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van den Besselaar AMHP, Chantarangkul V, Angeloni F, Binder NB, Byrne M, Dauer R, Gudmundsdottir BR, Jespersen J, Kitchen S, Legnani C, Lindahl TL, Manning RA, Martinuzzo M, Panes O, Pengo V, Riddell A, Subramanian S, Szederjesi A, Tantanate C, Herbel P, Tripodi A. International collaborative study for the calibration of proposed International Standards for thromboplastin, rabbit, plain, and for thromboplastin, recombinant, human, plain. J Thromb Haemost 2018; 16:142-149. [PMID: 29065247 DOI: 10.1111/jth.13879] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Indexed: 11/28/2022]
Abstract
Essentials Two candidate International Standards for thromboplastin (coded RBT/16 and rTF/16) are proposed. International Sensitivity Index (ISI) of proposed standards was assessed in a 20-centre study. The mean ISI for RBT/16 was 1.21 with a between-centre coefficient of variation of 4.6%. The mean ISI for rTF/16 was 1.11 with a between-centre coefficient of variation of 5.7%. SUMMARY Background The availability of International Standards for thromboplastin is essential for the calibration of routine reagents and hence the calculation of the International Normalized Ratio (INR). Stocks of the current Fourth International Standards are running low. Candidate replacement materials have been prepared. This article describes the calibration of the proposed Fifth International Standards for thromboplastin, rabbit, plain (coded RBT/16) and for thromboplastin, recombinant, human, plain (coded rTF/16). Methods An international collaborative study was carried out for the assignment of International Sensitivity Indexes (ISIs) to the candidate materials, according to the World Health Organization (WHO) guidelines for thromboplastins and plasma used to control oral anticoagulant therapy with vitamin K antagonists. Results Results were obtained from 20 laboratories. In several cases, deviations from the ISI calibration model were observed, but the average INR deviation attributabled to the model was not greater than 10%. Only valid ISI assessments were used to calculate the mean ISI for each candidate. The mean ISI for RBT/16 was 1.21 (between-laboratory coefficient of variation [CV]: 4.6%), and the mean ISI for rTF/16 was 1.11 (between-laboratory CV: 5.7%). Conclusions The between-laboratory variation of the ISI for candidate material RBT/16 was similar to that of the Fourth International Standard (RBT/05), and the between-laboratory variation of the ISI for candidate material rTF/16 was slightly higher than that of the Fourth International Standard (rTF/09). The candidate materials have been accepted by WHO as the Fifth International Standards for thromboplastin, rabbit plain, and thromboplastin, recombinant, human, plain.
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Affiliation(s)
- A M H P van den Besselaar
- Department of Thrombosis and Hemostasis, and Coagulation Reference Laboratory, Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | | | - F Angeloni
- Hemostasis Reference Laboratory, Hamilton, Canada
| | | | - M Byrne
- National Coagulation Laboratory, St James's Hospital, Dublin, Ireland
| | - R Dauer
- Haematology Laboratory, Pathology Department, Alfred Health, Melbourne, Australia
| | - B R Gudmundsdottir
- Department of Laboratory Hematology and Hemostasis Center, Landspitali University Hospital and University of Iceland School of Medicine, Reykjavik, Iceland
| | - J Jespersen
- Department of Clinical Biochemistry, Hospital of South West Jutland and Unit for Health Promotion Research, Institute of Public Health, University of Southern Denmark, Esbjerg, Denmark
| | - S Kitchen
- Sheffield Haemophilia and Thrombosis Centre, Royal Hallamshire Hospital, Sheffield, UK
| | - C Legnani
- Department of Angiology and Blood Coagulation, University Hospital S. Orsola-Malpighi, Bologna, Italy
| | - T L Lindahl
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - R A Manning
- Department of Coagulation, Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, UK
| | - M Martinuzzo
- Grupo Bioquímico, Laboratorio Central del Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
| | - O Panes
- Department of Hematology-Oncology, School of Medicine, Pontifical Catholic University of Chile, Santiago, Chile
| | - V Pengo
- Clinical Cardiology, Department of Cardiac, Thoracic, and Vascular Sciences, University of Padova, Padova, Italy
| | - A Riddell
- Haemophilia Laboratory (HSL), Katharine Dormandy Haemophilia and Thrombosis Centre, Royal Free Hospital, London, UK
| | - S Subramanian
- Department of Transfusion Medicine and Immunohaematology, St John's Medical College Hospital, Bangalore, India
