Procoagulant microparticles are associated with arterial disease in patients with systemic lupus erythematosus.

Microparticles (MPs) have been associated with inflammatory and thrombotic disease. High levels of MPs have been identified in patients with systemic lupus erythematosus (SLE) and associated with cardiovascular disease. We analyzed the procoagulant activity of MPs and its correlation with arteriosclerosis and arterial thrombosis in SLE patients. Eighty-seven patients with SLE were included: 22 (25.3%) with associated antiphospholipid syndrome (APS), 32 (36.8%) without antiphospholipid antibodies (aPL) and 33 (37.9%) with aPL but without APS. Subclinical arteriosclerosis, defined as the presence and number of plaques, was evaluated by ultrasonography of carotid arteries. Thrombotic events were confirmed by objective methods. The procoagulant activity of MPs was determined by a functional assay with annexin V. Subclinical arteriosclerosis was found in 19 (21.8%) patients. Thirteen episodes of arterial thrombosis and eight of venous thrombosis were recorded. The procoagulant activity of MPs was greater in patients with arterial thrombosis (17.28 ± 8.29 nM vs 12.96 ± 7.90 nM, p < 0.05). In patients without arterial thrombosis, greater procoagulant activity of MPs was identified in patients with multiple (≥ 2) carotid plaques (17.26 ± 10.63 nM vs 12.78 ± 7.15 nM, p = 0.04). In the multivariate analysis, the procoagulant activity of MPs was independently associated with multiple (≥ 2) carotid plaques and arterial thrombosis [OR = 1.094 (95%CI 1.010-1.185), p = 0.027 and OR = 1.101 (95%CI 1.025-1.182), p = 0.008; respectively]. In conclusion, the procoagulant activity of MPs is associated with arteriosclerosis burden and arterial thrombosis in patients with SLE.

Long-term follow-up of antiphospholipid syndrome: real-life experience from a single center.

OBJECTIVE: The objective of this paper is to assess the prevalence of the main clinical manifestations and laboratory features at disease onset and during the ensuing 10 years of a large cohort of patients with antiphospholipid syndrome (APS) from a single center. METHODS: The study included all consecutive APS patients followed longitudinally in our center from 2003 to 2013. Descriptive statistics for demographics, clinical and laboratory features and mortality were performed. RESULTS: A total of 160 patients were included. Most of them, 128 (78.8%), were women and the mean (SD) age at diagnosis was 39.1 (14.0) years. The majority of them, 104 (65.0%), had primary APS, 36 (22.5%) had APS associated with systemic lupus erythematous, and 20 (12.5%) had APS associated with other autoimmune disease. During the study period, thrombotic events occurred in 27 (16.9%) patients, the most common being strokes, nonbacterial thrombotic endocarditis and deep venous thrombosis. Regarding obstetric morbidity, 18 women (14.3%) became pregnant and 90% of pregnancies succeeded in having live births. The most common obstetric complication was early pregnancy loss (15% of pregnancies). Prematurity (11.1% of live births) and intrauterine growth restriction (5.6% of live births) were the most frequent fetal morbidities. Ten (6.3%) patients died and the most frequent causes of death were severe thrombosis, hemorrhage, and cancer. Three (0.9%) cases of catastrophic APS occurred. The survival probability at 10 years was 93.8%. CONCLUSIONS: Patients with APS develop significant morbidity and mortality despite current treatment. It is imperative to identify prognostic factors and therapeutic measures to prevent these complications.

The H1 haplotype of the endothelial protein C receptor protects against arterial thrombosis in patients with antiphospholipid syndrome.

