Evaluation of treatment with direct thrombin inhibitors in patients with heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia in lower extremity free tissue transfers

BACKGROUND

Heparin-induced thrombocytopenia (HIT) an immunologically mediated reaction to heparin products, can lead to severe thrombocytopenia and potentially life-threatening thrombotic events. In microsurgery, a missed or delayed diagnosis of HIT can cause complications requiring revision operations, flap loss, or limb loss. Surgeons must remain vigilant for this uncommon yet potentially devastating condition and keep abreast of management strategies.

METHODS

CPT and ICD-10 codes in electronic medical records were used to collect demographic information, clinical courses, and outcomes for patients with a HIT diagnosis who underwent lower extremity free tissue transfer in one institution.

RESULTS

The authors' institution performed 415 lower extremity free flaps in 411 patients during the 10-year study period. Flap salvage rate was 71% for compromised lower extremity flaps without HIT, and 25% in those with HIT. Four patients (four flaps) met study inclusion criteria during the study period. Three of the four flaps failed and were later debrided; one was rescued after a takeback for anastomosis revision. Two patients successfully underwent a delayed second free flap procedure after recovery, and one was salvaged with a pedicled muscle flap.

CONCLUSIONS

Surgeons should monitor for HIT by establishing coagulation panel and platelet count baselines and trending these values in the early post-operative period for patients treated with heparin products. The 4T score can be used to screen for HIT with high clinical suspicion. Arterial thrombosis or poor flap perfusion despite sound microvascular technique could suggest HIT. Surgical and medical management including strict heparin avoidance can prevent adverse events for these patients.

Novel Strategy to Combat the Procoagulant Phenotype in Heparin-Induced Thrombocytopenia Using 12-LOX Inhibition

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is a major concern for all individuals that undergo cardiac bypass surgeries or require prolonged heparin exposure. HIT is a life- and limb-threatening adverse drug reaction with an immune response following the formation of ultra-large immune complexes that drive platelet activation through the receptor FcγRIIA. Thrombotic events remain high following the standard of care treatment with anticoagulants, while increasing risk of bleeding complications. This study sought to investigate a novel approach to treatment of HIT. Recent reports demonstrate increased procoagulant activity in HIT; however, these reports required analysis ex vivo, and relevance in vivo remains unclear.

METHODS

Using human and mouse model systems, we investigated the cooperativity of PARs (protease-activated receptors) and FcγRIIA in HIT. We challenged humanized FcγRIIA transgenic mice with or without endogenous mouse Par4 (denoted as IIA-Par4+/+ or IIA-Par4-/-, respectively) with a well-established model IgG immune complex (anti [α]-CD9). Furthermore, we assessed the procoagulant phenotype and efficacy to treat HIT utilizing inhibitor of 12-LOX (12[S]-lipoxygenase), VLX-1005, previously reported to decrease platelet activation downstream of FcγRIIA and PAR4, using the triple allele HIT mouse model.

RESULTS

IIA-Par4+/+ mice given αCD9 were severely thrombocytopenic, with extensive platelet-fibrin deposition in the lung. In contrast, IIA-Par4-/- mice had negligible thrombocytopenia or pulmonary platelet-fibrin thrombi. We observed that pharmacological inhibition of 12-LOX resulted in a significant reduction in both platelet procoagulant phenotype ex vivo, and thrombocytopenia and thrombosis in our humanized mouse model of HIT in vivo.

CONCLUSIONS

These data demonstrate for the first time the need for dual platelet receptor (PAR and FcγRIIA) stimulation for fibrin formation in HIT in vivo. These results extend our understanding of HIT pathophysiology and provide a scientific rationale for targeting the procoagulant phenotype as a possible therapeutic strategy in HIT.

A Historical Perspective on the Reversal of Anticoagulants

There has been a landmark shift in the last several decades in the management and prevention of thromboembolic events. From the discovery of parenteral and oral agents requiring frequent monitoring as early as 1914, to the development of direct oral anticoagulants (DOACs) that do not require monitoring or dose adjustment in the late 20th century, great advances have been achieved. Despite the advent of these newer agents, bleeding continues to be a key complication, affecting 2 to 4% of DOAC-treated patients per year. Bleeding is associated with substantial morbidity and mortality. Although specific reversal agents for DOACs have lagged the release of these agents, idarucizumab and andexanet alfa are now available as antagonists. However, the efficacy of these reversal agents is uncertain, and complications, including thrombosis, have not been adequately explored. As such, guidelines continue to advise the use of nonspecific prohemostatic agents for patients requiring reversal of the anticoagulant effect of these drugs. As the indications for DOACs and the overall prevalence of their use expand, there is an unmet need for further studies to determine the efficacy of specific compared with nonspecific pro-hemostatic reversal agents. In this review, we will discuss the evidence behind specific and nonspecific reversal agents for both parenteral and oral anticoagulants.

A Multicenter Retrospective Evaluation of Direct Oral Anticoagulants for the Treatment of Heparin-Induced Thrombocytopenia

INTRODUCTION

Direct oral anticoagulants (DOACs) represent an off-label but potential alternative to traditional therapies for heparin-induced thrombocytopenia (HIT).

OBJECTIVE

The objective of this study was to evaluate the efficacy and safety of DOACs in patients with a diagnosis of laboratory-confirmed HIT.

METHODS

A multicenter retrospective cohort study of adult patients with HIT treated with apixaban, rivaroxaban, or dabigatran between 1 January 2013 and 1 January 2020 was performed. Patients with an intermediate or high pre-test probability for HIT and a positive antiplatelet factor 4/heparin complex assay, latex immunoturbidimetric assay, or serotonin release assay were included for analysis. The primary outcome was the composite of newly diagnosed venous or arterial thromboembolism, gangrene, or severe limb ischemia requiring amputation at 3 months following DOAC initiation. This study was approved by local institutional review boards, and the requirement for informed consent was waived.

RESULTS

A total of 77 patients from four health systems were included. The median 4Ts score was 5 (interquartile range 4.5-6), and 38 patients (49.4%) had a diagnosis of HIT with thrombosis. The most frequently used DOAC was apixaban (n = 51), followed by rivaroxaban (n = 24) and dabigatran (n = 2). In total, 63 (81.8%) patients received parenteral non-heparin anticoagulation prior to DOAC initiation. Nine patients (11.7%) experienced the primary outcome of HIT-related thrombotic events. Of the 14 patients who exclusively received DOAC therapy, none experienced the primary outcome. Major bleeding occurred in five (6.5%) patients.

CONCLUSION

In this retrospective cohort study, DOACs were associated with rates of thrombotic and hemorrhagic events similar to those with other therapies currently used in the treatment of HIT.

Is bivalirudin an alternative anticoagulant for extracorporeal membrane oxygenation (ECMO) patients? A systematic review and meta-analysis

BACKGROUND

Anticoagulation is important for extracorporeal membrane oxygenation (ECMO). Heparin is widely used; however, in some cases, it is not suitable for patients. Bivalirudin has been recently proposed for ECMO patients, and there is no evidence regarding its effectiveness and safety.

