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PubMed2001

Effect of computer-aided management on the quality of treatment in anticoagulated patients: a prospective, randomized, multicenter trial of APROAT (Automated PRogram for Oral Anticoagulant Treatment).

BACKGROUND AND OBJECTIVES: We carried out a prospective, randomized trial to test whether a computer-based decision support system to initiate and maintain oral anticoagulant (OA) treatment can improve the laboratory quality of therapy. DESIGN AND METHODS: Two separate sets of patients on oral anticoagulants, in five Italian anticoagulant clinics, were studied: 335 patients in the first three months of treatment (stabilization phase), 916 patients (775 patient-years) beyond the third month of treatment (maintenance phase). Patients were randomized to a computerized system, which included algorithms able to suggest OA dosing and to schedule appointments (computer-aided dosing) or to an arm in which OA were prescribed by the same teams of expert physicians without such algorithms (control group). Primary outcomes were: A) the percentage of patients reaching a stable state of anticoagulation during each of the first three months of treatment; B) the percentage of time individuals spent within the aimed therapeutic range (maintenance phase). RESULTS: Patients in the computer-aided dosing group achieved a stable state significantly faster (p<0.01) and they spent more time within the therapeutic range during maintenance (p<0.001) than controls. The favorable effect of computer-aided dosing was mainly due to a reduction of the time spent below the therapeutic range and was associated with an increase of mean INR value, of anticoagulant drug dosage, and with a reduction of the number of appointments per patient (all changes significant: p<0.001). INTERPRETATION AND CONCLUSIONS: The computer decision-aided support improves the laboratory quality of anticoagulant treatment, both during long-term maintenance and in the early, highly unstable phase of treatment, and it also significantly reduces the number of scheduled laboratory controls.

Algorithms↗
PubMed1978

Incidence of emboli with cloth-covered Starr-Edwards valve without anticoagulation and with varying forms of anticoagulation. Analysis of 183 patients followed for 3 1/2 years.

One hundred eighty-three patients with cloth-covered valves were studied from 1 1/2 to 8 years after operation, with an average follow-up time of 3 1/2 years. Over the total period, patients taking Coumadin sustained a 4 percent embolic incidence (1.2 per 100 patient-years); those taking aspirin had a 7 percent incidence (2.6 per 100 patient-years); and those taking Persantine had a 43 percent incidence (10 per 100 patient-years). Patients on no regimen of anticoagulation had a 16 percent embolic rate (four per 100 patient-years), whereas another group of patients who stopped anticoagulants after a year incurred a 13 percent embolic incidence in the subsequent 2 years (6.4 per 100 patient-years). These data showed a significantly lowered embolic rate with anticoagulation and suggest that all patients with cloth-covered valves should be taking anticoagulants. That these valves become epithelialized and do not form thrombus after a year was not borne out by this study. Persantine alone is not a satisfactory anticoagulant. Coumadin appears to be the superior anticoagulant, but if careful monitoring of its use is in question or if serious bleeding complications ensue, aspirin may provide satisfactory protection.

Anticoagulants↗
PubMed1993

In vivo anticoagulant properties of a novel nucleotide-based thrombin inhibitor and demonstration of regional anticoagulation in extracorporeal circuits.

Using a novel in vitro selection/amplification technique, we have recently identified a new class of thrombin inhibitors based on single-stranded DNA oligonucleotides. One oligonucleotide, GGTTGGTGTGGTTGG (thrombin, aptamer), showed potent anticoagulant activity in vitro. We have initiated pharmacologic studies in cynomolgus monkeys to study the thrombin aptamer's in vivo anticoagulant properties. Upon infusion of the thrombin aptamer, anticoagulation was rapidly achieved, with a plateau reached within 10 minutes. There was a linear dose-response relationship between thrombin aptamer infusion rate and prolongation of plasma prothrombin time. Ten minutes after the infusion was stopped, no prolongation of prothrombin time was observed, indicating that the thrombin aptamer has an extremely short in vivo half-life, estimated to be 108 +/- 14 seconds. In addition, inhibition of thrombin-induced platelet aggregation in platelet-rich plasma was observed ex vivo without an effect on collagen-induced aggregation, indicating that the inhibition was specific for thrombin and not due to a nonspecific inhibitory effect on platelets. To exploit the short in vivo half-life of the thrombin aptamer, its ability to achieve regional anticoagulation in an extracorporeal hemofiltration circuit in sheep was tested. Doubling of the prothrombin time in the circuit was observed, whereas the systemic prothrombin time was minimally prolonged. We conclude that the thrombin aptamer is a potent anticoagulant in vivo, and specifically inhibits thrombin-induced platelet aggregation ex vivo. The rapid onset of action and short half-life in vivo suggest that the thrombin aptamer may be useful in anticoagulation with extracorporeal circuits and may have distinct advantages in certain acute clinical settings.

