Renal Allograft Outcome After Simultaneous Heart and Kidney Transplantation

Evolutions in Combined Heart-Kidney Transplant

PURPOSE OF REVIEW

This review describes management practices, outcomes, and allocation policies in candidates for simultaneous heart-kidney transplantation (SHKT).

RECENT FINDINGS

In patients with heart failure and concomitant kidney disease, SHKT confers a survival advantage over heart transplantation (HT) alone in patients with dialysis dependence or an estimated glomerular filtration rate (eGFR) < 40 mL/min/1.73 m2. However, when compared to kidney transplantation (KT) alone, SHKT is associated with worse patient and kidney allograft survival. In September 2023, the United Network of Organ Sharing adopted a new organ allocation policy, with strict eligibility criteria for SHKT and a safety net for patients requiring KT after HT alone. While the impact of the policy change on SHKT outcomes remains to be seen, strategies to prevent and slow development of kidney disease in patients with heart failure and to prevent kidney dysfunction after HT and SHKT are necessary.

Improved waitlist and comparable post-transplant outcomes in simultaneous heart-kidney transplantation under the 2018 heart allocation system

OBJECTIVE

This study aimed to investigate the clinical trends and the impact of the 2018 heart allocation policy change on both waitlist and post-transplant outcomes in simultaneous heart-kidney transplantation in the United States.

METHODS

The United Network for Organ Sharing registry was queried to compare adult patients before and after the allocation policy change. This study included 2 separate analyses evaluating the waitlist and post-transplant outcomes. Multivariable analyses were performed to determine the 2018 allocation system's risk-adjusted hazards for 1-year waitlist and post-transplant mortality.

RESULTS

The initial analysis investigating the waitlist outcomes included 1779 patients listed for simultaneous heart-kidney transplantation. Of these, 1075 patients (60.4%) were listed after the 2018 allocation policy change. After the policy change, the waitlist outcomes significantly improved with a shorter waitlist time, lower likelihood of de-listing, and higher likelihood of transplantation. In the subsequent analysis investigating the post-transplant outcomes, 1130 simultaneous heart-kidney transplant recipients were included, where 738 patients (65.3%) underwent simultaneous heart-kidney transplantation after the policy change. The 90-day, 6-month, and 1-year post-transplant survival and complication rates were comparable before and after the policy change. Multivariable analyses demonstrated that the 2018 allocation system positively impacted risk-adjusted 1-year waitlist mortality (sub-hazard ratio, 0.66, 95% CI, 0.51-0.85, P < .001), but it did not significantly impact risk-adjusted 1-year post-transplant mortality (hazard ratio, 1.03; 95% CI, 0.72-1.47, P = .876).

CONCLUSIONS

This study demonstrates increased rates of simultaneous heart-kidney transplantation with a shorter waitlist time after the 2018 allocation policy change. Furthermore, there were improved waitlist outcomes and comparable early post-transplant survival after simultaneous heart-kidney transplantation under the 2018 allocation system.

Simultaneous Heart-kidney Transplant With Planned Delayed Implantation of the Kidney Graft After Ex Vivo Perfusion

BACKGROUND

Simultaneous heart-kidney transplant (SHK) is an established option for patients with severe heart failure and chronic kidney disease. Recent studies in simultaneous liver-kidney transplantation demonstrate favorable outcomes achieved by delaying implantation of the kidney for over 24 h. This report describes a case series of consecutive patients listed for SHK who had planned delayed implantation of the kidney graft.

METHODS

This case series represents a retrospective analysis of SHK patients extracted from the transplant database at a single center.

RESULTS

There were 7 patients who underwent SHK during the study period. In all cases, kidney grafts were maintained on hypothermic ex vivo pulsatile perfusion for delayed implantation (mean cold ischemia 53 h [range, 31-69]). The first 5 patients had 100% 1-y heart and kidney graft survival with good function. Patient 6 was unstable on extracorporeal membrane oxygenation post-heart transplant. The kidney was implanted at 69 h, and the patient died soon thereafter. Patient 7 was also unstable on extracorporeal membrane oxygenation after heart transplant. The decision was made to implant the kidney into a backup kidney recipient. The heart transplant recipient subsequently died several days later, whereas the kidney was successfully transplanted in the alternate candidate.