OBJECTIVE

We aimed to systematically review the effectiveness and safety of bivalirudin in ECMO patients.

STUDY DESIGN AND METHODS

PubMed, Web of Science, Cochrane Library, and EMBASE were searched to find relevant research on the use of bivalirudin versus heparin for anticoagulation in ECMO patients. Outcomes included in-hospital mortality, ECMO duration, major bleeding events, thrombosis events and circuit intervention events. Types of studies included randomized control trials (RCTs), cohort studies, and case-control studies. Case reports, studies lacking comparison with heparin, and where patients transitioned between heparin and bivalirudin, were excluded. Publication bias was evaluated when the number of included studies was more than ten. Sensitivity analysis was performed to examine the stability of the results.

RESULTS

Ten articles were selected, and nine articles were included in the meta-analysis. The results of the meta-analysis showed hospital mortality [OR = 0.65, 95%CI (0.44, 0.95), P = 0.03] and thrombosis events decreased (OR = 0.55, 95%CI [0.37, 0.83], P = 0.004) in bivalirudin group compared with heparin in adult patients. Major bleeding events (OR = 0.66, 95%CI [0.17, 2.55], P = 0.55), ECMO duration (MD = 18.92, 95%CI [-29.33, 67.17], P = 0.44) and circuit intervention events (OR = 1.67, 95%CI [0.54, 5.18], P = 0.37) in the bivalirudin group was not statistically significant compared with the heparin group.

CONCLUSION

Bivalirudin may provide survival benefits and reduce thrombosis in adult patients on ECMO compared with heparin. There is no difference in treating major bleeding events between bivalirudin and heparin group. However, because all included studies were retrospective observational studies, the evidence level of this systematic review is low and heterogeneity could not be avoided. More high-quality clinical studies are urgently needed to confirm these benefits.

Superior outcomes with Argatroban for heparin-induced thrombocytopenia: a Bayesian network meta-analysis

Background Argatroban, lepirudin, desirudin, bivalirudin, and danaparoid are commonly used to manage heparin-induced thrombocytopenia related complications. However, the most suitable drug for this condition still remains controversial. Aim of the review This Bayesian network meta-analysis study compared the most common anticoagulant drugs used in the management of heparin-induced thrombocytopenia. Method All clinical trials comparing two or more anticoagulant therapies for suspected or confirmed heparin-induced thrombocytopenia were considered for inclusion. Studies concerning the use of heparins or oral anticoagulants were not considered. Data concerning hospitalisation length, thromboembolic, major, and minor haemorrhagic events, and mortality rate were collected. The network analyses were made through the STATA routine for Bayesian hierarchical random-effects model analysis with standardised mean difference (SMD) and log odd ratio (LOR) effect measures. Results Data from a total of 4338 patients were analysed. The overall mean age was 62.31 ± 6.6 years old. Hospitalization length was considerably shorter in favour of the argatroban group (SMD: − 1.70). Argatroban evidenced the lowest rate of major (LOR: − 1.51) and minor (LOR: − 0.57) haemorrhagic events. Argatroban demonstrated the lowest rate of thromboembolic events (LOR: 0.62), and mortality rate (LOR: − 1.16). Conclusion Argatroban performed better overall for selected patients with HIT. Argatroban demonstrated the shortest hospitalization, and lowest rate of haemorrhages, thromboembolisms, and mortality compared to bivalirudin, lepirudin, desirudin, and danaparoid.

Heparin induced thrombocytopenia: position paper from the Italian Society on Thrombosis and Haemostasis (SISET)

Heparin induced thrombocytopenia (HIT) is a rare immune mediated adverse drug reaction occurring after exposure to heparin. It is a serious and potentially fatal condition, which may be associated with the development of arterial or venous thrombotic events. Although known for many years, HIT is still often misdiagnosed. Pre- test clinical probability, screening for anti-PF4/heparin antibodies and documentation of their platelet activating capacity are the cornerstones of diagnosis. However, both clinical algorithms and test modalities have limited predictive values and limited diffusion so that the diagnosis and management is challenging in the clinical practice. For this reason, there is an unmet need for novel rational non-anticoagulant therapies based on the pathogenesis of HIT.The present paper reports the position of the Italian Society on Haemostasis and Thrombosis (SISET) in order to increase awareness of HIT among clinicians and other health care professionals and to provide information on the most appropriate management.

Prognostic factors for patients with heparin-induced thrombocytopenia: a systematic review

Background  Little is known with regards to the prognostic factors for patients with suspected or diagnosed Heparin-Induced Thromobocytopenia (HIT). The role of patient and therapy characteristics may play a role in predicting the outcome. Aim of the review To investigate the role of patient and therapy characteristics as potential prognostic factors for HIT-related complications (haemorrhagic and thromboembolic events), and mortality. Method The present systematic review was conducted according to the PRISMA statement. In September 2020, the main online databases were accessed: Pubmed, EMBASE, Scopus, Google Scholar. All the clinical trials concerning the management of patients with suspected or confirmed HIT were eligible. Studies evaluating the use of oral anticoagulants (e.g. vitamin K antagonists, Apixaban) were not considered, along with those comparing the use of heparin. For pairwise correlation, the Pearson Product-Moment Correlation Coefficient (r) was used. The final effect was evaluated according to the Cauchy-Schwarz inequality.Results Data from 33 clinical studies (4338 patients) were retrieved. The overall mean age was 62.3 ± 6.6 years old. Patients with HIT-related thromboembolism at the moment of diagnosis were associated with greater rate of haemorrhages (P > 0.0001), thromboembolism (P > 0.0001) and mortality (P = 0.001). Patients with more comorbidities at diagnosis were associated with a greater risk of haemorrhages (P = 0.07), thromboembolism (P = 0.002) and mortality (P = 0.002). Patients with longer duration of the therapy were associated with lower rate of mortality (P = 0.04). ConclusionsPatient comorbidities, presence of HIT-related thromboembolism on admission and shorter anticoagulant therapy were found to be negative prognostic factors. Thrombocythemia on admission, patients age and gender did not influence the overall outcome.

Heparin-induced Thrombocytopenia: Pathophysiology, Diagnosis and Management

Heparin-induced thrombocytopenia (HIT), even rare, is a life-threatening, immune-mediated complication of heparin exposure. It is considered the most severe non-bleeding adverse reaction of heparin treatment and one of the most important adverse drug reactions. The pathophysiological basis of HIT results from the formation of an immunocomplex consisting of an auto-antibody against platelet factor 4 (PF4) - heparin complex, which binds to the surface of platelets and monocytes, provoking their activation by cross-linking FcgIIA receptors. Platelets and monocyte activation, leads to the generation of catastrophic arterial and venous thrombosis, with a mortality rate of 20%, without early recognition. The definitive diagnosis of HIT i.e., clinical and laboratory evidence, can not be done at the onset of symptoms because laboratory results may not be available for several days. Thus, the initial approach is to predict the likelihood of HIT, because in highly suspected patients immediate heparin cessation and initiation of alternative anticoagulation treatment are crucial for the prevention of the devastating thrombotic sequelae. Herein, we describe the pathophysiology, the clinical manifestations, the diagnostic approach, and the management of patients with HIT.