Animals↗
PubMed1996

Potential failure of the International Normalized Ratio (INR) System in the monitoring of oral anticoagulation in patients with lupus anticoagulants.

Patients with antiphospholipid antibody syndrome (APS) experience a higher rate of recurrence of thrombosis than the general population of patients with thrombotic disease. Based on a retrospective analysis, it has been suggested that patients with APS should be kept on prolonged anticoagulation aiming at international normalised ratio (INR) values > 3.0. To evaluate whether the requirement for more intense anticoagulation depends on the variable sensitivity of thromboplastin reagents to the influence of aPLA, we monitored oral anticoagulant treatment in 10 patients with persistent lupus anticoagulants (LA) and venous thromboembolic disease using two thromboplastin reagents: Pro-IL-Complex (Instrumentation Laboratory, combined) and Recombiplastin (Ortho, recombinant). Acenocoumarol dosage was always assigned based on INR values obtained with the combined thromboplastin using diluted (1:20) test plasma, aiming at an INR interval of 2.0 to 3.0. Single INR determinations with both reagents were obtained throughout the study period for 110 aPLA-free patients on stable oral anticoagulation. Using the manufacturer's instrument-certified international sensitivity index (ISI) values, INR obtained with the recombinant reagent were significantly higher than those obtained with the combined reagent in LA-positive patients, but they were lower in LA-negative patients. After correction for local ISI calibration in LA-negative patients, INR values of 3.1 and 4.6 with Recombiplastin corresponded, respectively, to INR values of 2.0 and 3.0 with Pro-IL-Complex. These results indicate the thromboplastin-dependency of INR values in patients with LA, thereby questioning the validity of the INR system for the monitoring of oral anticoagulant treatment in these patients.

Administration, Oral↗
PubMed1998

College of American Pathologists Conference XXXI on laboratory monitoring of anticoagulant therapy: laboratory monitoring of oral anticoagulant therapy.

OBJECTIVE: To review the state of the art of laboratory monitoring of oral anticoagulant therapy, as reflected by the medical literature and the consensus opinion of recognized experts in the field, and to make recommendations for improvement in laboratory monitoring of oral anticoagulant therapy. DATA SOURCES: Review of the medical literature, primarily from the last 10 years, and current laboratory practices by a panel of 8 international experts in the field of oral anticoagulant monitoring. DATA EXTRACTION AND SYNTHESIS: After an initial assessment of the literature, key points were identified. Experts were assigned to do an in-depth review of the literature and current practices relevant to each of the key points and to prepare a summary of their findings and recommendations. A draft manuscript was prepared and circulated to every participant in the College of American Pathologists Conference XXXI on Laboratory Monitoring of Anticoagulant Therapy prior to the conference. Each of the key points and associated recommendations was then presented for discussion at the Conference. Recommendations were accepted if a consensus of the 26 experts attending the Conference was reached. The results of the discussion were used to revise the manuscript into its final form. CONCLUSIONS: Consensus was reached on 12 recommendations concerning the laboratory monitoring of oral anticoagulant therapy. Detailed discussion of the rationale for each of these recommendations is found in the text of this article. Discussion of points on which consensus was not reached is also included in the text. It is hoped that widespread adoption of these recommendations will further improve the laboratory monitoring of oral anticoagulant therapy.

