Bivalirudin versus Heparin in Pediatric and Adult Patients on Extracorporeal Membrane Oxygenation: A Meta-analysis

Bivalirudin Monitoring in Pediatric Ventricular Assist Device and Extracorporeal Membrane Oxygenation: Analysis of Single-Center Retrospective Cohort Data 2018-2022

OBJECTIVES

The activated partial thromboplastin time (aPTT) is the most frequently used monitoring assay for bivalirudin in children and young adults on mechanical circulatory support including ventricular assist devices (VADs) and extracorporeal membrane oxygenation (ECMO). However, intrinsic variability of the aPTT complicates management and risks bleeding or thrombotic complications. We evaluated the utility and reliability of a bivalirudin-calibrated dilute thrombin time (Bival dTT) assay for bivalirudin monitoring in this population.

DESIGN

Retrospective analysis of clinical data (including aPTT, dilute thrombin time [dTT]) and results of residual plasma samples from VAD patients were assessed in two drug-calibrated experimental assays. One assay (Bival dTT) was validated for clinical use in VAD patients, and subsequently used by clinicians in ECMO patients. Pearson correlation and simple linear regression were used to determine R2 correlation coefficients between the different laboratory parameters using Statistical Package for Social Sciences (Armonk, NY).

SETTING

ICUs at Cincinnati Children's Hospital Medical Center.

SUBJECTS

Children on VAD or ECMO support anticoagulated with bivalirudin.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

One hundred fifteen plasma samples from 11 VAD patients were analyzed. Both drug-calibrated experimental assays (anti-IIa and Bival dTT) showed excellent correlation with each other ( R2 = 0.94) and with the dTT ( R2 = 0.87), but poor correlation with aPTT ( R2 = 0.1). Bival dTT was selected for validation in VAD patients. Subsequently, clinically ordered results (105) from 11 ECMO patients demonstrated excellent correlation between the Bival dTT and the standard dTT ( R2 = 0.86) but very poor correlation with aPTT ( R2 = 0.004).

CONCLUSIONS

APTT is unreliable and correlates poorly with bivalirudin's anticoagulant effect in ECMO and VAD patients. A drug-calibrated Bival dTT offers superior reliability and opportunity to standardize results across institutions. Additional studies are needed to determine an appropriate therapeutic range and correlation with clinical outcomes.

Antithrombin supplementation attenuates heparin resistance in plasma spiked with Gla-domainless factor Xa S195A in vitro

BACKGROUND

Andexanet alfa is a Gla-domainless mutant (S195A) factor Xa (GDXa) approved for acute reversal of oral factor Xa inhibitors. Cardiac surgery patients exposed to andexanet before cardiopulmonary bypass often exhibit severe heparin resistance. There is a paucity of data on the effectiveness and optimal dosage of antithrombin use in this setting. The objective of this study was to evaluate the in vitro effect of increased heparin with antithrombin levels on attenuating heparin resistance induced by GDXa.

METHODS

Heparinised normal pooled plasma and cardiopulmonary bypass plasma were spiked with GDXa 4 μM. Tissue factor-activated thrombin generation was used to assess heparin reversal effects of GDXa and restoration of anticoagulation with additional heparin with and without antithrombin. Serum thrombin-antithrombin complex, antithrombin activity, and tissue factor pathway inhibitor were also measured in tissue factor-activated, recalcified cardiopulmonary bypass plasma spiked with GDXa.

RESULTS

In normal pooled plasma, GDXa-induced heparin reversal was mitigated by maintaining a high heparin concentration (12 U ml-1) and supplementing antithrombin (1.5-4.5 μM) based on peak and velocity of thrombin generation. Heparin reversal by GDXa was also demonstrated in cardiopulmonary bypass plasma, but supplementing both heparin (8 U ml-1) and antithrombin (3 μM) attenuated GDXa-induced changes in peak and velocity of thrombin generation by 72.5% and 72.2%, respectively. High heparin and antithrombin levels attenuated thrombin-antithrombin complex formation in tissue factor-activated, GDXa-spiked cardiopulmonary bypass plasma by 85.7%, but tissue factor pathway inhibitor remained depleted compared with control cardiopulmonary bypass plasma.

CONCLUSIONS

Simultaneous supplementation of heparin and antithrombin mitigate GDXa-induced heparin resistance by compensating for the loss of tissue factor pathway inhibitor.

