-old woman who was on anticoagulant treatment with acenocoumarol for a mitral prothesis developed a cervical spinal epidural hematoma, probably triggered by coughing fits together with supratherapeutic anticoagulation. Because of the subacute evolution of the hematoma, it was not diagnosed until the patient was admitted to the hospital with profuse hemorrhages. Given the subacute nature of the hematoma, along with the favorable evolution, conservative treatment with dexamethasone was decided upon, and it was resolved with almost no sequelae. This unusual clinical entity definitely should be suspected in patients on anticoagulants who complain of severe localized neck pain, most often with radicular irradiation.

Optimal oral anticoagulant intensity to prevent secondary ischemic and hemorrhagic events in patients after infrainguinal bypass graft surgery. Dutch BOA Study Group

OBJECTIVES

The purpose of this study was to determine the optimal intensity of oral anticoagulation in patients who participated in a randomized trial of oral anticoagulants or aspirin after infrainguinal bypass graft surgery.

METHODS

The distribution of patient-time spent in international normalized ratio (INR) classes of 0.5 INR unit was calculated assuming a linear change between successive measurements. INR-specific incidence rates of ischemic and hemorrhagic events were calculated as the ratio of the number of events at a certain INR category and the total patient-time spent in that class. The relationship between INR class and event rates was quantified by rate ratios calculated in a Poisson regression model.

RESULTS

In 1326 patients (mean age, 69 years) 41,928 INR measurements were recorded in 1698 patient-years. Patients spent 50% of the total time within the target range of 3.0 to 4.5 INR. Most of the patient-time (60%) was spent between 2.5 and 3.5 INR. For each increasing class of 0.5 INR, the incidence of ischemic events (n = 154, INR data on event available in 49%) decreased by a factor of 0.97 (95% CI, 0.87-1.08). The incidence of major bleeding (n = 123, INR data on event available in 65%) increased significantly by a factor of 1.27 (95% CI, 1.19-1.34) for each increasing 0.5 INR category. The optimal target range was 3.0 to 4.0 INR, with an incidence of 3.8 events (0.9 ischemic and 2.9 hemorrhagic) per 100 patient-years.

CONCLUSIONS

The target range of 3.0 to 4.0 INR is the optimal range of achieved anticoagulation intensity and is safe for the prevention of ischemic events in patients after infrainguinal bypass graft surgery.

Low molecular weight heparin versus oral anticoagulants in the long-term treatment of deep venous thrombosis

PURPOSE

The purpose of this study was to evaluate whether low molecular weight heparin (LMWH) could be equal or more effective than conventional oral anticoagulants (OAs) in the long-term treatment of deep venous thrombosis (DVT).

METHODS

One hundred fifty-eight patients with symptomatic DVT of the lower limbs confirmed by means of duplex ultrasound scan were randomized to receive 3 to 6 months' treatment with nadroparine calcium or acenocoumarol. Quantitative and qualitative duplex scan scoring systems were used to study the evolution of thrombosis in both groups at 1, 3, 6, and 12 months.

RESULTS

During the 12-month surveillance period, two (2.5%) of the 81 patients who received LMWH and seven (9%) of the 77 patients who received OAs had recurrence of venous thrombosis (not significant). In the LMWH group no cases of major bleeding were found, and four cases (5.2%) occurred in the OA group (not significant). The mortality rate was nine (11.1%) in the LMWH group and 7.8% in the OA group (not significant). The quantitative mean duplex scan score decreased in both groups during the follow-up and had statistical significance after long-term LMWH treatment on iliofemoral DVT (1, 3, 6, and 12 months), femoropopliteal DVT (1-3 months), and infrapopliteal DVT (first month). Duplex scan evaluation showed that the rate of venous recanalization significantly increased in the common femoral vein at 6 and at 12 months and during each point of follow-up in the superficial and popliteal veins in the LMWH group. Reflux was significantly less frequent in communicating veins after LMWH treatment (17.9% vs 32.2% in the OA group). The reflux rates in the superficial (22.4% in the LMWH group, 30.6% in OA group) and deep (13.4% vs 17.7%) venous system showed no significant differences between groups.

CONCLUSIONS

The unmonitored subcutaneous administration of nadroparine in fixed daily doses was more effective than oral acenocoumarol with laboratory control adjustment in achieving recanalization of leg thrombi. With nadroparine, there was less late valvular communicating vein insufficiency, and it was at least as efficacious and safe as oral anticoagulants after long-term administration. These results suggest that LMWHs may therefore represent a real therapeutic advance in the long-term management of DVT.

[Secondary anticoagulant prophylaxis with low molecular heparins or oral anticoagulants and bone mineral density]

A broad spectrum of indications for low molecular weight heparin (LMWH) requires an assessment of side effects especially during prolonged administration. There are common risk factors for venous thromboembolism (VTE) and osteoporosis; heparin is "the drug of choice" for VTE treatment. The aim of our study was to assess the effect of treatment and prophylaxis with LMWH (enoxaparine sodium) and oral anticoagulant (acenocoumarol) for bone structure. Material consists of in- and outpatients. 49 densitometries were performed in 31 patients (in 15 cases double examination). We observed a decrease of bone mineral density in comparison to the initial examination in most cases: mean change of bone mass for examined areas was 3.05%.