Administration, Oral↗
PubMed1998

A cost-effectiveness analysis of aspirin versus oral anticoagulants after acute myocardial infarction in Italy -- equivalence of costs as a possible case for oral anticoagulants.

AIMS: The recent publication of two large trials of secondary prevention of coronary artery disease with oral anticoagulants (WARIS and ASPECT) has caused a revival of the interest for this antithrombotic therapy in a clinical setting where the use of aspirin is common medical practice. Despite this, the preferential use of aspirin has been supported by an American cost-effectiveness analysis (JAMA 1995; 273: 965). METHODS AND RESULTS: Using the same parameters used in that analysis and incidence of events from the Antiplatelet Trialists Collaboration and the ASPECT study, we re-evaluated the economic odds in favor of aspirin or oral anticoagulants in the Italian Health System, which differs significantly in cost allocation from the United States system and is, conversely, similar to other European settings. Recalculated costs associated with each therapy were 2,150 ECU/ patient/year for oral anticoagulants and 2,187 ECU/patient/year for aspirin. In our analysis, the higher costs of oral anticoagulants versus aspirin due to a moderate excess of bleeding (about 10 ECU/ patient/year) and the monitoring of therapy (168 ECU/ patient/year) are more than offset by an alleged savings for recurrent ischemic syndromes and interventional procedures (249 ECU/ patient/year). CONCLUSIONS: Preference of aspirin vs. oral anticoagulants in a pharmaco-economical perspective is highly dependent on the geographical situation whereupon calculations are based. On a pure cost-effectiveness basis, and in the absence of data of direct comparisons between aspirin alone versus I.N.R.-adjusted oral anticoagulants, the latter are not more expensive than aspirin in Italy and, by cost comparisons, in other European countries in the setting of post-myocardial infarction.

Administration, Oral↗
PubMed2005

Guidelines for implementation of patient self-testing and patient self-management of oral anticoagulation. International consensus guidelines prepared by International Self-Monitoring Association for Oral Anticoagulation.

AIMS: This document provides health care professionals involved in initiating and monitoring oral anticoagulation therapy with guidelines for the provision of safe and effective patient self-testing/patient self-management of oral anticoagulation. METHODS AND RESULTS: The consensus group has critically reviewed the literature and compared the results of usual care (UC) vs. anticoagulation clinic and patient self-management/patient self-testing (PSM/PST). The education and training of patients for self-monitoring are described, together with the suitability of patients, the effect on quality of life and cost-effectiveness. The consensus agrees that patient self-testing and patient self-management are effective methods of monitoring oral anticoagulation therapy, providing outcomes at least as good as, and possibly better than, those achieved with an anticoagulation clinic. All patients must be appropriately selected and trained. Currently available self-testing/self-management devices give INR results which are comparable with those obtained in laboratory testing. The most frequent testing frequency is weekly but lower frequency of testing can be justified based on institutional or patient conditions. CONCLUSIONS: The consensus agrees that there are several points in favour of PST/PSM, for example, a higher degree of medical safety, increased patient education, improved response to changes in lifestyle, increased independence for the patient and improved quality of life.

Administration, Oral↗
PubMed1988

Anticoagulant therapy for prevention of spontaneous abortion in a patient with a lupus anticoagulant.

Lupus anticoagulants are associated with venous and arterial thrombosis and with recurrent spontaneous abortion resulting from placental infarction. Treatment with high-dose prednisone and aspirin has been reported to reduce the otherwise very high frequency of spontaneous abortion in affected women. We report the case of a young woman with an idiopathic lupus anticoagulant who had a history of arterial and venous thrombosis and of previous spontaneous abortion; anticoagulation throughout pregnancy was associated with normal fetal growth and with an absence of placental infarction. We conclude that anticoagulation without concurrent prednisone or aspirin may provide an alternative approach to prevention of habitual abortion in some women with lupus anticoagulants.

