Optimal management of cardiac surgery patients using direct oral anticoagulants: recommendations for clinical practice

OBJECTIVES

Literature is scarce on the management of patients using direct oral anticoagulants (DOACs) undergoing elective, urgent and emergency surgery. Therefore, we summarize the current evidence and provide literature-based recommendations for the management of patients on DOACs in the perioperative phase.

METHODS

A general literature review was conducted on the pharmacology of DOACs and for recommendations on the management of cardiac surgical patients on DOACs. Additionally, we performed a systematic review for studies on the use of direct DOAC reversal agents in the emergency cardiac surgical setting.

RESULTS

When surgery is elective, the DOAC cessation strategy is relatively straightforward and should be adapted to the renal function. The same approach applies to urgent cases, but additional DOAC activity drug level monitoring tests may be useful. In emergency cases, idarucizumab can be safely administered to patients on dabigatran in any of the perioperative phases. However, andexanet alfa, which is not registered for perioperative use, should not be administered in the preoperative phase to reverse the effect of factor Xa inhibitors, as it may induce temporary heparin resistance. Finally, the administration of (activated) prothrombin complex concentrate may be considered in all patients on DOACs, and such concentrates are generally readily available.

CONCLUSIONS

DOACs offer several advantages over vitamin K antagonists, but care must be taken in patients undergoing cardiac surgery. Although elective and urgent cases can be managed relatively straightforwardly, the management of emergency cases requires particular attention.

Successful Nafamostat Mesilate Administration for Andexanet Alfa-Induced Heparin Resistance

Andexanet alfa is an analog of activated factor X and is used as an antagonist of anti-activated factor X agents. Andexanet alfa is useful for hemostasis in emergent bleeding during direct oral anticoagulant administration, which contributes to safety. In patients undergoing surgery with cardiopulmonary bypass because of heparin resistance, anesthesiologists are faced with a choice of anticoagulants. Herein, we experienced anesthesia for vascular prostheses with cardiopulmonary bypass for acute aortic dissection in a patient who had received andexanet alfa preoperatively. Heparin was initially used as the anticoagulant during cardiopulmonary bypass; however, despite the administration of large doses and antithrombin III preparations, anticoagulation was insufficient. Therefore, nafamostat mesilate was administered and sufficient anticoagulation was attained. The patient completed surgery under cardiopulmonary bypass, coagulation function was recovered shortly after withdrawal, and no obvious adverse effects were observed.

Off-pump coronary artery bypass with heparin in a patient with a history of heparin-induced thrombocytopenia: a case report

Background

Cardiovascular surgery for patients with a history of heparin-induced thrombocytopenia (HIT) with thrombosis requires careful perioperative anticoagulation therapy. When cardiovascular surgery is required for patients having ‘remote’ HIT, such as those who had a history of HIT and platelet factor-4/heparin antibodies turned out to be negative, it is recommended that re-exposure to heparin should be limited only to the intraoperative phase. However, few case reports have described detailed strategies for perioperative anticoagulation regimens.

Case presentation

We present the case of a 76-year-old woman, presenting with unstable angina pectoris and requiring coronary artery bypass grafting. She had a history of cardiac resuscitation and percutaneous coronary intervention for unstable angina pectoris with ventricular tachycardia 7 years prior, which caused HIT with thrombosis resulting in amputation of four fingers. On admission, platelet factor-4/heparin antibodies, biomarkers for HIT were not detected; the platelet count was 18.0 × 10⁴/µl. Off-pump coronary artery bypass grafting was performed using heparin; argatroban infusion was continued until 9 h prior to the operation and restarted 3 h postoperatively, bridged with regular warfarin from 4 days to 3 months postoperatively. Platelet factor-4 /heparin antibodies were detected on postoperative day 8 without any clinical symptoms and became negative by day 91.

Conclusion

We consider this anticoagulation strategy is effective especially in countries, where bivalirudin is not available. Re-exposure to heparin in cardiovascular surgery for patients with a history of ‘remote HIT’ is reasonable, and appropriate anticoagulation is important for an uneventful postoperative course.

Anticoagulation with Argatroban in a Patient with Heparin-Induced Thrombocytopenia and Renal Insufficiency Undergoing Orthotopic Heart Transplantation

Unfractionated heparin is the anticoagulant of choice for cardiac surgery that requires cardiopulmonary bypass. However, it can cause serious side effects like heparin-induced thrombocytopenia (HIT), an immune-mediated process where antibodies are directed against heparin and platelet 4 complexes. In such cases, alternative pharmacologic strategies are implemented to facilitate safe bypass conditions. A woman with severe decompensated heart failure was heparinized for intra-aortic balloon pump and subsequent LVAD placement. On day 6, a fall in platelets from 113,000 to 26,000 was noted. She was diagnosed with HIT. Heparin was discontinued and replaced with an argatroban infusion for the duration of her care until heart transplantation was completed. We review the mechanism, diagnosis, and complications of HIT. We discuss cardiopulmonary bypass and its relation to heparin, HIT, and heparin alternatives. We discuss argatroban's relevant pharmacology, clinical use, advantages, and disadvantages.

