Renal insufficiency and end-stage renal disease in the heart transplant population

Kidney disease in non-kidney solid organ transplantation

Kidney disease after non-kidney solid organ transplantation (NKSOT) is a common post-transplant complication associated with deleterious outcomes. Kidney disease, both acute kidney injury and chronic kidney disease (CKD) alike, emanates from multifactorial, summative pre-, peri- and post-transplant events. Several factors leading to kidney disease are shared amongst solid organ transplantation in addition to distinct mechanisms unique to individual transplant types. The aim of this review is to summarize the current literature describing kidney disease in NKSOT. We conducted a narrative review of pertinent studies on the subject, limiting our search to full text studies in the English language. Kidney disease after NKSOT is prevalent, particularly in intestinal and lung transplantation. Management strategies in the peri-operative and post-transplant periods including proteinuria management, calcineurin-inhibitor minimization/ sparing approaches, and nephrology referral can counteract CKD progression and/or aid in subsequent kidney after solid organ transplantation. Kidney disease after NKSOT is an important consideration in organ allocation practices, ethics of transplantation. Kidney disease after SOT is an incipient condition demanding further inquiry. While some truths have been revealed about this chronic disease, as we have aimed to describe in this review, continued multidisciplinary efforts are needed more than ever to combat this threat to patient and allograft survival.

Haemodynamic parameters associated with renal function prior to and following heart transplantation

AIMS

Abnormal renal function is a common feature in patients on heart transplant waiting lists. This study aimed to identify the haemodynamic parameters associated with decreased estimated glomerular filtration rate (eGFR) in patients listed for heart transplantation (HT) and renal function improvement following HT.

METHODS AND RESULTS

A total of 176 adults (52 years old, 81% men) with available right heart catheterization (RHC) listed in our centre for HT between 2014 and 2019 were studied. Cardiac catheterization measurements were obtained at time of HT listing evaluation. Changes in renal function were assessed between RHC and 6 months after HT. Median eGFR was 63 mL/min/1.73 m2 at time of RHC. Central venous pressure > 10 mmHg was associated with a two-fold increase in the likelihood of eGFR < 60 mL/min/1.73 m2 at time of RHC (adjusted odd ratio, 2.2; 95% confidence interval, 1.1-4.7; P = 0.04). In the 134 patients (76%) who underwent HT during follow-up, eGFR decreased by 7.9 ± 29.7 mL/min/1.73 m2 from RHC to 6 months after HT. In these patients, low cardiac index (<2.1 L/min/m2 ) at initial RHC was associated with a (adjusted) 6 month post-HT eGFR improvement of 12.2 mL/min/1.73 m2 (P = 0.018). Patients with eGFR < 60 mL/min/1.73 m2 and low cardiac index at time of RHC exhibited the greatest eGFR improvement (delta eGFR = 18.3 mL/min/1.73 m2 ) while patients with eGFR ≥ 60 mL/min/1.73 m2 and normal cardiac index had a marked decrease in eGFR (delta eGFR = -27.7 mL/min/1.73 m2 , P < 0.001).

CONCLUSIONS

Central venous pressure is the main haemodynamic parameter associated with eGFR < 60 mL/min/1.73 m2 in patients listed for HT. Low cardiac index prior to HT is associated with post-transplant renal function recovery.

Kidney Disease After Nonkidney Solid Organ Transplant

Nonkidney solid organ transplants (NKSOTs) are increasing in the United States with improving long-term allograft and patient survival. CKD is prevalent in patients with NKSOT and is associated with increased morbidity and mortality especially in those who progress to end-stage kidney disease. Calcineurin inhibitor nephrotoxicity is a main contributor to CKD after NKSOT, but other factors in the pretransplant, peritransplant, and post-transplant period can predispose to progressive kidney dysfunction. The management of CKD after NKSOT generally follows society guidelines for native kidney disease. Kidney-protective and calcineurin inhibitor-sparing immunosuppression has been explored in this population and warrants a discussion with transplant teams. Kidney transplantation in NKSOT recipients remains the kidney replacement therapy of choice for suitable candidates, as it provides a survival benefit over remaining on dialysis.