Argatroban Versus Bivalirudin in the Treatment of Suspected or Confirmed Heparin-Induced Thrombocytopenia

Background:

Argatroban and bivalirudin are direct thrombin inhibitors (DTIs) used for the treatment of heparin-induced thrombocytopenia (HIT). The purpose of this study was to determine whether either agent offered an advantage in efficacy and ability to remain within the targeted therapeutic anticoagulation range.

Methods:

This was a single-center, retrospective, observational cohort study at a large academic medical center. The primary efficacy outcome was time to therapeutic anticoagulation, defined as total number of hours to achieve 2 consecutive activated partial thromboplastin time (aPTT) values in goal range.

Results:

A total of 91 patients were included in the analysis. Average time to initial therapeutic anticoagulation was 4.71 hours and 9.8 hours for the argatroban and bivalirudin groups, respectively ( P < .01).

Conclusions:

Argatroban may be advantageous compared to bivalirudin in achieving initial therapeutic anticoagulation goals among patients with suspected or confirmed HIT.

Evaluation of intravenous direct thrombin inhibitor monitoring tests: Correlation with plasma concentrations and clinical outcomes in hospitalized patients

The parenterally administered direct thrombin inhibitors (DTIs) argatroban and bivalirudin are effective anticoagulants for acute heparin-induced thrombocytopenia (HIT) treatment. The activated partial thromboplastin time (aPTT) has classically been used as the monitoring test to assess degree of anticoagulation, however concerns exist with using aPTT to monitor DTI therapy. In this observational study plasma samples from DTI treated patients were analyzed by aPTT, dilute thrombin time (dTT) and ecarin chromogenic assay (ECA) to delineate results into concordant and discordant groups. Discordant samples were further analyzed via liquid chromatography with tandem mass spectrometry (LC MS/MS). In total 101 patients with 198 samples were evaluated. Discordance between tests were frequent (59% of DTI treated patients). Bivalirudin aPTT vs dTT discordance was observed in 45% (57/126) of samples. Amongst bivalirudin samples with test discordance dTT results were more likely to be concordant with LC MS/MS than the aPTT (77% vs 9%, p < 0.0001). Argatroban aPTT vs dTT discordance was observed in 43% (31/72) and aPTT vs ECA discordance was observed in 40% (29/72) of samples. Amongst argatroban samples with test discordance both the dTT and ECA tests were more likely to have concordant results with LC MS/MS than the aPTT (88% vs 9%, p < 0.0001 for both dTT and ECA tests). There were no differences between discordant and concordant patient groups in a composite outcome of bleeding/thrombosis rate (23% vs 27%, p = 0.689). Further investigation is warranted to elucidate the effect of suitable monitoring assays on patient outcomes in the setting of DTI therapy.

Comparison of polyspecific versus IgG specific ELISA in predominately cardiac patients with suspected heparin induced thrombocytopenia

A diagnosis of heparin induced thrombocytopenia (HIT) must often be made based on clinical and laboratory evidence. This was a quasi-experimental study of patients admitted from June 2016 to October 2017. The primary endpoint was the incidence of false positive results in polyspecific and IgG specific enzyme-linked immunosorbent assay (ELISA); then we compared the sensitivity and specificity of each assays in predominately cardiac patients with suspected HIT. A sensitivity/specificity analysis was conducted using serotonin release assay (SRA) as the 'gold standard'. The secondary outcome measures included length of hospital stay. We identified a total of 155 patients who met the inclusion criteria. Confirmatory tests with SRA on both groups were completed; false positive result was higher in the polyspecific group when compared to the IgG group [60% vs. 5%]. The IgG specific ELISA test yielded a sensitivity of 100% and a specificity of 95% however, the polyspecific ELISA had a low yield for specificity of 24% but maintained 100% sensitivity. In the IgG specific group with HIT-, their median length of stay was halved compared to those who were HIT + ; hospital LOS in days, IQR [30 (27-81) vs. 15 (7-33) p = 0.023] and a shorter median LOS in the ICU, IQR [24 (5-47) vs. 6 (2-14); p = 0.079]. Hospital or ICU LOS was the same in both (HIT+ and HIT-) groups managed with polyspecific ELISA. The IgG specific test had few false positive results and a high sensitivity score. Ensuring appropriate testing can bring a substantial decrease in drug expenditure, reduced length of stay and prevent unnecessary anticoagulation.

A Practical Review of the Emerging Direct Anticoagulants, Laboratory Monitoring, and Reversal Agents

Millions of patients in the United States use anticoagulation for a variety of indications, such as the prevention of stroke in those with atrial fibrillation (AF) and the treatment and prevention of venous thrombosis. For over six decades warfarin was the only available oral anticoagulant, but now several DOACs are available and their use has become more prevalent in recent years. In spite of this increased use, many physicians remain reluctant to prescribe DOACs due to concerns about bleeding and reversibility.

Heparin-Induced Thrombocytopenia: A Comprehensive Clinical Review

Heparin-induced thrombocytopenia is a profoundly dangerous, potentially lethal, immunologically mediated adverse drug reaction to unfractionated heparin or, less commonly, to low-molecular weight heparin. In this comprehensive review, the authors highlight heparin-induced thrombocytopenia's risk factors, clinical presentation, pathophysiology, diagnostic principles, and treatment. The authors place special emphasis on the management of patients requiring procedures using cardiopulmonary bypass or interventions in the catheterization laboratory. Clinical vigilance of this disease process is important to ensure its recognition, diagnosis, and treatment. Misdiagnosis of the syndrome, as well as misunderstanding of the disease process, continues to contribute to its morbidity and mortality.

Impact of a Pharmacist-Directed Anticoagulation Service on the Quality and Safety of Heparin-Induced Thrombocytopenia Management

BACKGROUND:

The use of anticoagulant medications is complex and prone to error in the inpatient setting. Patients with heparin-induced thrombocytopenia (HIT) must receive treatment with alternative anticoagulant agents to ensure optimal patient outcomes.

OBJECTIVE:

To evaluate the impact of an inpatient pharmacist-directed anticoagulation service (PDAS) on the safety and efficiency of direct thrombin inhibitor use in patients with HIT.

METHODS:

This was a quasi-experimental pre/postintervention study comparing patients with HIT managed with usual care to patients managed with a focused inpatient anticoagulation service. The primary endpoints of the study were the percent of time that the activated partial thromboplastin time (aPTT) remained within the therapeutic range and time to achievement of a therapeutic aPTT. Bleeding and appropriateness of warfarin initiation were evaluated as secondary endpoints.

RESULTS:

A total of 193 patients were included in the study. Percent of time that aPTT was in the therapeutic range was 32% higher with the PDAS (p < 0.001) and time to therapeutic aPTT was shortened by approximately 12.5 hours in patients managed by the PDAS (p < 0.001). There was a trend for more bleeding events, regardless of severity, among control patients (p = 0.130). Rate of TIMI (Thrombolysis in Myocardial Infarction) major bleeding was lower in the PDAS group (p = 0.006), but there was no significant difference between groups in GUSTO (Global Use of Strategies to Open Occluded Coronary Arteries) moderate/severe bleeding (p = 0.679). Appropriateness of warfarin initiation was also similar between groups.

