Desensitization strategies in adult heart transplantation-Will persistence pay off?

Sex differences in heart transplantation - analysis of the national inpatient sample 2012-2019

INTRODUCTION

Advanced heart failure therapies and heart transplantation (HT) have been underutilized in women. Therefore, we aimed to explore the clinical characteristics and outcomes of HT by sex.

METHODS

We conducted a retrospective analysis of adult discharges from the National Inpatient Sample (NIS) between 2012 and 2019. International Classification of Disease (ICD) procedure codes were used to identify those who underwent HT.

RESULTS

A total of 20,180 HT hospitalizations were identified from 2012-2019. Among them, 28 % were female. Women undergoing HT were younger (mean age 51 vs. 54.5 years, p<0.001). HT hospitalizations among men were more likely to have atrial fibrillation, diabetes, hypertension, renal failure, dyslipidemia, smoking, and ischemic heart disease. HT hospitalizations among women were more likely to have hypothyroidism and valvular heart disease. HT hospitalizations in women were associated with no significant difference in risk of in-hospital mortality (adjusted odds ratio [OR] 0.82; 95 % confidence interval [CI] 0.58-1.16, p=0.271), no significant difference in length of stay or inflation-adjusted cost. Men were more likely to develop acute kidney injury during HT hospitalization (69.2 % vs. 59.7 %, adjusted OR 0.71, 95 % CI 0.61-0.83, p<0.001).

CONCLUSIONS

HT utilization is lower in women. However, most major in-hospital outcomes for HT are similar between the sexes. Further studies are need to explore the causes of lower rates of HT in women.

Rapid desensitization through immunoadsorption during cardiopulmonary bypass. A novel method to facilitate human leukocyte antigen incompatible heart transplantation

BACKGROUND

Anti-human leukocyte antigen (HLA)-antibody production represents a major barrier to heart transplantation, limiting recipient compatibility with potential donors and increasing the risk of complications with poor waiting-list outcomes. Currently there is no consensus to when desensitization should take place, and through what mechanism, meaning that sensitized patients must wait for a compatible donor for many months, if not years. We aimed to determine if intraoperative immunoadsorption could provide a potential desensitization methodology.

METHODS

Anti-HLA antibody-containing whole blood was added to a Cardiopulmonary bypass (CPB) circuit set up to mimic a 20 kg patient undergoing heart transplantation. Plasma was separated and diverted to a standalone, secondary immunoadsorption system, with antibody-depleted plasma returned to the CPB circuit. Samples for anti-HLA antibody definition were taken at baseline, when combined with the CPB prime (on bypass), and then every 20 min for the duration of treatment (total 180 min).

RESULTS

A reduction in individual allele median fluorescence intensity (MFI) to below clinically relevant levels (<1000 MFI), and in the majority of cases below the lower positive detection limit (<500 MFI), even in alleles with a baseline MFI >4000 was demonstrated. Reduction occurred in all cases within 120 min, demonstrating efficacy in a time period usual for heart transplantation. Flowcytometric crossmatching of suitable pseudo-donor lymphocytes demonstrated a change from T cell and B cell positive channel shifts to negative, demonstrating a reduction in binding capacity.

CONCLUSIONS

Intraoperative immunoadsorption in an ex vivo setting demonstrates clinically relevant reductions in anti-HLA antibodies within the normal timeframe for heart transplantation. This method represents a potential desensitization technique that could enable sensitized children to accept a donor organ earlier, even in the presence of donor-specific anti-HLA antibodies.

End-stage heart failure: The future of heart transplant and artificial heart

In the last decades, outcomes significantly improved for both heart transplantation and LVAD. Heart transplantation remains the gold standard for the treatment of end stage heart failure and will remain for many years to come. The most relevant limitations are the lack of grafts and the effects of long-term immunosuppressive therapy that involve infectious, cancerous and metabolic complications despite advances in immunosuppression management. Mechanical circulatory support has an irreplaceable role in the treatment of end-staged heart failure, as bridge to transplant or as definitive implantation in non-transplant candidates. Although clinical results do not overcome those of HTx, improvement in the new generation of devices may help to reach the equipoise between the two therapies. This review will go through the evolution, current status and perspectives of both therapeutics.

Does bortezomib influence pre-transplant desensitization therapy or benefit post-heart transplant outcomes for highly sensitized patients?

BACKGROUND

The use of bortezomib which is a proteasome inhibitor has been demonstrated to be efficacious in small number of patients as a desensitization strategy in heart transplant. We reviewed our single center's experience using Bortezomib along with plasmapheresis as desensitization therapy for highly sensitized patients to assess pre- and post-transplant outcomes.