Low molecular weight heparin (enoxaparin) versus oral anticoagulant therapy (acenocoumarol) in the long-term treatment of deep venous thrombosis in the elderly: a randomized trial

This study aims to establish the relative effectiveness and safety of low molecular weight heparin in elderly patients with venous thrombosis in order to find an alternative to oral anticoagulant therapy with less bleeding complications in the long-term treatment of deep venous thrombosis (DVT). One hundred consecutive elderly patients (>75 years old) with venographically demonstrated proximal DVT were included in a randomized trial. All patients were treated for ten days with adjusted doses of intravenous heparin. Informed consent was obtained and on the eight day, patients were randomly allocated to receive acenocoumarol (INR 2.0-3.0) or subcutaneous enoxaparin (4000 anti-Xa units once a day) for three months. All patients were followed-up clinically and venographically for a one year period. The results were analyzed with Fisher's exact test or chi-square test as appropriate. During the treatment and surveillance period, 6 of the 50 patients (12%) who received acenocoumarol and 8 of the 50 patients (16%) who received enoxaparin had new episodes of venous thromboembolism confirmed by objective testing (p = 0.6; 95% CI for the difference: -19.5 to 11.5). Hemorrhagic complications occurred in six of the 50 patients (12%) who received acenocoumarol and in one (2%) of those on enoxaparin (p = 0.1; 95% CI for the difference: -1.8 to 21.8). Vertebral fractures developed in 2 patients (4%) in the enoxaparin group (p = 0.5; 95% CI for the difference: -11.4 to 3.4). These results show that fixed dose enoxaparin seems to be effective and safe in the long-term treatment of proximal DVT in the elderly. In comparison with oral anticoagulants, the findings are inconclusive due to the wide confidence intervals for differences between outcomes, however they suggest that the former may have less bleeding complications with similar efficacy.

[Gastrointestinal hemorrhage needing blood transfusion as the first manifestation of small bowel carcinoid tumor]

Carcinoid tumors arise from enterochromaffin or enterochromaffin-like cells that are present in the gastrointestinal tract, ovaries, and lungs. Over 90% of carcinoids originate in the gastrointestinal tract with the most common sites in order of frequency being the appendix, terminal ileum, rectum, and the remainder of the colon. Gastroduodenal and pancreatic carcinoids are infrequent. Carcinoid syndrome is associated with small intestine carcinoids in about 40%. Common symptoms include intermittent intestinal obstruction with crampy abdominal pain and vomiting, and weight loss. Upper gastrointestinal bleeding with melaena or hematochezia is a relatively rare early symptom of patients with small intestine carcinoid tumors. We report on a 69-year-old man, treated with acenocoumarol for previous thromboembolic complications of hereditary protein S deficiency. He was admitted to hospital because of an acute episode of hematochezia followed by melaena. Endoscopic evaluation of esophagus, stomach, duodenum and colonoscopy revealed no apparent source of bleeding. Selective angiographic evaluation of mesenterial arteries showed pathologic vasculature approximately in mid jejunum. Laparotomy revealed bleeding from a small submucosal malignant carcinoid tumor in small intestine and multiple large metastases within mesenteric tissue. Segmental resection of small intestine and exstirpation of the metastatic masses was performed. Postoperative period was uneventful. Cytotoxic chemotherapy in this adjuvant setting has not been recommended. Small intestinal carcinoid tumor has to be considered as a rare cause of gastrointestinal bleeding with melaena or hematochezia. Nevertheless, bleeding is a relatively rare early symptom of patients with small intestine carcinoid tumor.

Assessment of patient capability to self-adjust oral anticoagulant dose: a multicenter study on home use of portable prothrombin time monitor (COAGUCHECK)

BACKGROUND AND OBJECTIVES

Self-testing and self-monitoring with portable prothrombin time (PT) monitors has been shown to be feasible and safe. However the ability of patients on chronic oral anticoagulant therapy (OAT) to self-adjust their dose without specific training has never been properly evaluated. The aims of this study were to evaluate: 1) the ability of patients on chronic OAT to self-adjust their dose without specific training; 2) the integration of a portable PT monitor (Coagucheck, Roche Diagnostics, Germany) for home use into routine patient care in anticoagulation clinics.

DESIGN AND METHODS

A nested case-control study was conducted in four centers of the Italian Federation of Anticoagulation Clinics (FCSA). Patients (n=78) on stable OAT for at least 6 months (cases: 47 men, 31 women, age range: 18-75 years) were enrolled on a volunteer basis after passing an Abbreviated Mental Test and providing informed consent. After three instruction sessions on the use of Coaguchek, subjects performed the PT test at home, communicated the INR results to the Center and suggested the dose adjustment and date for next control as they thought appropriate. However, they were requested to follow the prescription made by the Center. Controls (78 subjects) matched by age (+/- 5 years), sex and therapeutic range with the cases, were selected from among those who attended the anticoagulation clinics and managed by usual care.