CONCLUSIONS

This case series highlights the potential utility of delayed kidney implantation in SHK patients. SHK with delayed renal transplant may provide an improved physiologic environment for renal transplant, which may result in improved early renal graft function. Delayed kidney transplant also provides the opportunity to transplant the kidney graft into an alternate candidate.

Dual-Organ Transplantation: Indications, Evaluation, and Outcomes for Heart-Kidney and Heart-Liver Transplantation: A Scientific Statement From the American Heart Association

Although heart transplantation is the preferred therapy for appropriate patients with advanced heart failure, the presence of concomitant renal or hepatic dysfunction can pose a barrier to isolated heart transplantation. Because donor organ supply limits the availability of organ transplantation, appropriate allocation of this scarce resource is essential; thus, clear guidance for simultaneous heart-kidney transplantation and simultaneous heart-liver transplantation is urgently required. The purposes of this scientific statement are (1) to describe the impact of pretransplantation renal and hepatic dysfunction on posttransplantation outcomes; (2) to discuss the assessment of pretransplantation renal and hepatic dysfunction; (3) to provide an approach to patient selection for simultaneous heart-kidney transplantation and simultaneous heart-liver transplantation and posttransplantation management; and (4) to explore the ethics of multiorgan transplantation.

Outcomes of Simultaneous Heart and Kidney Transplantation

BACKGROUND

Simultaneous heart-kidney transplantation has been increasingly performed in end-stage heart failure patients with concurrent kidney dysfunction despite limited evidence supporting its indications and utility.

OBJECTIVES

The purpose of this study was to investigate the effects and utility of simultaneously implanted kidney allografts with various degrees of kidney dysfunction during heart transplantation.

METHODS

Using the United Network for Organ Sharing registry, long-term mortality was compared in recipients with kidney dysfunction who underwent heart-kidney transplantation (n = 1,124) vs isolated heart transplantation (n = 12,415) in the United States between 2005 and 2018. In heart-kidney recipients, contralateral kidney recipients were compared for allograft loss. Multivariable Cox regression was used for risk adjustment.

RESULTS

Long-term mortality was lower among heart-kidney recipients than among heart-alone recipients when recipients were on dialysis (26.7% vs 38.6% at 5 years; HR: 0.72; 95% CI: 0.58-0.89) or had a glomerular filtration rate (GFR) of <30 mL/min/1.73 m² (19.3% vs 32.4%; HR: 0.62; 95% CI: 0.46-0.82) and GFR of 30 to 45 mL/min/1.73 m² (16.2% vs 24.3%; HR: 0.68; 95% CI: 0.48-0.97) but not in GFR of 45 to 60 mL/min/1.73 m². Interaction analysis showed that the mortality benefit of heart-kidney transplantation continued up to GFR 40 mL/min/1.73 m². The incidence of kidney allograft loss was higher among heart-kidney recipients than among contralateral kidney recipients (14.7% vs 4.5% at 1 year; HR: 1.7; 95% CI: 1.4-2.1).

CONCLUSIONS

Heart-kidney transplantation relative to heart transplantation alone provided superior survival for dialysis-dependent recipients and non-dialysis-dependent recipients up to a GFR of approximately 40 mL/min/1.73 m² but at the cost of almost twice the risk of kidney allograft loss than contralateral kidney allograft recipients.

Simultaneous Heart-Kidney Transplant-Does Hospital Experience With Heart Transplant or Kidney Transplant Have a Greater Impact on Patient Outcomes?

High institutional transplant volume is associated with improved outcomes in isolated heart and kidney transplant. The aim of this study was to assess trends and outcomes of simultaneous heart-kidney transplant (SHKT) nationally, as well as the impact of institutional heart and kidney transplant volume on survival. All adult patients who underwent SHKT between 2005-2019 were identified using the United Network for Organ Sharing (UNOS) database. Annual institutional volumes in single organ transplant were determined. Univariate and multivariable analyses were conducted to assess the impact of demographics, comorbidities, and institutional transplant volumes on 1-year survival. 1564 SHKT were identified, increasing from 54 in 2005 to 221 in 2019. In centers performing SHKT, median annual heart transplant volume was 35.0 (IQR 24.0-56.0) and median annual kidney transplant volume was 166.0 (IQR 89.5-224.0). One-year survival was 88.4%. In multivariable analysis, increasing heart transplant volume, but not kidney transplant volume, was associated with improved 1-year survival. Increasing donor age, dialysis requirement, ischemic times, and bilirubin were also independently associated with reduced 1-year survival. Based on this data, high-volume heart transplant centers may be better equipped with managing SHKT patients than high-volume kidney transplant centers.