METHOD

We assessed 43 highly sensitized patients awaiting HTx (defined as cPRA > 50%) between 2010 and 2021 who underwent desensitization therapy with bortezomib. Only those patients who subsequently underwent HTx were included in this study. Enrolled patients received up to four doses of bortezomib (1.3 mg/m2 ) over 2 weeks in conjunction with plasmapheresis. The efficacy of PP/BTZ was assessed by comparing the calculated panel reactive antibodies to HLA class I or class II antigens. Post-transplant outcomes including overall survival and incidence of rejection were compared to those of non-sensitized patients (PRA < 10%, n = 649) from the same center.

RESULTS

The average cPRA prior to PP/BTZ was 94.5%. Post-PP/BTZ there was no statistically significant decline in mean cPRA, class I cPRA, or class II cPRA, though the average percentage decrease in class I cPRA (8.7 ± 17.0%) was higher than the change in class II cPRA (4.4 ± 13.3%). Resulted were also replicated with C1q-binding antibodies showing more effect on I class compared to class II (15.0 ± 37.4% vs. 6.8 ± 33.6%) as well as with 1:8 dilutional assay (14.0 ± 23.0% vs. 9.1 ± 34.9%). Additionally, PP/BTZ treated patients and the control group of non-sensitized patients had similar overall 1 year survival (95.4 vs. 92.5%) but patients with PP/BTZ had increased incidence of AMR (79.1% vs. 97.1%, p = < .001), any treated rejection (62.8% vs. 86.7%, p = < .001) and de novo DSA development (81.4% vs. 92.5%, p = .007). Major side effects of PP/BTZ included thrombocytopenia (42%), infection requiring antibiotics (28%), and neuropathy (12%).

CONCLUSION

The use of bortezomib in highly sensitized patients does not significantly lower circulating antibodies prior to heart transplantation. However, its use may improve the chances of obtaining an immuno-compatible donor heart and contribute to acceptable post-transplant outcomes.

Sex Differences in Cardiac Transplantation

PURPOSE OF REVIEW

The goal of this review was to summarize contemporary evidence surrounding sex differences in heart transplantation (HT).

RECENT FINDINGS

Women have steadily comprised approximately 25% of waitlist candidates and HT recipients. This disparity is likely multifactorial with possible explanations including barriers in referral to advanced heart failure providers, implicit bias, and concerns surrounding sensitization. Women continue to experience higher waitlist mortality at the highest priority tiers. After HT, there are differences in post-transplant complications and outcomes. Future areas of study should include sex differences in noninvasive surveillance, renal outcomes after transplantation, and patient-reported outcomes. There are important sex-specific considerations that impact candidate selection, donor matching, waitlist and post-transplant outcomes. Concerted efforts are needed to improve referral patterns to ensure transplantation is allocated equally.

Intermediate-term outcomes of complement inhibition for prevention of antibody-mediated rejection in immunologically high-risk heart allograft recipients

Allosensitization represents a major barrier to heart transplantation. We previously reported favorable 1-year outcomes of complement inhibition at transplant in highly sensitized recipients. We now report a longer follow-up. In this single-arm trial (NCT02013037), 20 patients with panel reactive antibodies ≥70% and preformed donor-specific antibodies received eculizumab during the first 2 months post-transplant. The primary end-point was antibody-mediated rejection ≥ pAMR2 and/or left ventricular dysfunction. The median follow-up was 4.8 years. Beyond the first year post-transplant, there were no episodes of pAMR2 or greater and no Left Ventricular (LV) dysfunction. There were 3 deaths, 1 episode of pAMR1, and 1 patient with minimal de novo cardiac allograft vasculopathy. Compared to a matched control group, we observed a nonstatistically significant benefit of eculizumab with a lower incidence of the primary end-point or death (primary end-point: hazard ratio = 0.50, 95% confidence interval = 0.15-1.67, and p = 0.26; mortality: hazard ratio = 0.51, 95% confidence interval = 0.13-2.07, and p = 0.35). Our results support the utility of complement inhibition for high-immunological-risk recipients. CLINICAL TRIAL REGISTRATION: ClinincalTrials.gov, NCT02013037. https://clinicaltrials.gov/ct2/show/NCT02013037?term=eculizumab&cond=heart+transplantation&draw=2&rank=1.

Three year post heart transplant outcomes of desensitized durable mechanical circulatory support patients

BACKGROUND

The risks and benefits of desensitization therapy (DST) in highly sensitized mechanical circulatory support (MCS) patients are not well known. We investigated 3 year post-transplant outcomes of desensitized durable MCS patients.

METHODS

Among 689 consecutively enrolled heart transplantation recipients between 2010 and 2016, we categorized them into Group A (desensitized MCS patients, n = 21), Group B (desensitized non-MCS patients, n = 28) and Group C (all nondesensitized patients, n = 640). Post-transplant outcomes included the incidence of primary graft dysfunction, 3-year survival, freedom from cardiac allograft vasculopathy, nonfatal major adverse cardiac events, any treated rejection, acute cellular rejection, antibody mediated rejection (AMR) and infectious complications.