Clinical Factors Associated with Renal Outcome After Heart Transplantation

Cardiorenal syndrome (CRS) frequently occurs in end-stage heart failure patients waiting for heart transplantation (HT). Decision-making regarding simultaneous heart and kidney transplantation is an unresolved issue in these patients. We investigated clinical factors associated with renal outcome after HT. A total of 180 patients who received HT from 1996 to 2015 were included. Factors associated with early post-HT chronic kidney disease (CKD, estimated glomerular filtration rate [eGFR] < 60 mL/minute/1.73 m² within 1 year post-HT), post-HT end-stage kidney disease (ESKD), and significant renal function improvement (%ΔeGFR > 15%) at 1 year post-HT were analyzed. Early post-HT CKD and post-HT ESKD developed in 61 (33.9%) and 8 (4.4%) of 180 patients, respectively. Old age was only independently associated with early post-HT CKD and preexisting CKD tended to be associated with early post-HT CKD. Old age and preexisting CKD were independently associated with post-HT ESKD. Low pre-HT eGFR and preoperative renal replacement therapy were not associated with early post-HT CKD or post-HT ESKD. Young age, low pre-HT eGFR, and high %ΔeGFR 1 month post-HT were independently associated with significant renal function improvement. Preoperative renal function, including preoperative RRT, was not associated with post-HT mortality. In conclusion, preexisting CKD may impact renal outcomes after HT, but preoperative severe renal dysfunction, even that severe enough to require RRT, may not be a contraindication for HT alone. Our data suggest the necessity of early HT in end-stage heart failure patients with CRS and the importance of careful management during the early postoperative period.

Trends in Renal Function Among Heart Transplant Recipients of Donor-Derived Hepatitis C Virus

Donor-derived hepatitis C (dd-HCV) infection may increase the risk of renal impairment (RI) among heart transplantation (HT) recipients. Sofosbuvir, an integral component of HCV direct-acting antivirals (DAAs) has also been linked to RI. To date, no study has examined the trends in renal function for HT recipients of dd-HCV infection and assessed safety and efficacy of Sofosbuvir-based DAAs. Between September 2016 and June 2018, 46 HCV-naive patients and one patient with a history of HCV treated pretransplant, underwent HT from HCV-positive donors (follow-up available through October 10, 2018). Patients were treated with Ledipasvir-Sofosbuvir (genotype 1) or Sofosbuvir-Velpatasvir (genotype 3) for 12 or 24 weeks; no dose adjustments were made for renal function. Data on renal function were available for 23 patients who achieved a sustained virologic response at 12 weeks after the treatment (SVR12; cohort A) and 18 patients who completed 1 year of follow-up (cohort B). Treatment of dd-HCV infection was initiated at a median of 6 weeks post-HT. In both cohorts, a nonsignificant reduction in median estimated glomerular filtration rate (eGFR; ml/min/1.73 m) was noted (cohort A: pretransplant eGFR: 62 [interquartile range {IQR}: 1-84] to SVR12 eGFR: 49 [IQR: 37-82]; p = 0.43; cohort B: pretransplant eGFR: 65 [IQR: 54-84] to 1 year post-HT eGFR: 56 [IQR: 39-75]; p = 0.29). Pretreatment renal function had no significant impact on changes in renal function during treatment. All patients tolerated DAAs well with 100% completion rate to the assigned therapy and duration and 100% success at achieving SVR12. In this first and largest reported case series to date of HT recipients with dd-HCV infection, we observed that neither the dd-HCV infection nor its treatment with Sofosbuvir-based DAAs increased the risk of RI. Sofosbuvir-based DAAs appear safe, tolerable, and effective for HCV treatment even in presence of severe RI.