CONCLUSIONS:

Implementation of a focused inpatient PDAS was associated with improved efficiency of dosing, improved monitoring, and low bleeding risk.

Prevention of sinonasal inflammation by a synthetic glycosaminoglycan

BACKGROUND

Glycosaminoglycans (GAGs) are polysaccharides that are distributed on respiratory epithelial cells, endothelial cells, and submucosal glands. Uniquely positioned, certain GAGs exhibit anti-inflammatory properties in respiratory diseases and serve important roles in repairing mucosal surfaces and modulating mucociliary clearance. We hypothesized that topical administration of a synthetic GAG (GM-0111) would prevent sinonasal inflammation in a mouse model of rhinosinusitis (RS).

METHODS

To test our hypothesis, C57BL/6 mice were intranasally administered fluorescent GM-0111, and sinonasal tissues were examined for coating and penetration ability. To test therapeutic feasibility, mice (n = 6) were given GM-0111 or hyaluronic acid (HA; 800 μg dose) prior to inducing RS with inflammatory molecule LL-37 (115 μg dose). After 24 hours, sinonasal tissues were harvested for histological and biochemical analysis of inflammatory markers (inflammatory cell infiltration, lamina propria [LP] thickening, and neutrophil enzyme myeloperoxidase [MPO]) and cell death.

RESULTS

GM-0111 was observed within sinonasal tissues 1 hour and 24 hours after intranasal administration, indicating rapid and effective coating and penetration. GM-0111 prevented sinonasal tissues from developing inflammatory changes, with significant reductions in mast cell infiltration (p < 0.05), LP thickening (p < 0.001), and MPO levels (p < 0.01) when compared to tissues treated with LL-37 and those pretreated with HA. GM-0111 reduced cell death within sinonasal tissues in contrast to LL-37-treated tissues.

CONCLUSION

We report a new synthetic GAG (GM-0111) that uniformly coats and penetrates into the sinonasal mucosa to prevent sinonasal inflammation and cell death in a mouse model of RS.

Cost-effectiveness of anticoagulants for suspected heparin-induced thrombocytopenia in the United States

Despite the availability of multiple nonheparin anticoagulants for the treatment of heparin-induced thrombocytopenia (HIT), few data are available comparing the cost-effectiveness of these agents. This analysis is particularly important when considering differences in the risk of adverse effects, routes of administration, requirements for phlebotomy and laboratory monitoring, and overall drug costs. We conducted a cost-effectiveness analysis of argatroban, bivalirudin, and fondaparinux for the treatment of suspected HIT from the institutional perspective. A 3-arm decision-tree model was developed that employs standard practices for anticoagulation monitoring. We incorporated published data on drug efficacy and probability of HIT-related thromboembolism and major bleeding. We considered both institutional costs and average wholesale price (AWP) and performed probabilistic sensitivity analyses (PSA) to address any uncertainty in model parameters. Using institutional costs, fondaparinux prevailed over both argatroban and bivalirudin in terms of cost ($151 vs $1250 and $1466, respectively) and adverse events averted (0.9989 vs 0.9957 and 0.9947, respectively). Results were consistent when AWP was used, with fondaparinux being less expensive ($555 vs $3081 and $2187, respectively) and more effective in terms of adverse events averted (0.9989 vs 0.9957 and 0.9947, respectively). The PSA confirmed our findings using both institutional costs and AWP. In conclusion, fondaparinux subcutaneous injection afforded significant advantages in terms of cost savings and adverse events averted compared with IV argatroban or bivalirudin infusions. Our data strongly suggest potential cost savings with fondaparinux and underscore the critical need for larger clinical studies of fondaparinux in the treatment of suspected HIT.

Anticoagulation management associated with extracorporeal circulation

The use of extracorporeal circulation requires anticoagulation to maintain blood fluidity throughout the circuit, and to prevent thrombotic complications. Additionally, adequate suppression of hemostatic activation avoids the unnecessary consumption of coagulation factors caused by the contact of blood with foreign surfaces. Cardiopulmonary bypass represents the greatest challenge in this regard, necessitating profound levels of anticoagulation during its conduct, but also quick, efficient reversal of this state once the surgical procedure is completed. Although extracorporeal circulation has been around for more than half a century, many questions remain regarding how to best achieve anticoagulation for it. Although unfractionated heparin is the predominant agent used for cardiopulmonary bypass, the amount required and how best to monitor its effects are still unresolved. This review discusses the use of heparin, novel anticoagulants, and the monitoring of anticoagulation during the conduct of cardiopulmonary bypass.

Efficacy and Safety of Argatroban and Bivalirudin in Patients with Suspected Heparin-Induced Thrombocytopenia

Background: Argatroban is the only commercially available Food and Drug Administration (FDA)–approved anticoagulant for managing heparin-induced thrombocytopenia (HIT). However, bivalirudin may be an attractive alternative. Objective: To assess the efficacy and safety of argatroban and bivalirudin in patients with suspected HIT. Methods: This single-center, retrospective analysis included patients who received argatroban or bivalirudin for at least 24 hours between January 1, 2000, and June 30, 2012. The primary end point assessed anticoagulation goals, specifically time to therapeutic activated partial thromboplastin time (aPTT) goal and percentage of aPTT values within therapeutic range. Secondary end points included new thromboembolic events, bleeding, and mortality. Results: Of the 68 patients who met the inclusion criteria, 48 received argatroban and 20 received bivalirudin. Baseline characteristics were similar between the 2 groups except for age, percentage of patients with liver dysfunction, aPTT immediately prior to drug initiation, and the serotonin release assay results. The mean ± SD times to reach therapeutic aPTT goal for argatroban and bivalirudin were 14 ± 15 and 7 ± 8 hours, respectively ( P = 0.024). The mean ± SD percentage of aPTT values within therapeutic aPTT goal was 69% ± 23% for argatroban and 84% ± 18% for bivalirudin ( P = 0.005). Rates of thromboembolic events were similar between the 2 groups, as were the rates of bleeding and all-cause mortality. Conclusions: Bivalirudin appears to reach therapeutic aPTT goal faster with more aPTT values within therapeutic aPTT goal while achieving similar clinical outcomes. Although not approved by the FDA for managing HIT, bivalirudin may be an attractive alternative anticoagulant.

Use of argatroban and catheter-directed thrombolysis with alteplase in an oncology patient with heparin-induced thrombocytopenia with thrombosis

PURPOSE

The case of an oncology patient who developed heparin-induced thrombocytopenia with thrombosis (HITT) and was treated with argatroban plus catheter-directed thrombolysis (CDT) with alteplase is presented.