Anticoagulation during extracorporeal membrane oxygenation: A narrative review

Extracorporeal Membrane Oxygenation (ECMO) is a technology that offers organ support for critically ill patients with respiratory and/or cardiac failure. Despite improvements in recent years in technology and the biocompatibility of circuits, patients on ECMO remain at high risk of hematologic complications, such as bleeding or thrombosis. Anticoagulation is required in most cases to limit the risk of clotting, but questions persist regarding the optimal anticoagulation strategy. More precisely, there is still debate around the best anticoagulation agent and monitoring tools as well as on the transfusion thresholds and appropriate corrective measures when faced with complications. This narrative review provides an overview of hemostasis on ECMO and the impact of circuit size and coating. The benefits and downsides of unfractionated heparin (UHF) and Direct Thrombin Inhibitors (DTIs) as anticoagulation agents are reviewed. Finally, commonly available coagulation tests (activated clotting time, activated partial thrombin time, anti-Xa, and viscoelastic tests) and their limitations are addressed. In conclusion, future research is needed to determine the best anticoagulation strategy for patients on ECMO.

Comparison of bleeding and thrombotic outcomes in veno-venous extracorporeal membrane oxygenation: Heparin versus bivalirudin

OBJECTIVES

We aimed to evaluate thrombotic and hemorrhagic complications with heparin versus bivalirudin use in veno-venous extracorporeal membrane oxygenation (V-V ECMO).

METHODS

We performed a retrospective cohort study of adult patients placed on V-V ECMO with intravenous anticoagulation with either heparin or bivalirudin. Time to thrombotic event and major bleed were analyzed in addition to related outcomes.

RESULTS

We identified 95 patients placed on V-V ECMO: 61 receiving heparin, 34 bivalirudin. The bivalirudin group had a higher rate of severe COVID-19, higher BMI, and longer ECMO duration. Despite this, bivalirudin was associated with reduced risk of thrombotic event (HR 0.14, 95% CI 0.06-0.32, p < .001) and increased average lifespan of the circuit membrane lung (16 vs. 10 days, p = 0.004). While there was no difference in major bleeding, the bivalirudin group required fewer transfusions of packed red blood cells and platelets per 100 ECMO days (means of 13 vs. 39, p = 0.004; 5 vs. 19, p = .014, respectively). Lastly, the bivalirudin group had improved survival to ECMO decannulation in univariate analysis (median OS 53 vs. 26 days, p = .015).

CONCLUSIONS

In this real-world analysis of bivalirudin versus heparin, bivalirudin is a viable option for V-V ECMO and associated with lower risk of thrombotic complications and fewer transfusion requirements.

Bivalirudin-hydrogel coatings of polyvinyl chloride on extracorporeal membrane oxygenation for anticoagulation

Introduction

Thromboembolic events associated with extracorporeal membrane oxygenation (ECMO) in clinical treatment are typical. Heparin coating has been widely employed as a surface modification strategy for ECMO tubes. However, its clinical application is often accompanied by unavoidable complications due to its mechanism of action. As a direct thrombin inhibitor with a single target, Bivalirudin (BV) has exhibited a lower incidence of adverse events and superior pharmacokinetic performance compared to heparin.

Methods

A gelatin methacrylate hydrogel (GelMA) coating layer with BV was successfully synthesized on polyvinyl chloride, and the drug release ratio was close to complete release within 7 days.

Results and discussion

Simulated extracorporeal circulation experiments using roller pumps in vitro and jugular arteriovenous bypass experiments in rabbits demonstrated its outstanding anticoagulant efficacy. The systemic anticoagulant assay proved that BV hydrogel coating does not affect the coagulation level, and reduces the risk of complications such as systemic bleeding compared to intravenous injection. BV-Coating GelMA hydrogel tube has exhibited good biocompatibility and significantly improved anticoagulant performance, making it an optimal choice for surface materials used in blood-contacting medical devices.

Anticoagulants in adult extracorporeal membrane oxygenation: alternatives to standardized anticoagulation with unfractionated heparin

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is a vital technique for severe respiratory or heart failure patients. Bleeding and thrombotic events are common during ECMO and negatively impact patient outcomes. Unfractionated heparin is the primary anticoagulant, but its adverse effects limit its use, necessitating alternative anticoagulants.

OBJECTIVE

Review available alternative anticoagulants for adult ECMO patients. Explore potential novel anticoagulants for future ECMO use. Aim to reduce complications (bleeding and thrombosis) and improve safety and efficacy for critically ill ECMO patients.

METHODS

Comprehensive literature review of existing and emerging anticoagulants for ECMO.