Everolimus Initiation With Early Calcineurin Inhibitor Withdrawal in De Novo Heart Transplant Recipients: Long-term Follow-up From the Randomized SCHEDULE Study

BACKGROUND

A calcineurin inhibitor (CNI)-free immunosuppressive regimen has been demonstrated to improve renal function early after heart transplantation, but long-term outcome of such a strategy has not been well described.

METHODS

In the randomized SCHEDULE trial, de novo heart transplant recipients received (1) everolimus with reduced-exposure CNI (cyclosporine) followed by CNI withdrawal at week 7-11 posttransplant or (2) standard-exposure cyclosporine, both with mycophenolate mofetil and corticosteroids; 95/115 randomized patients were followed up at 5-7 years posttransplant.

RESULTS

Mean measured glomerular filtration rate was 74.7 mL/min and 62.4 mL/min with everolimus and CNI, respectively. The mean difference was in favor of everolimus by 11.8 mL/min in the intent-to-treat population (P = 0.004) and 17.2 mL/min in the per protocol population (n = 75; P < 0.001). From transplantation to last follow-up, the incidence of biopsy-proven acute rejection (BPAR) was 77% (37/48) and 66% (31/47) (P = 0.23) with treated BPAR in 50% and 23% (P < 0.01) in the everolimus and CNI groups, respectively; no episode led to hemodynamic compromise. Coronary allograft vasculopathy (CAV) assessed by coronary intravascular ultrasound was present in 53% (19/36) and 74% (26/35) of everolimus- and CNI-treated patients, respectively (P = 0.037). Graft dimensions and function were similar between the groups. Late adverse events were comparable.

CONCLUSIONS

These results suggest that de novo heart transplant patients randomized to everolimus and low-dose CNI followed by CNI-free therapy maintain significantly better long-term renal function as well as significantly reduced CAV than patients randomized to standard CNI treatment. Increased BPAR in the everolimus group during year 1 did not impair long-term graft function.

Combined Heart-Kidney Transplant Versus Sequential Kidney Transplant in Heart Transplant Recipients

OBJECTIVES

In patients with reduced kidney function there are no established guidelines to suggest combined heart-kidney transplant (HKTx) versus sequential kidney transplant (SKTx) using preoperative value of estimated glomerular filtration (eGFR).

METHODS

The United Network for Organ Sharing database was queried from 2000 to 2015 to evaluate survival of HKTx and SKTx population stratified by preoperative eGFR rate <45 mL/min. Aim of the study was to assess the eGFR rate that is most beneficial to perform a concomitant or a SKTx at time of transplant evaluation.

RESULTS

In our analysis, patients who required SKTx are recipients that, after heart transplantation, developed or worsened kidney insufficiency due to calcineurin inhibitor nephrotoxicity. In recipients with eGFR <30 or dialysis, a total of 545 received HKTx and 80 received SKTx. The median waiting time between heart and kidney transplant in SKTx group was 6 years. The overall post-transplant survival was 81% and 80% and 75% and 59% at 5 and 1 years for the HKTx and SKTx groups, respectively (P = .04). In recipients with eGFR from 30 to 44, a total of 107 received HKTx and 112 received SKTx. The median waiting time between heart and kidney transplant in SKTx group was 4 years. Overall post-transplant survival showed no statistically significant differences in HKTx group (n=107) compared with SKTx group (n=112) and was 90% and 95% at 1 year and 74% and 52% at 5 years, respectively (P = .4) .

CONCLUSIONS

To optimize organ and patient survival, eGFR value can be utilized to discern between HKTx versus SKTx in patients with decreased renal function at the time of heart transplantation. Patients with eGFR<30 or in dialysis presented better survival with HKTx, while both SKTx and HKTx are suitable for patients with eGFR between 30 and 45.