Abortion, Spontaneous↗
PubMed1998

Anticardiolipin antibodies predict early recurrence of thromboembolism and death among patients with venous thromboembolism following anticoagulant therapy. Duration of Anticoagulation Study Group.

PURPOSE: To compare the risk of recurrent venous thromboembolism in patients with and without antiphospholipid antibodies. PATIENTS AND METHODS: Anticardiolipin antibodies were tested 6 months after a first or second episode of venous thromboembolism. Of the patients with a first episode of venous thromboembolism only the 412 who received 6 months of anticoagulation were studied. Two hundred and eleven patients with a second episode received oral anticoagulation for 6 months or indefinitely. The therapy was targeted at an international normalized ratio (INR) of 2.0 to 2.85. All patients were followed up for 4 years after enrollment. RESULTS: Among the 412 patients with a first episode of venous thromboembolism the risk of recurrence was 29% in patients with anticardiolipin antibodies and 14% in those without antibodies (P = 0.0013). In those with antibodies, there was an increased risk during the first 6 months after cessation of anticoagulation. The risk of recurrence increased with the titer of the antibodies. Four-year mortality rate was 15% in those with antibodies and 6% in those without (P = 0.01). Among 34 patients with a second event of venous thromboembolism and anticardiolipin antibodies, there were no recurrences during anticoagulant therapy versus 20% in those who received only 6 months of treatment (P = 0.08). CONCLUSIONS: The presence of elevated titers of anticardiolipin antibodies 6 months after an episode of venous thromboembolism is a predictor for an increased risk of recurrence and of death. Patients with anticardiolipin antibodies and venous thromboembolism seem to benefit from prolonged oral anticoagulation.

Aged↗
PubMed1997

Hemorrhagic complication of anticoagulation during pregnancy in a woman with lupus anticoagulant.

BACKGROUND: Lupus anticoagulant is an acquired antiphospholipid antibody that can increase greatly the risk of thromboembolism during pregnancy. Because a baseline elevated activated partial thromboplastin time (PTT) is associated frequently with this antibody, monitoring anticoagulant effect with activated PTT can be unreliable. CASE: A pregnant woman with lupus anticoagulant being treated with adjusted dose heparin experienced concurrent severe thrombotic and hemorrhagic complications. CONCLUSION: This case illustrates the pitfall of activated PTT monitoring when administering anticoagulation therapy to a patient with a baseline elevated activated PTT. We propose that heparin levels be used to monitor anticoagulation in these patients.

Adult↗
PubMed1997

Monitoring of oral anticoagulant therapy in lupus anticoagulant positive patients with the anti-phospholipid syndrome.

Introduction of the International Normalized Ratio (INR) has improved the standardization of laboratory control of oral anticoagulant therapy (OAT). However, it has been reported that misleading INR results can be obtained from OAT patients with lupus anticoagulant (LA). To investigate this claim, we studied 35 OAT patients, 14 of whom had anti-phospholipid syndrome (APS) with a documented LA. Attainment of anticoagulation was confirmed by chromogenic assay of factor VII and factor X. Prothrombin times were performed using eight thromboplastins (five derived from rabbit brain, two recombinant human tissue factor and one made from human placenta) with an International Sensitivity Index (ISI) of <1.40. When using the thromboplastin manufacturers' ISI there was a significant difference (ANOVA, P<0.0001) between INR results obtained with the eight reagents for both APS (average CV = 12.4%) and non-APS (average CV = 12.5%) patient groups. Variation using the eight thromboplastins was assessed by calculating the CV for each sample; these values were then pooled for each patient group to give the average CV for all samples with all reagents for the two patient groups. Results for both patient groups exhibited markedly reduced variation (APS group average CV = 6.5%, non-APS group average CV = 5.8%) when locally assigned ISI values were employed in the calculation of INRs. Our data does not support the suggestion that the INR may not reflect the true level of anticoagulation in the long-term warfarin-treated patient, in whom lupus anticoagulant was detected. However, there was strong evidence that thromboplastin use should be restricted to those clot detection systems for which the reagent's manufacturer has assigned an ISI, or local ISI assignment must be undertaken. The inappropriate use of a generic (i.e. optical or mechanical clot detection system without regard to specific analyser type) ISI value can lead to ambiguous results.

