Time in Therapeutic Range for Left Ventricular Assist Device Patients Anticoagulated With Warfarin: A Correlation to Clinical Outcomes

Evaluation of the Hemocompatibility of the Direct Oral Anticoagulant Apixaban in Left Ventricular Assist Devices: The DOAC LVAD Study

BACKGROUND

Patients receiving left ventricular assist device (LVAD) support require long-term anticoagulation to reduce the risk of thromboembolic complications. Apixaban is a direct oral anticoagulant that has become first-line therapy; however, its safety in LVAD recipients has not been well described.

OBJECTIVES

This study sought to investigate whether, in patients with a fully magnetically levitated LVAD, treatment with apixaban would be feasible and comparable with respect to safety and freedom from the primary composite outcome of death or major hemocompatibility-related adverse events (HRAEs) (stroke, device thrombosis, major bleeding, aortic root thrombus, and arterial non-central nervous system thromboembolism) as compared with treatment with warfarin.

METHODS

The DOAC LVAD (Evaluation of the Hemocompatibility of the Direct Oral Anti-Coagulant Apixaban in Left Ventricular Assist Devices) trial was a phase 2, open label trial of LVAD recipients randomized 1:1 to either apixaban 5 mg twice daily or warfarin therapy. All patients were required to take low-dose aspirin. Patients were followed up for 24 weeks to evaluate the primary composite outcome.

RESULTS

A total of 30 patients were randomized: 14 patients to warfarin and 16 patients to apixaban. The median patient age was 60 years (Q1-Q3: 52-71 years), and 47% were Black patients. The median time from LVAD implantation to randomization was 115 days (Q1-Q3: 56-859 days). At 24 weeks, the primary composite outcome occurred in no patients receiving apixaban and in 2 patients (14%) receiving warfarin (P = 0.12); these 2 patients experienced major bleeding from gastrointestinal sources.

CONCLUSIONS

Anticoagulation with apixaban was feasible in patients with an LVAD without an excess of HRAEs or deaths. This study informs future pivotal clinical trials evaluating the safety and efficacy of apixaban in LVAD recipients. (Evaluation of the Hemocompatibility of the Direct Oral Anti-Coagulant Apixaban in Left Ventricular Assist Devices [DOAC LVAD]; NCT04865978).

An ISHLT consensus statement on strategies to prevent and manage hemocompatibility related adverse events in patients with a durable, continuous-flow ventricular assist device

Life expectancy of patients with a durable, continuous-flow left ventricular assist device (CF-LVAD) continues to increase. Despite significant improvements in the delivery of care for patients with these devices, hemocompatability-related adverse events (HRAEs) are still a concern and contribute to significant morbility and mortality when they occur. As such, dissemination of current best evidence and practices is of critical importance. This ISHLT Consensus Statement is a summative assessment of the current literature on prevention and management of HRAEs through optimal management of oral anticoagulant and antiplatelet medications, parenteral anticoagulant medications, management of patients at high risk for HRAEs and those experiencing thrombotic or bleeding events, and device management outside of antithrombotic medications. This document is intended to assist clinicians caring for patients with a CF-LVAD provide the best care possible with respect to prevention and management of these events.

Design and Rationale for the Direct Oral Anticoagulant Apixaban in Left Ventricular Assist Devices (DOAC LVAD) Study

Implantable left ventricular assist device (LVAD) therapy is used to improve quality of life, alleviate symptoms and extend survival rates in patients with advanced heart failure. Patients with LVADs require chronic anticoagulation to reduce the risk of thromboembolic complications, and they commonly experience bleeding events. Apixaban is a direct oral anticoagulant that has become first-line therapy for patients with nonvalvular atrial fibrillation and venous thromboembolism; however, its safety in patients with LVADs has not been well characterized. The evaluation of the hemocompatibility in the DOAC LVAD (Direct Oral Anti-Coagulant apixaban in Left Ventricular Assist Devices) trial is a phase 2, open-label trial of patients with LVADs who were randomized to either apixaban or warfarin therapy. Patients randomized to apixaban will be started on a dosage of 5 mg twice daily, whereas those randomized to warfarin will be managed at an International Normalized Ratio goal of 2.0-2.5. All patients will be treated with aspirin at 81 mg daily. We plan to randomize and follow as many as 40 patients for 24 weeks to evaluate the primary outcomes of freedom from death or hemocompatibility-related adverse events (stroke, device thrombosis, bleeding, aortic root thrombus, and arterial non-CNS thromboembolism). The DOAC LVAD trial will establish the feasibility of apixaban anticoagulant therapy in patients with LVADs. Clinicaltrials.gov: NCT04865978.