Toward Precision Medicine in the Cardiorenal Syndrome

Although the field of oncology has made significant steps toward individualized precision medicine, cardiology and nephrology still often use a "one size fits all" approach. This applies to the intersection of the heart-kidney interaction and the cardiorenal syndrome as well. Recent studies have shown that the prognostic implications of worsening renal function (WRF) in acute heart failure are variable; thus, there is a need to differentiate the implications of WRF to better guide precise care. This may best be performed with biomarkers that can give the clinician a real-time evaluation of the physiologic state at the time of developing WRF. This review will summarize current cardiac and renal biomarkers and their status in the evaluation of cardiorenal syndrome. Although we have made progress in our understanding of this syndrome, further investigation is needed to bring precision medicine into routine clinical practice for the care of patients with cardiorenal syndrome.

Kidney transplantation as a therapeutic option for end-stage renal disease developing after heart transplantation

BACKGROUND

Progressive renal failure is a frequent complication after heart transplantation (HTx). It may result in end-stage renal disease (ESRD), prompting consideration of kidney Tx after HTx (KAH).

METHODS

We performed a retrospective single-center study of 268 HTx recipients to evaluate outcomes after KAH compared with HTx recipients with and without ESRD.

RESULTS

During a median follow-up of 76 months, ESRD developed in 51 patients (19), and 39 of them (76%) underwent KAH. The mean time from HTx to ESRD was 83 months. The incidence of switching to a calcineurin inhibitor (CNI)-free regimen based on sirolimus was significantly lower among recipients with ESRD (6% vs 57%, p = 0.0001), and prolonged exposure to CNI significantly increased the risk for ESRD (hazard ratio, 1.09; 95% confidence interval, 1.03-1.15; p < 0.005). Death-censored renal graft survival after KAH was 95%, 95%, and 83% at 1, 5, and 10 years, respectively. Median long-term survival of KAH patients was comparable to HTx recipients without ESRD (17.5 vs 17.1 years, p = 0.27) and significantly better compared with HTx recipients with ESRD (17.5 vs 7.3 years, p < 0.001).

CONCLUSIONS

Prolonged exposure to CNI immunosuppression medications significantly increases the risk for ESRD among HTx recipients. KAH is a good therapeutic option for HTx recipients with ESRD, with survival benefit comparable to HTx without ESRD.

Heart Retransplant Recipients Have Better Survival With Concurrent Kidney Transplant Than With Heart Retransplant Alone

BACKGROUND

Heart retransplant (HRT) recipients represent a growing number of transplant patients. The impact of concurrent kidney transplants (KTs) in this population has not been well studied. We tested the hypothesis that recipients of HRT with concurrent KT (HRT-KT) would have worse survival than recipients of HRT alone.

METHODS AND RESULTS

A retrospective analysis of the United Network of Organ Sharing database was performed for all patients undergoing HRT from 1987 to 2011. There were 1660 HRT patients, of which 116 (7%) received concurrent KT. Those who received HRT-KT had older age, longer wait-list time, worse kidney function, and more known diabetes. Survival among recipients of HRT-KT was significantly better than that of recipients of HRT alone (P=0.005). A subgroup of 323 HRT patients with severe kidney dysfunction (estimated glomerular filtration rate <30 mL/min per 1.73 m(2) or on dialysis) was studied in more detail, and 76 (24%) received concurrent KT. Those on dialysis at the time of HRT had better survival with versus without concurrent KT (P<0.0001). On multivariable analysis, concurrent KT was independently associated with better outcomes for all patients with HRT and for the subgroup of patients with severe kidney dysfunction.

CONCLUSIONS

Recipients of HRT-KT have better survival than recipients of HRT alone. Further research is needed to determine which HRT patients may benefit the most from concurrent KT.

Chronic renal insufficiency in heart transplant recipients: risk factors and management options