INTRODUCTION: Genetic variants in the endothelial protein C receptor gene (PROCR) may contribute to the thrombosis risk by regulating levels of the soluble form of this protein (sEPCR). We evaluated whether PROCR polymorphisms and sEPCR levels play a role in the thrombotic manifestations of antiphospholipid syndrome. MATERIALS AND METHODS: One hundred and seventy-five patients (62 with primary antiphospholipid syndrome, 30 with antiphospholipid syndrome associated with systemic lupus erythematosus, 40 with systemic lupus erythematosus without antiphospholipid antibodies and 43 with systemic lupus erythematosus and antiphospholipid antibodies) and 66 healthy controls were included. PROCR H1 and H3 haplotypes were determined by genotyping 7014G/C and 1651C/G tag-polymorphisms, respectively. sEPCR levels were determined by enzyme-linked immunosorbent assay. RESULTS: PROCR haplotype distribution was similar among groups of patients and controls. PROCR H1 and H3 haplotypes were less prevalent in antiphospholipid syndrome patients with arterial thrombosis than those without arterial thrombosis, but statistical significance was only reached for the H1 haplotype (58.0% vs. 85.7%, p = 0.003; odds ratio: 0.23 [95% CI 0.08-0.65]). No relationship between the PROCR H1 and H3 haplotypes and venous thrombosis was found. sEPCR levels were higher in H3 than in H1 carriers (175.5 [95% CI 60.9-290.1] ng/ml vs. 69.1 [95% CI 61.5-76.9] ng/ml, p < 0.01). No relationship of sEPCR with arterial or venous thrombosis was found. CONCLUSION: The PROCR H1 haplotype was less frequently found in APS patients with arterial thrombosis, suggesting a protective effect of PROCR H1 against arterial thrombosis in these patients. No relationship between sEPCR and thrombosis was found.

Can inherited thrombophilia modulate the clinical phenotype of patients with antiphospholipid syndrome?

OBJECTIVES: The current case-control study was aimed to determine the prevalence and the clinical significance of inherited thrombophilia - factor V Leiden and G20210A prothrombin polymorphisms - in patients with antiphospholipid syndrome (APS). METHODS: 100 patients with APS (77 with primary APS and 23 with systemic lupus erythematosus [SLE]-APS), and 100 patients with first lower extremity deep venous thrombosis (DVT), and 200 healthy individuals as a control groups were analysed. Patients and control group were tested for factor V Leiden and prothrombin G20210A gene polymorphism. RESULTS: Factor V Leiden variant was found in 1% of APS patients, in 3% of healthy individuals (p=0.49), and 16% of patients with first DVT (p<0.0005). Prothrombin gene polymorphism was found in 6% of APS patients and in 2.5% of healthy subjects (p=0.21), and 13% of patients with DVT (p=0.14). In primary APS patients, factor V Leiden was present in 1.3% (1/77) and prothrombin gene polymorphism in 6.5% (5/77). No patient with SLE-APS had factor V Leiden and prothrombin gene variant was present in only one patient (4.3%). Patients with prothrombin polymorphism had higher prevalence of venous thrombosis, with no statistical significance (80% vs. 47.9%, p=0.35). There were no differences in the prevalence of recurrent thrombosis before or after APS diagnosis in patients with or without prothrombin gene polymorphism. CONCLUSIONS: Factor V Leiden and G20210A prothrombin variant seem to play no role in either the development of APS or in the type of involved vessel, with no increased risk of re-thrombosis during follow-up.

Repeated episodes of hypoglycemia as a potential aggravating factor for preclinical atherosclerosis in subjects with type 1 diabetes.