SUMMARY

A 63-year-old Caucasian man with renal amyloidosis undergoing peripheral blood stem cell collection for an autologous stem cell transplant developed extensive bilateral upper-extremity deep venous thrombosis (DVT) and pulmonary embolism secondary to heparin-induced thrombocytopenia. A continuous i.v. infusion of argatroban was initiated, and the patient was managed on the general medical floor. After one week of therapy, he was transferred to the intensive care unit with cardiopulmonary compromise related to superior vena cava (SVC) syndrome. A percutaneous mechanical thrombectomy and CDT with alteplase were attempted, but the procedure was aborted due to epistaxis. The epistaxis resolved the next day, and the patient was restarted on argatroban. A second percutaneous mechanical thrombectomy was performed six days later and resulted in partial revascularization of the SVC and central veins. Postthrombectomy continuous CDT with alteplase was commenced while argatroban was withheld, and complete patency of the SVC and central veins was achieved after three days of therapy. Alteplase was discontinued, and the patient was reinitiated on argatroban; ultimately, he was transitioned to warfarin for long-term anticoagulation. Although the patient recovered, he experienced permanent vision and hearing loss, as well as end-stage renal disease.

CONCLUSION

A 63-year-old man with renal amyloidosis and SVC syndrome secondary to HITT was successfully treated with argatroban and CDT with alteplase.

Bivalirudin for the treatment of patients with confirmed or suspected heparin-induced thrombocytopenia

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is an adverse immune-mediated response to unfractionated heparin and, less commonly, low molecular weight heparin. It is associated with a high thrombotic risk and the potential for limb and life-threatening complications. Argatroban is the only approved and currently available anticoagulant for HIT treatment in the USA.

OBJECTIVES

To report safety and efficacy outcomes with bivalirudin for HIT treatment.

METHODS

We retrospectively examined records from our registry of patients with a suspected, confirmed or previous history of HIT and who had received bivalirudin for anticoagulation in a single tertiary-care center over a 9-year period.

RESULTS

We identified 461 patients who received bivalirudin: 220 (47.7%) were surgical patients, and 241 (52.3%) were medical patients. Of this population, 107 (23.2%) were critically ill, and 109 (23.6%) were dialysis-dependent. Suspected, confirmed and previous history of HIT were reported in 262, 124 and 75 patients, respectively. Of 386 patients with suspected or confirmed HIT, 223 patients (57.8%) had thrombosis at HIT diagnosis. New thrombosis was identified in 21 patients (4.6%) while they were on treatment with therapeutic doses of bivalirudin. No patient required HIT-related amputation. Major bleeding occurred in 35 patients (7.6%). We found a significant increase in major bleeding risk in the critically ill population (13.1%; odds ratio 2.4, 95% confidence interval 1.2-4.9, P = 0.014). The 30-day all-cause mortality rate was 14.5% (67 patients), and eight of 67 (1.7%) deaths were HIT-related.

CONCLUSION

Bivalirudin may be an effective and safe alternative option for the treatment of both suspected and confirmed HIT, and appears to reduce the rate of HIT-related amputation.

Development and implementation of a nurse-driven, sliding-scale nomogram for bivalirudin in the management of heparin-induced thrombocytopenia

PURPOSE

A simplified dosing nomogram to assist nurses in adjusting the rate of i.v. bivalirudin administration in cases of heparin-induced thrombocytopenia (HIT) is described.

SUMMARY

To facilitate the availability of bivalirudin [corrected] as an alternative direct thrombin inhibitor (DTI) for patients with HIT at The Ohio State University Wexner Medical Center (OSUWMC), a team of clinical pharmacists developed a nomogram designed to simplify infusion dosage adjustments by nurses. In contrast to bivalirudin nomograms requiring patient-specific, percentage-based dose adjustments, the nomogram developed at OSUWMC specifies fixed adjustments (0.005 or 0.01 mg/kg/hr) according to the current activated partial thromboplastin time (aPTT) value relative to aPTT goals. During pilot testing over three years, the nomogram was used to guide dosage adjustments in 65 adult patients receiving continuous infusions of bivalirudin for suspected or confirmed HIT in intensive care units. Overall, the use of the nomogram resulted in adequate anticoagulation, with 53.7% of all measured aPTT values in the target range; 30.5% of aPTT values were below target, and 15.8% of values were above target. The median time to steady state was 11.0 hours (range, 5.0-31.8 hours), and bleeding rates were consistent with those reported in the literature. Nurse adherence to the nomogram was 100%, and no dosing errors occurred during a total of 487 dosage changes. Based on the pilot study results, the nomogram was refined to improve initial dosing for patients with creatinine clearance values of >30 mL/min; other refinements were made to enhance the safety of bivalirudin therapy for HIT in patients with severe renal impairment.

CONCLUSION

A nurse-driven, sliding-scale nomogram for bivalirudin therapy in patients with HIT provided a simple dosing protocol and resulted in a high rate of adherence by nurses.

Argatroban therapy in heparin-induced thrombocytopenia

Argatroban is a direct thrombin inhibitor approved for anticoagulation in heparin-induced thrombocytopenia (HIT; in several countries) and in patients with or at risk of HIT undergoing percutaneous coronary intervention (PCI; in the USA). HIT is a relatively common extreme prothrombotic condition. When HIT is reasonably suspected, an alternative anticoagulant should be promptly initiated. In historical controlled studies, argatroban reduced new thrombosis, mortality from thrombosis and the composite of death, amputation or thrombosis, without increasing bleeding. With intravenous infusion, advantages include short half-life, easy monitoring and elimination primarily by hepatobiliary (rather than renal) means. In patients undergoing PCI, argatroban with or without glycoprotein IIb/IIIa inhibition leads to high rates of procedural success with low bleeding risk. Herein we review argatroban therapy for HIT and for PCI.

Diagnosis and management of heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder caused by antibodies to platelet factor 4/heparin (PF4/H) complexes. It presents with declining platelet counts 5 to 14 days after heparin administration and results in a predisposition to arterial and venous thrombosis. Establishing the diagnosis of HIT can be extremely challenging. It is essential to conduct a thorough clinical evaluation in addition to laboratory testing to confirm the presence of PF4/H antibodies. Multiple clinical algorithms have been developed to aid the clinician in predicting the likelihood of HIT. Once HIT is recognized, an alternative anticoagulant should be initiated to prevent further complications.

Evaluation of dose requirements for prolonged bivalirudin administration in patients with renal insufficiency and suspected heparin-induced thrombocytopenia

Bivalirudin, a direct thrombin inhibitor, is indicated for patients with suspected heparin-induced thrombocytopenia (HIT) with anticipated percutaneous coronary intervention (PCI). Data is limited on dose selection among patients with renal insufficiency, particularly with prolonged infusion durations. The study cohort comprised 73 patients with renal dysfunction who received bivalirudin for suspected HIT with or without acute coronary syndrome. We reviewed individual pharmacy and medical records for laboratory and bivalirudin dosing information, medical comorbidities, and adverse clinical outcomes during administration. When estimated glomerular filtration rate (eGFR) was calculated by the Cockcroft-Gault (CG; ml/min) formula, the average bivalirudin dose (mg/kg/h) achieving a therapeutic activated partial thromboplastin time (aPTT) was 0.07 ± 0.04, 0.15 ± 0.08, and 0.16 ± 0.07 for patients with eGFR between 15-30, 31-60, and >60, respectively. When eGFR was calculated by the modification of diet in renal disease (MDRD; ml/min/1.73 m(2)) formula, the average bivalirudin dose achieving a therapeutic aPTT was 0.07 ± 0.04, 0.12 ± 0.07, and 0.20 ± 0.07 for patients with eGFR between 15-30, 31-60, >60, respectively. The difference between the dose achieving a therapeutic aPTT for patients with eGFR >60 when calculated by MDRD versus CG was completely abolished when obese patients were excluded from the CG cohort. The results of our series of patients with renal dysfunction receiving prolonged duration of bivalirudin in the setting of acute coronary syndrome (ACS) suggests that dose adjustment is safe and should be considered for patients with moderate to severe renal impairment (eGFR < 60 ml/min/1.73 m(2)).

