HFSA Expert Consensus Statement on the Medical Management of Patients on Durable Mechanical Circulatory Support

The medical management of patients supported with durable continuous flow left ventricular assist device (LVAD) support encompasses pharmacologic therapies administered in the preoperative, intraoperative, postoperative and chronic LVAD support stages. As patients live longer on LVAD support, the risks of LVAD-related complications and progression of cardiovascular and other diseases increase. Using existing data from cohort studies, registries, randomized trials and expert opinion, this Heart Failure Society of America Consensus Document on the Medical Management of Patients on Durable Mechanical Circulatory Support offers best practices on the management of patients on durable MCS, focusing on pharmacological therapies administered to patients on continuous flow LVADs. While quality data in the LVAD population are few, the utilization of guideline directed heart failure medical therapies (GDMT) and the importance of blood pressure management, right ventricular preload and afterload optimization, and antiplatelet and anticoagulation regimens are discussed. Recommended pharmacologic regimens used to mitigate or treat common complications encountered during LVAD support, including arrhythmias, vasoplegia, mucocutaneous bleeding, and infectious complications are addressed. Finally, this document touches on important potential pharmacological interactions from anti-depressants, herbal and nutritional supplements of relevance to providers of patients on LVAD support.

Assays to Monitor Bivalirudin

Bivalirudin (Angiomax, Angiox) is a parenteral direct thrombin inhibitor (DTI) that is used for patients with heparin-induced thrombocytopenia (HIT), where heparin cannot be used due to the risk of thrombosis. Bivalirudin is also licensed for use in cardiology procedures (e.g., percutaneous transluminal coronary angioplasty; PTCA). Bivalirudin is a synthetic analogue of hirudin found in the saliva of the medicinal leech and has a relatively short half-life of ~25 min. Several assays can be used to monitor bivalirudin; these include the activated partial thromboplastin time (APTT), activated clotting time (ACT), ecarin clotting time (ECT), an ecarin-based chromogenic assay, thrombin time (TT), the dilute TT, and the prothrombinase-induced clotting time (PiCT). Drug concentrations can also be measured using liquid chromatography tandem mass spectrometry (LC/MS) and clotting or chromogenic-based assays with specific drug calibrators and controls.

Bivalirudin vs. Enoxaparin in Intubated COVID-19 Patients: A Pilot Multicenter Randomized Controlled Trial

(1) Background: In COVID-19 patients, the occurrence of thromboembolic complications contributes to disease progression and mortality. In patients at increased risk for thrombotic complications, therapeutic enoxaparin should be considered. However, critically ill COVID-19 patients could develop resistance to enoxaparin. Bivalirudin, a thrombin inhibitor, may be an alternative. This pilot multicenter randomized controlled trial aims to ascertain if bivalirudin may reduce the time spent under invasive mechanical ventilation, as compared to enoxaparin. (2) Methods: Intubated COVID-19 patients at risk for thrombo-embolic complications were randomized to receive therapeutic doses of enoxaparin or bivalirudin. We ascertained the time spent under invasive mechanical ventilation during the first 28 days from Intensive Care Unit (ICU) admission. A standardized weaning protocol was implemented in all centers. In addition, we assessed the occurrence of thromboembolic complications, the number of patients requiring percutaneous tracheostomy, the gas exchange, the reintubation rate, the ICU length of stay, the ICU and 28-days mortalities. (3) Results: We enrolled 58 consecutive patients. Bivalirudin did not reduce the time spent under invasive mechanical ventilation as compared to enoxaparin (12 [8; 13] vs. 13 [10; 15] days, respectively; p = 0.078). Thrombotic (p = 0.056) and embolic (p = 0.423) complications, need for tracheostomy (p = 0.423) or reintubation (p = 0.999), the ICU length of stay (p = 0.076) and mortality (p = 0.777) were also similar between treatments. Patients randomized to bivalirudin showed a higher oxygenation at day 7 and 15 after randomization, when compared to enoxaparin group. (4) Conclusions: In intubated COVID-19 patients at increased risk for thromboembolic complications, bivalirudin did not reduce the time spent under invasive mechanical ventilation, nor improved any other clinical outcomes.