Epistaxis Rates and Health Care Utilization in Patients With a Ventricular Assist Device

Objective

Identify baseline epistaxis rates and epistaxis-related health care utilization trends in the ventricular assist device (VAD) population.

Methods

Single center, retrospective cohort study consisting of chart review of adult VAD patients. Analysis of descriptive statistics was assessed using χ 2 tests, independent sample t tests, or Fisher's exact when expected counts were low. Logistic regression was used to assess associations between epistaxis and variables of interest.

Results

Two hundred ninety patients were included in the analysis. Ninety-eight (33.8%) patients developed epistaxis and 84 (29.0%) received medical attention. Patients with gastrointestinal (GI) bleeding had increased rates of epistaxis (42.4% vs 29.0%). Logistic regression analysis found GI bleeding to have an adjusted odds of developing epistaxis of 1.94 (95% confidence interval [CI]: 1.12-3.37) and kidney disease to have an adjusted odds of 1.83 (95% CI: 1.06, 3.13).

Discussion

VAD implantation improves survival and quality of life but also carries significant bleeding risks. At our institution, 29% of VAD patients received medical attention for epistaxis. GI bleeding and kidney disease were found to have increased adjusted odds of developing epistaxis. Fifty-nine percent of epistaxis events occurred while inpatient and 32.8% of events were seen in the emergency department.

Implications for Practice

VAD patients are an at-risk group that could potentially benefit from preventative nasal hydration regimen.

Role of Electrode Configuration and Morphology in Printed Prothrombin Time Sensors

Patients on long-term anticoagulation therapy require frequent testing of prothrombin time/international normalized ratio (PT/INR) to ensure therapeutic efficacy. Point-of-care (POC) PT tests for at-home monitoring eliminate the burden of visiting the clinic, but realizing a cost-effective and robust at-home POC test for PT has remained elusive. Recent demonstrations of printed PT sensors show promise for addressing the cost concerns; however, the printed sensors have lacked quality control to ensure reliability between tests. In this work, on-chip redundancy is introduced with fully printed impedimetric PT sensors by incorporating simultaneous testing with a single fingerstick volume of blood (8 μL). The influence of electrode dimensions and composition were studied, revealing an optimal electrode spacing of 200 μm and an unexpected dependence on the morphology of the electrodes. Three distinct silver morphologies were studied: aerosol jet printed silver nanoparticles (AgNPs), aerosol jet printed silver nanowires (AgNWs), and evaporated silver (Ag). In general, AgNPs exhibited the best PT sensor performance, due to relatively low conductance and high porosity. Overall, the printed impedimetric PT sensor functionalization was improved by incorporating simultaneous testing and, when combined with a handheld control device, shows promise for leading to a system that overcomes the challenges of commercial PT/INR coagulometers.

Thrombotic and Hemorrhagic Complications Following Left Ventricular Assist Device Placement: An Emphasis on Gastrointestinal Bleeding, Stroke, and Pump Thrombosis

The left ventricular assist device (LVAD) is a mechanical circulatory support device that supports the heart failure patient as a bridge to transplant (BTT) or as a destination therapy for those who have other medical comorbidities or complications that disqualify them from meeting transplant criteria. In patients with severe heart failure, LVAD use has extended survival and improved signs and symptoms of cardiac congestion and low cardiac output, such as dyspnea, fatigue, and exercise intolerance. However, these devices are associated with specific hematologic and thrombotic complications. In this manuscript, we review the common hematologic complications of LVADs.

