Continuous flow left ventricular assist device technology has influenced wait times and affected donor allocation in cardiac transplantation

Impact of Continuous Flow Left Ventricular Assist Device on Heart Transplant Candidates: A Multi-State Survival Analysis

(1) Objectives: The aim of this study was to investigate the impact of the prolonged use of continuous-flow left ventricular assist devices (LVADs) on heart transplant (HTx) candidates. (2) Methods: Between January 2012 and December 2019, we included all consecutive patients diagnosed with end-stage heart failure considered for HTx at our institution, who were also eligible for LVAD therapy as a bridge to transplant (BTT). Patients were divided into two groups: those who received an LVAD as BTT (LVAD group) and those who were listed without durable support (No-LVAD group). (3) Results: A total of 250 patients were analyzed. Of these, 70 patients (28%) were directly implanted with an LVAD as BTT, 11 (4.4%) received delayed LVAD implantation, and 169 (67%) were never assisted with an implantable device. The mean follow-up time was 36 ± 29 months. In the multivariate analysis of survival before HTx, LVAD implantation showed a protective effect: LVAD vs. No-LVAD HR 0.01 (p < 0.01) and LVAD vs. LVAD delayed HR 0.13 (p = 0.02). Mortality and adverse events after HTx were similar between LVAD and No-LVAD (p = 0.65 and p = 0.39, respectively). The multi-state survival analysis showed a significantly higher probability of death for No-LVAD vs. LVAD patients with (p = 0.03) or without (p = 0.04) HTx. (4) Conclusions: The use of LVAD as a bridge to transplant was associated with an overall survival benefit, compared to patients listed without LVAD support.

Competing Risks to Transplant in Bridging with Continuous Flow Left Ventricular Assist Devices

BACKGROUND

Continuous flow left ventricular assist device(CF-LVAD) support is a mainstay in the hemodynamic management of patients with end-stage heart failure refractory to optimal medical therapy. In this report, we evaluated waitlist complications and competing outcomes for CF-LVAD patients compared to primary transplant candidates listed for orthotopic heart transplantation(OHT) at a single center.

METHODS

All patients listed for OHT between 2006-2020 at our institution were retrospectively reviewed(n=300 CF-LVAD; n=244 primary transplant). Kaplan-Meier methodology with log-rank testing was used to evaluate survival outcomes. Terminal outcomes of death, delisting, and transplant were assessed as competing risks and compared between groups using Gray's test. Multivariable Fine-Gray regression was used to identify predictors of transplantation.

RESULTS

One-year rates of transplant, delisting, and death were 48%, 8%, and 2%, respectively for CF-LVAD patients and 45%, 15%, and 9% for primary transplant(all P<0.001). Waitlist mortality at 5 years was 4% among CF-LVAD patients and 13% for primary transplants. All-cause mortality after listing was lower for CF-LVAD patients(P=0.017). There was no difference in post-transplant survival between groups(P=0.250). On multivariable Fine-Gray regression, stroke(P=0.017), respiratory failure(P=0.032), right ventricular failure(P=0.019), and driveline infection(P=0.050) were associated with decreased probability of transplantation. Post-transplant survival was not significantly worse for CF-LVAD patients who experienced device-related complications(P=0.901).

CONCLUSIONS

While device related-complications were significantly associated with decreased rates of transplant, CF-LVAD patients had excellent waitlist outcomes overall. In light of the 2018 allocation score change, the risk of complications should be taken into account when deciding whether to offer CF-LVAD as a bridge to transplant.

Heart transplant waiting list implications of increased ventricular assist device use as a bridge strategy: A national analysis

The use of ventricular assist devices (VADs) as a bridge to heart transplant (HT) is increasing, while HT volume remains stagnant. This may portend longer waiting times and an otherwise more competitive environment for all patients on the HT waiting list. A retrospective analysis of patients who were listed for HT in the United Network for Organ Sharing (UNOS) database from 2000 to 2015 was conducted. Mean waiting time, proportion of HT reception (%HT), proportion of death (%death), and proportion of waiting list removal (%removal) were calculated across three eras: Era 1 (2000-2007), Era 2 (2008-2011), and Era 3 (2012-2015). During the study period, 29 728 patients successfully underwent HT. 19 127 (64.3%) were directly transplanted (direct HT); 4491 (15.1%) received VADs prior to listing as a bridge to decision (BTD); and 4593 (15.5%) received VADs after listing as a bridge to transplant (BTT). Across the three eras, the average number of registrants per year grew. Among all groups, waiting time increased across the eras. %HT generally decreased in the BTD and BTT groups but remained constant in the direct HT group. %removal increased, while %death decreased in all group across the eras. Waiting time for HT increased from 2000 to 2015. Patients with VADs as a bridge strategy experienced decreasing %HT and increasing %removal but stable survival. Improvements in VAD safety and durability will ensure their success as part of a bridge strategy to HT under the new UNOS allocation policy.