Renal dysfunction after heart transplantation is a frequently observed complication, in some cases resulting in significant limitation of quality of life and reduced survival. Since the pathophysiology of renal failure (RF) is multifactorial, the current etiologic paradigm for chronic kidney disease after heart transplantation relies on the concept of calcineurin inhibitor (CNI)-related nephrotoxicity acting on a predisposed recipient. Until recently, the management of RF has been restricted to the minimization of CNI dosage and general avoidance of classic nephrotoxic risk factors, with somewhat limited success. The recent introduction of proliferation signal inhibitors (PSIs) (sirolimus and everolimus), a new class of immunosuppressive drugs lacking intrinsic nephrotoxicity, has provided a completely new alternative in this clinical setting. As clinical experience with these new drugs increases, new renal-sparing strategies are becoming available. PSIs can be used in combination with reduced doses of CNIs and even in complete CNI-free protocols. Different strategies have been devised, including de novo use to avoid acute renal toxicity in high-risk patients immediately after transplantation, or more delayed introduction in those patients developing chronic RF after prolonged CNI exposure. In this review, the main information on the clinical relevance and pathophysiology of RF after heart transplantation, as well as the currently available experience with renal-sparing immunosuppressive regimens, particularly focused on the use of PSIs, is reviewed and summarized, including the key practical points for their appropriate clinical usage.

Difficulty of patient selection in a combined heart-kidney transplant: a case report

Combined heart-kidney transplant has become an alternative for heart transplant candidates with significant chronic kidney disease. However, it is not clear which patients will benefit most from such intervention, and in whom cardiac transplant alone will be sufficient to restore adequate renal function. We report the case of a man with ischemic cardiomyopathy and chronic kidney disease who was wait-listed for heart-kidney transplant after acute decompensated heart failure and renal failure requiring hemodialysis. Because of unexpected circumstances, the kidney transplant was cancelled, and only a heart transplant was performed. Nonetheless, the kidney function rapidly improved beyond the levels before hospitalization and remains stable months after transplant. This case illustrates the difficulties in assessing the reversibility of kidney damage in the context of heart failure requiring transplant. This issue is primordial to improve selection of patients who will benefit most from combined heart-kidney transplant in a context of scarce organ allocation resources.

Cellular effects of everolimus and sirolimus on podocytes

Everolimus (EVL) and Sirolimus (SRL) are potent immunosuppressant agents belonging to the group of mammalian target of rapamycin (mTOR) inhibitors used to prevent transplant rejection. However, some patients develop proteinuria following a switch from a calcineurin inhibitor regimen to mTOR inhibitors. Whether different mTOR inhibitors show similar effects on podocytes is still unknown. To analyze this, human podocytes were incubated with different doses of EVL and SRL. After incubation with EVL or SRL, podocytes revealed a reduced expression of total mTOR. Phosphorylation of p70S6K and Akt was diminished, whereas pAkt expression was more reduced in the SRL group. In both groups actin cytoskeletal reorganization was increased. Synaptopodin and podocin expression was reduced as well as nephrin protein, particularly in the SRL group. NFκB activation and IL-6 levels were lower in EVL and SRL, and even lower in SRL. Apoptosis was more increased in SRL than in the EVL group. Our data suggests that mTOR inhibitors affect podocyte integrity with respect to podocyte proteins, cytoskeleton, inflammation, and apoptosis. Our study is the first to analyze both mTOR inhibitors, EVL and SRL, in parallel in podocytes. Partially, the impact of EVL and SRL on podocytes differs. Nevertheless, it still remains unclear whether these differences are of relevance regarding to proteinuria in transplant patients.

Postoperative care of the transplanted patient

The successful delivery of optimal peri-operative care to pediatric heart transplant recipients is a vital determinant of their overall outcomes. The practitioner caring for these patients must be familiar with and treat multiple simultaneous issues in a patient who may have been critically ill preoperatively. In addition to the complexities involved in treating any child following cardiac surgery, caretakers of newly transplanted patients encounter multiple transplant-specific issues. This chapter details peri-operative management strategies, frequently encountered early morbidities, initiation of immunosuppression including induction, and short-term outcomes.

Incidence, risk factor, and prognosis of end-stage renal disease after heart transplantation in Chinese recipients

BACKGROUND/PURPOSE

End-stage renal disease (ESRD) is an important complication arising after heart transplantation. At least 3-10% of recipients reach ESRD within 10 years after transplant. The incidence of ESRD in Chinese recipients has not been reported. Here we sought to assess the incidence, prognosis, and risk factors for ESRD in Chinese recipients.