RESULTS

Identified a range of alternative anticoagulants beyond unfractionated heparin. Evaluated their potential utility in mitigating ECMO-related complications.

CONCLUSION

Diverse anticoagulant options are available and under investigation for ECMO. These alternatives may enhance patient safety and outcomes during ECMO support. Further research and clinical studies are warranted to determine their effectiveness and safety profiles.

Anticoagulation strategies in patients with extracorporeal membrane oxygenation: A network meta-analysis and systematic review

OBJECTIVES

Extracorporeal membrane oxygenation (ECMO) plays an important role in providing temporary life support for patients with severe cardiac or pulmonary failure, but requires strict anticoagulation and monitoring. This network meta-analysis systematically explored the most effective anticoagulation and monitoring strategies for patients receiving ECMO.

METHODS

MEDLINE, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials were searched up to January 31, 2023, for studies comparing unfractionated heparin (UFH), argatroban (Arg), bivalirudin (Biv), and/or nafamostat mesylate (NM) in patients receiving ECMO. The primary outcomes included device-related thrombosis, patient-related thrombosis, and major bleeding events. The secondary outcomes included ECMO survival, ECMO duration, and in-hospital mortality.

RESULTS

A total of 2522 patients from 23 trials were included in the study. Biv was associated with a decreased risk of device-related thrombosis (odd ratio [OR] 0.51, 95% confidence interval [CI]: 0.33-0.84) compared with UFH, whereas NM (OR 2.2, 95% CI: 0.24-65.0) and Arg (OR 0.92, 95% CI: 0.43-2.0) did not reduce the risk of device-related thrombosis compared with UFH. Biv was superior to Arg in decreasing the risk of device-related thrombosis (OR 0.14, 95% CI: 0.03-0.51). Biv reduced the risk of patient-related thrombosis compared with UFH (OR 0.44, 95% CI: 0.18-0.85); NM (OR 0.65, 95% CI: 0.14-3.3) and Arg (OR 3.1, 95% CI: 0.94-12.0) did not decrease risk of patient-related thrombosis compared with UFH. No significant difference was observed in the risk of major bleeding between three alternatives and UFH: Biv (OR 0.54, 95% CI: 0.23-1.3), Arg (OR 1.3, 95% CI: 0.34-5.8), and NM (OR 0.60, 95% CI: 0.13-2.6). NM showed a reduced risk of in-hospital mortality compared with UFH (OR 0.27, 95% CI: 0.091-0.77), whereas Arg (OR 0.43, 95% CI: 0.15-1.2) and Biv (OR 0.75, 95% CI: 0.52-1.1) did not decrease risk of in-hospital mortality.

CONCLUSIONS

Compared with UFH and Arg, Biv reduces the risk of thrombosis and appears to be a better choice for patients requiring ECMO. NM was associated with a reduced risk of in-hospital mortality.

Bivalirudin versus heparin anticoagulation in patients receiving extracorporeal membrane oxygenation

OBJECTIVE

Bivalirudin has been suggested as an alternative to heparin for anticoagulation in patients receiving extracorporeal membrane oxygenation (ECMO). Nevertheless, there is limited evidence about the benefit of bivalirudin in ECMO patients compared with heparin. Hence, we conducted a meta-analysis to assess the effect of bivalirudin versus heparin on clinical outcomes in patients receiving ECMO.

METHODS

PubMed, Embase, and the Cochrane Library were systematically searched from inception up to 1 April 2022 for cohort studies and randomized controlled trials comparing bivalirudin versus heparin in patients who received ECMO. The primary outcome was short-term death. Secondary outcomes included thrombotic events and bleeding events.

RESULTS

We selected 12 retrospective cohort studies with 1232 ECMO patients focusing on bivalirudin anticoagulation (n = 497) versus heparin anticoagulation (n = 735). Two hundred and one of 497 patients (40.4%) in the bivalirudin group versus 350 of 735 patients (47.6%) in the heparin group did not survive to hospital discharge. Compared with the heparin group, bivalirudin anticoagulation did not significantly decrease in-hospital mortality in patients receiving ECMO (RR, 0.95; 95% CI, 0.79-1.13; p = 0.546). Fifty-seven of 374 patients (15.2%) in the bivalirudin versus 99 of 381 patients (26.0%) in the heparin group suffered from thrombotic events. Compared with the heparin group, bivalirudin anticoagulation did not significantly decrease the rate of thrombotic events for patients receiving ECMO (RR, 0.78; 95% CI, 0.45-1.35; p = 0.378). However, bivalirudin anticoagulation significantly decreased the incidence of bleeding events compared to the heparin group (RR, 0.48; 95% CI, 0.25-0.95; p = 0.035).