Quality of Anticoagulation With Phenprocoumon and Warfarin in Left Ventricular Assist Device Patients: A Multicenter Study

VISUAL ABSTRACT

of key results. INR, international normalized ratio; TTR, time in therapeutic range; PTR, percentage of tests in range; HRAE, hemocompatibility-related adverse event; FFUV, first follow-up visit; GIB, gastrointestinal bleeding; HR, hazard ratio.http://links.lww.com/ASAIO/A961.

Impact of Initial Warfarin Dosing on Time in Therapeutic Range for Postoperative Left Ventricular Assist Device Patients

ABSTRACT

Initial warfarin dosing and time in therapeutic range (TTR) are poorly characterized for early post-operative left ventricular assist device (LVAD) patients. This study evaluated TTR after LVAD implantation compared between patients receiving low-dose (<3 mg) and high-dose (≥3 mg) warfarin. This single-center, retrospective analysis included 234 LVAD patients who received warfarin within 5 days of implantation. The primary outcome was TTR during the 5 days following first international normalized ratio (INR) ≥2 compared between low-dose and high-dose groups. Secondary outcomes were hospital and intensive care unit length of stay, time to first INR ≥2, TTR after first INR ≥2, and reinitiation of parenteral anticoagulation. No difference in TTR was detected between warfarin groups (57.2% vs. 62.7%, P = 0.13). Multivariable analysis did not detect any factors predictive of TTR during the primary outcome timeframe, but age and body mass index were associated with the warfarin dose. The low-dose group received a mean warfarin dose of 1.9 mg (±0.64 mg), and the high dose group received 4.34 mg (±1.38 mg). Cohort TTR during the primary outcome timeframe was 60.5% and 56.5% for hospitalization. The low-dose group had longer intensive care unit length of stay, shorter time to therapeutic INR, and more frequently reinitiated parenteral anticoagulation. Patients with recent LVAD implantation are complex and have diverse warfarin sensitivity factors, which did not allow for optimal warfarin dose detection, although half of all patients received doses between 2.04 mg and 4.33 mg. Individualized dosing should be used, adjusting for patient-specific factors such as age, body mass index, and drug interactions.

Protocol-based anticoagulation management for mechanical circulatory support patients can be safe and efficient

BACKGROUND

Achieving optimal anticoagulation remains a significant challenge in managing patients on left ventricular assist device (LVAD) support. Maintaining tight control of anticoagulation can be time-consuming but essential in preventing serious complications such as pump thrombosis and bleeding.

OBJECTIVES

The efficacy and safety of a nurse coordinator-driven outpatient protocol (NCDOP) was evaluated for managing anticoagulation for LVAD patients.

METHODS

A retrospective analysis was performed as part of a single-center quality improvement project. The primary outcome was time in therapeutic range (TTR), a measure of anticoagulation target efficacy before and after the implementation of the protocol.

RESULTS

Among 47 patients, who served as their own control, there was no significant change in TTR or proportion of hospitalizations following institution of the protocol. Pre-NCDOP, there were six major bleeding and two thrombotic events, and none during the post-NCDOP period.

CONCLUSIONS

A NCDOP is a reliable method to manage anticoagulation in LVAD patients and facilitates efficient care delivery. Future multicenter studies with larger patient cohorts are warranted to expand on the findings outlined in this manuscript.

Time in Therapeutic Range Significantly Impacts Survival and Adverse Events in Destination Therapy Patients

The study aim was to examine the impact time in therapeutic range (TTR, International Normalized Ratio [INR] 2.0-3.0) has on survival and adverse events in patients receiving the HeartWare HVAD System in the ENDURANCE and ENDURANCE Supplemental Trials. Evaluable subjects (n = 495) had >1 INR value recorded 1-24 months postimplant and were categorized as: low TTR (10-39%), moderate TTR (40-69%), and high TTR (≥70%). Baseline characteristics, adverse events, and survival were analyzed. Low TTR patients experienced higher rates of major bleeding (1.69 vs. 0.54 events per patient year [EPPY]; p < 0.001), GI bleeding (1.22 vs. 0.38 EPPY; p < 0.001), stroke (0.47 vs. 0.17 EPPY; p < 0.001), thrombus requiring exchange (0.05 vs. 0.01 EPPY; p = 0.02), infection (1.44 vs. 0.69 EPPY; p < 0.001), and renal dysfunction (0.23 vs. 0.05 EPPY; p < 0.001) compared with high TTR. Moderate TTR had higher rates of major bleeding (0.75 vs. 0.54 EPPY; p < 0.001), thrombus requiring exchange (0.05 vs. 0.01 EPPY; p = 0.007), cardiac arrhythmia (0.32 vs. 0.24 EPPY; p = 0.04), and infection (0.90 vs. 0.69 EPPY; p = 0.001) compared with high TTR. Two year survival was greater among moderate and high versus low cohorts (Log-rank p = 0.001). The significant reduction in morbidity and mortality in destination therapy (DT) HVAD patients with well-controlled TTR (≥70%) emphasizes the importance of vigilant anticoagulation management.