OBJECTIVE: To evaluate through early preclinical atherosclerosis assessment whether repeated episodes of hypoglycemia represent an aggravating factor for macrovascular disease in type 1 diabetes. RESEARCH DESIGN AND METHODS: After sample-size calculation, a case-control study of 25 patients with type 1 diabetes and repeated severe/nonsevere hypoglycemia (H-group) compared with 20 age- and sex-matched type 1 diabetes control subjects (C-group) was designed. Assessment of preclinical atherosclerosis consisted of flow-mediated brachial dilatation (FMD) and carotid and femoral intima-media thickness (IMT) studies. To consider hypoglycemia awareness, two different questionnaires and symptomatic response to an acute induction to hypoglycemia were used. Evaluation of the glycemic profile was obtained from continuous glucose monitoring. Endothelial function/inflammation markers were measured in euglycemia/hypoglycemia. A multivariate linear regression analysis was performed to test whether repeated hypoglycemia was independently associated with atherosclerosis. RESULTS: H-group subjects displayed hypoglycemia unawareness and presented a higher percentage of continuous glucose values and area under the curve <70 mg/dl compared with the C-group (14.2 ± 8.9 vs. 6.3 ± 7.1%, P < 0.02 and 2.4 ± 1.8 vs. 0.6 ± 1.0 mg/dl/day, P < 0.01). The percentage of maximal FMD was lower in the H-group than in the C-group (6.52 ± 2.92 vs. 8.62 ± 3.13%, P < 0.05). A significantly higher IMT was observed at both carotid and femoral sites in the H-group (carotid 0.53 ± 0.09 vs. 0.47 ± 0.08 mm, P < 0.05 and femoral 0.51 ± 0.17 vs. 0.39 ± 0.09 mm, P < 0.05). Baseline inflammation and endothelial function markers were higher in the H-group (leukocytes 7.0 ± 1.8 vs. 5.6 ± 1.4 × 10³/ml, von Willebrand factor 119 ± 29 vs. 93 ± 26%, fibrinogen 2.82 ± 0.64 vs. 2.29 ± 0.44 g/l, and soluble intercellular adhesion molecule-1 408 ± 224 vs. 296 ± 95 ng/ml; P < 0.05 for all). CONCLUSIONS: In addition to the induction of hypoglycemia unawareness and an increased risk for severe hypoglycemia, repeated hypoglycemia could be related to and considered an aggravating factor for preclinical atherosclerosis in type 1 diabetes. The precise mechanisms explaining this association remain to be clarified.

Solid cancer, antiphospholipid antibodies, and venous thromboembolism.

The pathogenic role of antiphospholipid antibodies (aPL) in the development of venous thromboembolism (VTE) in patients with malignancies has not been established. From May 2006 to April 2008, 258 consecutive patients with solid-organ malignancies who developed VTE (VTE+) were recruited. A group of 142 patients matched for age, sex and tumor type cancer patients without VTE (VTE-) and an age-and-sex matched group of 258 healthy subjects were also included. A second blood sample was taken in positive aPL patients at least 12 weeks later. Twenty-one (8.1%) VTE+ patients, 2 (1.4%) VTE- patients (p=0.006) and 2 (0.8%) healthy subjects (p<0.001) were positive for aPL. Persistent aPL positivity was observed in only 4 out of 15 available VTE+ patients. No differences in demographic characteristics, clinical pattern and outcome were observed in VTE+ patients according to aPL status. The low prevalence and transience of aPL positivity in patients with solid-organ malignancies with VTE argues against a pathogenic role in the development of thrombosis in this setting. The published evidence of the relationship between cancer, aPL, and thrombosis is reviewed.

Thrombin-activatable fibrinolysis inhibitor genetic polymorphisms as markers of the type of acute coronary syndrome.

INTRODUCTION: In patients with coronary disease at risk of acute coronary events it is unclear which biological factors could predict the type of acute coronary syndrome clinical presentation. The aim of the study was to investigate the role of genetic polymorphisms in key proteins in fibrinolysis in the type of acute coronary syndrome. MATERIALS AND METHODS: 248 patients with acute coronary syndrome (unstable angina or myocardial infarction) (77% male, mean age 60.75 SD 13.30years) were prospectively recruited. PAI-1 (type-1 plasminogen activator inhibitor) 4G/5G and TAFI (thrombin-activatable fibrinolysis inhibitor) Ala147Thr, C+1542G, and Thr325Ile polymorphisms were determined by PCR. RESULTS: 147 (59.3%) patients presented with ST-segment elevation acute coronary syndrome (all Q-wave myocardial infarction), and 101 (40.7%) with non-ST-elevation acute coronary syndrome (52 non-Q wave myocardial infarction, and 49 unstable angina). Homozygous TAFI +1542G and TAFI 325Ile genotypes were less prevalent in patients with ST elevation acute coronary syndrome (p<0.001, OR: 0.22, 95% CI 0.10-0.50 and p<0.001, OR: 0.25, 95% CI 0.11-0.55, respectively). There were no differences in TAFI Ala147Thr or PAI genotype distribution between ST elevation and non-ST elevation acute coronary syndrome. In the multivariate analysis including clinical variables, the best model for ST elevation acute coronary syndrome included TAFI +1542GG (p<0.001, OR: 0.17, 95% CI 0.07-0.30), age (in years, p<0.005, OR: 0.97, 95% CI 0.94-0.98) and dyslipidemia (p<0.005, OR: 2.33, 95% CI 1.42-3.80). CONCLUSION: TAFI polymorphism C+1542G and Thr325/Ile are related to the type of acute coronary syndrome. Patients with coronary disease would benefit from individualized cardiovascular prophylaxis based on genetic risk.