Anticoagulation strategies in critically-ill SARS-CoV-2 patients: the role of direct thrombin inhibitors

Objectives

To compare heparin-based anticoagulation and bivalirudin-based anticoagulation within the context of critically ill patients with a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

Design

An observational study.

Setting

At the intensive care unit of a university hospital.

Participants and Interventions

Critically ill patients with a SARS-CoV-2 infection receiving full anticoagulation with heparin or bivalirudin.

Measurements and Main Results

Twenty-three patients received full anticoagulation with bivalirudin and 60 with heparin. Despite patients in the bivalirudin group having higher mortality risk scores (SAPS II 60 ± 16 v 39 ±7, p < 0.001) and a higher need for extracorporeal support compared to the heparin group, hospital mortality was comparable (57% v 45, p = 0.3). No difference in thromboembolic complications was observed, and bleeding events were more frequent in patients treated with bivalirudin (65% v 40%, p = 0.01). Similar results were confirmed in the subgroup analysis of patients undergoing intravenous anticoagulation; in addition to comparable thrombotic complications occurrence and thrombocytopenia rate, however, no difference in the bleeding rate was observed (65% v 35%, p = 0.08).

Conclusions

Although heparin is the most used anticoagulant in the intensive care setting, bivalirudin-based anticoagulation was safe and effective in a cohort of critically ill patients with SARS-CoV-2. Bivalirudin may be given full consideration as an anticoagulation strategy for critically ill patients with SARS-CoV-2, especially in those with thrombocytopenia and on extracorporeal support.

Eleven Years of Venovenous Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome: From H1N1 to SARS-CoV-2. Experience and Perspectives of a National Referral Center

OBJECTIVE

Despite growing expertise and wide application of venovenous extracorporeal membrane oxygenation (VV ECMO) treatment for acute respiratory distress syndrome (ARDS) of different origin and during pandemics (H1N1 Influenza A virus and SARS-CoV-2), large reports are few and pertain mostly to multicenter registries, and randomized trials are difficult to perform. The aim of this study was to report outcomes, trends, and innovations of VV ECMO treatment over the last 11 years.

DESIGN, SETTING, AND PARTICIPANTS

Observational study on 142 patients treated at the IRCCS San Raffaele Hospital in Milan from June 2009 (year of the H1N1 pandemic) to May 2020 (SARS-CoV-2 pandemic).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The main causes of ARDS were H1N1 pneumonia in 36% of patients, bacterial pneumonia in 17%, and SARS-CoV-2 in 9%. Seventy-two percent of patients were centralized from remote hospitals, of whom 33% had implanted VV ECMO before transport. The most common cannulation strategy was the dual-lumen catheter cannulation system (55%), and anticoagulation was performed with bivalirudin in most patients (79%). Refractory hypoxia was treated with intravenous beta-blockers (64%), nitric oxide (20%), and pronation (8%). Almost one-third of patients (32%) were extubated while on ECMO. Forty-nine percent of patients were discharged from the intensive care unit, and hospital discharge was 46%; survival was lower in patients requiring VV ECMO for more than three weeks compared with shorter support duration (23% v 56%, p = 0.007). Anticoagulation with bivalirudin was associated with higher survival, compared with heparin (55% v 31%, p = 0.03), and lower thrombocytopenia incidence (69% v 35%, p = 0.003).

CONCLUSION

VV ECMO is the pivotal rescue treatment for refractory ARDS-timely treatment and optimal care are needed to optimize therapy, as duration of support is associated with outcome. Anticoagulation with bivalirudin may improve outcome.