CARDIAC TRANSPLANT -A SINGLE CENTRE RETROSPECTIVE OBSERVATION

Background and Aim: Advances in pharmacological and nonpharmacological management of heart failure shifted the paradigm to transplantation of heart. Currently so many centers are doing heart transplant as the availability of donors and recipients are increasing day by day. The goal of this study is to share our experience in all our heart transplantation procedures. Ours is a tertiary care government multi super Speciality hospital. In our institute we have been doing cardiac surgeries for six years and heart transplants for past three years. In this discussion we share our experience about how we did all the procedures in our center . Method: After getting approval from institutional research committee we analyzed 8 transplants done in our center. The preoperative optimization, monitoring tools, anesthetic technique and post-operative complications and management are discussed . Apart from routine monitors we have used BIS, Cerebral oximetry and cardiac output monitors. Result: Of the eight cases, six are doing well including a (pediatric) 10-year-old recipient. Of the remaining two, one patient died on 3rd Post-Operative Day due to acute kidney injury and the other was death due to acute rejection. Conclusion: The key points we have learnt from our experience are careful selection and preparation of the donor, adequate preload with optimal inotropic support during weaning, minimizing increase in pulmonary vascular resistance and good pain relief are key aspects for successful outcome.

Ventricular assist devices and middle age reduce heart transplantation rates for waitlist candidates

BACKGROUND

Ventricular assist devices (VADs) are commonly employed as a bridge to transplantation for heart failure. The full effects of VADs on transplantation rates are not fully understood. We sought to compare transplantation rates stratified by age and VAD status.

METHODS

Using the Organ Procurement and Transplantation Network (OPTN) database, we investigated the impact of age and VAD status on heart allocation rates among all transplant-eligible patients from January 2005 to September 2018. Patients were grouped based on the presence (+) or absence (-) of a VAD as well as age (<45, 45-65, and >65 years). Demographics were compared with a multivariate competing risk analysis that yielded risk-adjusted subdistribution hazard ratios (SHR).

RESULTS

Among the 50 602 total waitlist candidates, 18 271 patients with a VAD had higher rates of diabetes and cerebrovascular disease at waitlist entry. Multivariate analysis found statistically significant lower rates of transplantation for all (+)VAD groups compared with age-matched (-)VAD counterparts, with the 45- to 65-year-old (+)VAD group having the lowest transplantation rate (SHR = 0.62; P < .0005). Among (-)VAD patients, transplantation rates increased with increase in age.

CONCLUSIONS

There is a statistically significant reduced rate of transplantation for patients with a VAD compared with those without a VAD, with the lowest rate among those of ages 45 to 65 years with a VAD. The increasing prevalence of this demographic and the deprioritization of VADs in the new heart allocation criteria have the potential to further exacerbate this difference.

Heart Transplantation After Ventricular Assist Device Therapy: Benefits, Risks, and Outcomes

Heart transplantation is an established treatment for end-stage heart failure. Due to the increase in demand and persistent scarcity of organ, mechanical circulatory devices have played a major role in therapy for advanced heart failure. Usage of left ventricular assist device (LVAD) has gone up from 6% in 2006 to 43% in 2013 as per the United Network of Organ Sharing database. Majority of patients presenting for a heart transplantation are often bridged with an assist device prior for management of heart failure while on wait-list. On one hand, it is well established that LVADs improve survival on wait-list; on the other hand, the effect of LVAD on morbidity and survival after a heart transplantation is still unclear. In this article, we review the available literature and attempt to infer the outcomes given the risks and benefits of heart transplantation with prior LVAD patients.