Heart-kidney listing is better than isolated heart listing for pediatric heart transplant candidates with significant renal insufficiency

OBJECTIVES

Significant renal insufficiency is identified as a risk factor for post-transplantation mortality in pediatric heart transplant recipients. This study evaluates simultaneous heart-kidney transplantation listing outcomes compared with heart transplant for pediatric candidates with significant renal insufficiency.

METHODS

The United Network for Organ Sharing registry was searched for patients (January 1987 to March 2020) who were simultaneously listed for a heart-kidney transplantation or for heart transplant with significant renal insufficiency at the time of listing. Significant renal insufficiency was defined as needing dialysis or having a low estimated glomerular filtration rate (<40 mL/min). Survival was calculated using Kaplan-Meier analysis.

RESULTS

A total of 427 cases were identified; 109 were listed for heart-kidney transplantation, and 318 were listed for heart transplant alone. Median time on the waitlist was 101 days (interquartile range, 28-238) for heart-kidney transplantation listings compared with 39 days (14-86) and 23.5 days (6-51) for heart transplant recipients with a low estimated glomerular filtration rate (P = .002) or on dialysis (P < .001), respectively. Of all heart-kidney transplantation listings, 66% (n = 71) received a transplant compared with 54% (n = 173) of heart transplantation with significant renal insufficiency (P = .005) with a mean survival of 14.6 years (12.7-16.4 years) for heart transplant without significant renal insufficiency at transplantation and 7.6 years (5.4-9.9 years) for heart transplant with significant renal insufficiency at transplantation. At 1 year after listing, 69% of heart-kidney transplantation listed recipients were alive, compared with 51% of heart transplant listed recipients (P = .029). Heart-kidney transplantation recipients had better 1-year post-transplantation survival (86%) than heart transplantation with significant renal insufficiency at transplant (66%) (P = .001). There was no significant difference in the 1- and 5-year survivals of those undergoing heart transplantation listed with significant renal insufficiency but no significant renal insufficiency at the time of transplant (89% and 78%) and heart-kidney transplantation recipients (86% and 81%; P = .436).

CONCLUSIONS

Pediatric candidates with significant renal insufficiency listed for heart-kidney transplantation have superior waitlist and post-transplantation outcomes compared with those listed for heart transplant alone. Patients with significant renal insufficiency should be listed for heart-kidney transplantation, however; if their renal function improves significantly, heart transplant alone appears judicious.

Combined Heart-Kidney Transplantation: Indications, Outcomes, and Controversies

Renal dysfunction, a prevalent comorbidity in advanced heart failure, is associated with significant morbidity and mortality after heart transplantation. In the recent era, the field of combined heart-kidney transplantation has experienced great success in the treatment of both renal and cardiac dysfunction in end-stage disease states, and the number of transplants has increased dramatically. In this review, we discuss appropriate indications and selection criteria, overall and organ-specific outcomes, and future perspectives in the field of combined heart-kidney transplantation.

New Approaches to Cardiovascular Disease and Its Management in Kidney Transplant Recipients

Cardiovascular events, including ischemic heart disease, heart failure, and arrhythmia, are common complications after kidney transplantation and continue to be leading causes of graft loss. Kidney transplant recipients have both traditional and transplant-specific risk factors for cardiovascular disease. In the general population, modification of cardiovascular risk factors is the best strategy to reduce cardiovascular events; however, studies evaluating the impact of risk modification strategies on cardiovascular outcomes among kidney transplant recipients are limited. Furthermore, there is only minimal guidance on appropriate cardiovascular screening and monitoring in this unique patient population. This review focuses on the limited scientific evidence that addresses cardiovascular events in kidney transplant recipients. Additionally, we focus on clinical management of specific cardiovascular entities that are more prevalent among kidney transplant recipients (ie, pulmonary hypertension, valvular diseases, diastolic dysfunction) and the use of newer evolving drug classes for treatment of heart failure within this cohort of patients. We note that there are no consensus documents describing optimal diagnostic, monitoring, or management strategies to reduce cardiovascular events after kidney transplantation; however, we outline quality initiatives and research recommendations for the assessment and management of cardiovascular-specific risk factors that could improve outcomes.