Adult↗
PubMed2001

Laboratory control of oral anticoagulant treatment by the INR system in patients with the antiphospholipid syndrome and lupus anticoagulant. Results of a collaborative study involving nine commercial thromboplastins.

Because of the variable responsiveness of thromboplastins to lupus anticoagulants (LA), concerns have been raised about the validity of the prothrombin time-International Normalized Ratio (PT-INR) in monitoring oral anticoagulant treatment in patients with the antiphospholipid syndrome (APS) and LA. To date, few studies have been performed, numbers of patients investigated are relatively small and results are conflicting. We report on a multicentre study organized to investigate further this clinically relevant issue. Each of nine thrombosis centres was asked to collect plasma samples from patients with APS who were on oral anticoagulants (cases) and patients without APS who were on oral anticoagulants (controls). Nine thromboplastins (three human recombinant, one from human placenta and five from rabbit brain) were calibrated at the co-ordinating centre according to World Health Organization guidelines. Measurements of the INR and factor X amidolytic activity for all frozen plasmas were performed centrally. The numbers of patients investigated were 58 cases and 57 controls. Between-reagent variability of the INR was higher in cases [coefficient of variation (CV) = 12.4%] than in controls (CV = 6.7%), but this was because of one of the thromboplastins only (Thromborel R, human recombinant), which measured considerably higher INR values than the others in cases but not in controls. In conclusion, our data indicate that LA interference on the PT-INR measured with the majority of commercial thromboplastins is not enough to cause concern if insensitive thromboplastins, properly calibrated to assign them an instrument-specific International Sensitivity Index are used. New thromboplastins, especially those made of relipidated tissue factor, should be checked for their responsiveness to LA before they are used to monitor oral anticoagulant treatment in patients with APS.

Animals↗
PubMed1995

A comparison of six weeks with six months of oral anticoagulant therapy after a first episode of venous thromboembolism. Duration of Anticoagulation Trial Study Group.

BACKGROUND: The optimal duration of oral anticoagulant therapy after a first episode of venous thromboembolism is still a matter of debate. METHODS: We performed a multicenter trial comparing six weeks of oral anticoagulant treatment with six months of such therapy in patients who had a first episode of venous thromboembolism. Anticoagulant therapy consisted of warfarin or dicumarol. Of the 902 patients enrolled, 5 were later excluded because they had congenital protein C deficiency; 443 were randomly assigned to receive six weeks of oral anticoagulant therapy with a targeted international normalized ratio (INR) of 2.0 to 2.85, and 454 were randomly assigned to receive six months of such therapy. The initial diagnoses were confirmed by means of venography in cases of deep-vein thromboses (n = 790) and with perfusion-ventilation scanning or angiography in cases of pulmonary embolism (n = 107); recurrences were confirmed in the same way. RESULTS: After two years of follow-up, there had been 123 recurrences of venous thromboembolism that met the diagnostic criteria, 80 in the six-week group (18.1 percent; 95 percent confidence interval, 14.5 to 21.6) and 43 in the six-month group (9.5 percent; 95 percent confidence interval, 6.8 to 12.2). The odds ratio for recurrence in the six-week group was 2.1 (95 percent confidence interval, 1.4 to 3.1). There was no difference in mortality or the rate of major hemorrhage between the six-week and six-month groups. CONCLUSIONS: Six months of prophylactic oral anticoagulation after a first episode of venous thromboembolism led to a lower recurrence rate than did treatment lasting for six weeks. The difference between the two groups occurred between 6 weeks and 6 months after the start of treatment, and the rates of recurrence remained nearly parallel for 1 1/2 years thereafter.

Anticoagulants↗
PubMed1999

A comparison of three months of anticoagulation with extended anticoagulation for a first episode of idiopathic venous thromboembolism.

