Pharmacotherapy considerations for long-term management of patients with left ventricular assist devices

Retrospective Evaluation of Inpatient Warfarin Management Practices in Patients Immediately Following Left Ventricular Assist Device Implantation

Background: The International Society for Heart and Lung Transplantation recommends patients receive warfarin and aspirin following left ventricular assist device (LVAD) placement. Optimal warfarin management in this population has not been well established. Objectives: The objectives of this study were to evaluate warfarin practices in patients immediately post-LVAD implantation. Methods: This single-center, retrospective cohort study included patients 18 years and older following LVAD placement from August 1, 2012 to April 1, 2020. The primary outcome was to assess patient-specific risk factors affecting time to therapeutic range. Secondary outcomes included bleeding events, thrombotic events, and warfarin dosing patterns. Results: Of 104 included patients, 91% reached the therapeutic range at a median of 8 days. A higher proportion of patients started on 3.5 mg or higher reached therapeutic international normalized ratio (INR) and faster (96% vs 90%; 8 vs 5 days) compared to lower doses. Univariate analysis of associations with reaching therapeutic INR range included initial warfarin dose, cumulative warfarin, and warfarin dosing changes, whereas HAS-BLED and CHA2DS2VAC were associated with slower time to therapeutic INR. Overall, 44% of patients met Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) bleeding criteria. There were a total of 12 thrombotic events and no pump thrombotic events. Total weekly warfarin dosing was significantly lower post-LVAD (24.3 mg vs 35 mg, P = 0.0009). In addition, warfarin requirements were statistically higher after the first week of therapy (4.0 mg vs 2.89 mg, P < 0.0001). Conclusion: Based on the results, consider warfarin starting dose between 2.5 and 4 mg for patients on LVAD therapy, while balancing patient-specific risks for bleeding.

Significance of right ventricular function for the outcome of treatment and remodeling of the heart after left ventricular assist device implantation

The efficiency of the device for permanent circulatory support of the left ventricle has been proven through clinical practice with the trend of constant improvement of treatment results along with biotechnological progress and improvement of surgical implantation techniques. The published reports of most reference cardiac surgery centers present a one-year survival rate of over 85%, a two-year survival rate of 70% and a five-year survival rate of 45-50%. In addition to clear benefits for the patient, implantation of LVAD also carries significant specific risks, so infections, post-implantation bleeding, strokes, and right ventricular postimplantation weakness are the most common complications. Given that the progress of the LVAD program is ensured primarily by reducing the incidence of complications not related to the functioning of individual segments of the cardiovascular system, and as left ventricular function is completely replaced by LVAD device, the most recent challenge is the decision to install LVAD device in the heart with right ventricular, given that the postimplantation weakness of right ventricular is associated with proven increased mortality and morbidity. Since the 1990s, studies on hearts with implanted LVAD as a bridge to heart transplantation have shown regression of cell hypertrophy, normalization of cell size, muscle fiber architecture, and heart chamber geometry. The described changes are characterized by the notion of reverse remodeling, which is synonymous with function recovery. It is this process at the level of the right ventricle that is recognized as extremely important for the success of LVAD programs, especially in the group of patients who have a certain degree of right ventricular weakness preoperatively. The basic requirements of the cardiac surgery team are adequate preoperative assessment of right ventricular weakness, then application of measures to prevent damage and load on the right ventricle during and after LVAD implantation, as well as providing adequate therapeutic measures for right ventricular recovery in the postimplantation period.

Enoxaparin Use and Adverse Events in Outpatients With a Continuous Flow Left Ventricular Assist Device at a Single Institution

BACKGROUND

Patients with left ventricular assist devices (LVADs) are anticoagulated with warfarin and may receive enoxaparin bridging for a subtherapeutic international normalized ratio (INR). There is no guideline regarding enoxaparin bridging in LVAD patients and a dosing strategy to ensure efficacy and safety is uncertain.

OBJECTIVE

The objective was to characterize the use of enoxaparin bridging for subtherapeutic INRs and its impact on thrombotic or major bleeding events (MBE) in patients with an LVAD.