Time in Therapeutic Range for Bivalirudin Among Pediatric Ventricular Assist Device Recipients

Given the adverse event rates involving bleeding and thrombosis among children on ventricular assist devices (VADs), anticoagulant management has become a focal point for quality improvement and innovation. There may be advantages to using direct thrombin inhibitors, such as bivalirudin, though this has not been fully explored. As the percent time in therapeutic range (%TTR) for anticoagulants is classically associated with improved clinical outcomes, we evaluated the %TTR for bivalirudin among pediatric VAD recipients. Using a modification of the Rosendaal method, %TTR was calculated using activated partial thromboplastin time measurements for 11 VAD recipients in the early postoperative period (postoperative days 0-14) and for the duration of VAD support. In the initial 2 weeks after VAD implant, mean %TTR was 68.7 (±13.0). During the entire support course, the mean %TTR improved to 79.6 (±11.0). There was an era effect with improving %TTR in the latter half of the study period. We report very good %TTR for bivalirudin both in the first 2 weeks post implant and this improved over the duration of support. Because %TTR reflects the degree of safety and efficacy in chronic anticoagulation, this relatively high %TTR among a diverse, often critically ill cohort suggests that bivalirudin may be a promising agent. Although this study was underpowered to comprehensively evaluate adverse events on bivalirudin, this represents an important next step for larger scale study.

Argatroban versus heparin in patients without heparin-induced thrombocytopenia during venovenous extracorporeal membrane oxygenation: a propensity-score matched study

BACKGROUND

During venovenous extracorporeal membrane oxygenation (vvECMO), direct thrombin inhibitors are considered by some potentially advantageous over unfractionated heparin (UFH). We tested the hypothesis that Argatroban is non-inferior to UFH regarding thrombosis and bleeding during vvECMO.

METHODS

We conducted a propensity-score matched observational non-inferiority study of consecutive patients without heparin-induced-thrombocytopenia (HIT) on vvECMO, treated between January 2006 and March 2019 in the medical intensive care unit at the University Hospital Regensburg. Anticoagulation was realized with UFH until August 2017 and with Argatroban from September 2017 onwards. Target activated partial thromboplastin time was 50 ± 5seconds in both groups. Primary composite endpoint was major thrombosis and/or major bleeding. Major bleeding was defined as a drop in hemoglobin of ≥ 2 g/dl/day or in transfusion of ≥ 2 packed red cells/24 h, or retroperitoneal, cerebral, or pulmonary bleeding. Major thrombosis was defined as obstruction of > 50% of the vessel lumen diameter by means of duplex sonography. We also assessed technical complications such as oxygenator defects or pump head thrombosis, the time-course of platelets, and the cost of anticoagulation (including HIT-testing).

RESULTS

Out of 465 patients receiving UFH, 78 were matched to 39 patients receiving Argatroban. The primary endpoint occurred in 79% of patients in the Argatroban group and in 83% in the UFH group (non-inferiority for Argatroban, p = 0.026). The occurrence of technical complications was equally distributed (Argatroban 49% vs. UFH 42%, p = 0.511). The number of platelets was similar in both groups before ECMO therapy but lower in the UFH group after end of ECMO support (median [IQR]: 141 [104;198]/nl vs. 107 [54;171]/nl, p = 0.010). Anticoagulation costs per day of ECMO were higher in the Argatroban group (€26 [13.8;53.0] vs. €0.9 [0.5;1.5], p < 0.001) but not after accounting for blood products and HIT-testing (€63 [42;171) vs. €40 [17;158], p = 0.074).