Comparison of bivalirudin dosing strategies using total, adjusted, and ideal body weights in obese patients with heparin-induced thrombocytopenia

STUDY OBJECTIVES

To compare dosing strategies using total body weight (actual measured body weight), adjusted body weight, and ideal body weight when starting bivalirudin for the treatment for heparin-induced thrombocytopenia (HIT) in obese patients, and to compare differences in dosing requirements and clinical outcomes between obese and nonobese patients.

DESIGN

Retrospective medical record review.

SETTING

Academic tertiary care medical center.

PATIENTS

One hundred thirty-five medical and surgical patients who were treated with bivalirudin for HIT between June 1, 2004, and October 1, 2009.

MEASUREMENTS AND MAIN RESULTS

The 135 patients were separated into two groups based on body mass index (BMI): 46 patients had a BMI greater than 30 kg/m(2) and were classified in the obese group; the nonobese group consisted of 89 patients with a BMI less than 30 kg/m(2) . The mean BMI in the obese group was 37.7 kg/m(2) (range: 30.1-56.2 kg/m(2) ). Weight-standardized doses that achieved activated partial thromboplastin time (aPTT) goal were compared in the obese group. The mean ± SD doses that achieved aPTT goal with total (actual), adjusted, and ideal body weights in this group were 0.1 ± 0.07, 0.11 ± 0.08, and 0.14 ± 0.09 mg/kg/hour, respectively. Of the three weight-based dosing approaches, total body weight followed by adjusted body weight provided the closest correlation to rates observed at the target aPTT goal. The secondary analysis compared initial doses of bivalirudin, doses required to reach goal aPTT, time to achieve goal aPTT, and clinical outcomes (number of patients not achieving goal, new thrombosis, major bleeding, and 30-day all-cause mortality) between the obese and nonobese groups. A significant difference in initial dose was noted between groups; however, no significant differences in dose required to achieve goal aPTT, time to achieve goal aPTT, and clinical outcomes were noted between the obese and nonobese groups.

CONCLUSION

This study provides evidence that the dosing strategy for bivalirudin based on total body weight is the most accurate predictor of achieving aPTT goal in obese patients with HIT. The study also suggests that there are no clinical differences that warrant different dosing strategies between obese and nonobese patients. Further prospective studies are needed to confirm these findings.

Acute pulmonary embolism

Venous thromboembolism is the third leading cause of cardiovascular death in the United States and is the second leading cause of death among hospitalized cancer patients. Continued controversy exists regarding the role of thrombolytic therapy among patients with acute pulmonary embolism. Limited research exists on thrombolytic therapy in this setting, most of which has focused on symptoms, including right ventricular function, hemodynamic status, and electrocardiographic changes. However, these studies have excluded patients with a known malignancy. Presented is an interesting case of a patient, in remission from breast cancer, who presented to the emergency department with symptomatic pulmonary emboli. The presentation, medical management, and consequences of the treatment have been discussed. Also, a brief review of the literature is presented regarding the treatment of acute pulmonary embolism.

Treatment and prevention of heparin-induced thrombocytopenia: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is an antibody-mediated adverse drug reaction that can lead to devastating thromboembolic complications, including pulmonary embolism, ischemic limb necrosis necessitating limb amputation, acute myocardial infarction, and stroke.

METHODS

The methods of this guideline follow the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

Among the key recommendations for this article are the following: For patients receiving heparin in whom clinicians consider the risk of HIT to be > 1%, we suggest that platelet count monitoring be performed every 2 or 3 days from day 4 to day 14 (or until heparin is stopped, whichever occurs first) (Grade 2C). For patients receiving heparin in whom clinicians consider the risk of HIT to be < 1%, we suggest that platelet counts not be monitored (Grade 2C). In patients with HIT with thrombosis (HITT) or isolated HIT who have normal renal function, we suggest the use of argatroban or lepirudin or danaparoid over other nonheparin anticoagulants (Grade 2C). In patients with HITT and renal insufficiency, we suggest the use of argatroban over other nonheparin anticoagulants (Grade 2C). In patients with acute HIT or subacute HIT who require urgent cardiac surgery, we suggest the use of bivalirudin over other nonheparin anticoagulants or heparin plus antiplatelet agents (Grade 2C).

CONCLUSIONS

Further studies evaluating the role of fondaparinux and the new oral anticoagulants in the treatment of HIT are needed.

Bivalirudin dosing adjustments for reduced renal function with or without hemodialysis in the management of heparin-induced thrombocytopenia

BACKGROUND

While not approved by the Food and Drug Administration for treatment of heparin-induced thrombocytopenia (HIT), except in patients undergoing percutaneous interventions, the direct thrombin inhibitor bivalirudin is a treatment option that is gaining use. An initial dose of bivalirudin 0.15-0.2 mg/kg/h, adjusted to an activated partial thromboplastin time (aPTT) of 1.5-2.5 times the baseline value, has been suggested. Initial dosing in patients with renal dysfunction, including those on hemodialysis, is unclear.

OBJECTIVE

To evaluate initial bivalirudin dosing requirements in patients with and without renal dysfunction, including patients on different forms of dialysis.

METHODS

A retrospective analysis of 135 patients treated with bivalirudin for HIT between June 2004 and October 2009 was conducted at a tertiary care medical center. The patients were divided into groups, based on renal function. Patients receiving dialysis were divided into 3 subgroups based on the mode of hemodialysis: intermittent hemodialysis (IHD, n = 24), sustained low-efficiency daily diafiltration (SLEDD, n = 12), or continuous renal replacement therapy (CRRT, n = 5). Patients not receiving dialysis were separated into 3 subgroups based on calculated creatinine clearance (CrCl): CrCl >60 mL/min (n = 52), CrCl 30-60 mL/min (n = 26), and CrCl <30 mL/min (n = 16).

RESULTS

Compared with patients with normal renal function (CrCl >60 mL/min), patients with differing degrees of renal dysfunction (CrCl 30-60 and <30 mL/min) required lower doses of bivalirudin to achieve aPTT goal (0.13 vs 0.08 vs 0.05 mg/kg/h, respectively; p < 0.001). Patients on dialysis (IHD, SLEDD, CRRT) also required dose reductions (0.07, 0.09, and 0.07 mg/kg/h) compared with patients with normal renal function, but higher dosing requirements than patients not receiving dialysis with CrCl <30 mL/min.

CONCLUSIONS

Patients with renal dysfunction require a reduced dose of bivalirudin to reach a therapeutic aPTT goal. Slightly higher doses may be observed in patients receiving hemodialysis.