BACKGROUND: Patients who have a first episode of venous thromboembolism in the absence of known risk factors for thrombosis (idiopathic thrombosis) are often treated with anticoagulant therapy for three months. Such patients may benefit from longer treatment, however, because they appear to have an increased risk of recurrence after anticoagulant therapy is stopped. METHODS: In this double-blind study, we randomly assigned patients who had completed 3 months of anticoagulant therapy for a first episode of idiopathic venous thromboembolism to continue receiving warfarin, with the dose adjusted to achieve an international normalized ratio of 2.0 to 3.0, or to receive placebo for a further 24 months. Our goal was to determine the effects of extended anticoagulant therapy on rates of recurrent symptomatic venous thromboembolism and bleeding. RESULTS: A prespecified interim analysis of efficacy led to the early termination of the trial after 162 patients had been enrolled and followed for an average of 10 months. Of 83 patients assigned to continue to receive placebo, 17 had a recurrent episode of venous thromboembolism (27.4 percent per patient-year), as compared with 1 of 79 patients assigned to receive warfarin (1.3 percent per patient-year, P<0.001). Warfarin resulted in a 95 percent reduction in the risk of recurrent venous thromboembolism (95 percent confidence interval, 63 to 99 percent). Three patients assigned to the warfarin group had nonfatal major bleeding (two had gastrointestinal bleeding and one genitourinary bleeding), as compared with none of those assigned to the placebo group (3.8 vs. 0 percent per patient-year, P=0.09). CONCLUSIONS: Patients with a first episode of idiopathic venous thromboembolism should be treated with anticoagulant agents for longer than three months.

Anticoagulants↗
PubMed2002

Laboratory diagnosis of lupus anticoagulants for patients on oral anticoagulant treatment. Performance of dilute Russell viper venom test and silica clotting time in comparison with Staclot LA.

The detection of lupus anticoagulant (LA) in plasmas from patients on oral anticoagulants is problematic because of their prolonged clotting times. Mixing of patients and normal plasmas prior to testing for LA is employed to overcome this problem. We investigated the diagnostic efficacy of silica clotting time (SCT) and dilute Russell viper venom test (dRVVT) performed at low and high phospholipid concentrations, to diagnose LA in patients on oral anticoagulants, in comparison with Staclot LA (Stago) performed with and without hexagonal phospholipids and normal plasma. Case materials were 114 filtered plasmas from patients on oral anticoagulants with (n = 62) and without (n = 52) the antiphospholipid syndrome. Plasmas were considered LA-positive when Staclot LA (taken as the "gold standard") was diagnostic for LA. Forty-four plasmas were positive with Staclot LA. Forty and 39 of these were also positive with SCT and dRVVT (sensitivity relative to Staclot LA was 91% and 89%, respectively). Seventy plasmas were negative with Staclot LA. Three of these were positive with both SCT and dRVVT (specificity relative to Staclot LA was 96%). Kappa values for measure of agreement were 0.87 and 0.85 (p <0.001), respectively. In conclusion, SCT and dRVVT performed at low and high phospholipid concentrations without normal plasma can be considered as reliable as Staclot LA performed with hexagonal phospholipids and normal plasma to diagnose LA in patients on oral anticoagulants. Advantages of SCT and Drvvt over Staclot LA are easy automation, no need for normal plasma and relatively low cost.

Administration, Oral↗
PubMed2004

[Purification, identification of acoagulatin, an anticoagulation factor from the venom of Chinese Agkistrodon, and observation of its anticoagulation effect].