Consensus conference on heart-kidney transplantation

Simultaneous heart-kidney transplant (sHK) has enabled the successful transplantation of patients with end-stage heart disease and concomitant kidney disease, with non-inferior outcomes to heart transplant (HT) alone. The decision for sHK is challenged by difficulties in differentiating those patients with a significant component of reversible kidney injury due to cardiorenal syndrome who may recover kidney function after HT, from those with intrinsic advanced kidney disease who would benefit most from sHK. A consensus conference on sHK took place on June 1, 2019 in Boston, Massachusetts. The conference represented a collaborative effort by experts in cardiothoracic and kidney transplantation from centers across the United States to explore the development of guidelines for the interdisciplinary criteria for kidney transplantation in the sHK candidate, to evaluate the current allocation of kidneys to follow the heart for sHK, and to recommend standardized care for the management of sHK recipients. The conference served as a forum to unify criteria between the different specialties and to forge a pathway for patients who may need dual organ transplantation. Due to the continuing shortage of available donor organs, ethical problems related to multi-organ transplantation were also debated. The findings and consensus statements are presented.

Outcomes of Older Patients in the Recent Era of Heart Kidney Transplantation

BACKGROUND AND OBJECTIVE

Variable age thresholds are often used at transplant centers for simultaneous heart and kidney transplantation (HKT). We hypothesize that selected older recipients enjoy comparable outcome to younger recipients in the current era of HKT.

METHODS

We performed a retrospective analysis of HKT outcomes in the United Network for Organ Sharing (UNOS) registry from 2006 to 2018, classifying patients by age at transplant as ≥ 65 or < 65 years. The primary outcome was patient death. Secondary outcomes included all-cause kidney graft failure and death-censored kidney allograft failure.

RESULTS

Of 973 patients, 774 (80%) were younger than 65 years (mean 52 ± 10 years) and 199 (20%) were 65 years or older (mean 67 ± 2 years). The older HKT cohort had fewer blacks (22% vs 35%, P = .01) and women (12 vs 18%, P = .04). Fewer older patients received dialysis (30% vs 54%, P < .001) and mechanical support (36% vs 45%, P = .03) before HKT. Older recipients received organs from slightly older donors. The median follow-up time was shorter for patients 65 years or older than for the younger group (2.3 vs 3.3 years, P < .001). Patient survival was similar between the groups (mean 8.8 vs 9.8 years, P = .3), with the most common causes of death being cardiovascular (29%) and infectious complications (28%). There was no difference in all-cause kidney graft survival (mean 8.7 vs 9.3 years, P = .8). Most commonly, recipients died with a functional renal allograft (59.8%), and this occurred more commonly in older patients (81.4% vs 54.8%, P = .001). Cox proportional hazard modeling showed that higher donor age (hazard ratio [HR] 1.015, P = .01; HR 1.022, P = .02) and use of pre-transplant dialysis (HR 1.5, P = .004; HR 1.8, P = .006) increased the risk for both all-cause and death-censored kidney allograft failure, respectively.

CONCLUSIONS

Our study showed that carefully selected older patients have outcomes similar to those of a younger cohort and argues for comprehensive evaluation of the recipients with age as part of comorbidity assessment rather than use of an arbitrary age threshold for candidacy.