RESULTS

The types of DST in Groups A and B were similar and included combinations of rituximab/intravenous immunoglobulin and plasmapheresis/bortezomib. Group A, compared with Group B, showed significantly higher pre-DST panel reactive antibody (PRA) (92.2 ± 9.8 vs. 83.3 ± 15.6, P = 0.007) and higher PRA reduction after DST (-22.2 ± 26.9 vs. -6.3 ± 7.5, P = 0.015). Groups A and C showed comparable primary graft dysfunction, 3-year survival, freedom from cardiac allograft vasculopathy, nonfatal major adverse cardiac events, any treated rejection, acute cellular rejection, and AMR. Although statistically not significant, Group A showed numerically higher 3-year freedom from AMR than Group B. Infectious complications were similar in both Groups A and B.

CONCLUSIONS

DST for MCS patients showed significant PRA reduction, resulting in an expansion of the donor pool. The post-transplant outcome of desensitized MCS patients showed comparable clinical outcomes to non-desensitized control patients in the same study period, revealing the safety and efficacy of DST.

Lung transplantation in an 18-month-old with donor specific antibodies - The use of intraoperative, targeted plasma exchange

BACKGROUND

Sensitised patients undergoing Human Leukocyte Antigen-incompatible transplantation are at increased risk of hyperacute rejection and may be predisposed to antibody-mediated rejection, chronic lung allograft dysfunction and higher mortality.

CASE

We present a case of primary lung transplantation in the setting of late identification of donor specific antibodies treated with intraoperative target plasma exchange. The patient was treated with fresh human plasma to a final volume of 1.5 times the patient's systemic circulation. From a pre-transplant mean fluorescence intensity of 5002, donor-specific antibodies were undetectable following plasma exchange on single antigen bead assay.

CONCLUSIONS

This method represents a potential desensitisation technique for use in the intraoperative period.

Trends in cardiovascular medicine: Update on cardiac transplantation

Advanced heart failure affects more than 250,000 people in the United States alone and is associated with high risk of morbidity and mortality. Cardiac transplantation provides a cure for patients with advanced disease but has historically been limited by donor availability. Recent changes in the allocation system as well as advances in donor selection, procurement and desensitization protocols have served to widen the donor pool and increase the availability of cardiac transplantation for those in need. This review provides an update on recent advances in cardiac transplantation.

Sensitization during short-term mechanical circulatory support. Determinants, therapeutic management, and outcomes after heart transplant

INTRODUCTION AND OBJECTIVES

The development of human-leukocyte antigen antibodies is a well-known adverse effect of the use of long-term ventricular assist devices (VADs). The aim of this study was to determine the incidence of sensitization during short-term mechanical circulatory support with VAD (CentriMag), its determinants, and its impact on posttransplant outcomes.

METHODS

We performed a retrospective review of patients who were bridged to transplant with short-term VAD from 2009 to 2019. Sensitization was defined as a calculated panel-reactive antibody> 10%. The endpoints included overall survival and rejection-free survival.

RESULTS

A total of 89 patients (median age 56.0 [interquartile range, 50.0-59.9] years, 16.8% female) received a short-term VAD as a bridge to transplant. The median duration of support was 23.6 [interquartile range, 16.6-35.0] days. Eleven patients (12.4%) became sensitized during support. The only factor significantly associated with sensitization was female sex (OR, 8.67; 95%CI, 1.93-38.8; P=.005). Of the 89 patients, 21 patients died during support; 68 patients underwent heart transplant. After a mean follow-up of 49.6 ±31.2 months, 8 patients (11.8%) died and 20 (29.4%) had at least 1 rejection episode. On multivariate analysis, sensitization was an independent predictor of acute rejection (HR, 3.64; 95%CI, 1.42-9.33; P=.007), with a nonstatistically significant trend to higher mortality (HR, 4.07; 95%CI, 0.96-17.3; P=.057).

CONCLUSIONS

Sensitization with short-term VADs can occur and is significantly associated with female sex and with rejection. Sensitization also showed a nonstatistically significant trend to higher mortality.

Evaluation of donor heart for transplantation

Cardiac transplantation is considered the gold-standard treatment option for patients suffering from end-stage heart failure refractory to maximum medical therapy. A major determinant of graft function and recipient survival is a comprehensive evaluation of the donor allograft. Challenges arise when designing and implementing an evidence-based donor evaluation protocol due to the number of influential donor-specific characteristics and the complex interactions that occur between them. Here, we present our systematic approach to donor evaluation by examining the impact that relevant donor variables have on graft function and recipient outcomes.