Quantitative and Qualitative Platelet Derangements in Cardiac Surgery and Extracorporeal Life Support

Thrombocytopenia and impaired platelet function are known as intrinsic drawbacks of cardiac surgery and extracorporeal life supports (ECLS). A number of different factors influence platelet count and function including the inflammatory response to a cardiopulmonary bypass (CPB) or to ECLS, hemodilution, hypothermia, mechanical damage and preoperative treatment with platelet-inhibiting agents. Moreover, although underestimated, heparin-induced thrombocytopenia is still a hiccup in the perioperative management of cardiac surgical and, above all, ECLS patients. Moreover, recent investigations have highlighted how platelet disorders also affect patients undergoing biological prosthesis implantation. Though many hypotheses have been suggested, the mechanism underlying thrombocytopenia and platelet disorders is still to be cleared. This narrative review aims to offer clinicians a summary of their major causes in the cardiac surgery setting.

A 24-hour perioperative case study on argatroban use for left ventricle assist device insertion during cardiopulmonary bypass and veno-arterial extracorporeal membrane oxygenation

A 44-year-old male with ongoing chest pain and left ventricular ejection fraction <20% was transferred from a peripheral hospital with intra-aortic balloon pump placement following a non-ST-elevation myocardial infarction (STEMI). The patient underwent emergent multi-vessel coronary artery bypass grafting requiring veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) on post-operative day (POD)#9 secondary to cardiogenic shock with biventricular failure. Due to clot formation, an oxygenator change-out was necessary shortly after initiation. Following a positive heparin-induced thrombocytopenia (HIT) assay, a total circuit exchange was required to eliminate all heparin coating and argatroban was deemed the anticoagulant of choice due to acute kidney injury. On POD#24, the decision was made to implant a left ventricle assist device (LVAD) as a bridge to heart transplantation. There was difficulty achieving an activated clotting time (ACT) >400 s: multiple argatroban bolus doses were required, along with accelerated up-titration of infusion dosing. Despite maintaining an ACT >484 s, clot formation was observed in the cardiotomy reservoir prior to separation. Subsequently, the patient developed severe disseminated intravascular coagulopathy, with both intra-cardiac and intravascular thrombi, requiring massive transfusion and continuous cell saving due to severe hemorrhage post cardiopulmonary bypass (CPB). The patient received a total of 105 units of plasma, 74 units of packed red cells, 19 units of platelets, 13 bottles of 5% albumin, 6 units of cryoprecipitate and 2 doses of factor VIIa intraoperatively over the course of 24 hours. A total of 19.7 L of washed red blood cells were returned to the patient from the cell saver. With the LVAD in place, the patient developed transfusion-related acute lung injury and acute respiratory distress syndrome with right ventricular dysfunction requiring VA ECMO once again. On POD#30, ECMO was discontinued and the patient was discharged from the intensive care unit (ICU) on POD 66. After a very complex post-operative stay with numerous surgeries and extensive rehabilitation, the patient was discharged home with the LVAD on POD#112.

Heparin-induced thrombocytopenia in cardiac surgery and critically ill patients

Thrombocytopenia as well as anti-platelet factor 4/heparin (PF4/H) antibodies are common in cardiac surgery patients and those treated in the intensive care unit. In contrast, heparin-induced thrombocytopenia (HIT) is uncommon in these populations (∼1 % and ∼0.5 %, respectively). A stepwise approach where testing for anti-PF4/H antibodies is performed only in patients with typical clinical symptoms of HIT improves diagnostic specificity of the laboratory assays without losing sensitivity, thereby helping to avoid overdiagnosis and resulting HIT overtreatment. Short-term re-exposure to heparin, especially given intraoperatively for cardiovascular surgery, is a reasonable therapeutic option in patients with a history of HIT who subsequently test negative for HIT antibodies. Organ failure(s), enhanced bleeding risks, and other characteristics require special considerations regarding non-heparin anticoagulation: Argatroban is the alternative anticoagulant with pharmacokinetics independent of renal function, but it has a prolonged half-life in case of impaired liver function. For bivalirudin, protocols during cardiopulmonary bypass surgery are established, and it is suitable for patients with liver insufficiency. A major issue of direct thrombin inhibitors are false high activated partial thromboplastin time values in patients with comorbidities affecting prothrombin, which can result in systematic underdosing of the drugs. This is not the case for danaparoid and fondaparinux, which can be monitored by anti-factor Xa assays, but have long half-lives and no suitable antidote. This review includes also information on management of on- and off-pump cardiac surgery, ventricular assist devices, percutaneous interventions, continuous renal replacement therapy, and extracorporeal membrane oxygenation in patients with HIT.