Preparation for pacemaker or implantable cardiac defibrillator implants in patients with high risk of thrombo-embolic events: oral anticoagulation or bridging with intravenous heparin? A prospective randomized trial.

AIMS: Current guidelines recommend stopping oral anticoagulation (OAC) and starting heparin infusion before implanting/replacing a pacemaker/implantable cardioverter-defibrillator (ICD) in patients with high risk for thrombo-embolic events. The aim of this study was to demonstrate that the maintenance of OAC during device implantation/replacement is as safe as bridging to intravenous heparin and shortens in-hospital stay. METHODS AND RESULTS: A cohort of 101 consecutive patients with high risk for embolic events and indication for implant/replacement of a pacemaker/ICD were randomized to two anticoagulant strategies: bridging from OAC to heparin infusion (n = 51) vs. maintenance of OAC to reach an INR = 2 +/- 0.3 at the day of the procedure (n = 50). Haemorrhagic and thrombo-embolic complications were evaluated at discharge, 15 and 45 days after the procedure. A total of 4/51 patients (7.8%) from heparin group and 4/50 (8.0%) from the OAC group developed pocket haematoma following the implant (P = 1.00). One haematoma in each group required evacuation (1.9 vs. 2%, P = 1.00). No other haemorrhagic events or embolic complications developed during the follow-up. Duration of the hospital stay was longer in the heparin group [median of 5 (4-7) vs. 2 (1-4) days; P < 0.001]. CONCLUSION: Implant of devices maintaining OAC is as safe as bridging to heparin infusion and allows a significant reduction of in-hospital stay.

Factor XIII-A subunit Val34Leu polymorphism is associated with the risk of thrombosis in patients with antiphospholipid antibodies and high fibrinogen levels.

Recent reports have described the factor XIII A subunit (FXIII-A) Val34Leu polymorphism as a protective factor against venous and arterial thrombosis. The aim of this study was to investigate the association between the FXIII-A Val34Leu polymorphism, its interaction with fibrinogen concentration, and thrombosis in patients with antiphospholipid antibodies (aPL). We included 172 consecutive patients with aPL: 88 with primary antiphospholipid syndrome (APS), 38 with APS associated with systemic lupus erythematosus (APS-SLE), 32 with SLE and aPL but without APS (SLE-aPL), and 14 asymptomatic individuals with aPL (A-aPL). The FXIII-A Val34Leu polymorphism was assessed by polymerase chain reaction techniques. We found no significant differences in FXIII-A Leu34 allele frequencies between primary APS (allele frequency 0.22), APS-SLE (0.23), SLE-aPL (0.22) and A-aPL (0.32) patients, or between patients with (0.21) and without thrombosis (0.26). FXIII-A Leu34 allele frequencies were significantly lower in patients with thrombosis and those in the upper fibrinogen tertile (>3.40 g/l) (allele frequency 0.07) compared with patients without thrombosis in the upper fibrinogen tertile (0.29) and patients with (0.29) and without (0.25) thrombosis in the mid- and lower fibrinogen tertiles. The FXIII-A Leu34 allele had a protective effect against thrombosis in patients in the upper fibrinogen tertile (odds ratio [OR] = 0.20, 95% confidence interval [CI] 0.07-0.60) but not in those in the other tertiles (OR = 1.20, 95% CI 0.67-2.16). The FXIII-A Leu34 allele seems to have a protective effect on the development of thrombosis in patients with aPL, but only in those with high plasma fibrinogen values.