Cardiac Surgery in Advanced Heart Failure

Mechanical circulatory support and heart transplantation are established surgical options for treatment of advanced heart failure. Since the prevalence of advanced heart failure is progressively increasing, there is a clear need to treat more patients with mechanical circulatory support and to increase the number of heart transplantations. This narrative review summarizes recent progress in surgical treatment options of advanced heart failure and proposes an algorithm for treatment of the advanced heart failure patient at >65 years of age.

Induction Therapy and Therapeutic Antibodies

Prevention of allograft rejection is one of the crucial goals in solid organ transplantation to ensure durability of the graft and is chiefly mediated by cellular and humoral pathways targeting cell surface alloantigens. The risk of rejection is highest in the first post-transplant year and wanes with time albeit the risk always exists and varies with the type of organ transplanted. Induction therapies refer to the use of high-intensity immunosuppression in the immediate post-operative period to mitigate the highest risk of rejection. This term encompasses chiefly the use of antibody therapies directed against one of the key pathways in T-cell activation or abrogating effects of circulating alloantibodies. These antibodies carry more potent immunomodulatory effect than maintenance immunosuppressive therapy alone and many of them lead to durable immune cell depletion. A variety of monoclonal and polyclonal antibodies have been utilized for use not only for induction therapy, but also for treatment of allograft rejection when it occurs and as components of desensitization therapy before and after transplantation to modulate circulating alloantibodies.

Innovations in Heart Transplantation: A Review

Advanced heart failure affects tens of thousands of people in the United States alone with high morbidity and mortality. Cardiac transplantation offers the best treatment strategy but has been historically limited by donor availability. Recently, there have been significant advances in organ allocation, donor-recipient matching, organ preservation and expansion of the donor pool. The current heart allocation system prioritizes the sickest patients to minimize waitlist mortality. Advances in donor organ selection including predicted heart mass calculations and more sophisticated antibody detection methods for allosensitized patients offer more effective matching of donors and recipients. Innovations in organ preservation such as with organ preservation systems have geographically widened the donor pool. The use of hepatitis C donors is possible with the advent of effective direct-acting antiviral agents to cure donor-transmitted hepatitis C. Finally, further expansion of the donor pool is occurring with the utilization of higher-risk donors with advanced age, medical comorbidities, and left ventricular dysfunction and advances in donation after circulatory death. This review provides an update on the new technologies and transplantation strategies that serve to widen the donor pool and more effectively match donors and recipients so that heart transplant candidates may derive the best outcomes from heart transplantation.

Heart transplantation for patients with single ventricle physiology

Background

There is a growing population of palliated and unpalliated single ventricle physiology patients for whom heart transplantation is the only treatment option available. There is a paucity of reports of heart transplantation in this challenging and growing subset of patients from our part of the world. The purpose of the article is to briefly review our experience in the subgroup and compare it with the available literature.

Methods

This was a single-institution retrospective observational study of 16 patients with single ventricle physiology who were transplanted between 2016 and 2019 and their outcomes. The study groups were divided into those with ventricular dysfunction (group 1), who fare substantially better than those with normal ventricular function (group 2) whose short-term outcomes were poorer. Worsening cyanosis, poor candidature for completion Fontan procedure due to severe atrioventricular valve regurgitation or pulmonary artery anatomy, protein-losing enteropathy, plastic bronchitis, and worsening systemic venous congestion are indications in those with normal ventricular function.

Results

Patients with ventricular dysfunction as the main indication had excellent early survival with no early mortality compared to 40% mortality in patients with normal ventricular function. Patients who survived to leave the hospital had however similar long-term outcomes. Two patients with protein-losing enteropathy resolved completely by one month. Normal ventricular function, pulmonary artery stenting, early Fontan failure (6 months), ascites, and need for desensitization were risk factors for early mortality. After the early acute phase of increased risk, the mortality risk plateaued off.

Conclusion

Transplantation in patients with single ventricle and ventricular dysfunction can be offered with a good early and late outcome. There is a need to have multi-institutional and multi-disciplinary collaboration along with work in basic sciences to better understand the effects of failed Fontan physiology with normal ventricular function.

Outcome of urgent desensitization in sensitized heart transplant recipients

BACKGROUND/PURPOSE

Sensitization, the presence of preformed anti-human antibody in recipients, restricts access to ABO-compatible donors in heart transplant. Desensitization therapy works by reducing preformed antibodies to increase the chances of a negative crossmatch or permit safe transplantation across positive crossmatch. There is no consensus regarding the desensitization protocol in cardiac patients, and the outcome of desensitization remains under debate.

METHODS

Twenty-five consecutive sensitized heart transplant recipients received perioperative desensitization in our institution from 2012 to 2019. One-year patient survival and graft rejection rate were analyzed and compared between sensitized recipients and non-sensitized recipients.