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.

Cardiopulmonary Bypass Without Heparin

Due to familiarity, short half-life, ease of monitoring, and the availability of a reversal agent, heparin remains the anticoagulant of choice for cardiac operations requiring cardiopulmonary bypass (CPB). However, occasionally patients require CPB but should not receive heparin, most often because of acute or subacute heparin-induced thrombocytopenia (HIT). In these cases, if it is not feasible to wait for the disappearance of HIT antibodies, an alternative anticoagulant must be selected. A number of non-heparin anticoagulant options have been explored. However, current recommendations suggest the use of a direct thrombin inhibitor such as bivalirudin. This review describes the use of heparin alternatives for the conduct of CPB with a focus on the direct thrombin inhibitors.

Fondaparinux for intra and perioperative anticoagulation in patients with heparin-induced thrombocytopenia candidates for peripheral vascular surgery: Report of 4 cases

INTRODUCTION

Intra and perioperative anticoagulation in patients with heparin induced thrombocytopenia (HIT), candidates for peripheral vascular surgery remains a challenge, as the best alternative to heparin has not yet been established. We evaluated the off-label use of fondaparinux in four patients with HIT, undergoing peripheral vascular surgery procedures.

PRESENTATION OF CASES

Four patients of whom 3 men of a mean age of 66 years, with proven heparin induced thrombocytopenia (HIT) underwent two axillo-femoral bypasses, one femoro-popliteal bypass and one resection of a splenic artery aneurysm under fondaparinux. No intra or perioperative bleeding or thrombosis of new onset was observed.

DISCUSSION

In the absence of a valid alternative to heparin for intra and perioperative anticoagulation in HIT, several other anticoagulants can be used in an off-label setting. However, no general consensus exist on which should be the one of choice. In this small series fondaparinux appeared to be both safe and effective.

CONCLUSIONS

These preliminary results seem to justify the off-label use of fondaparinux for intra and perioperative anticoagulation in patients with HIT, candidates for peripheral vascular surgery interventions.

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.

[Argatroban, a new antithrombotic treatment for heparin-induced thrombocytopenia application in cardiac surgery and in intensive care]

OBJECTIVES

Although heparin-induced thrombocytopemia (HIT) is uncommon, its thromboembolic complications are potentially life-threatening. The low-molecular weight heparins are less responsible of HIT than unfractionated heparin (UFH) but this latter is still indicated in some circumstances such as cardiac surgery. Argatroban, a selective thrombin inhibitor, recently available, has been indicated in HIT treatment. This review presents the main pharmacological characteristics, its indications and uses in the context of cardiac surgery and in intensive care medicine.

METHODS

Review of the literature in Medline database over the past 15 years using the following keywords: argatroban, cardiac surgery, circulatory assistance, cardiopulmonary bypass.

RESULTS

Despite its short-acting pharmacokinetic, argatroban cannot be recommended during cardiopulmonary bypass. On the contrary, argatroban is indicated in many circumstances in postoperative period of various cardiac surgeries (on-pump, off-pump, circulatory assistance). Nevertheless, after cardiac surgery, doses have to be adapted according to coagulation laboratory testing (ACT), particularly in patients presenting acute organ failure (kidney injury, heart failure, liver failure). This compound has no antagonist and is excluded during severe hepatic failure. The continuous intravenous administration is a drawback.

CONCLUSION

Argatroban is a new direct competitive thrombin inhibitor well evaluated as treatment of HIT after cardiac surgery. In HIT management, argatroban is an interesting alternative to lepirudin that is not anymore available and danaparoid because of supply disturbances.