CONCLUSION

In patients without HIT on vvECMO, Argatroban was non-inferior to UFH regarding bleeding and thrombosis. The occurrence of technical complications was similarly distributed. Argatroban may have less impact on platelet decrease during ECMO, but this finding needs further evaluation. Direct drug costs were higher for Argatroban but comparable to UFH after accounting for HIT-testing and transfusions.

International Normalized Ratio Test Frequency in Left Ventricular Assist Device Patients Affects Anticoagulation Quality and Adverse Events

Anticoagulation therapy in patients using left ventricular assist device (LVAD) is essential to reduce hemocompatibility related adverse events (HRAEs). Vitamin K-antagonist dosage must be adapted and monitored by INR point-of-care testing (POCT) in outpatients. The study aims to determine if the frequency of INR POCT in LVAD outpatients has an influence on the quality of anticoagulation therapy (ACQ), HRAEs, and outcomes. This retrospective study included n = 48 patients who received LVAD implantation (HMII, HM3, and HVAD) between 2013 and 2017. ACQ (% of INR tests in range, PTR), outcomes and HRAEs using Kaplan-Meier curves were compared in a daily (n = 36) and 3×/week (n = 12) INR POCT group. Further, based on the achieved PTR ranging from 0-60% (poor), 61-70% (acceptable), and 71-100% (well controlled), HRAEs and outcomes were compared. Daily and 3×/week groups were similar in perioperative risk factors and INR target (p = 0.28). Freedom from any HRAE (38.9% vs. 25.0%, p = 0.44), any readmission (72.2% vs. 75.0%, p = 0.97), and 1 year survival (91.7% vs. 91.7%, p = 0.98) were comparable in both groups. The PTR was significantly higher with the daily self-assessments (73.5% vs. 68.4%, p = 0.006). Well vs. poorly controlled INR POCT patients more often had (p = 0.01) a daily POCT frequency (92%) vs. poorly controlled (54%) and significantly higher freedom from neurologic events (96.0 vs. 69.2%, p = 0.024) as well as hemorrhagic strokes (100% vs. 76.9%, p = 0.011). Well-controlled anticoagulation of LVAD outpatients is associated with less neurologic events. The frequency of INR POCT could be one of the key factors in the reduction of HRAEs, so future prospective, large-scale studies should help to clarify the effects.

Comparison of Outcomes of Enoxaparin Bridge Therapy in HeartMate II versus HeartWare HVAD Recipients

BACKGROUND

There is a lack of robust data evaluating outcomes of enoxaparin "bridge" therapy in left ventricular assist device (LVAD) patients.

METHODS

We performed a retrospective study of HeartMate II (HM II) and HeartWare HVAD recipients that received therapeutic enoxaparin as "bridge" therapy to describe bleeding and thrombotic events and compare outcomes between devices. The primary endpoint was the incidence of bleeding within 30 days of "bridge" episode. Major bleeding was defined by INTERMACS criteria.

RESULTS

We evaluated 257 "bridge" episodes in 54 patients, 35 with a HM II device and 19 with an HVAD device that underwent 176 and 81 bridging episodes, respectively. The median INR prior to "bridge" was lower in the HM II group compared to the HVAD group (1.5 vs 1.7, P < .01), however, there was no difference in the median duration of "bridge" therapy (7 vs 7 days, P = .42). There were a total of 30 (12%) bleeding episodes, with the majority in the HM II group vs HVAD (26 [15%] vs 4 [5%], P = .02). We observed 3 (1%) thromboembolic events in 2 (4%) patients with an HVAD device. On multivariate analysis, the presence of a HM II device was associated with a 4-fold increased risk of bleeding.

CONCLUSION

We found the use of enoxaparin "bridge" therapy to be associated with a higher incidence of bleeding in patients with a HM II device compared with an HVAD device. Assessment of device- and patient-specific factors should be evaluated to minimize bleeding events.