RESULTS

Within the first year after transplant, patient survival in sensitized recipients was 76%. Infection was the major cause of death. The cumulative incidence of rejection was 8% for antibody-mediated rejection and 16% for acute cellular rejection. No significant difference in 1-year survival or rejection rate could be demonstrated between sensitized and nonsensitized recipients.

CONCLUSION

Acceptable early outcomes in patient survival and graft rejection could be anticipated in sensitized heart transplant recipients under a perioperative algorithm using complement-dependent cytotoxicity crossmatch- or panel-reactive antibody-directed urgent immunomodulation strategies, while infection remains the major concern.

Complement inhibition for prevention of antibody-mediated rejection in immunologically high-risk heart allograft recipients

Allosensitization represents a major barrier to heart transplantation (HTx). We assessed the efficacy and safety of complement inhibition at transplant in highly sensitized heart transplant recipients. We performed a single-center, single-arm, open-label trial (NCT02013037). Patients with panel reactive antibodies (PRA) ≥70% and pre-formed donor-specific antibodies (DSA) were eligible. In addition to standard of care, patients received nine infusions of eculizumab during the first 2 months posttransplant. The primary composite endpoint was antibody-mediated rejection (AMR) ≥pAMR2 and/or left ventricular dysfunction during the first year. Secondary endpoints included hemodynamic compromise, allograft rejection, and patient survival. Twenty patients were included. Median cPRA and mean fluorescence intensity of immunodominant DSA were 95% (90%-97%) and 6250 (5000-10 000), respectively. Retrospective B cell and T cell flow crossmatches were positive in 14 and 11 patients, respectively. The primary endpoint occurred in four patients (20%). Survival at 1 year was 90% with no deaths resulting from AMR. In a prespecified analysis comparing treated patients to matched control patients, we observed a dramatic reduction in the risk of biopsy-proven AMR in patients treated with eculizumab (HR = 0.36, 95% CI = 0.14-0.95, p = .032). Our findings support the prophylactic use of complement inhibition for heart transplantation at high immunological risk. ClinincalTrials.gov, NCT02013037.

Emerging New Approaches in Desensitization: Targeted Therapies for HLA Sensitization

There is an urgent need for therapeutic interventions for desensitization and antibody-mediated rejection (AMR) in sensitized patients with preformed or de novo donor-specific HLA antibodies (DSA). The risk of AMR and allograft loss in sensitized patients is increased due to preformed DSA detected at time of transplant or the reactivation of HLA memory after transplantation, causing acute and chronic AMR. Alternatively, de novo DSA that develops post-transplant due to inadequate immunosuppression and again may lead to acute and chronic AMR or even allograft loss. Circulating antibody, the final product of the humoral immune response, has been the primary target of desensitization and AMR treatment. However, in many cases these protocols fail to achieve efficient removal of all DSA and long-term outcomes of patients with persistent DSA are far worse when compared to non-sensitized patients. We believe that targeting multiple components of humoral immunity will lead to improved outcomes for such patients. In this review, we will briefly discuss conventional desensitization methods targeting antibody or B cell removal and then present a mechanistically designed desensitization regimen targeting plasma cells and the humoral response.

Heart-After-Liver Transplantation Attenuates Rejection of Cardiac Allografts in Sensitized Patients

BACKGROUND

In patients undergoing heart transplantation, significant allosensitization limits access to organs, resulting in longer wait times and high waitlist mortality. Current desensitization strategies are limited in enabling successful transplantation.

OBJECTIVES

The purpose of this study was to describe the cumulative experience of combined heart-liver transplantation using a novel heart-after-liver transplant (HALT) protocol resulting in profound immunologic protection.

METHODS

Reported are the results of a clinical protocol that was instituted to transplant highly sensitized patients requiring combined heart and liver transplantation at a single institution. Patients were dual-organ listed with perceived elevated risk of rejection or markedly prolonged waitlist time due to high levels of allo-antibodies. Detailed immunological data and long-term patient and graft outcomes were obtained.

RESULTS

A total of 7 patients (age 43 ± 7 years, 86% women) with high allosensitization (median calculated panel reactive antibody = 77%) underwent HALT. All had significant, unacceptable donor specific antibodies (DSA) (>4,000 mean fluorescence antibody). Prospective pre-operative flow cytometric T-cell crossmatch was positive in all, and B-cell crossmatch was positive in 5 of 7. After HALT, retrospective crossmatch (B- and T-cell) became negative in all. DSA fell dramatically; at last follow-up, all pre-formed or de novo DSA levels were insignificant at <2,000 mean fluorescence antibody. No patients experienced >1R rejection over a median follow-up of 48 months (interquartile range: 25 to 68 months). There was 1 death due to metastatic cancer and no significant graft dysfunction.