METHODS

We conducted a retrospective analysis of 248 heart recipients who survived >1 year from 1998 through 2007. ESRD was defined as the requirement of maintenance dialysis.

RESULTS

Renal dysfunction was present in 20 patients (8%) prior to transplant. With a follow-up duration of 5.8 ± 3.9 years, 30 patients developed ESRD. The cumulative incidence of ESRD after heart transplantation was 2.1% ± 0.9%, 6.5% ± 1.8%, 16.8% ± 3.3%, and 36.5% ± 9.5% at 2, 5, 10, and 15 years after transplant, respectively. Median onset of ESRD was 6.9 years after transplant. Actuarial survival after dialysis was 74.8% ± 8.3%, 66.6% ± 9.2%, and 43.6% ± 12.6% at 1, 2, and 5 years, respectively. Independent risk factors for ESRD included pretransplant serum creatinine (hazard ratio, 1.84; p = 0.001), presence of diabetes prior to transplant (hazard ratio, 2.51; p = 0.017), and old age at transplant (hazard ratio, 1.05; p = 0.008).

CONCLUSION

There was a high incidence of ESRD in Chinese heart recipients. Patients with ESRD had poor prognosis after dialysis.

PRKCB is associated with calcineurin inhibitor-induced renal dysfunction in heart transplant recipients

OBJECTIVES

Single nucleotide polymorphisms (SNPs) in the transforming growth factor-β1 gene (TGFB1) have been inconsistently associated with calcineurin inhibitor (CNI)-induced renal dysfunction following cardiac transplantation. The impact of genetic variants related to the renin-angiotensin-aldosterone system (RAAS) and natriuretic peptides, which are implicated in CNI nephrotoxicity, is unknown. The primary objective of this study was to validate the association between two common variants in TGFB1 (rs1800470, rs1800471) and postcardiac transplant renal function. The secondary objective was to investigate the effect of candidate genes related to the RAAS, natriuretic peptides, and other elements involved in the intracellular signaling of these pathways.

METHODS

We conducted a retrospective cohort study of 158 heart transplant recipients treated with CNIs, and evaluated the association between select SNPs and the estimated glomerular filtration rate as calculated by the Modification of Diet in Renal Disease simplified formula. A total of 273 SNPs distributed in 44 genes were tested.

RESULTS

No association was observed between TGFB1 variants and renal function. One polymorphism in the protein kinase C-β gene (PRKCB; rs11074606), which is implicated in the RAAS intracellular signaling, was significantly associated with post-transplant estimated glomerular filtration rate after adjusting for possible confounders (P=0.00049). This marker is in linkage disequilibrium with two variants located in putative regulatory regions of the gene (rs2283541, rs1013316).

CONCLUSION

Our results suggest that PRKCB may be a potential predictor of CNI-induced nephrotoxicity in heart transplant recipients, and could therefore be a promising candidate to identify patients who are most susceptible to this adverse drug reaction.

Renal comorbidity after solid organ and stem cell transplantation

After transplantation of solid organs or hematopoietic stem cells, a significant acute decrease in renal function occurs in the majority of patients. Depending on the degree of kidney injury, a large number of patients develop chronic kidney disease (CKD) and some develop end-stage renal disease requiring renal replacement therapy. The incidence varies depending on the transplanted organ, but important risk factors for the development of CKD are preexisting renal disease, hepatitis C, diabetes, hypertension, age, sex, posttransplant acute kidney injury and thrombotic microangiopathy. This review article focuses on the risk factors of posttransplant chronic kidney disease after organ transplantation, considering the current literature and integrates the incidence and the associated mortality rates of acute and chronic kidney disease. Furthermore, we introduce the RECAST (REnal Comorbidity After Solid organ and hematopoietic stem cell Transplantation) registry.