Cardiovascular disease in the kidney transplant recipient: epidemiology, diagnosis and management strategies

Kidney transplantation (KT) is the optimal therapy for end-stage kidney disease (ESKD), resulting in significant improvement in survival as well as quality of life when compared with maintenance dialysis. The burden of cardiovascular disease (CVD) in ESKD is reduced after KT; however, it still remains the leading cause of premature patient and allograft loss, as well as a source of significant morbidity and healthcare costs. All major phenotypes of CVD including coronary artery disease, heart failure, valvular heart disease, arrhythmias and pulmonary hypertension are represented in the KT recipient population. Pre-existing risk factors for CVD in the KT recipient are amplified by superimposed cardio-metabolic derangements after transplantation such as the metabolic effects of immunosuppressive regimens, obesity, posttransplant diabetes, hypertension, dyslipidemia and allograft dysfunction. This review summarizes the major risk factors for CVD in KT recipients and describes the individual phenotypes of overt CVD in this population. It highlights gaps in the existing literature to emphasize the need for future studies in those areas and optimize cardiovascular outcomes after KT. Finally, it outlines the need for a joint 'cardio-nephrology' clinical care model to ensure continuity, multidisciplinary collaboration and implementation of best clinical practices toward reducing CVD after KT.

Combined Heart and Kidney Transplantation: Clinical Experience in 100 Consecutive Patients

Background

Combined heart and kidney transplantation (HKTx) is performed in patients with severe heart failure and advanced renal insufficiency. We analyzed the long‐term survival after HKTx, the influence of age and dialysis status, the rates of cardiac rejection, and the influence of sensitization.

Methods and Results

From June 1992 to December 2016, we performed 100 HKTx procedures. We compared older (≥60 years, n=53) with younger (<60 years, n=47) recipients, and recipients on preoperative dialysis (n=49) and not on dialysis (n=51). We analyzed actuarial freedom from any cardiac rejection, acute cellular rejection, and antibody‐mediated rejection, and survival rates by sensitized status with panel‐reactive antibody levels <10%, 10% to 50%, and >50%, and compared these survival rates with those from the United Network for Organ Sharing database. There was no difference in 15‐year survival between the 2 age groups (35±12.4% and 49±17.3%, ≥60 versus <60 years; P=0.45). There was no difference in 15‐year survival between the dialysis and nondialysis groups (44±13.4% and 37±15.2%, P=0.95). Actuarial freedom from any cardiac rejection (acute cellular rejection>0 or antibody‐mediated rejection>0) was 92±2.8% and 84±3.8%, acute cellular rejection (≥2R/3A) 98±1.5% and 94±2.5%, and antibody‐mediated rejection (≥1) 96±2.1% and 93±2.6% at 30 days and 1 year after HKTx. There was no difference in the 5‐year survival among recipients by sensitization status with panel‐reactive antibody levels <10%, 10% to 50%, and >50% (82±5.9%, 83±10.8%, and 92±8.0%; P=0.55). There was no difference in 15‐year survival after HKTx between the United Network for Organ Sharing database and our center (38±3.2% and 40±10.1%, respectively; P=0.45).

Conclusions

HKTx is safe to perform in patients 60 years and older or younger than 60 years and with or without dialysis dependence, with excellent outcomes. The degree of panel‐reactive antibody sensitization did not appear to affect survival after HKTx.

Cardiorenal Syndrome: Classification, Pathophysiology, Diagnosis, and Treatment Strategies: A Scientific Statement From the American Heart Association

Cardiorenal syndrome encompasses a spectrum of disorders involving both the heart and kidneys in which acute or chronic dysfunction in 1 organ may induce acute or chronic dysfunction in the other organ. It represents the confluence of heart-kidney interactions across several interfaces. These include the hemodynamic cross-talk between the failing heart and the response of the kidneys and vice versa, as well as alterations in neurohormonal markers and inflammatory molecular signatures characteristic of its clinical phenotypes. The mission of this scientific statement is to describe the epidemiology and pathogenesis of cardiorenal syndrome in the context of the continuously evolving nature of its clinicopathological description over the past decade. It also describes diagnostic and therapeutic strategies applicable to cardiorenal syndrome, summarizes cardiac-kidney interactions in special populations such as patients with diabetes mellitus and kidney transplant recipients, and emphasizes the role of palliative care in patients with cardiorenal syndrome. Finally, it outlines the need for a cardiorenal education track that will guide future cardiorenal trials and integrate the clinical and research needs of this important field in the future.

Incidence of end-stage renal disease after heart transplantation and effect of its treatment on survival

Aims

Many heart transplant recipients will develop end‐stage renal disease in the post‐operative course. The aim of this study was to identify the long‐term incidence of end‐stage renal disease, determine its risk factors, and investigate what subsequent therapy was associated with the best survival.