CONCLUSIONS

A heart-after-liver transplantation protocol enables successful transplantation via near-elimination of DSA and is effective in preventing adverse immunological outcomes in highly sensitized patients listed for combined heart-liver transplantation.

Impact of carfilzomib-based desensitization on heart transplantation of sensitized candidates

BACKGROUND

Allosensitization in heart transplant candidates is associated with longer transplant wait times and post-transplant complications. We summarize our experience with desensitization using carfilzomib, an irreversible proteasome inhibitor that causes plasma cell apoptosis.

METHODS

One cycle of desensitization consisted of plasmapheresis and carfilzomib 20 mg/m² on days 1, 2, 8, 9, 15, and 16 with intravenous immune globulin 2 g/kg after carfilzomib on day 16. Patients underwent repeat cycles as indicated. We compare calculated panel-reactive antibody (cPRA) for neat combined Class I and II IgG and C1q pre- and post-treatment using a cutoff for cPRA entry of ≥ 4000 and 500 MFI, respectively.

RESULTS

From June 2013 to October 2019, 9 patients underwent 20 cycles of carfilzomib-based desensitization. Each cycle resulted in an average cPRA decrease of 24% (95% CI: 6-42) for IgG and 36% (95% CI: 17-55) for C1q. From treatment start to finish, mean cPRA fell from 76% to 40% (p = 0.01) for IgG and 56% to 4% (p = 0.017) for C1q. Six of 9 patients have been transplanted with 5 of the transplanted hearts crossing preoperative donor-specific antibodies. During a median follow-up of 35.1 months, all transplanted patients have survived with only 1 occurrence of treated rejection. Side effects of desensitization included acute kidney injury (67%) and thrombocytopenia (33%) with all episodes self-resolving.

CONCLUSIONS

A carfilzomib-based desensitization strategy among heart transplant candidates reduces the level of HLA antibodies and complement binding, facilitates successful transplantation, and is associated with excellent outcomes at 3 years.

Clinical Outcomes of Perioperative Desensitization in Heart Transplant Recipients

Background.

Sensitization remains a barrier to heart transplantation (HT). Perioperative desensitization strategies have been described; however, a paucity of evidence exists to demonstrate efficacy and safety in HT.

Methods.

This single-center, retrospective study consisted of adults who received an HT. Perioperative desensitization was initiated if virtual crossmatch or flow-cytometry crossmatch was positive. Therapy consisted of plasmapheresis, intravenous immunoglobulin, and rabbit antithymocyte globulin. Historical controls received standard immunosuppression or induction. The primary endpoint was survival at 12 mo. Secondary endpoints included freedom from acute rejection, cardiac allograft vasculopathy (CAV), and infectious complications.

Results.

Of the 104 patients included, 48 received no induction, 46 received induction, and 10 underwent perioperative desensitization. No differences were observed in the primary endpoint at 12 mo (90.0% versus 97.9%, P = 0.25 for desensitization versus no-induction; 90.0% versus 100%, P = 0.72 for desensitization versus induction). Rates of acute rejection were lower with induction and desensitization compared with no-induction. There were no significant differences in CAV between the groups. Infectious complications were also similar among the groups (10.0% versus 16.7%, P = 0.62 for desensitization versus no-induction; 10.0% versus 30.4%, P = 0.34 for desensitization versus induction).

Conclusions.

This study suggests that a perioperative desensitization strategy triggered by positive virtual crossmatch or flow-cytometry crossmatch allows for successful transplantation of sensitized HT recipients and results in acceptable rates of survival, rejection, CAV, and infection at 12 mo.

Heart Transplant Immunosuppression Strategies at Cedars-Sinai Medical Center

Heart transplant is the optimal treatment for selected patients with end-stage heart failure. Immunosuppression after heart transplantation has significantly reduced the incidence of rejection and improved patient outcomes with the routine use of calcineurin inhibitors. Antimetabolites and proliferation signal inhibitors add to the improvement in patient outcomes as well. The goal of induction therapy is to provide intense immunosuppression when the risk of allograft rejection is highest. Most maintenance immunosuppressive protocols employ a 3-drug regimen consisting of a calcineurin inhibitor, an antimetabolite agent and glucocorticoids. The management of rejection proceeds in a stepwise fashion based on the severity of rejection detected on biopsy and the patient's clinical presentation. This review will cover induction, maintenance, rejection therapy and some special considerations including sensitization, renal sparing protocol, and corticosteroid weaning. It will end in consideration of potential future directions in immunosuppressive strategies to promote patient and graft survival.