Responding to Ventricular Assist Device Recalls: An Ethical Guide for Mechanical Circulatory Support Programs

We discuss the ethical responsibilities of mechanical circulatory support (MCS) programs in the context of cardiac device recalls, particularly the near-simultaneous recalls of Abbott HeartMate 3 left ventricular assist device (VAD) and Medtronic HVAD devices in 2018. We consider MCS programs' ethical responsibilities toward patients who already have VADs and their caregivers, as well as the impact of recalls on informed consent and shared decision-making in patients under consideration for new VADs. Timely communication to affected patients is imperative throughout the recall process. MCS programs are required to notify existing VAD patients about the nature and likelihood of risk. A press release from the device manufacturer or other press reports may occur before MCS teams learn about the recall. This leads to a disclosure gap, where the programs are actively deciding on an appropriate action plan while simultaneously fielding patient concerns. From an ethics standpoint, if all device users are owed the recall information from the manufacturer, all patients are owed the information from their treating team. The question is what to disclose specifically, and how.

Prediction Model for Wait Times in Cardiac Transplantation

Wait times have increased for patients approved for heart transplants. We reviewed United Network for Organ Sharing (UNOS) data for 14,242 patients listed for isolated heart transplant (2009-2013) to develop a risk score model for timing left ventricular assist device (LVAD) implantation in bridge-to-transplant patients. We used a multivariable Cox proportional hazards regression model with subsequent bootstrap resampling for internal validation to develop a scoring system that combined risk factors, weighted by the corresponding regression coefficients, to define an individual's risk score. Four risk factors were identified (body mass index, blood type, region, and urgency status) to be significantly and independently associated with wait time (p < 0.001), showing adequate model discrimination (C = 0.704) and calibration. Higher risk scores correlated with shorter wait times. Our model corresponded closely with observed transplant rates, predicting longer wait times for lower status, larger size, certain blood groups, and some UNOS regions. This tool has the potential to more accurately describe the wait-time duration for an individual patient, which may influence care decisions. The wait-time discrepancies (blood types/regions) reinforce the need to reevaluate the geographic-allocation policy. The proposed review of the UNOS heart allocation policy may make this model especially relevant.

Changing our Approach to Stage D Heart Failure

Despite the tremendous progress made in the management of heart failure (HF), many patients reach advanced stages. This paper aims to present a practical approach to the stage D HF patient who is no longer responding to optimal medical therapy. We discuss all available therapies for this patient population. We also offer some important caveats with regard to identification, risk stratification, evaluation and treatment including early patient referral to a center with an advanced HF program. Given the changing landscape of heart transplantation and an impending change in the allocation system, we also intend to engage a discussion on the need for a paradigm shift towards left ventricular assist device therapy in this population.

Comparing open gastrostomy tube to percutaneous endoscopic gastrostomy tube in heart transplant patients

Introduction

Impaired wound healing due to immunosuppression has led some surgeons to preferentially use open gastrostomy tube (OGT) over percutaneous gastrostomy tube (PEG) in heart transplant patients when long-term enteral access is deemed necessary.

Methods

The National Inpatient Sample (NIS) database (2005–2010) was queried for all heart transplant patients. Those receiving OGT were compared to those treated with PEG tube.

Results

There were 498 patients requiring long-term enteral access treated with a gastrostomy tube, with 424 (85.2%) receiving a PEG and 74 (14.8%) an OGT. The PEG cohort had higher Charlson comorbidity Index (4.1 vs. 2.0, p = 0.002) and a higher incidence of post-operative acute renal failure (31.5 vs. 12.7%, p = 0.001). Post-operative mortality was not different when comparing the two groups (13.8 vs. 6.1%, p = 0.06). On multivariate analysis, while both PEG (OR: 7.87, 95%C.I: 5.88–10.52, p < 0.001) and OGT (OR 5.87, 95%CI: 2.19–15.75, p < 0.001) were independently associated with mortality, PEG conferred a higher mortality risk.

Conclusions

This is the largest reported study to date comparing outcomes between PEG and OGT in heart transplant patients. PEG does not confer any advantage over OGT in this patient population with respect to morbidity, mortality, and length of stay.

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OGT may result in less mortality than PEG in heart transplant patients.

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Complications occur more frequently when heart transplant recipients receive PEG.

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PEG in heart transplant recipients does not result in decreased LOS or total cost.