The role of kidney biopsy in heart transplant candidates with kidney disease

BACKGROUND

Kidney disease is common in patients with advanced heart failure and can result from intrinsic parenchymal disease or to reversible hemodynamic factors. Distinguishing the two is difficult but is important when selecting patients who will benefit from combined heart and kidney transplantation (HKT) versus heart transplantation (OHT) alone. The goal of this study was to characterize kidney biopsy findings in this population and follow the outcome of patients based on the biopsy results.

METHODS

Thirty heart transplant candidates with an estimated glomerular filtration rate less than 40 mL/min or proteinuria greater than 500 mg/day or a history of amyloidosis underwent kidney biopsies between June 2001 and March 2009. The renal pathologic diagnosis as well as the percent tubular atrophy and interstitial fibrosis on renal biopsy were assessed.

RESULTS

Proteinuria and glomerular filtration rate at the time of evaluation for heart transplant did not correlate with the degree of fibrosis on biopsy. On the basis of the biopsy results, nine patients were listed for OHT and eight patients were listed for HKT. One patient originally triaged to receive OHT and was listed for HKT due to subsequent worsening of renal function. Eight patients received OHT, none required dialysis during a median follow-up period of 18 months.

CONCLUSIONS

Renal biopsy provides useful diagnostic information to differentiate intrinsic renal disease from renal hypoperfusion and helps guide the decision for OHT alone versus combined HKT.

Kidney transplantation in patients with a prior heart transplant

BACKGROUND

Chronic kidney disease among prior heart transplant recipients is a growing problem that is likely to place an increased demand on a limited supply of kidney allografts. Allocation of the limited resource of kidneys for transplantation requires consideration of the demands of fair distribution and optimizing patient and graft survival. The aim of this study was to compare the kidney transplant outcomes among recipients of kidney after prior heart transplantation (KAH, n=456) with kidney transplantation in other clinical settings.

METHODS

A retrospective cohort study using United Network for Organ Sharing registry data (1995-2008) was performed comparing renal allograft survival among KAH recipients with patients who underwent simultaneous kidney-heart transplant (SKH, n=252), primary kidney transplant alone (KA1, n=112,882), or repeat kidney transplant alone (KA2, n=14,070).

RESULTS

The annual number of KAH recipients more than quadrupled during the study period from 24 in 1995 to 99 in 2008. In a multivariable analysis using Cox regression, allograft survival among KAH recipients was not different from SKH (P=0.16, hazards ratio [HR]=0.79, confidence interval [CI]=0.57-1.10), and KA2 (P=0.11, HR=0.86, CI=0.72-1.04), but it was inferior to KA1 (P<0.001, HR=0.66, CI=0.55-0.80). Patient death accounted for 75.2% of KAH kidney loss. Kidney quality as measured by living or deceased donors (P=0.62) and standard criteria or extended criteria (P=0.87) was not associated with survival; however, there was a trend toward improved survival (P=0.08) among recipients of a preemptive transplant.

CONCLUSION

Kidney graft survival among prior heart transplant recipients is inferior to KA1 but similar to other clinical scenarios. Preemptive transplantation with an extended criteria or living donor kidney should be encouraged.

The clinical impact of an early decline in kidney function in patients following heart transplantation

Renal dysfunction is a well-known complication following heart transplantation. We examined an early decline in kidney function as a predictor of progression to end-stage renal disease and mortality in heart transplant recipients. We performed a retrospective cohort study of 233 patients who received a heart transplant between July 1985 and July 2004, and who survived >1 month. The decline in estimated creatinine clearance (CrCl) was used to predict the outcomes of need for chronic dialysis or mortality >1-year posttransplant. The earliest time to chronic dialysis was 484 days. A 30% decline in CrCl between 1 month and 12 months predicted the need for chronic dialysis (p = 0.01), all-cause mortality (p < 0.0001) and time to first CrCl </=30 mL/min at >1-year posttransplant (p = 0.02). A 30% decline in CrCl between 1 month and 3 months also independently predicted the need for chronic dialysis (p = 0.04) and time to first CrCl </= 30 mL/min at >1-year posttransplant (p = 0.01). In conclusion, an early drop in CrCl within the first year is a strong predictor of chronic dialysis and death >1-year postheart transplantation. Future studies should focus on kidney function preservation in those identified at high risk for progression to end-stage kidney disease and mortality.