The meaning of donor-specific antibodies after heart transplant

PURPOSE OF REVIEW

Antibody-mediated rejection (AMR) is a major contributor of impaired long-term survival after heart transplantation (HTx). The presence of circulating donor-specific antihuman leukocyte antigen (HLA) antibodies (DSAs) is considered as a mandatory criterion for AMR after HTx. DSA are known prognostic biomarkers of outcome, for example, recipients with de-novo DSA have a three-fold increased risk of mortality.

RECENT FINDINGS

Although the awareness of the impact and prognosis of DSA on the survival has been increased in the HTx community over the last decade, the management of DSA pre and posttransplant varies among centers and is mainly based on the experience of transplant physicians. Thus, firm consensus strategies for each HTx recipient should be established by a center advisory board of experts in the field of HLA genetics, transplantation immunology, and HTx to evaluate the immunological risk preoperatively and also continuously during the posttransplant course. Consequently, the recent advances of invasive and noninvasive diagnostic tools should be applied, according to the risk, laboratory findings, and clinical events of the recipient. Such individual strategy will result in tailored therapeutic options.

SUMMARY

Novel standards for the management of DSA in HTx recipients on the basis of an interdisciplinary approach of experts will improve diagnostics for personalized medicine.

Sex differences in eligibility for advanced heart failure therapies

OBJECTIVES

We investigated sex-based differences in eligibility for and outcomes after receipt of advanced heart failure (HF) therapies.

BACKGROUND

Although women are more likely to die from HF than men, registry data suggest that women are less likely to receive heart transplant (HT) or left ventricular assist device (LVAD) for largely unknown reasons.

METHODS

We performed a single-center retrospective cohort study of patients evaluated for advanced HF therapies from 2012 to 2016. Logistic regression was used to determine the association of sex with eligibility for HT/LVAD. Competing risks and Kaplan-Meier analysis were used to examine survival.

RESULTS

Of 569 patients (31% women) evaluated, 223 (39.2%) were listed for HT and 81 (14.2%) received destination (DT) LVAD. Women were less likely to be listed for HT (adjusted odds ratio [OR] 0.36, 95% confidence interval [CI] 0.21-0.61; P < .0001), based on allosensitization (P < .0001) and obesity (P = .02). Women were more likely to receive DT LVAD (adjusted OR 2.29, 95% CI 1.23-4.29; P = .01). Survival was similar between men and women regardless of whether they received HT and DT LVAD or were ineligible for therapy.

CONCLUSION

Women are less likely to be HT candidates, but more likely to receive DT LVAD.

Does the Canadian allocation system for highly sensitized patients work?

PURPOSE OF REVIEW

The number of sensitized heart transplant candidates is rising. Highly sensitized patients are disadvantaged because they encounter longer waiting times to heart transplant. Strategies to reduce their waiting times include waitlist prioritization and desensitization therapies. The purpose of this review is to describe the listing category for highly sensitized patients in the Canadian allocation system, examine the advantages and limitations of this strategy and provide an approach to the management of the highly sensitized patient awaiting heart transplant.

RECENT FINDINGS

Analysis of data from the United Network of Organ Sharing shows that the incidence of death or removal from the waitlist in patients listed for heart transplant increases as the calculated panel reactive antibody (cPRA) increases and is independent of medical urgency. In the Canadian allocation system, patients with cPRA more than 80% have a similar incidence of death on the waitlist as less sensitized patients, suggesting they survive to be transplanted. Furthermore, prioritizing and transplanting highly sensitized patients has been associated with acceptable post-transplant outcomes.

SUMMARY

The Canadian allocation system prioritizes highly sensitized patients to increase equity and access to transplantation while maintaining good post-transplant outcomes. Not all highly sensitized patients can wait for an organ, even if prioritized. A pragmatic individualized approach would consider the medical stability of the patient, the likelihood of transplant with a negative crossmatch and then determine whether waitlist prioritization or desensitization is the more appropriate strategy.

Sensitization in Heart Transplantation: Emerging Knowledge: A Scientific Statement From the American Heart Association

Sensitization, defined as the presence of circulating antibodies, presents challenges for heart transplant recipients and physicians. When present, sensitization can limit a transplantation candidate’s access to organs, prolong wait time, and, in some cases, exclude the candidate from heart transplantation altogether. The management of sensitization is not yet standardized, and current therapies have not yielded consistent results. Although current strategies involve antibody suppression and removal with intravenous immunoglobulin, plasmapheresis, and antibody therapy, newer strategies with more specific targets are being investigated.