RESULTS

When compared with the dose prescribed by the Clinic, the dose suggested by warfarin and acenocoumarol users was equal to or within +/- 6% of the mean weekly dose in 80% and 82% of suggestions, respectively. Time spent in the therapeutic range during the study was the same (80%) for cases and controls.

INTERPRETATION AND CONCLUSIONS

Selected patients on chronic anticoagulant therapy can acquire a satisfactory ability for self-adjustment of OAT dose without specific training.

Potentiation of vitamin K antagonists by high-dose intravenous methylprednisolone

BACKGROUND

Oral anticoagulants and pulse high-dose intravenous methylprednisolone are often administered concomitantly, but no data on potential interactions are available.

OBJECTIVE

To assess possible potentiation of oral anticoagulation by high-dose intravenous methylprednisolone.

DESIGN

Prospective cohort study.

SETTING

University hospital in Paris, France.

PATIENTS

10 consecutive patients concomitantly receiving methylprednisolone and oral anticoagulants (fluindione and acenocoumarol) and 5 consecutive controls receiving methylprednisolone alone.

MEASUREMENTS

Serial determinations of the international normalized ratio (INR) and clotting factors during administration of pulse methylprednisolone. The total plasma fluindione concentration was determined in 3 patients.

RESULTS

The mean INR was 2.75 (range, 2.02 to 3.81) at baseline and increased to 8.04 (range, 5.32 to 20.0) after methylprednisolone administration. Plasma fluindione concentrations and the INR increased after methylprednisolone administration. Methylprednisolone alone did not increase prothrombin time.

CONCLUSIONS

The action of oral anticoagulants is potentiated by intravenous high-dose methylprednisolone. The INR should be monitored daily during concomitant administration of these medications.

Efficacy of oral anticoagulants compared with aspirin after infrainguinal bypass surgery (The Dutch Bypass Oral Anticoagulants or Aspirin Study): a randomised trial

BACKGROUND

Oral anticoagulants and aspirin are antithrombotic drugs that are commonly used in patients with vascular disease. We investigated whether either of these treatments prevented more effectively than the other bypass complications after infrainguinal bypass surgery.

METHODS

We did a multicentre, randomised, open trial. 2690 patients who had undergone infrainguinal grafting were randomly assigned oral anticoagulants (target international normalised ratio 3.0-4.5, n=1339) or aspirin (80 mg daily, n=1351). We followed up patients for a mean of 21 months. The primary outcome was graft occlusion.

FINDINGS

308 graft occlusions occurred in the oral-anticoagulants group compared with 322 in the aspirin group (hazard ratio 0.95 [95% CI 0.82-1.11]), which suggested no overall advantage for either treatment. Oral anticoagulants were beneficial in patients with vein grafts (0.69 [0.54-0.88]), whereas aspirin had better results for nonvenous grafts (1.26 [1.03-1.55]). The composite outcome of vascular death, myocardial infarction, stroke, or amputation occurred 248 times in the oral-anticoagulants group and 275 times in the aspirin group (0.89 [0.75-1.06]). Patients treated with oral anticoagulants had more major bleeding episodes than those treated with aspirin (108 vs 56; 1.96 [1.42-2.71]).

INTERPRETATION

Oral anticoagulation was better for the prevention of infrainguinal-vein-graft occlusion and for lowering the rate of ischaemic events. Aspirin was better for the prevention of non-venous graft occlusion, and was associated with fewer bleeding episodes.

Efficacy of oral anticoagulants compared with aspirin after infrainguinal bypass surgery (The Dutch Bypass Oral Anticoagulants or Aspirin Study): a randomised trial

BACKGROUND

Oral anticoagulants and aspirin are antithrombotic drugs that are commonly used in patients with vascular disease. We investigated whether either of these treatments prevented more effectively than the other bypass complications after infrainguinal bypass surgery.

METHODS

We did a multicentre, randomised, open trial. 2690 patients who had undergone infrainguinal grafting were randomly assigned oral anticoagulants (target international normalised ratio 3.0-4.5, n=1339) or aspirin (80 mg daily, n=1351). We followed up patients for a mean of 21 months. The primary outcome was graft occlusion.

FINDINGS

308 graft occlusions occurred in the oral-anticoagulants group compared with 322 in the aspirin group (hazard ratio 0.95 [95% CI 0.82-1.11]), which suggested no overall advantage for either treatment. Oral anticoagulants were beneficial in patients with vein grafts (0.69 [0.54-0.88]), whereas aspirin had better results for nonvenous grafts (1.26 [1.03-1.55]). The composite outcome of vascular death, myocardial infarction, stroke, or amputation occurred 248 times in the oral-anticoagulants group and 275 times in the aspirin group (0.89 [0.75-1.06]). Patients treated with oral anticoagulants had more major bleeding episodes than those treated with aspirin (108 vs 56; 1.96 [1.42-2.71]).

INTERPRETATION

Oral anticoagulation was better for the prevention of infrainguinal-vein-graft occlusion and for lowering the rate of ischaemic events. Aspirin was better for the prevention of non-venous graft occlusion, and was associated with fewer bleeding episodes.