CONCLUSIONS

Compared with heparin anticoagulation, bivalirudin did not decrease the rates of short-term mortality and thrombotic events, but reduced the incidence of bleeding events in patients receiving ECMO.

Bivalirudin or heparin for systemic anticoagulation during pediatric extracorporeal membrane oxygenation: Multicenter retrospective study

BACKGROUND

The objective of this study is to evaluate the outcomes of unfractionated heparin (UFH) compared to bivalirudin anticoagulation in pediatric ExtraCorporeal Membrane Oxygenation (ECMO).

METHODS

A multicenter retrospective study, that included pediatric patients <18 years of age, who were supported on ECMO between June 2017 and May 2020. Patients treated with UFH were matched 2:1 by age and type of ECMO support to the bivalirudin group.

RESULTS

The bivalirudin group (75 patients) were matched to 150 patients treated with UFH. Baseline characteristics and comorbidities of the two groups were similar. Veno-Arterial ECMO was the most common mode (141/225 [63 %]) followed by extracorporeal cardiopulmonary resuscitation (48/225 [21 %]). Bivalirudin treatment was associated with lower odds of bleeding events (aOR 0.23, 95%CI 0.12-0.45, p < 0.001) and lower odds of thrombotic events (aOR 0.48, 95%CI 0.23-0.98, p = 0.045). Patients who received bivalirudin had lesser odds for transfusion with fresh frozen plasma, and platelets (aOR 0.26, CI 0.12-0.57, p ≤0.001 and aOR 0.28, CI 0.15-0.53, p < 0.001, respectively). After adjusting for the type of ECMO support and adjusting for age, bivalirudin was associated with a decrease in hospital mortality by 50 % compared to the UFH group (aOR 0.50, 95%CI 0.27-0.93, p = 0.028). Similarly, for neurological disability at time of discharge, bivalirudin was associated with higher odds of intact neurological outcomes compared to UFH (OR 1.99 [95%CI 1.13-3.51], p = 0.017).

CONCLUSIONS

This study demonstrated that effective anticoagulation can be achieved with bivalirudin, which was associated with lesser odds of bleeding events and utilization of blood products. Bivalirudin, in comparison with UFH, was associated with greater odds of hospital survival and intact neurological function at the time of discharge. A prospective randomized trial is required to validate the results of this study.

Is it time to switch to bivalirudin for ECMO anticoagulation?

For decades, unfractionated heparin (hereafter, heparin) has been the primary anticoagulant used for extracorporeal membrane oxygenation (ECMO) support. More recently, however, bivalirudin, a direct thrombin inhibitor, has emerged as an alternative. This systematic review based on PRISMA guidelines, aims to summarize 16 comparative studies and 8 meta-analysis and review articles published from January, 2011 till May, 2023 which directly compares ECMO courses using heparin versus bivalirudin as the anticoagulant. While this comparison is complicated by the lack of a standardized definition of major bleeding or thrombosis, our overall findings suggest there is no statistical difference between heparin and bivalirudin in incidence of bleeding and thrombosis. That said, some studies found a statistical significance favoring bivalirudin in reducing major bleeding, thrombosis, and the need for transfusions. We also offer essential guidance for appropriately selecting an anticoagulant and monitoring its effect in ECMO settings.

Bivalirudin Compared to Heparin as the Primary Anticoagulant in Pediatric Berlin Heart Recipients

Bivalirudin has been used in increasing frequency as an alternative to unfractionated heparin (UFH) in pediatric recipients of Berlin Heart EXCOR ventricular assist devices (VAD). This single-center, retrospective review characterizes anticoagulant trends and outcomes in pediatric Berlin Heart VAD recipients implanted between September 1, 2013, and August 31, 2021, anticoagulated with either bivalirudin or UFH. Thirty-one patients were included; 65% who received bivalirudin and 35% who received UFH. The median age was 2.9 years, included 64.5% females, with 61.3% of patients diagnosed with dilated cardiomyopathy and 25.8% of patients with congenital heart disease. Therapeutic anticoagulation was achieved sooner in the bivalirudin group compared to UFH via anti-Xa monitoring (median 5.7 and 69.5 hours, respectively, p < 0.001). Bivalirudin had a greater number of therapeutic values comparatively to UFH (52% and 24%, respectively; p < 0.001) and a superior number of hours in the therapeutic range (67% and 32%, respectively; p < 0.001). Secondary outcomes were similar among the two groups, apart from greater chest tube output (UFH), more frequent events of elevated plasma-free hemoglobin (bivalirudin), and more frequent elevated inflammatory markers postimplant (bivalirudin). Prevalence of pump replacements secondary to significant clot burden and prevalence of stroke was comparable. In this patient cohort, bivalirudin demonstrated greater anticoagulation stability comparatively to UFH. Multicenter collaboration would be necessary to identify whether this further translates into improved patient outcomes.