OBJECTIVE: To isolate and identify an anticoagulation factor, acoagulatin, from the venom of Chinese Agkistrodon and to observe its anticoagulation effect. METHOD: The venom of Chinese Agkistrodon was isolated and purified using ion-exchange chromatography on DEAE-Sepharose Fast Flow and CM-sepharose Fast Flow. High-performance liquid chromatography (HPLC) was performed for determination of the purity of acoagulatin, and SDS-PAGE electrophoresis (with 5% concentrated gel of pH 6.8, 12% separation gel of pH 8.8, Tris-aminoacetic acid buffer of pH 8.3 as the electrode buffer) for determining the relative molecular mass. For observation of the anticoagulation effect, 20 microl acoagulatin solution at the concentration of 0.30, 0.20 and 0.15 microg/microl, respectively, was mixed with 100 microl rabbit anticoagulated plasma and the thrombin time (TT), prothrombin time (PT) and activated partial thromboplastin time (APTT) were determined. RESULTS: Acoagulatin was found to consist of two subunits with relative molecular mass of 14 400 and 17 000 respectively, resulting in the total relative molecular mass of 31 400 as determined by SDS-PAGE. HPLC demonstrated good homogeneity of this protein, which significantly prolonged the PT and APTT without affecting TT. CONCLUSION: DEAE-Sepharose Fast Flow and CM-sepharose Fast Flow ion exchange column chromatographies are effective to isolate acoagulatin of high purity, which possesses anticoagulation effect.

Animals↗
PubMed2004

Anticoagulant monitoring techniques in a heparin-induced thrombocytopenia patient undergoing cardiopulmonary bypass using bivalirudin anticoagulant.

Heparin is widely used as the anticoagulant of choice for cardiopulmonary bypass. However, some patients exposed to heparin therapies develop heparin-induced thrombocytopenia (HIT). Severe complications of HIT-induced thrombosis may lead to end-organ dysfunction and death. Bivalirudin, a hirudin analog, is an alternative anticoagulant that may be used in the patient with HIT without inducing thrombotic disorders. This case report provides a look at the successful use of bivalirudin as the sole anticoagulant in a patient diagnosed with HIT undergoing minimally invasive cardiothoracic surgery requiring cardiopulmonary bypass for severe mitral insufficiency. An 80-year-old male presented to the operating room for a minimally invasive mitral valve repair. Past medical history included mitral valve prolapse, atrial fibrillation, hypertension, and congestive heart failure. Preoperative evaluation noted the existence of HIT with heparin exposure 2 months prior. The decision was made to use bivalirudin as the sole anticoagulant for the operative procedure. Anticoagulation evaluation was performed with both high-does thrombin time (HiTT) and Celite activated clotting time tubes for comparison using a Hemochron device. Cardiopulmonary bypass was initiated, and the patient's mitral valve was repaired using a 34-mm annuloplasty ring. The patient was successfully weaned from bypass. No complications or evidence of HIT exacerbation were noted in the postoperative course.

Aged↗
PubMed1997

Thrombotic events during oral anticoagulant treatment: results of the inception-cohort, prospective, collaborative ISCOAT study: ISCOAT study group (Italian Study on Complications of Oral Anticoagulant Therapy).

The paper reports on rate and type of thrombotic events occurring during the observational, prospective, inception-cohort, multicenter ISCOAT study. 2,745 unselected, daily practice patients, consecutively referring to 34 Italian anticoagulation clinics to monitor the oral anticoagulant treatment, were included in the study from beginning of their first anticoagulant course. During a total follow-up of 2,011 patient-years of treatment 70 thrombotic events (3.5 per 100 patient years) were recorded in 67 patients: 20 fatal (1%), 39 major (1.9%) and 11 minor (0.6%). 34/70 events occurred within the first 90 days of treatment (relative risk - at multivariate analysis - of < or =90 days vs. >90 = 20.6, C.I. 12.7-33.5; p <0.0001). The risk was higher in patients aged > or =70 y (1.62, C.I. 1.0-2.61; p <0.05), and when indication for anticoagulant treatment was peripheral/cerebral arterial disease (1.84, C.I. 1.01-3.36; p <0.05). The frequency of thrombotic events was 17.5% when international normalised ratio (INR) levels were < 1.5, decreasing to 2.3% for INRs within the 2-2.99 category (relative risk of INRs <2.0 vs. > or =2 = 1.88, C.I. 1.16-3.07; p <0.05). The recorded rate of thrombotic events was lower than that reported in the few available studies. A greater risk should be expected during the first 90 days of treatment, when anticoagulation levels are <2.0 INR, in patients > 70 years and in those with cerebrovascular/peripheral arterial disease.

Administration, Oral↗