A Review of Bivalirudin for Pediatric and Adult Mechanical Circulatory Support

As the use of mechanical circulatory support has increased in volume and complexity, anticoagulation remains an intricate component of a patient’s pharmacotherapy plan. Traditionally, heparin has been the primary anticoagulant utilized because of its ease of titration and  familiarity of use. More recently, bivalirudin, a direct thrombin inhibitor, has attracted attention as a potential alternative to traditional therapy. While labeled for use in percutaneous coronary interventions, it is utilized off-label for heparin-induced thrombocytopenia and mechanical circulatory support. A literature search identified ten studies in which bivalirudin was used in extracorporeal membrane oxygenation and five studies in which it was used in ventricular assist devices. The purpose of this review was to summarize the currently available literature for bivalirudin use for mechanical circulatory support in both adult and pediatric patients.

Impact of CytoSorb on kinetics of vancomycin and bivalirudin in critically ill patients

CytoSorb is a promising tool to treat severe inflammatory status with multiple mechanisms in the acute care setting. Its effect on drugs is, however, poorly documented in vivo, although removal of small molecules might translate into decreased blood levels of life-saving medications. The aim of this study was to assess the impact of CytoSorb on vancomycin and bivalirudin clearance in a large population of critically ill patients. We performed a single-center analysis of CytoSorb treatments performed between January 2018 and March 2019 in critically ill patients admitted to our intensive care unit. A total of 109 CytoSorb treatments were performed in 89 patients. A decrease in lactate dehydrogenase (P = .007), troponin T (P = .022), and creatine phosphokinase (P = .013) was reported during treatment. Vancomycin dose required significant adjustments during treatment (P < .001), but no significant change was necessary after the first 3 days. Similarly, the requirements of bivalirudin significantly changed over days (P < .001), but no dose adjustment was needed after the first 3 days of treatment. No differences in terms of vancomycin and bivalirudin dose need was observed between patients on extracorporeal membrane oxygenation and those who were not (P = .6 and P = .6, respectively), between patients with and without continuous veno-venous hemofiltration (P = .9 and P = .9, respectively), and between CytoSorb responders or not (P = .4 and P = .7, respectively). CytoSorb is effective in mitigating the systemic inflammatory response and safe with respect to vancomycin and bivalirudin administration. These preliminary data further support the use of CytoSorb as adjunct therapy in critically ill patients.

Pharmacotherapy for durable left ventricular assist devices

Left ventricular assist devices (LVADs) have revolutionized the care of patients with advanced heart failure, yet still require concomitant medications in order to achieve the best possible clinical outcomes. Since the outset of routine placement of durable, continuous-flow LVADs, much of the medication management of these patients to date has been based on International Society of Heart and Lung Transplantation (ISHLT) guidance, most recently published in 2013. Since 2013, numerous multidisciplinary pharmacotherapy publications have increased the LVAD community's understanding of best practices with respect to medications. We identified the major domains of LVAD medication management and conducted a comprehensive search of US National Library of Medicine MEDLINE^® database using keywords chosen to identify medication-related publications of significance dated 2013 or later. Trials pertaining to the HeartMate II™ and the HeartMate™ 3 LVADs (Abbott, Chicago, IL) and the HeartWare™ HVAD™ System (Medtronic, Minneapolis, MN) were chosen for inclusion. Highest priority for inclusion was given to prospective, randomized, controlled studies. Absent these, controlled trials (retrospective or prospective observational) were given next-highest consideration, followed by retrospective uncontrolled studies, and finally case series. Reference lists of qualified publications were reviewed to find any other publications of interest that were not discovered on initial search. Case reports were generally excluded, except where the insight gained was deemed to be uniquely pertinent. This document serves to provide a comprehensive review of the current understanding of optimal medication management in patients with durable, continuous-flow LVADs.

Hemostatic complications associated with ventricular assist devices

Hemostatic complications are common in patients with ventricular assist devices. The pathophysiologic mechanisms that lead to dysregulated hemostasis involve complex interactions between device surface, sheer stress, and blood flow. These factors lead to various manifestations that require a thorough understanding of the interplay among platelets, coagulation factors, and red cells. In this article, we review the pathophysiology of hematologic complications (bleeding, acquired von Willebrand disease, heparin-induced thrombocytopenia, hemolysis, stroke and pump thrombosis), the clinical manifestations, and the management of each. We summarize the evidence available for management of these entities and provide a pragmatic clinical review.