High-speed visualization of disturbed pathlines in axial flow ventricular assist device under pulsatile conditions

OBJECTIVE

To investigate potentially prothrombotic flow patterns within an axial flow ventricular assist device under clinically relevant pulsatile hemodynamic conditions.

METHODS

A transparent replica of the HeartMate-II left ventricular assist device (Thoratec, Pleasanton, Calif) was visualized using a high speed camera at both low and high frame rates (125 and 3000 fps). Three steady-state conditions were studied: nominal (4.5 lpm), low flow (3.0 lpm), and high flow (6.0 lpm). Time-varying conditions were introduced with an external pulsatile pump that modulated the flow rate by approximately ± 50% of the mean, corresponding to a pulsatility index of 1.0.

RESULTS

At nominal and high flow rates, the path lines within the upstream region were generally stable, well attached, and streamlined. As the flow rate was reduced below 3.8 lpm, a rapid transition to a chaotic velocity field occurred, exhibiting a large toroidal vortex adjacent to the upstream bearing. The pathlines in the downstream stator section were consistently chaotic for all hemodynamic conditions investigated. It was common to observe tracer particles trapped within recirculation bubbles and drawn retrograde, causing repeated contact with the bearing surfaces. The addition of pulsatility caused the flow field to become periodically chaotic during the diastolic portion of the cardiac cycle depending on the instantaneous flow rate and acceleration.

CONCLUSIONS

The contribution of pulsatility by the native heart may induce a periodic disturbance to an otherwise stable flow field within an axial flow ventricular assist device, particularly during the diastolic and decelerating portion of the cardiac cycle. Potentially prothrombotic flow features were found to occur periodically in the region of the upstream bearing.

Long-term continuous-flow left ventricular assist devices (LVAD) as bridge to heart transplantation

Heart transplantation (HTx) is the treatment of choice for end-stage heart failure but the limited availability of heart's donors still represents a major issue. So long-term mechanical circulatory support (MCS) has been proposed as an alternative treatment option to assist patients scheduled on HTx waiting list bridging them for a variable time period to cardiac transplantation-the so-called bridge-to-transplantation (BTT) strategy. Nowadays approximately 90% of patients being considered for MCS receive a left ventricular assist device (LVAD). In fact, LVAD experienced several improvements in the last decade and the predominance of continuous-flow over pulsatile-flow technology has been evident since 2008. The aim of the present report is to give an overview of continuous-flow LVAD utilization in the specific setting of the BTT strategy taking into consideration the most representative articles of the scientific literature and focusing the attention on the evolution, clinical outcomes, relevant implications on the HTx strategy and future perspectives of the continuous-flow LVAD technology.

What's new in clinical solid organ transplantation by 2013

Innovative and exciting advances in the clinical science in solid organ transplantation continuously realize as the results of studies, clinical trials, international conferences, consensus conferences, new technologies and discoveries. This review will address to the full spectrum of news in transplantation, that verified by 2013. The key areas covered are the transplantation activity, with particular regards to the donors, the news for solid organs such as kidney, pancreas, liver, heart and lung, the news in immunosuppressive therapies, the news in the field of tolerance and some of the main complications following transplantation as infections and cancers. The period of time covered by the study starts from the international meetings held in 2012, whose results were published in 2013, up to the 2013 meetings, conferences and consensus published in the first months of 2014. In particular for every organ, the trends in numbers and survival have been reviewed as well as the most relevant problems such as organ preservation, ischemia reperfusion injuries, and rejections with particular regards to the antibody mediated rejection that involves all solid organs. The new drugs and strategies applied in organ transplantation have been divided into new way of using old drugs or strategies and drugs new not yet on the market, but on phase Ito III of clinical studies and trials.

Adult heart transplant: indications and outcomes

Cardiac transplantation is the treatment of choice for many patients with end-stage heart failure (HF) who remain symptomatic despite optimal medical therapy. For carefully selected patients, heart transplantation offers markedly improved survival and quality of life. Risk stratification of the large group of patients with end-stage HF is essential for identifying patients who are most likely to benefit, particularly as the number of suitable donors is insufficient to meet demand. The indications for heart transplant and review components of the pre-transplant evaluation, including the role for exercise testing and risk scores such as the Heart Failure Survival Score (HFSS) and Seattle Heart Failure Model (SHFM) are summarized. Common contraindications are also discussed. Outcomes, including survival and common complications such as coronary allograft vasculopathy are reviewed.