Antiplatelet and anticoagulation strategies for left ventricular assist devices

Left ventricular assist devices (LVAD) have revolutionized the management of advanced heart failure. However, complications rates remain high, among which hemorrhagic and thrombotic complications are the most important. Antiplatelet and anticoagulation strategies form a cornerstone of LVAD management and may directly affect LVAD complications. Concurrently, LVAD complications influence anticoagulation and anticoagulation management. A thorough understanding of device, patient, and management, including anticoagulation and antiplatelet therapies, are important in optimizing LVAD outcomes. This article provides a comprehensive state of the art review of issues related to antiplatelet and anticoagulation management in LVADs. We start with a historical overview, the epidemiology and pathophysiology of bleeding and thrombotic complications in LVADs. We then discuss platelet and anticoagulation biology followed by considerations prior to, during, and after LVAD implantation. This is followed by discussion of anticoagulation and the management of thrombotic and hemorrhagic complications. Specific problems, including management of heparin-induced thrombocytopenia, anticoagulant reversal, novel oral anticoagulants, artificial heart valves, and noncardiac surgeries are covered in detail.

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.

Early Detection of Pump Thrombosis in Patients With Left Ventricular Assist Device

Pump thrombosis (PT) is a serious adverse event in patients receiving left ventricular assist devices (LVAD). The study aims to determine whether pump parameters and clinical data may enable early detection of PT. This retrospective study included 88 patients who received an LVAD between 2012 and 2015 among which those with intra-PT were identified. In a propensity score-matched control group observation, time periods were matched with time before thrombosis. International normalized ratio (INR) time in therapeutic range (TTR) and lactate dehydrogenase (LDH) were analyzed for 60 days preceding PT. Furthermore, pump data (power, flow, and speed) in HeartWare ventricular assist devices (HVAD) patients were analyzed 7 days before PT using a mixed-design analysis of variance to investigate temporal changes in pump data. Pump thrombosis occurred in 15 patients (13 males, age 58 ± 10 years, 7 HeartMate II and 8 HVAD). International normalized ratio therapeutic range (2.0-3.0) and acetylsalicylic acid daily doses (100-200 mg) were similar for both groups, but patients with PT had lower TTR (36% vs. 65%; p = 0.025). No significant difference in LVAD power between groups was seen at baseline (p = 0.31), and power did not change in the control group over time (p > 0.99). Lactate dehydrogenase increased already 1 week prior PT and power from 4.4 ± 0.8 W at baseline to 4.9 ± 0.8 W (p = 0.007) 2 days before readmission and to 6.5 ± 1.8 W (p = 0.015) at readmission. Pump thrombosis is associated with a lower percentage of INR TTR and elevated LDH before the event. A better monitoring of pump parameters would enable PT detection already up to 2 days in advance.

Acquired Von Willebrand Syndrome (AVWS) in cardiovascular disease: a state of the art review for clinicians

Von Willebrand Factor (vWF) is a large glycoprotein with a broad range of physiological and pathological functions in health and disease. While vWF is critical for normal hemostasis, vascular integrity and repair, quantitative and qualitative abnormalities in the molecule can predispose to serious bleeding and thrombosis. The heritable form of von Willebrand Disease was first described nearly a century ago, but more recently, recognition of an acquired condition known as acquired von Willebrand Syndrome (AVWF) has emerged in persons with hematological, endocrine and cardiovascular diseases, disorders and conditions. An in-depth understanding of the causes, diagnostic approach and management of AVWS is important for practicing clinicians.

Development of Multidisciplinary Anticoagulation Management Guidelines for Patients Receiving Durable Mechanical Circulatory Support