Simultaneous comparison of thrombogenic reactions to different combinations of anticoagulants, activated clotting times, and materials

Thrombogenic reactions under multiple interactions of pharmacological agents, doses, and materials have not been well understood yet. The aim of this study was to investigate the ability to simultaneously compare thrombogenic reactions to different combinations of anticoagulants, doses, and blood-contacting materials, in a single human blood using an in vitro test method. Four venous blood samples were drawn from each of six healthy volunteers into syringes that contained two different amounts of heparin and argatroban to set the activated clotting time (ACT) to approximately 200 or 500 s, respectively. The four blood samples from each volunteer were immediately poured into two clinical-grade extracorporeal circulation tubes: a polyvinyl chloride (PVC) tube and a poly(2-methoxyethyl acrylate)-coated (PMEA) PVC tube. These tubes with an inner diameter of 12.7 mm were rotated at 183 rpm in a 37°C chamber for 10 min. The results indicated that the in vitro thrombogenicity test method was capable of assessing differences in platelet factor 4 and β-thromboglobulin increases among different combinations of the two materials, two anticoagulants, and two ACTs. Higher amounts of total plasma proteins were absorbed on PVC tubes than on PMEA-coated tubes when using the same anticoagulant and dose. These data elucidate that the in vitro thrombogenicity test method is useful for the simultaneous quantitative evaluation of the influences of various combinations of materials, pharmacological agents, and doses on thrombogenicity in a single human blood.

Non-recovery of ACT in a patient with heparin-induced thrombocytopenia type II during mitral valve replacement using argatroban anticoagulation

Argatroban was used as the anticoagulant during cardiopulmonary bypass (CPB) in a patient with heparin-induced thrombocytopenia (HIT) type II undergoing mitral valve replacement. Dosage was reduced because of preoperative congestive liver disorder. Perioperative coagulability was poor, and, ultimately, failure of hemostasis led to a fatal outcome. Although argatroban use as an anticoagulant for HIT is reported, the optimal dose has not been established. During long-term CPB, increasing the total dosage may extend anticoagulant ability, leading to dose dependence. Because no antagonist for argatroban exists, failure of hemostasis might occur.

Difficulty in the management of anticoagulation with argatroban during off-pump coronary artery bypass grafting

Heparin-induced thrombocytopenia (HIT) can often result in devastating thromboembolic outcomes. Argatroban is frequently administered as an alternative anticoagulant to heparin. We present a complicated case of HIT in which off-pump coronary artery bypass grafting was performed using anticoagulation with argatroban. Although the active clotting time was maintained between 220 and 270 s using argatroban, intraoperative thrombotic complications and postoperative prolonged coagulopathy were encountered. <Learning objective: The use of argatroban involves a potential risk of inadequate anticoagulation or life-threatening postoperative bleeding depending on the dose. We recommend that the target ACT during off-pump coronary artery bypass grafting with argatroban should be strictly maintained over 250 s, although an ACT exceeding 300 s may cause prolonged coagulopathy>.

Challenges encountered with argatroban anticoagulation during cardiopulmonary bypass

Use of argatroban as an alternative to heparin during cardiopulmonary bypass (CPB) in patients with heparin-induced thrombocytopenia has gained some attention in the past two decades. Dosing of argatroban during CPB is complex due to lack of complete understanding of its pharmacokinetic profile and the various elements during CPB that may alter its plasma levels. We report a case where the challenges in dosing argatroban led to failure to provide adequate anticoagulation during CPB, as evidenced by clot formation in the oxygenator, and extensive bleeding in the postoperative period.

Strategies in heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is an uncommon condition that may confront cardio-thoracic surgeons with difficult problems. The underlying cause of HIT is the formation of antibodies against platelet factor 4/heparin complexes, leading to platelet activation and intravascular platelet aggregation. HIT occurs following heparin administration usually with a time delay of 5-10 days. Clinical suspicion and laboratory tests for platelet-activating antibodies are the cornerstone of diagnosis. Appropriate strategies in HIT are stopping heparin and use of alternative anticoagulants. In addition, surgery with extracorporeal circulation (ECC) should be postponed whenever possible or alternative anticoagulants have to be used during ECC.

Coagulation considerations for infants and children undergoing cardiopulmonary bypass

Cardiac surgery involving cardiopulmonary bypass imposes a significant pathophysiologic burden on patients. Pediatric patients are especially predisposed to the adverse effects of surgery and bypass on the coagulation system, with resultant bleeding, transfusion, and poor outcomes. These risks accrue to pediatric patients in inverse proportion to their weight and are attributable to hematologic immaturity, coagulation defects associated with congenital heart disease, bypass equipment, and the nature of congenital heart surgery. Standard anticoagulation does not completely inhibit thrombin generation, and continuous consumption of coagulation factor continues throughout bypass. Conventional measurements of anticoagulation during bypass poorly reflect this incomplete anticoagulation, and alternate methods may improve anticoagulant therapy. Emerging therapies for blocking the effects of bypass on the coagulation system hold promise for decreasing bleeding and related complications, and improving outcomes in congenital heart surgery.