Optimal patient selection for simultaneous heart-kidney transplant: A modified cost-effectiveness analysis

High Rate of Kidney Graft Failure after Simultaneous Heart-Kidney Transplantation

Key Points

Simultaneous heart–kidney transplant is associated with high rates of kidney graft failure which are worse when compared with kidney transplant alone. The major causes of kidney graft failure in simultaneous heart–kidney transplant recipients were patient death and primary nonfunction of kidney graft.

Background

The indications and outcomes of simultaneous heart–kidney transplantation (SHKT) remain suboptimally defined. Risk factors for renal graft failure after SHKT also remain poorly defined.

Methods

We analyzed the renal graft outcomes among SHKT recipients using United Network for Organ Sharing database from 2015 to 2020. To evaluate for factors associated with poor renal outcomes, we compared SHKT and kidney transplantation alone recipients using propensity score matching.

Results

Among SHKT recipients, the rate of primary nonfunction (PNF) of kidney graft was 3%, the 30-day kidney graft failure rate was 7.0%, and the 30-day post-transplant mortality rate was 4.1%. The incidence of kidney delayed graft function was 27.5%. Kidney graft failure was seen early post-SHKT with most common causes of patient death (43.9%) and PNF of kidney graft (41.5%). One- and 2-year patient survival was 89.2% and 86.5%, and 1- and 2-year freedom from kidney graft failure was 85.4% and 82.7%, respectively. In subgroup analysis of SHKT recipients, use of pretransplant mechanical cardiac support (adjusted odds ratio [aOR], 2.57; P = 0.017), higher calculated panel reactive antibody (aOR, 1.76; P = 0.016), and older donor age per 10 years (aOR, 1.94; P = 0.001) were associated with PNF. Pretransplant extracorporeal membrane oxygenation support was associated with the increased risk of 30-day recipient mortality (aOR, 5.55; P = 0.002). Increased 30-day graft failure was seen in SHKT recipients with pretransplant mechanical cardiac support (aOR, 1.77; P = 0.038) and dialysis at the time of transplant (aOR, 1.72; P = 0.044). Multivariable Cox hazard analysis demonstrated that SHKT, when compared with kidney transplantation alone, is associated with increased kidney graft failure (hazard ratio, 2.56; P < 0.001) and recipient mortality (hazard ratio, 2.65; P < 0.001).

Conclusions

SHKT is associated with high rates of kidney graft failure. Identification of risk factors of renal graft failure can help optimize recipient selection for SHKT versus kidney after heart transplantation, especially after introduction of the new safety-net policy.

Decreased survival of simultaneous heart-kidney transplant recipients in the new heart allocation era

BACKGROUND

In 2018, the United Network for Organ Sharing (UNOS) modified their heart allocation policy to reduce waitlist mortality. The rates of simultaneous heart-kidney transplant (SHKT) have dramatically increased in recent years, despite increased rates of posttransplant renal failure in the new policy era. This study sought to investigate the impact of the new allocation system on waitlist and posttransplant outcomes of simultaneous heart-kidney transplantation.

METHODS

Adult patients listed for SHKT between 2012 and 2021 were included. Patients were cross-validated across both Thoracic and Kidney UNOS databases to confirm accurate listing and transplant data. Patients were stratified according to listing era. The Fine and Gray model was used to assess waitlist outcomes and posttransplant renal graft function. Kaplan-Meier analysis and Cox regression were used to compare posttransplant survival.

RESULTS

A total of 2,588 patients were included, of whom 1,406 (54.1%) were listed between 2012 and 2018 (era 1) and 1,182 (45.9%) between 2019 and 2021 (era 2). Era 2 was associated with increased likelihood of transplant (adjusted Sub-hazard ratios (aSHR): 1.52; p < 0.01) and decreased waitlist mortality (aSHR: 0.63; p < 0.01). Posttransplant survival at 2 years was decreased in era 2 (78.8% vs 86.9%; p < 0.01). Undersized hearts (hazard ratio [HR]: 2.02; p < 0.01), use of extracorporeal membrane oxygenation (HR: 2.67; p < 0.1), and transplants performed following the policy change (HR: 1.45; p = 0.03) were associated with increased mortality. Actuarial survival (combined waitlist and posttransplant) was significantly lower in the modern era (71.6% vs 62.2%; p = 0.02).

CONCLUSIONS

The allocation policy change has improved waitlist outcomes in patients listed for SHKT but potentially at the cost of worsened posttransplant outcomes.

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 Combined Heart-Kidney Transplantation in Older Recipients

Objectives

The upper limit of recipient age for combined heart-kidney transplantation (HKT) remains controversial. This study evaluated the outcomes of HKT in patients aged ≥65 years.

Methods

The United Network of Organ Sharing (UNOS) was used to identify patients undergoing HKT from 2005 to 2021. Patients were stratified by age at transplantation: <65 and ≥ 65 years. The primary outcome was one-year mortality. Secondary outcomes included 90-day and 5-year mortality, postoperative new-onset dialysis, postoperative stroke, acute rejection prior to discharge, and rejection within one-year of HKT. Survival was compared using Kaplan-Meier analysis, and risk adjustment for mortality was performed using Cox proportional hazards modeling.

Results

HKT in recipients aged ≥65 significantly increased from 5.6% of all recipients in 2005 to 23.7% in 2021 (p=0.002). Of 2,022 HKT patients in the study period, 372 (18.40%) were aged ≥65. Older recipients were more likely to be male and white, and fewer required dialysis prior to HKT. There were no differences between cohorts in unadjusted 90-day, 1-year, or 5-year survival in Kaplan-Meier analysis. These findings persisted after risk-adjustment, with an adjusted hazard for one-year mortality for age ≥65 of 0.91 (95% CI (0.63-1.29), p=0.572). As a continuous variable, increasing age was not associated with one-year mortality (HR 1.01 (95% CI (1.00-1.02), p=0.236) per year). Patients aged ≥65 more frequently required new-onset dialysis prior to discharge (11.56% vs. 7.82%, p=0.051). Stroke and rejection rates were comparable.

Conclusion

Combined HKT is increasing in older recipients, and advanced age ≥65 should not preclude HKT.

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.

Current considerations for heart-kidney transplantation

Cardiorenal syndrome is a complex syndrome characterized by dysfunction of the heart and kidneys in an interdependent fashion and is further divided into different subtypes based on primary organ dysfunction. Simultaneous Heart-Kidney transplantation is the treatment of choice for end-stage irreversible dysfunction of both organs, however it may be avoided with determination of cardiorenal subtype and management of primary organ dysfunction. This article discusses types of cardiorenal syndrome, indications and concerns regarding the use of simultaneous heart-kidney transplantation, and outlines algorithms for determination of need for dual vs. single organ transplantation.