METHODS

A retrospective review from 6/1/17 to 6/30/18 was performed. Patients with an LVAD were excluded if they had less than 60 days of outpatient anticoagulation or age <18 years old. Patients were divided into 2 cohorts based on enoxaparin exposure. MBE and thrombotic events were classified as related to enoxaparin if events occurred while receiving enoxaparin and up to 7 days or 30 days, respectively, after discontinuation.

RESULTS

Seventy-one LVAD patients met inclusion criteria and 50 patients received enoxaparin bridging. Therapeutic-dose enoxaparin was initiated at a mean INR of 1.8 for a mean duration of 2.8 days. In the enoxaparin exposure group, one MBE occurred 6 days after enoxaparin discontinuation, coinciding with an INR increase from 1.8 to 4.7. One thrombotic event occurred 2 days after enoxaparin discontinuation at an INR of 5.0.

CONCLUSION

This institution's bridging strategy of therapeutic-dose enoxaparin with a short duration has a low rate of bleeding and thrombotic events. Additional prospective studies of anticoagulation bridging based on characteristics such as type of LVAD device are warranted.

Efficacy and safety of chronic antimicrobial suppression therapy for left ventricular assist device driveline infections: A single-center descriptive experience

BACKGROUND

Driveline infection (DLI) is the most common left ventricular assist device (LVAD) infectious complication. Short-term antimicrobial therapy and local debridement are the cornerstones of management for these infections, but the use of chronic antimicrobial suppression (CAS) therapy is not well characterized.

METHODS

To better characterize the efficacy of CAS therapy, we performed a retrospective review of all patients (N = 219) receiving care at our tertiary transplant center with continuous-flow LVADs placed between August 2007 and July 2019.

RESULTS

A total of 24 patients were identified as having received CAS therapy as treatment for DLIs. The mean age was 56 years, 50% were female, and chronic kidney disease affected 63% of patients. Staphylococcus aureus accounted for half of all initial DLIs, and the mean length of CAS therapy was 486 days (range 48-2287 days). All patients received per os regimens as suppression therapy. Adverse events impacted 5 of 24 patients (0.43 events per 1000 days). Overall, the use of CAS therapy led to successful outcomes in 50% of patients and 29% experienced treatment failures. The remaining patients experienced stable symptoms. Relapses were the most common cause of treatment failure, and three patients experienced reinfections while on CAS therapy.

CONCLUSIONS

Our study suggests that CAS therapy for DLIs can be well tolerated, and future studies are needed to determine which patients merit suppression.

Over 870 days of successful antibiotic suppression therapy for VRE-infected left ventricular assist device

Left ventricular assist devices (LVADs) are used in patients with advanced heart failure. Infections are common complications following device placement; however, the efficacy of chronic antimicrobial suppression therapy for deep-seated infections is not well characterized. We report the case of a 49-year-old male with a HeartMate II LVAD who presented with a methicillin-sensitive Staphylococcus aureus pump pocket infection that was subsequently treated with antibiotics and HeartMate III pump exchange. A vancomycin-resistant Enterococcus faecium (VRE) pump pocket infection then developed and responded to surgical drainage followed by long-term suppression with daptomycin then linezolid for over 870 days. A second pump exchange was not required. To our knowledge, this represents the longest reported use of daptomycin (341 days) without symptomatic adverse events. Managing infections caused by multidrug-resistant pathogens presents a clinical challenge. This case demonstrates the potential for antimicrobial suppression therapy to allow for successful retention of a VRE-infected LVAD.

Chronic Heart Failure Treatment With the Left Ventricular Assist Device

The prevalence of chronic heart failure is increasing in the United States due to the increase in the number of older adults and because many people are surviving acute cardiac events and living longer with chronic heart disease. In end-stage heart failure, heart transplant was once the gold standard of treatment and patients had to wait for a matching heart donor. In the past, the left ventricular assist device (LVAD) was a mechanical circulatory support treatment used temporarily for those awaiting heart transplant. However, the LVAD is increasingly becoming the chosen treatment of patients in lieu of heart transplant. Home healthcare nurses and clinicians need to be familiar with LVADs in order to care for patients in end-stage heart failure who are using these devices. This article explains the mechanism, potential complications, and nursing implications of caring for the patient who is using an LVAD.