Heparin-based versus bivalirudin-based anticoagulation in pediatric extracorporeal membrane oxygenation: A systematic review

Introduction

Optimal anticoagulation therapy is essential for the prevention of thrombotic and hemorrhagic complications in pediatric patients supported with extracorporeal membrane oxygenation (ECMO). Recent data have demonstrated bivalirudin has the potential to surpass and replace heparin as the anticoagulant of choice.

Methods

We conducted a systematic review comparing the outcomes of heparin-based versus bivalirudin-based anticoagulation in pediatric patients supported on ECMO to identify the preferred anticoagulant to minimize bleeding events, thrombotic complications, and associated mortality. We referenced the PubMed, Cochrane Library, and Embase databases. These databases were searched from inception through October 2022. Our initial search identified 422 studies. All records were screened by two independent reviewers using the Covidence software for adherence to our inclusion criteria, and seven retrospective cohort studies were identified as appropriate for inclusion.

Results

In total, 196 pediatric patients were anticoagulated with heparin and 117 were anticoagulated with bivalirudin while on ECMO. Across the included studies, it was found that for patients treated with bivalirudin, trends were noted toward lower rates of bleeding, transfusion requirements, and thrombosis with no difference in mortality. Overall costs associated with bivalirudin therapy were lower. Time to therapeutic anticoagulation varied between studies though institutions had different anticoagulation targets.

Conclusion

Bivalirudin may be a safe, cost-effective alternative to heparin in achieving anticoagulation in pediatric ECMO patients. Prospective multicenter studies and randomized control trials with standard anticoagulation targets are needed to accurately compare outcomes associated with heparin versus bivalirudin in pediatric ECMO patients.

Evaluation of clinical outcomes in patients treated with heparin or direct thrombin inhibitors during extracorporeal membrane oxygenation: a systematic review and meta-analysis

BACKGROUND

The number of patients treated with extracorporeal membrane oxygenation (ECMO) devices is increasing. Anticoagulation therapy is crucial to prevent thrombosis during ECMO therapy. Predominantly, heparin has been used as primary anticoagulant but direct thrombin inhibitors (DTI) have been established as alternatives. The aim of this systematic review and meta-analysis was to evaluate clinical outcomes in patients treated with heparin compared to different DTI during ECMO.

METHODS

A systematic search was conducted. Full scientific articles were sought for inclusion if heparin anticoagulation was compared to DTI (argatroban/bivalirudin) in ECMO patients. Risk of bias was assessed by Newcastle Ottawa scale. Primary endpoint was in-hospital mortality. Bleeding events, thrombotic events, hours of ECMO support, days of hospital stay, percentage of time within therapeutic range and time to therapeutic range were extracted from full texts as secondary endpoints. Results were presented as Forrest-plots. GRADE was used for confidence assessment in outcomes.

RESULTS

Systematic search identified 4.385 records, thereof 18 retrospective studies for a total of 1942 patients, complied with the predefined eligibility criteria:15 studies investigated bivalirudin and 3 studies investigated argatroban versus heparin. Risk of bias was high for most studies. In-hospital mortality, major bleeding events and pump-related thrombosis were less frequent in DTI group as compared to heparin [mortality-OR 0.69, 95% CI 0.54-0.86; major bleeding-OR 0.48, 95% CI 0.29-0.81; pump thrombosis-OR 0.55, 95% CI 0.40-0.76]. Additionally, percentage of time within therapeutic range was higher for DTI [SMD 0.54, 95% CI 0.14-0.94]. GRADE approach revealed a very low level of certainty for each outcome.

CONCLUSION

In this meta-analysis, DTI and especially bivalirudin showed beneficial effects on clinical outcomes in ECMO patients as compared to heparin. However, due to the lack of randomized trials, certainty of evidence is low.

TRIAL REGISTRATION

This systematic review and meta-analysis was prospectively registered at PROSPERO data base (reference number CRD42021237252 ).