| | - A Szederjesi
- Hemostasis Laboratory, St István and St László Hospital, Budapest, Hungary
| | - C Tantanate
- Department of Clinical Pathology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - P Herbel
- Roche Diagnostics GmbH Mannheim, Mannheim, Germany
| | - A Tripodi
- Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Department of Clinical Sciences and Community Health, Università degli Studi di Milano and IRCCS Cà Granda Maggiore Hospital Foundation, Milano, Italy
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Onundarson PT, Arnar DO, Lund SH, Gudmundsdottir BR, Francis CW, Indridason OS. Fiix-prothrombin time monitoring improves warfarin anticoagulation outcome in atrial fibrillation: a systematic review of randomized trials comparing Fiix-warfarin or direct oral anticoagulants to standard PT-warfarin. Int J Lab Hematol 2017; 38 Suppl 1:78-90. [PMID: 27426862 DOI: 10.1111/ijlh.12537] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 04/22/2016] [Indexed: 12/01/2022]
Abstract
BACKGROUND Monitoring warfarin with Fiix-prothrombin time (Fiix-PT), which is only affected by coagulation factors II and X, stabilizes anticoagulation and reduces thromboembolism compared to PT/INR monitoring. We compared outcome in nonvalvular atrial fibrillation (NVAF) patients treated with Fiix-warfarin, direct oral anticoagulants (DOACs), or PT-warfarin. METHODS A systematic efficacy and safety assessment by retrieving data from the Fiix trial and the four major phase III DOAC trials in NVAF. Prespecified outcomes included stroke and systemic embolism (SSE), SSE and myocardial infarction (MI), major bleeding (MB), composite major vascular events (SSEMI and MB; CMVE), and deaths. We calculated relative risk, 95% CI, and 95% confidence limits (CL) for each outcome and performed meta-analysis using fixed- and random-effects modeling. RESULTS There were 613 and 628 observation years with Fiix-warfarin and PT-warfarin in the Fiix trial, and 70 628 and 57 962 with DOACs and PT-warfarin in DOAC trials. Populations were comparable although death rates were lower in the Fiix trial. Compared to pooled PT-warfarin, Fiix-warfarin reduced SSE (RR 0.54;95% CI 0.26-1.10/95% CL <1.00), SSEMI (0.51;0.26-0.99/<0.90), MB (RR 0.63;0.37-1.07/<0.99), and CMVE (RR 0.66;0.43-1.00/<0.94). Vascular death was lower (RR 0.13;0.04-0.47/<0.42). Compared to pooled DOACs, Fiix-warfarin consistently had lower point estimates for the RR for efficacy and safety, but only significant for lower death rates (vascular death RR 0.14;0.04-0.49/<0.43). Meta-analysis comparing Fiix-warfarin and DOACs with PT-warfarin consistently found Fiix-warfarin to have the lowest point estimates for efficacy. CONCLUSION Monitoring warfarin with Fiix-PT reduces risk of vascular events in NVAF patients as much as DOACs. Warfarin monitored with Fiix-PT is an improved anticoagulant.
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Affiliation(s)
- P T Onundarson
- Landspitali National University Hospital of Iceland, Reykjavik, Iceland.,University of Iceland Faculty of Medicine, Reykjavik, Iceland
| | - D O Arnar
- Landspitali National University Hospital of Iceland, Reykjavik, Iceland
| | - S H Lund
- University of Iceland Faculty of Medicine, Reykjavik, Iceland
| | | | - C W Francis
- University of Rochester Medical Center, Rochester, NY, USA
| | - O S Indridason
- Landspitali National University Hospital of Iceland, Reykjavik, Iceland
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Jonsson PI, Letertre L, Juliusson SJ, Gudmundsdottir BR, Francis CW, Onundarson PT. During warfarin induction, the Fiix-prothrombin time reflects the anticoagulation level better than the standard prothrombin time. J Thromb Haemost 2017; 15:131-139. [PMID: 27774726 DOI: 10.1111/jth.13549] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Indexed: 01/18/2023]
Abstract
Essentials Fiix-prothrombin time (PT) monitoring of warfarin measuring factor (F) II and X, is effective. Plasma obtained during warfarin induction and stable phase in Fiix-trial was assayed. Fiix-PT stabilized anticoagulation earlier than monitoring with traditional PT-INR. FVII had little effect on thrombin generation that was mainly determined by FII and FX. SUMMARY Background The prothrombin time (PT) is equally prolonged by reduction of each of the vitamin K-dependent (VKD) factors (F) II, VII and X. The Fiix-PT is only affected by FII and FX, the main contributors to thrombin generation (TG). Objective To test the hypothesis that variability in warfarin anticoagulation is reduced early during monitoring with the normalized PT-ratio calculated from Fiix-PT (Fiix-International Normalized Ratio [INR]) compared with traditional PT-INR monitoring. Also, that because of its insensitivity to FVII, Fiix-PT more accurately reflects TG when Fiix-INR and PT-INR are discrepant. Methods Samples from Fiix-trial participants monitored with either Fiix-PT or PT were used. VKD coagulation factors and TG were measured in samples from 40 patients during stable anticoagulation and in serial samples obtained from 26 patients during warfarin induction. TG was assessed in relation to selective reduction in single VKD factors. Results During Fiix-warfarin induction full anticoagulation measured as FII or FX activity was achieved at a similar rate to that with PT-warfarin but subsequently stabilized better. Fiix-INR but not PT-INR mirrored total TG during initiation. During induction, FII (R2 = 0.66) and FX (R2 = 0.52) correlated better with TG and with a steeper slope than did FIX (R2 = 0.37) and in particular FVII (R2 = 0.21). In vitro, FII and FX were the main determinants of TG at concentrations observed during VKA anticoagulation, whereas FVII and FIX had little influence. Conclusions Fiix-PT monitoring reduces anticoagulation variability, suggesting that monitoring FVII has a limited role during VKA management. TG is better reflected by Fiix-PT.
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Affiliation(s)
- P I Jonsson
- Landspitali - The National University Hospital of Iceland, Reykjavik, Iceland
| | - L Letertre
- Landspitali - The National University Hospital of Iceland, Reykjavik, Iceland
| | - S J Juliusson
- Landspitali - The National University Hospital of Iceland, Reykjavik, Iceland
| | - B R Gudmundsdottir
- Landspitali - The National University Hospital of Iceland, Reykjavik, Iceland
| | - C W Francis
- University of Rochester Medical Center, Rochester, NY, USA
| | - P T Onundarson
- Landspitali - The National University Hospital of Iceland, Reykjavik, Iceland
- Faculty of Medicine, University of Iceland School of Health Sciences, Reykjavik, Iceland
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Letertre LR, Gudmundsdottir BR, Francis CW, Gosselin RC, Skeppholm M, Malmstrom RE, Moll S, Hawes E, Francart S, Onundarson PT. A single test to assay warfarin, dabigatran, rivaroxaban, apixaban, unfractionated heparin, and enoxaparin in plasma. J Thromb Haemost 2016; 14:1043-53. [PMID: 26924677 DOI: 10.1111/jth.13300] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 02/04/2016] [Indexed: 11/28/2022]
Abstract
UNLABELLED Essentials Simple and fast assaying of different anticoagulants (ACs) is useful in emergent situations. We used highly diluted prothrombin time (dPT) or highly diluted Fiix-PT (dFiix-PT) to assay ACs. Both tests could quantify target specific anticoagulants and warfarin anticoagulation. Improved results were consistently observed with the dFiix-PT compared with the dPT. SUMMARY Background Assaying anticoagulants is useful in emergency situations or before surgery. Different specific assays are currently needed depending on the anticoagulant. Objectives We hypothesized that levels of warfarin, dabigatran, rivaroxaban, apixaban, and heparins could be measured with use of the diluted prothrombin time (dPT) and diluted Fiix-PT (dFiix-PT), using highly diluted thromboplastin (TP). The latter test is affected only by reduced levels of active factors II and X but corrects test plasma for other deficiencies Methods Increasing TP dilutions were used to identify suitable dilutions to measure dabigatran, rivaroxaban, apixaban, unfractionated heparin (UFH), and enoxaparin. Calibrators containing known amounts of direct oral anticoagulants (DOACs) were used to make standard curves. Citrated plasma samples were obtained from patients taking warfarin or DOACs with known drug concentrations as determined by specific assays. Results The dFiix-PT at a TP dilution of 1:1156 could be used to measure all of the drugs tested at therapeutic concentrations except for fondaparinux. The dPT achieved the same but required two TP dilutions (1:750 and 1:300). The warfarin effect could be assessed by using dFiix-PT at 1:1156 with a PT ratio identical to the international normalized ratio. Six different TPs yielded similar results, but two were less sensitive. Dabigatran, rivaroxaban, and apixaban could be accurately measured in patient samples using both dilute PT assays, but a better correlation was consistently observed between the dFiix-PT and specific assays than with the dPT. Conclusion The dFiix-PT using a single dilution of TP may be suitable to assess the anticoagulant effects of warfarin, dabigatran, rivaroxaban, apixaban, heparin, and enoxaparin.