Patients receiving durable mechanical circulatory support (MCS) require life-long anticoagulation with a vitamin K antagonist (VKA). Due to alternations in hemostasis, concomitant therapy with antiplatelet agents and critical illness, they are at increased risk of thromboembolic and bleeding complications compared with the general population managed on VKAs. To prevent thrombotic events, current guidelines recommend that patients with MCS receive long-term anticoagulation with a VKA to maintain a target international normalized ratio (INR) as specified by device manufacturers, but limited data exist regarding specific routine management of anticoagulation therapy and its potential complications. To optimize anticoagulation management and minimize risk in these patients, we have centralized anticoagulation management in a collaborative approach between the inpatient hemostatic and antithrombotic (HAT) stewardship service and between ambulatory anticoagulation management service (AMS) and the advanced heart disease team. Patients are followed by these three services beginning when the device is implanted and extending the duration that patients have the device. The teams include multiple clinicians from cardiac surgery, cardiology, hematology, pharmacy, nursing, case management, nutrition, and psychiatry, therefore, in order to standardize practice among clinicians without compromising patient centered decision making, we assembled an interdisciplinary team to create multiple treatment guidelines. In addition to a centralized and collaborative approach, our guidelines ensure seamless transitions of care between the inpatient and outpatient settings. We believe our approach has demontrated a positive improvement in the care of these challenging patients. In this article, we present our comprehensive centralized anticoagulation management approach for patients with left ventricular assist systems (LVAS).

Anticoagulation management following left ventricular assist device implantation is similar across all provider strategies

OBJECTIVES

Thromboembolic and bleeding events are potential complications following left ventricular assist device implantation. A tight control of the international normalized ratio (INR) is believed to be crucial in the reduction of postimplant complications. There is significant variability among institutions as to whether a device implanting centre should be managing the INR. In this study, we evaluated the effect of INR management strategies in maintaining a therapeutic INR.

METHODS

A retrospective review was utilized to identify patients implanted with either the HeartMate II or the HeartWare HVAD between January 2011 and February 2016. Patients were stratified into 4 groups based on the post-discharge INR management strategy: outside hospital system anticoagulation clinic, outside hospital primary care provider, implanting centre anticoagulation clinic or implanting centre ventricular assist device office. The INR data were collected and analysed for both the early (discharge, 7, 14, 21 and 30 days) and late (3, 6, 9 and 12 months) postoperative periods.

RESULTS

There were 163 patients identified during the study period who met the study inclusion criteria: 49 (30%) patients were managed by an outside hospital system anticoagulation clinic, 59 (36.2%) patients by an outside hospital physician/primary care provider, 22 (13.5%) patients by the implanting centre anticoagulation clinic and 33 (20.2%) patients by the implanting centre ventricular assist device office. There were no statistically significant differences found between management strategies across all time points.

CONCLUSIONS

There was no statistically significant difference found between the management strategies examined. Regardless of the chosen INR management strategy, patients have similar INR values and postoperative outcomes.

Improving anticoagulation of patients with an implantable left ventricular assist device

Patients supported with implantable left ventricular assist devices (LVAD) have a significant risk of bleeding and thromboembolic complications. All patients require anticoagulation with warfarin, aiming for a target international normalised ratio (INR) of 2.5 and most patients also receive antiplatelet therapy. We found marked variation in the frequency of INR measurements and proportion of time outside the therapeutic INR range in our LVAD-supported patients. As part of a quality improvement initiative, home INR monitoring and a networked electronic database for recording INR results and treatment decisions were introduced. These changes were associated with increased frequency of INR measurement. We anticipate that changes introduced in this quality improvement project will reduce the likelihood of adverse events during long-term LVAD support.

A Standardized Telephone Intervention Algorithm Improves the Survival of Ventricular Assist Device Outpatients

Ventricular assist devices (VADs) are an established therapeutic option for patients with chronic heart failure. Continuous monitoring of VAD parameters and their adherence to guidelines are crucial to detect problems in an early stage to optimize outcomes. A telephone intervention algorithm for VAD outpatients was developed, clinically implemented and evaluated. During the phone calls, a structured inquiry of pump parameters, alarms, blood pressure, INR, body weight and temperature, exit‐site status and heart failure symptoms was performed and electronically categorized by an algorithm into 5 levels of severity. VAD outpatient outcomes without (n = 71) and with bi‐weekly telephone interviews in their usual care (n = 25) were conducted using proportional hazard Cox regression, with risk adjustment based on a propensity score model computed from demographics and risk factors. From February 2015 through October 2017, 25 patients (n = 3 HeartMate II, n = 4 HeartMate 3 and n = 18 HeartWare HVAD) underwent 637 telephone interventions. In 57.5% of the calls no problems were identified, 3.9% were recalled on the next day because of alarms. In 26.5% (n = 169), the VAD Coordinator had to refer to the physician due to elevated blood pressure (n = 125, >85 mm Hg), INR < 2.0 or > 4.0 (n = 24) or edema (n = 10), 11.9% of the calls led to a follow‐up because of equipment or exit‐site problems. Propensity‐adjusted 2‐year survival (89% vs. 57%, P = 0.027) was significantly higher for the telephone intervention group. Continuous, standardized communication with VAD outpatients is important for early detection of upcoming problems and leads to significantly improved survival.