The clinical impact of donor-specific antibodies in heart transplantation

Donor-specific antibodies (DSA) are integral to the development of antibody-mediated rejection (AMR). Chronic AMR is associated with high mortality and an increased risk for cardiac allograft vasculopathy (CAV). Anti-donor HLA antibodies are present in 3-11% of patients at the time of heart transplantation (HTx), with de novo DSA (predominantly anti-HLA class II) developing post-transplant in 10-30% of patients. DSA are associated with lower graft and patient survival after HTx, with one study suggesting a three-fold increase in mortality in patients who develop de novo DSA (dnDSA). DSA against anti-HLA class II, notably DQ, are at particularly high risk for graft loss. Although detection of DSA is not a criterion for pathologic diagnosis of AMR, circulating DSA are found in almost all cases of AMR. MFI thresholds of ~5000 for DSA against class I antibodies, 2000 against class II antibodies, or an overall cut-off of 5-6000 for any DSA, have been suggested as being predictive for AMR. There is no firm consensus on pre-transplant strategies to treat HLA antibodies, or for the elimination of antibodies after diagnosis of AMR. Minimizing the risk of dnDSA is rational but data on risk factors in HTx are limited. The effect of different immunosuppressive regimens is largely unexplored in HTx, but studies in kidney transplantation emphasize the importance of adherence and maintaining adequate immunosuppression. One study has suggested a reduced risk for dnDSA with rabbit antithymocyte globulin induction. Management of DSA pre- and post-HTx varies but typically most centers rely on a plasmapheresis or immunoadsorption, with or without rituximab and/or intravenous immunoglobulin. Based on the literature and a multi-center survey, an algorithm for a suggested surveillance and therapeutic strategy is provided.

Honoring 50 Years of Clinical Heart Transplantation in Circulation

Heart transplantation has become a standard therapy option for advanced heart failure. The translation of heart transplantation from innovative experiments to long-term clinical success has married prescient insights with discipline and organization in the domains of surgical techniques, organ preservation, immunosuppression, organ donation and transplantation logistics, infection control, and long-term graft surveillance. This review explores the key milestones of the past 50 years of heart transplantation and discusses current challenges and promising innovations on the clinical horizon.

Human Leukocyte Antigen Sensitization in Solid Organ Transplantation: A Primer on Terminology, Testing, and Clinical Significance for the Apheresis Practitioner

The human leukocyte antigen (HLA) system is an important immunologic barrier that must be considered for successful solid organ transplantation. Formation of donor-specific HLA antibodies in solid organ transplantation is an important cause of allograft injury and may contribute to recipient morbidity and mortality. Therapeutic plasma exchange is often requested to lower HLA antibody levels prior to or after transplantation and for management of HLA antibodies in the context of organ rejection. In this review, we summarize the current terminology, laboratory testing, and clinical significance of HLA sensitization in the solid organ transplant population. Furthermore, to illustrate applications of HLA testing in clinical practice, we summarize our own lung and kidney institutional protocols for managing HLA antibodies in the peri-transplant setting.

Application and interpretation of histocompatibility data in thoracic (heart and lung) transplantation

PURPOSE OF REVIEW

The purpose of the review is to update our current understanding and utilization of immunogenetic tools in heart and lung transplant.

RECENT FINDINGS

Increasingly, complex patients have been managed perioperatively for heart and lung transplant using a variety of tests and techniques. Recent treatment regimens and listing strategies have exploited recent laboratory advances. However, the better characterization has led to an even more complex description of sensitized heart and lung candidates. Several recent studies have examined antibody strengths and behavior to guide clinical decision-making and examine postoperative outcomes. Finally, non-human leukocyte antigen antibodies have emerged as possible determinants of allograft outcome in heart and lung transplant.

SUMMARY

Heart and lung transplant candidates with preformed and de-novo posttransplant antibodies continue to represent a challenging and high-risk group of patients. Modern immunogenetic techniques have broadened our understanding and have revealed an even more complex relationship between antibodies, allografts, and outcomes.

Significance of Anti-HLA Antibodies on Adult and Pediatric Heart Allograft Outcomes

As methods for human leukocyte antigens (HLA) antibody detection have evolved and newer solid phase assays are much more sensitive, the last 15 years has seen a renewed focus on the importance of HLA antibodies in solid organ transplant rejection. However, there is still much controversy regarding the clinical significance of antibody level as depicted by the mean fluorescence intensity of a patient’s neat serum. Emerging techniques, including those that identify antibody level and function, show promise for the detection of individuals at risk of allograft rejection, determination of the effectiveness of desensitization prior to transplant, and for monitoring treatment of rejection. Here, we review current publications regarding the relevance of donor-specific HLA antibodies (DSA) in adult and pediatric heart transplantation (HT) with graft survival, development of antibody-mediated rejection and cardiac allograft vasculopathy (CAV). The negative impact of DSA on patient and allograft survival is evident in adult and pediatric HT recipients. Many questions remain regarding the most appropriate frequency of assessment of pre- and posttransplant DSA as well as the phenotype of DSA memory vs. true de novo antibody using large multicenter adult and pediatric cohorts and state-of-the-art methodologies for DSA detection and characterization.