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Affiliation(s)
- L R Letertre
- Landspitali The National University Hospital of Iceland, Reykjavik, Iceland
| | - B R Gudmundsdottir
- Landspitali The National University Hospital of Iceland, Reykjavik, Iceland
| | - C W Francis
- University of Rochester Medical Center, Rochester, NY, USA
| | - R C Gosselin
- University of California, Davis Medical Center, Sacramento, CA, USA
| | - M Skeppholm
- Danderyd Hospital and Department of Clinical Sciences & Department of Medicine, Solna, Karolinska Institute, Stockholm, Sweden
| | - R E Malmstrom
- Clinical Pharmacology, Karolinska University Hospital & Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden
| | - S Moll
- University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - E Hawes
- University of North Carolina School of Medicine, Chapel Hill, NC, USA
- University of North Carolina Department of Pharmacy, Chapel Hill, NC, USA
| | - S Francart
- University of North Carolina Department of Pharmacy, Chapel Hill, NC, USA
| | - P T Onundarson
- Landspitali The National University Hospital of Iceland, Reykjavik, Iceland
- Faculty of Medicine, University of Iceland School of Health Sciences, Reykjavik, Iceland
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Hjorleifsson E, Sigurdsson MI, Gudmundsdottir BR, Sigurdsson GH, Onundarson PT. Prediction of survival in patients suspected of disseminated intravascular coagulation. Acta Anaesthesiol Scand 2015; 59:870-80. [PMID: 25912049 DOI: 10.1111/aas.12537] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 03/10/2015] [Accepted: 03/15/2015] [Indexed: 01/21/2023]
Abstract
BACKGROUND Although antithrombin (AT), protein C (PC), and antiplasmin (AP) are consumed during disseminated intravascular coagulation (DIC), their association with mortality in patients initially suspected of acute DIC is unknown. We examined how these proteins associate with mortality in consecutive patients initially suspected of DIC, fulfilling or not fulfilling overt DIC criteria. METHODS All consecutive patients clinically suspected of acute DIC during 5 years at a tertiary referral hospital were scored according to overt International Society of Thrombosis and Haemostasis (ISTH) DIC criteria. The influence of ISTH DIC score and measurements of AT, PC, and AP measured in all on mortality was assessed. RESULTS During 1825 occurrences in 1814 patients, 91 fulfilled ISTH criteria for overt DIC (score ≥ 5). Both 28-day and 1-year mortality increased progressively as AT and in particular PC decreased. AT and PC correlated inversely with ISTH score (AT: R(2 ) = 0.14, P < 0.001, PC: R(2 ) = 0.21, P < 0.001). AP decreased when ISTH score of > 3 was reached. The 28-day mortality was 3%, 11%, 16%, 23%, 35%, and 52% and 1-year mortality 5%, 18%, 24%, 36%, 54%, and 63%, respectively for patients with an ISTH score of 0, 1, 2, 3, 4, and ≥5 (P < 0.001 for all). CONCLUSIONS Lowered AT and in particular PC activity was predictive of mortality risk upfront in critically ill patients suspected of acute DIC. Mortality in patients suspected of acute DIC increased progressively across the spectrum of the overt ISTH score and not only in those fulfilling overt DIC criteria.