[Impact of implementing common guidelines at different care levels in a healthcare area on the improvement of atrial fibrillation treatment]. / Impacto de la instauración de un protocolo común en los distintos niveles asistenciales de un área sanitaria para la mejora del tratamiento de la fibrilación auricular.

INTRODUCTION AND OBJECTIVES: Atrial fibrillation (AF) is treated in different settings by different specialists. The objective of the study was to analyze the impact of the implementation of a practice guideline about AF treatment common to the different levels of health attention on the adequacy of AF treatment and on corrective interventions. METHODS: The study was performed in two periods, before and after the implementation of a practice guideline common to all health care levels. In each period, patients with AF who consulted to any of the health care attention levels of a sanitary area were included. Data referring to treatment and compliance of guidelines before and after the visit were recorded prospectively. RESULTS: 293 patients were included in the first period and 267 in the second one. After the guideline implementation, adequacy before the visit, both of antiarrythmic treatment and of antithrombotic prophylaxis were superior than in the first period (80% vs 71%, P=.009 and 81% vs 67%, P<.001, respectively). The percentage of improvement in case of a previous inadequacy of antithrombotic prophylaxis was significantly better in the second period than in the first one (35% vs 9%, P<.001), but the percentage of corrective interventions on antiarrhythmic treatment was similar in both periods. CONCLUSIONS: The implementation of a common practice guideline in the different levels of health care attention is useful to improve adequacy of AF treatment, although there is still some reluctance to change an inadequate antiarrythmic treatment.

Impacto de la instauración de un protocolo común en los distintos niveles asistenciales de un área sanitaria para la mejora del tratamiento de la fibrilación auricular / Impact of implementing common guidelines at different care levels in a healthcare area on the improvement of atrial fibrillation treatment

Introducción y objetivos. La fibrilación auricular (FA) se trata en múltiples ámbitos asistenciales. El objetivo del estudio fue analizar el impacto de la instauración de un protocolo de tratamiento de la FA común a todos ellos en la adecuación del tratamiento y en las intervenciones correctoras en caso de inadecuación. Métodos. El estudio se realizó en 2 períodos, antes y después de la elaboración y difusión de un protocolo de tratamiento de la FA común para los distintos ámbitos de atención sanitaria de un hospital de tercer nivel y de un centro de atención primaria relacionado. En cada período se incluyó a todos los pacientes adultos con FA que consultaron en ellos. Se registraron el tratamiento de la FA y la adecuación de éste a las guías clínicas vigentes antes y después de la visita. Resultados. Se incluyó a 293 pacientes en el primer período y a 267 en el segundo. La adecuación antes de la visita fue superior en el segundo período (tratamiento antiarrítmico del 80 frente al 71%; p = 0,009; profilaxis antitrombótica del 81 frente al 67%; p < 0,001). El porcentaje de intervenciones correctoras en caso de profilaxis antitrombótica inadecuada fue superior en el segundo período (el 35 frente al 9%; p < 0,001), pero este porcentaje no cambió en el tratamiento antiarrítmico. Conclusiones. La elaboración y difusión de un protocolo de tratamiento de la FA común a los distintos ámbitos asistenciales es útil para la mejora de la adecuación del tratamiento de la FA, pero persiste la reticencia a cambiar un tratamiento antiarrítmico inadecuado (AU)