Evaluation of empiric versus nomogram-based direct thrombin inhibitor management in patients with suspected heparin-induced thrombocytopenia

The aim of this study was to evaluate a direct thrombin inhibitor (DTI) titration protocol in patients with suspected HIT. This observational study compared patients treated with argatroban or bivalirudin according to the University of Colorado Hospital DTI titration protocol versus a control group treated prior to protocol implementation. Protocol patients had DTI initial doses based on organ function and fixed dosage adjustments of 10, 25, or 50%. Initial doses and titrations in the control group were made per physician discretion. A total of 130 patients were enrolled: 47 in the protocol group and 83 in the control group (median age 54 years, 63% male, 78% critically ill, and 54% received argatroban). Goal aPTT was achieved with initial DTI dose in 64% of protocol patients and 46% of control patients (P = 0.07). Median (IQR) time to goal aPTT was reduced in the protocol group compared to the control group [5 hr (2-10 hr) vs. 13 hr (6-29 hr); P < 0.0001]. Median time to dose stabilization was 10 hr (6-27 hr) and 22 hr (13-40 hr) in the protocol and control groups, respectively; P < 0.0001. Median number of titrations to goal was 0 (0-1) versus 1 (0-4), respectively; P = 0.02. Median percentage of aPTT values in goal was 67% (41-100%) versus 53% (33-76%), respectively; P = 0.027. The DTI titration protocol shortened time to achieve goal aPTT, reduced time to dose stabilization, decreased the number of titrations required to achieve aPTT goal, and improved the percentage of aPTT values in goal range.

Lower extremity manifestations and treatment of heparin-induced thrombocytopenia syndromes: a cohort study

Heparin-induced thrombocytopenia (HIT) and heparin-induced thrombocytopenia with thrombosis (HITT) syndromes are the result of an adverse reaction to heparin that results in a spectrum of laboratory and end-organ manifestations secondary to thrombosis of both arterial and venous small and large vessels. HITT most often manifests in the extremities as acral ischemia and necrosis, with a spectrum of severity. The lower extremity surgical patient is at risk for deep venous thrombosis, and when exposed to heparin products, is also at risk for the development of a heparin-induced thrombocytopenic syndrome. This article reports on a cohort of patients from a tertiary referral lower extremity reconstruction practice with the HIT/HITT syndromes, with an analysis of the frequency, medical characteristics, clinical settings, lower extremity manifestations, management, and outcomes of patients with HIT/HITT.).

Pharmacist-Managed Direct Thrombin Inhibitor Protocol Improves Care of Patients with Heparin-Induced Thrombocytopenia

Use of direct-thrombin inhibitors (DTIs) for the management of patients with heparin-induced thrombocytopenia (HIT) is challenging. A pharmacist-managed DTI protocol was implemented to standardize and improve the care of patients with HIT. A background study that compared DTI protocol–treated patients to those who did not receive treatment with the DTI protocol found that significantly more of the DTI protocol–treated patients received care that was consistent with level 1 guidelines from the American College of Chest Physicians (41% vs 0%). Because outcomes were poor regardless of whether the DTI protocol was used, the protocol was revised to require pharmacist implementation and oversight. A follow-up study compared DTI protocol patients from the background study (non-pharmacist-managed) to the pharmacist-managed DTI protocol group. There were significantly fewer dosing errors, improved nursing documentation, and less reexposure to heparin when the pharmacist was responsible for managing the DTI protocol. A trend toward reduced bleeding was noted. The management of patients with HIT is complex, and there are a number of pitfalls that may lead to poor outcomes. DTIs are high-risk medications that require careful dosing and monitoring to minimize risk for adverse drug events. A DTI protocol may improve care of patients with HIT, and pharmacist oversight of DTI use can help to reduce risk for errors and adverse medication events.

Fondaparinux (Arixtra®), a Safe Alternative for the Treatment of Patients With Heparin-Induced Thrombocytopenia?

Fondaparinux, a pentasaccharide which selectively binds to antithrombin III, has negligible to no cross-reactivity with heparin-induced thrombocytopenia (HIT) antibodies in in vitro studies. The lack of cross-reactivity suggests a potential role in the management of HIT, and indeed, there are several such case reports and small studies. These published data have used both the prophylactic and weight-based treatment doses. However, due to the small possibility of developing HIT with thromboembolic complications while receiving fondaparinux, it is suggested that the appropriate weight-based treatment dose be used. In all these reports, fondaparinux provided adequate anticoagulation, prevented further thromboembolic events, and platelet counts returned to normal. However, there have been a couple of case reports on possible HIT or HIT-like syndrome secondary to fondaparinux use. Conclusion: Fondaparinux is an attractive anticoagulant therapy in patients with HIT. There is still the need for larger randomized trials evaluating the true efficacy, appropriate dose, safe duration of treatment, and the true incidence of HIT associated with fondaparinux.

What is the optimal anticoagulation level with argatroban during percutaneous coronary intervention?

Argatroban is increasingly used in patients with heparin-induced thrombocytopenia. Although the recommended activated clotting time during percutaneous coronary intervention is 300-450 s, this recommendation is based on the limited data. This single-center, retrospective study evaluated the efficacy (composite of death, myocardial infarction, or urgent revascularization) and safety (evaluated by thrombolysis in myocardial infarction major bleeding) of argatroban during percutaneous coronary intervention according to activated clotting time levels. Patients were divided into three groups according to the activated clotting time achieved during the procedure (<300s, 300-450s, and >450 s). In this study, 120 consecutive patients with confirmed or suspected heparin-induced thrombocytopenia received argatroban (241 +/- 104 mug/kg bolus, followed by a 18 +/- 10 microg/kg per min infusion) during percutaneous coronary intervention. The indication for percutaneous coronary intervention was stable angina in 20% of patients, unstable angina or non-ST elevation myocardial infarction in 58%, and ST elevation myocardial infarction in 22%. An adjunctive glycoprotein IIb/IIIa inhibitor was used in 56 patients (46.7%). When divided into three groups on the basis of the activated clotting time (<300, 300-450, >450 s), no significant difference was observed between the groups in the efficacy endpoint, which occurred in 9.8% (6/61) of patients in the group with activated clotting time less than 300 s, 19.6% (9/46) of patients in the group with activated clotting time 300-450 s, and 7.7% (1/13) of patients in the group with activated clotting time more than 450 s (P = 0.58). The rate of major bleeding was higher in the group of patients with activated clotting time more than 450 s (1.6, 0, and 15.4% patients, respectively; P = 0.006). These results suggest that in patients undergoing percutaneous coronary intervention, argatroban provides adequate anticoagulation with a low bleeding rate, when activated clotting time is maintained below 450 s.