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Affiliation(s)
- E. Hjorleifsson
- University of Iceland School of Health Sciences; Landspitali National University Hospital; Reykjavik Iceland
| | - M. I. Sigurdsson
- Department of Anaesthesiology and Intensive Care Medicine; Landspitali National University Hospital; Reykjavik Iceland
- Department of Anesthesiology, Perioperative and Pain Medicine; Brigham and Women's Hospital; Boston MA USA
| | - B. R. Gudmundsdottir
- Central Laboratory; Division of Laboratory Hematology and Coagulation Disorders; Landspitali National University Hospital; Reykjavik Iceland
| | - G. H. Sigurdsson
- University of Iceland School of Health Sciences; Landspitali National University Hospital; Reykjavik Iceland
- Department of Anaesthesiology and Intensive Care Medicine; Landspitali National University Hospital; Reykjavik Iceland
| | - P. T. Onundarson
- University of Iceland School of Health Sciences; Landspitali National University Hospital; Reykjavik Iceland
- Central Laboratory; Division of Laboratory Hematology and Coagulation Disorders; Landspitali National University Hospital; Reykjavik Iceland
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Abstract
BACKGROUND Bleeding symptoms are so commonly reported that it is not known whether they associate causally or coincidentally with mild but measurable primary hemostatic defects. OBJECTIVES/PATIENTS/METHODS: In order to evaluate if the mild primary hemostatic defects are truly causative of increased bleeding symptoms, we surveyed a population of healthy teenagers for bleeding symptoms. Using a case-control approach, we then estimated the risk of excessive bleeding associated with low von Willebrand factor (defined as VWF below the 5th percentile of a normal reference population), and with mild platelet dysfunction [PD, defined as concurrent reduced platelet aggregation responses to two agonists (adenosine diphosphate and epinephrine)]. RESULTS Excessive bleeding was present in 63 out of 809 teenagers (7.8%). Among the 49 cases who were tested for VWF, low values by three measures were more commonly present than in 166 controls, specifically, ristocetin cofactor (RCo) activity [20.4% vs. 5.4%, odds ratio (OR) 4.5], collagen binding (14.3% vs. 4.2%, OR 3.8), and antigen level (20.4% vs. 6.0%, OR 4.0). The low RCo values ranged from 35 to 45 U dL(-1) except for a single case with 26 U dL(-1). Of the 47 teenagers with excessive bleeding who underwent platelet aggregation studies, reduced responses were more common than in controls (12.8% vs. 4.4%, OR 3.2). Twenty-nine per cent of cases with excessive bleeding had either low RCo or PD. CONCLUSION Almost one in three teenagers who report excessive bleeding is likely to have a measurable hemostatic disturbance manifested either by marginally low VWF (by three measures) or by mild PD.
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Affiliation(s)
- B R Gudmundsdottir
- Department of Laboratory Hematology and Hemostasis Center and University of Iceland Medical School, Landspitali University Hospital, Reykjavik, Iceland
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Onundarson PT, Gudmundsdottir BR, Arnfinnsdottir AV, Kjeld M, Olafsson O. Von Willebrand factor does not vary during normal menstrual cycle. Thromb Haemost 2001; 85:183-4. [PMID: 11204575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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Haraldsson M, Onundarson PT, Gudmundsdottir BR, Einarsdottir KA, Kristinsson A, Palsson K, Petursson MK. [A prospective study of oral anticoagulation therapy monitored with the P&P-test.]. LAEKNABLADID 1998; 84:32-40. [PMID: 19667428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023] Open
Abstract
OBJECTIVE To analyze the outcome of patients on oral anticoagulation therapy who are monitored with the prothrombin proconvertin time (P&P-test, PP). MATERIAL AND METHODS The prothrombin-proconvertin time was used to adjust anticoagulant intensity in a prospective study of 326 patients treated with oral anticoagulants for a study period of 121 patient years. The goal intensity INR was 2.0-3.0 for all patients. The main indications were: artificial heart valves 26%, venousthromboembolism 25%, atrial fibrillation 23%, atherosclerotic disease 14% and systemic arterial embolism of uncertain etiology 7%. RESULTS INR calculated directly from the PP correlated well with INR calculated from the PT. The mean time adjusted anticoagulant intensity was 2.3 and did not differ significantly according to indication. Six major bleedings, including one fatal, occurred in five patients during the study period. The INR was 1.8 in one patient who bled from a duodenal ulcer, but 6.8,7.9,8.6,11.6 (died) and 15.5 at five other events. The INR was <4.5 during 97% of the treatment time of the whole group and 1% of treat notment time were at an INR>6.0. The bleeders had a different pattern with 18% of the treatment time at INR>6.0. The risk of bleeding was one for every 73 days at that intensity or an almost 600 fold risk increase compared to an INR<4.5. One patient anticoagulated for systemic embolism had cerebral infarction with an event related INR of 2.0. Two patients with atrial fibrillation died from acute myocardial infarction but event related INR's were not available. One patient anticoagulated for venous thromboembolism died suddenly but was not autopsied. No embolic events occurred in patients with artificial heart valves in spite of the low intensity anticoagulation. CONCLUSION Despite a relatively low intensity in all patient groups in this study thromboembolic events were rare. The risk of bleeding increased markedly at INR>6.0. The mortality rate of the ariticoagulated population was comparable to the expected age adjusted Icelandic mortality rate.
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