Antithrombotic therapy in ventricular assist device (VAD) management: From ancient beliefs to updated evidence. A narrative review

Platelets play a key role in the pathogenesis of ventricular assist device (VAD) thrombosis; therefore, antiplatelet drugs are essential, both in the acute phase and in the long-term follow-up in VAD management. Aspirin is the most used agent and still remains the first-choice drug for lifelong administration after VAD implantation. Anticoagulant drugs are usually recommended, but with a wide range of efficacy targets. Dual antiplatelet therapy, targeting more than one pathway of platelet activation, has been used for patients developing a thrombotic event, despite an increased risk of bleeding complications. Although different strategies have been attempted, bleeding and thrombotic events remain frequent and there are no uniform strategies adopted for pharmacological management in the short and mid- or long-term follow up. The aim of this article is to provide an overview of the evidence from randomized clinical trials and observational studies with a focus on the pathophysiologic mechanisms underlying bleeding and thrombosis in VAD patients and the best antithrombotic regimens available.

Argatroban and Bivalirudin for Perioperative Anticoagulation in Cardiac Surgery

Argatroban and bivalirudin are used as replacement anticoagulants for heparin. The authors review clinical studies for these drugs in the perioperative setting of cardiac surgical patients including extracorporeal management and mechanical support therapy.

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.

Ventricular assist devices and non-cardiac surgery

The use of ventricular assist devices has expanded significantly since their approval by the Food and Drug Administration in the United States in 1994. In addition to this, the prevalence of heart failure continues to increase. We aim to provide an overview of perioperative considerations and management of these patients for non-cardiac surgery. We performed a Medline search for the words “ventricular assist device,” “Heartmate” and “HeartWare” to gain an overview of the literature surrounding these devices, and chose studies with relevance to the stated aims of this review. Patients with ventricular assist devices are presenting more frequently for surgery not related to their cardiac pathology. As the mechanically supported population grows, general anesthesiologists will be faced with managing these patients, possibly outside of the tertiary care setting. The unique challenges of this patient population can best be addressed by a thorough understanding of ventricular assist device physiology and a multidisciplinary approach to care.

Antithrombotic therapy for left ventricular assist devices in adults: a systematic review

BACKGROUND

Left ventricular assist devices (LVADs) have dramatically increased the survival of adults with end-stage systolic heart failure. However, rates of bleeding and thromboembolism remain high.

OBJECTIVES

We completed a systematic review to evaluate outcomes of adults with LVADs treated with various anticoagulant and antiplatelet strategies.

METHODS

Databases were searched using the terms 'assist device', 'thrombosis', and 'anticoagulant' or 'platelet aggregation inhibitor' with appropriate synonyms, device names and manufacturers.

RESULTS AND CONCLUSIONS

Of 977 manuscripts, 24 articles met the inclusion criteria of adults with implanted LVADs where clinical outcomes were defined based on anticoagulant and/or antiplatelet regimen. Most studies reported treatment with unfractionated heparin post-operatively which was transitioned to a vitamin K antagonist (VKA). Goal INR varied between 1.5-3.5. Antiplatelet regimens ranged from no treatment to dual therapy. Definition of major bleeding differed between trials and incidence varied between 0% and 58%. The available evidence could not demonstrate a clear benefit of aspirin compared with VKA therapy alone [stroke RR 1.02 (95% CI 0.49-2.1)]. There was a suggestion that treatment with aspirin and dipyridamole decreased the risk of thromboembolism compared to aspirin [RR 0.50 (0.36-0.68)], but the comparison is limited by differences in demographics, devices, and INR goals among studies. Additionally, most studies did not blind investigators to outcomes thus contributing to an increased risk for bias. Clinical equipoise exists as to the most appropriate antithrombotic therapy in LVAD patients. Randomization between regimens within a prospective trial is needed to define the treatment regimen that minimizes both bleeding and thrombotic complications.