Reducing harm associated with anticoagulation: practical considerations of argatroban therapy in heparin-induced thrombocytopenia

Argatroban is a hepatically metabolized, direct thrombin inhibitor used for prophylaxis or treatment of thrombosis in heparin-induced thrombocytopenia (HIT) and for patients with or at risk of HIT undergoing percutaneous coronary intervention (PCI). The objective of this review is to summarize practical considerations of argatroban therapy in HIT. The US FDA-recommended argatroban dose in HIT is 2 microg/kg/min (reduced in patients with hepatic impairment and in paediatric patients), adjusted to achieve activated partial thromboplastin times (aPTTs) 1.5-3 times baseline (not >100 seconds). Contemporary experiences indicate that reduced doses are also needed in patients with conditions associated with hepatic hypoperfusion, e.g. heart failure, yet are unnecessary for renal dysfunction, adult age, sex, race/ethnicity or obesity. Argatroban 0.5-1.2 microg/kg/min typically supports therapeutic aPTTs. The FDA-recommended dose during PCI is 25 microg/kg/min (350 microg/kg initial bolus), adjusted to achieve activated clotting times (ACTs) of 300-450 sec. For PCI, argatroban has not been investigated in hepatically impaired patients; dose adjustment is unnecessary for adult age, sex, race/ethnicity or obesity, and lesser doses may be adequate with concurrent glycoprotein IIb/IIIa inhibition. Argatroban prolongs the International Normalized Ratio, and published approaches for monitoring the argatroban-to-warfarin transition should be followed. Major bleeding with argatroban is 0-10% in the non-interventional setting and 0-5.8% periprocedurally. Argatroban has no specific antidote, and if excessive anticoagulation occurs, argatroban infusion should be stopped or reduced. Improved familiarity of healthcare professionals with argatroban therapy in HIT, including in special populations and during PCI, may facilitate reduction of harm associated with HIT (e.g. fewer thromboses) or its treatment (e.g. fewer argatroban medication errors).

The costs of heparin-induced thrombocytopenia: a patient-based cost of illness analysis

SUMMARY BACKGROUND AND OBJECTIVES: Due to the complexity of heparin-induced thrombocytopenia (HIT), currently available cost analyses are rough estimates. The objectives of this study were quantification of costs involved in HIT and identification of main cost drivers based on a patient-oriented approach.

METHODS

Patients diagnosed with HIT (1995-2004, University-hospital Greifswald, Germany) based on a positive functional assay (HIPA test) were retrieved from the laboratory records and scored (4T-score) by two medical experts using the patient file. For cost of illness analysis, predefined HIT-relevant cost parameters (medication costs, prolonged in-hospital stay, diagnostic and therapeutic interventions, laboratory tests, blood transfusions) were retrieved from the patient files. The data were analysed by linear regression estimates with the log of costs and a gamma regression model. Mean length of stay data of non-HIT patients were obtained from the German Federal Statistical Office, adjusted for patient characteristics, comorbidities and year of treatment. Hospital costs were provided by the controlling department.

RESULTS AND CONCLUSIONS

One hundred and thirty HIT cases with a 4T-score >or=4 and a positive HIPA test were analyzed. Mean additional costs of a HIT case were 9008 euro. The main cost drivers were prolonged in-hospital stay (70.3%) and costs of alternative anticoagulants (19.7%). HIT was more costly in surgical patients compared with medical patients and in patients with thrombosis. Early start of alternative anticoagulation did not increase HIT costs despite the high medication costs indicating prevention of costly complications. An HIT cost calculator is provided, allowing online calculation of HIT costs based on local cost structures and different currencies.

Safety, efficacy, and dosing requirements of bivalirudin in patients with heparin-induced thrombocytopenia

STUDY OBJECTIVE

To evaluate the safety, efficacy, and dosing requirements of bivalirudin in patients with heparin-induced thrombocytopenia (HIT).

DESIGN

Retrospective cohort study.

SETTING

University-affiliated hospital.

PATIENTS

Thirty-seven adults with a diagnosis or history of HIT who were treated with bivalirudin between January 1, 2004, and March 31, 2007.

MEASUREMENTS AND MAIN RESULTS

Patients had a mean +/- SD age of 50 +/- 16 years and weighed 80 +/- 20 kg; 62% were male, 73% were Caucasian, and 95% were treated in the intensive care unit. Patients were divided into three renal function groups for assessment of bivalirudin dosing requirements: creatinine clearance (Cl(cr)) greater than 60 ml/minute (12 patients, group 1); Cl(cr) 30-60 ml/minute (11 patients, group 2); and Cl(cr) lower than 30 ml/minute or receiving continuous renal replacement therapy ([RRT] 14 patients, group 3). Except for renal function, baseline demographic characteristics were similar among groups. A total of 19 (51%) of the 37 patients achieved goal activated partial thromboplastin time (aPTT) with initial mean +/- SD bivalirudin doses of 0.14 +/- 0.04 (median 0.15), 0.1 +/- 0.07 (median 0.08), and 0.05 +/- 0.05 (median 0.05) mg/kg/hour in groups 1, 2, and 3, respectively. Doses remained similar over the study period and were 0.13 +/- 0.04 (median 0.15), 0.1 +/- 0.06 (median 0.1), and 0.04 +/- 0.02 (median 0.03) mg/kg/hour for groups 1, 2, and 3, respectively. The mean +/- SD aPTT value after achieving goal range was 64 +/- 9 seconds (all patients). Bivalirudin dosing requirements correlated with Cl(cr) (r(2) = 0.37, p<0.0001). Therapy duration was a mean +/- SD of 11 +/- 13 days (median 7 days). Systemic thrombosis and bleeding while receiving bivalirudin were also evaluated. Thrombosis occurred in one patient; clinically significant bleeding occurred in two patients.

CONCLUSION

Bivalirudin dosing requirements correlated with renal function; therefore, dosage reduction is required in patients with moderate or severe renal dysfunction. Starting bivalirudin at 0.15 mg/kg/hour in patients with Cl(cr) greater than 60 ml/minute, 0.08-0.1 mg/kg/hour in patients with Cl(cr) 30-60 ml/minute, and 0.03-0.05 mg/kg/hour in patients with Cl(cr) below 30 ml/minute or receiving continuous RRT is effective at achieving goal aPTT values in most patients.

Dosing Nomograms: Silos on a Slope

Developing dosing management guidelines or protocol approaches to pharmacotherapy can provide several benefits for standardization of care. Frequently, clinicians may need to incorporate multiple influencing factors to individualize management. In some cases, preestablished, standardized approaches may create barriers to individualized care, potentially categorizing patients into dosing categories (silos) that minimize their individualized needs. Approaches to managing direct thrombin inhibitor therapy have been recently explored and dosing approaches different from those provided in the prescribing information have been proposed. Considerations regarding individualized management of anticoagulant therapy, including the use of standardized dosing or monitoring protocols, are discussed here.

Role of citrate and other methods of anticoagulation in patients with severe liver failure requiring continuous renal replacement therapy

Anticoagulation is required during continuous renal replacement therapy to prevent filter clotting and optimize filter performance. However, anticoagulation may also be associated with serious bleeding complications. Patients with liver failure often suffer from underlying coagulopathy and are especially prone to anticoagulation complications. The aim of this review is to present the unique features of patients with hepatic injury in terms of anticoagulation disorders and to analyze data on safety and efficacy of the different anticoagulation methods for liver failure patients undergoing continuous renal replacement therapy.