Effects of vitamin K epoxide reductase complex 1 gene polymorphisms on warfarin control in Japanese patients with left ventricular assist devices (LVAD)

PURPOSE

This study aimed to investigate relationships between times in therapeutic range (TTR) or warfarin sensitivity indexes (WSI) and VKORC1-1639G>A and CYP2C9 polymorphisms in patients with left ventricular assist devices (LVAD).

METHODS

Severe heart failure patients who received LVAD from January 1, 2013 to October 31, 2017 were recruited. Relationships between TTR or WSI and VKORC1-1639G>A and CYP2C9 gene polymorphisms were investigated immediately after LVAD implantation (period 1) and immediately prior to hospital discharge (period 2).

RESULTS

Among 54 patients, 31 (72.1%) had VKORC1-1639AA and CYP2C9*1/*1 (AA group) polymorphisms and 12 (27.9%) had VKORC1-1639GA and CYP2C9*1/*1 (GA group) polymorphisms. During period 1, mean prothrombin time-international normalized ratio (PT-INR) values were significantly higher in the AA group than in the GA group (2.21 vs. 2.05, p < 0.0001). Mean WSI values were 1.68-fold greater in the AA group than in the GA group (1.14 vs. 0.68, p < 0.0001). In addition, times below the therapeutic range (TBTR) in the GA group were significantly greater than in the AA group during period 1 (39.8 vs. 28.3%, p = 0.032), and insufficient PT-INR was more frequent in the GA group than in the AA group. However, mean PT-INR values during period 2 did not differ and no significant differences in TTR, TATR, and TBTR values were identified. In subsequent multivariable logistic regression analyses, the VKORC1-1639GA allele was significantly associated with insufficient anticoagulation.

CONCLUSION

Patients with the VKORC1-1639GA and CYP2C9*1/*1 alleles may receive insufficient anticoagulation therapy during the early stages after implantation of LVAD, and VKORC1-1639G>A and CYP2C9 genotyping may contribute to more appropriate anticoagulant therapy after implantation of LVAD.

Effects of Dicloxacillin on Warfarin Dose in Patients With a Left Ventricular Assist Device

Patients with a durable, continuous flow left ventricular assist device (CF-LVAD) require anticoagulation with warfarin to prevent thromboembolic events. Driveline infections (DLIs) are a common CF-LVAD complication. A common pathogen implicated in DLI is oxacillin-sensitive Staphylococcus aureus (OSSA), which is effectively treated by oral dicloxacillin. Previous published experiences have observed a significant drug interaction between dicloxacillin and warfarin resulting in decreased international normalized ratio (INR) and increased warfarin dosing requirements. We sought to analyze the effect of dicloxacillin on INR and warfarin dose when used for DLI in our CF-LVAD program. Five of 106 patients having received an CF-LVAD at our institution met the inclusion criteria for this case series. These patients required a mean 51.8% (standard deviation of 29.8%) weekly warfarin dose increase to restore INR to the therapeutic range after the addition of dicloxacillin. Three of the five patients subsequently had their dicloxacillin discontinued, with a mean decrease in weekly warfarin dose of 30.6% (standard deviation of 19.1%). In our experience, when coalesced with prior published reports, an empiric warfarin dose increase of 25% to 33% is reasonable upon initiation of dicloxacillin and an empiric warfarin dose reduction of 10% to 15% is recommended upon discontinuation of dicloxacillin. Close INR follow-up is warranted during and after dicloxacillin treatment.