Methods and results

A retrospective, single‐centre study was performed in all adult heart transplant patients from 1984 to 2016. Risk factors for end‐stage renal disease were analysed by means of multivariable regression analysis and survival by means of Kaplan–Meier. Of 685 heart transplant recipients, 71 were excluded: 64 were under 18 years of age and seven were re‐transplantations. During a median follow‐up of 8.6 years, 121 (19.7%) patients developed end‐stage renal disease: 22 received conservative therapy, 80 were treated with dialysis (46 haemodialysis and 34 peritoneal dialysis), and 19 received a kidney transplant. Development of end‐stage renal disease (examined as a time‐dependent variable) inferred a hazard ratio of 6.45 (95% confidence interval 4.87–8.54, P < 0.001) for mortality. Tacrolimus‐based therapy decreased, and acute kidney injury requiring renal replacement therapy increased the risk for end‐stage renal disease development (hazard ratio 0.40, 95% confidence interval 0.26–0.62, P < 0.001, and hazard ratio 4.18, 95% confidence interval 2.30–7.59, P < 0.001, respectively). Kidney transplantation was associated with the best median survival compared with dialysis or conservative therapy: 6.4 vs. 2.2 vs. 0.3 years (P < 0.0001), respectively, after end‐stage renal disease development.

Conclusions

End‐stage renal disease is a frequent complication after heart transplant and is associated with poor survival. Kidney transplantation resulted in the longest survival of patients with end‐stage renal disease.

Kidney transplantation and cardiomyopathy: Concepts and controversies in clinical decision-making

Increasing comorbidities and an aging population have led to a tremendous increase in the burden of both kidney and cardiac dysfunction. Concomitant cardiomyopathy exposes the patients with kidney disease to further physiological, hemodynamic, and pathologic alterations. Kidney transplantation imposes lesser anesthetic and surgical complexities compared to another solid organ transplant. The surgical decision-making remains an unsettled issue in these conditions. The surgical choices, techniques, and sequences in kidney transplant and cardiac surgery depend on the pathophysiological perturbations and perioperative outcomes. The absence of randomized controlled trials eludes us from suggesting definite management protocol in patients with end-stage kidney disease with cardiomyopathy. Nevertheless, in this review, we extracted data from published literature to understand the pathophysiologic interactions between end-stage renal diseases with cardiomyopathy and also proposed the management algorithm in this challenging scenario. The proposed management algorithm would ensure consensus across all stakeholders involved in decision-making. Our simplistic evidence-based approach would augur future randomized trials and would further ensure refinement in our management approach after the emergence of more definitive evidence.

Effects of Pulmonary Hypertension and Right Ventricular Function in Short and Long-Term Kidney Function

BACKGROUND

Pulmonary hypertension is not uncommon in patients with renal disease and vice versa; therefore, it influences treatments and outcomes. There is a large body of literature on pulmonary hypertension in patients with kidney disease, its prognostic implications, economic burden, and management strategies. However, the converse, namely the hemodynamic effects of pulmonary hypertension on kidney function (acute and chronic kidney injury) is less studied and described. There is also increasing interest in the effects of pulmonary hypertension on kidney transplant outcomes. The relationship is a complex phenomenon and multiple body systems and mechanisms are involved in its pathophysiology. Although the definition of pulmonary hypertension has evolved over time with the understanding of multiple interplays between the heart, lungs, kidneys, etc; there is limited evidence to provide a specific treatment strategy when kidneys and lungs are affected at the same time. Nevertheless, available evidence appears to support new therapeutics and highlights the importance of individualized approach. There is sufficient research showing that the morbidity and mortality from PH are driven by the influence of the pulmonary hemodynamic dysfunction on the kidneys.

CONCLUSION

This concise review focuses on the effects of pulmonary hypertension on the kidneys, including, the patho-physiological effects of pulmonary hypertension on acute kidney injury, progression of CKD, effects on kidney transplant outcomes, progression of kidney disease in situations such as post LVAD implantation and novel diagnostic indices. We believe a review of this nature will fill in an important gap in understanding the prognostic implication of pulmonary hypertension on renal disease, and help highlight this important component of the cardio-reno-pulmonary axis.