Introduction and objectives. Atrial fibrillation (AF) is treated in different settings by different specialists. The objective of the study was to analyze the impact of the implementation of a practice guideline about AF treatment common to the different levels of health attention on the adequacy of AF treatment and on corrective interventions. Methods. The study was performed in two periods, before and after the implementation of a practice guideline common to all health care levels. In each period, patients with AF who consulted to any of the health care attention levels of a sanitary area were included. Data referring to treatment and compliance of guidelines before and after the visit were recorded prospectively. Results. 293 patients were included in the first period and 267 in the second one. After the guideline implementation, adequacy before the visit, both of antiarrythmic treatment and of antithrombotic prophylaxis were superior than in the first period (80% vs 71%, P=.009 and 81% vs 67%, P<.001, respectively). The percentage of improvement in case of a previous inadequacy of antithrombotic prophylaxis was significantly better in the second period than in the first one (35% vs 9%, P<.001), but the percentage of corrective interventions on antiarrhythmic treatment was similar in both periods. Conclusions. The implementation of a common practice guideline in the different levels of health care attention is useful to improve adequacy of AF treatment, although there is still some reluctance to change an inadequate antiarrythmic treatment (AU)

No impact of factor IX Ala-10 mutations in acenocoumarol-treated southern Europeans.

Increased risk of bleeding during oral anticoagulant (OA) treatment may be related to mutations in the precursor of coagulation factor IX. Missense mutations at Ala-10 (Ala-10Thre and Ala-10Val) in the factor IX propeptide lead to impaired carboxylation of factor IX. When patients carrying these mutations are treated with coumarins, functional factor IX levels decrease significantly, leading to an excessively prolonged activated partial thromboplastin time (aPTT) and an increased bleeding risk. Mutations at Ala-10 have been described in northern-European patients, but it is not known whether geographical differences play a role in the prevalence of these mutations. We aimed to analyze the prevalence of mutations at Ala-10 in factor IX in southern-European patients on OA treatment. Patients attending the Oral Anticoagulant Unit of the Hospital Clinic were prospectively included. The aPTT was determined at their normal International Normalized Ratio (INR) control. When the aPTT was excessively prolonged for the INR value, determination of factor IX and genotyping for Ala-10 mutations was performed. A total of 2360 patients were included (1289 men, 1071 women; mean age, 70.5 +/- 12.1 years). Twenty-four patients (16 men, eight women; mean age, 61.0 +/- 16.2 years) had an aPTT over that expected for the INR. The mean aPTT was 69.6 +/- 16.2 s. Only one patient presented with a factor IX level lower than 10%. None of the 24 patients carried mutations at Ala-10. Mutations at Ala-10 in factor IX were non-existent in the southern-European population analyzed, and thus, do not represent a relevant cause of bleeding during OA treatment.

A randomized unblinded pilot study comparing albumin versus hydroxyethyl starch in spontaneous bacterial peritonitis.

The administration of albumin improves circulatory function, prevents hepatorenal syndrome, and reduces hospital mortality in patients with cirrhosis and spontaneous bacterial peritonitis. This randomized unblinded pilot study compared the effect of albumin (10 patients) and the synthetic plasma expander hydroxyethyl starch 200/0.5 (10 patients) on the systemic hemodynamics of patients with spontaneous bacterial peritonitis. Baseline measurements were performed within 12 hours after diagnosis of infection. Patients then received 2 doses of the volume expander (1.5 g/kg body weight after baseline measurements and 1 g/kg body weight on day 3). Measurements were repeated after infection resolution. Treatment with albumin was associated with a significant increase in arterial pressure and a suppression of plasma renin activity, indicating an improvement in circulatory function. This occurred in the setting of a significant expansion of central blood volume (increase in cardiopulmonary pressures and atrial natriuretic factor) and an increase in systolic volume and systemic vascular resistance. In contrast, no significant changes were observed in these parameters in patients treated with hydroxyethyl starch. Von Willebrand-related antigen plasma levels significantly decreased in patients treated with albumin but not in those treated with hydroxyethyl starch. Serum nitrates and nitrites increased in patients treated with hydroxyethyl starch but not in those treated with albumin. These data suggest an effect of albumin on endothelial function. In conclusion, albumin but not hydroxyethyl starch improves systemic hemodynamics in patients with spontaneous bacterial peritonitis. This effect is due not only to volume expansion but also to an action on the peripheral arterial circulation.

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 (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.