The profile of renal function over time in a cohort of pediatric heart transplant recipients

To assess the burden over time of renal dysfunction in pediatric heart transplant patients using an objective measure on an annual basis for serial comparison. GFR was measured at regular interval by nuclear medicine scintigraphy. Results were analyzed in relation to age, time post-transplantation, gender, and average calcineurin-inhibitor dose for the first two months post-transplantation. Results were compared with cGFR using the Schwartz equation. A total of 91 patients (56 males) transplanted between 1990 and 2004 underwent 373 GFR measurements. Median age at transplantation was 3.3 yr (birth - 17.8). Median first GFR at 0.7 yr (0.1-4.1) post-transplant was normal (94 mL/kg/1.73 m(2)). Freedom from at least mild renal insufficiency was 84% and 33% at one and five years post-transplant. Females had better renal function early post-transplant (GFR 105 mL/min/1.73 m(2)) but an increased probability of an abnormal GFR over time. Higher calcineurin inhibitor dose in the first two months post-transplantation was associated with an increasing probability of an abnormal GFR over time. The cGFR overestimated the measured GFR by 33 +/- 26 mL/kg/1.73 m(2). Renal insufficiency is an important morbidity after pediatric transplantation with the majority of patients experiencing at least mild renal dysfunction. Calculated GFR significantly underestimates the burden of renal insufficiency in this patient population.

Predictors of rehospitalization time during the first year after heart transplant

BACKGROUND

Patient problems after heart transplant (HT) can lead to rehospitalization.

OBJECTIVE

To examine rehospitalization patterns and identify predictors of the number of days rehospitalized at the transplant site during the first year after HT surgery.

METHODS

Hierarchical regression identified predictors of greater rehospitalization time from chart data collected from two transplant sites during the first posttransplant year on 269 adult HT recipients. Variables (total = 32) were entered in six steps: clinical site, demographics, perioperative variables, cardiac function, immunosuppressant dosages, and post-HT complications.

RESULTS

The number of days rehospitalized at the transplant site during the first year after HT ranged from 0 to 142 (mean = 25, median = 16); 64% were rehospitalized; 37% were rehospitalized more than once. Main reasons were rejections, infections, cardiovascular problems, and gastrointestinal (GI) problems. The regression model explained 48.7% of the variance in rehospitalization time, with post-HT complications explaining the most variance. Ten predictors were significant: intravenously treated infections, treated acute rejections, shorter stay for HT surgery, GI complications, higher prednisone dose, female gender, coma, sex mismatch between donor and recipient, renal complications, and clinical site.

CONCLUSION

Sixty-four percent of the patients were rehospitalized at the transplant site during the first year after HT surgery (with a median of 16 hospital days); 37% were rehospitalized more than once. Significant predictors of the amount of time rehospitalized pertained to five types of complications (rejections, infections, GI, renal, coma), shorter HT surgical stay, female gender, higher prednisone dose, sex-mismatched donor, and clinical site. The study identifies who uses the most hospital resources during the first year after HT.

Renal function impacts outcomes after intestinal transplantation

BACKGROUND

Although renal dysfunction (RD) has been commonly associated with poor outcome after other solid organ transplants, it has not been studied in detail after intestinal transplantation (ITx). Here we provide a detailed analysis of renal function after ITx, and identify predictors of post-ITx RD.

METHODS

A retrospective analysis of patients undergoing ITx from 1991 to 2006 was performed. For each patient, the estimated glomerular filtration rate (eGFR) was compared with the normal GFR for age and gender to obtain the percent of normal eGFR. Chi-square analysis and log-rank tests were used to identify categorical variables associated with RD (eGFR <75% of normal) and to determine if RD was predictive of post-ITx survival.

RESULTS

Sixty-eight transplantations were performed in 62 patients. Overall patient survival at 1 and 5 years was 78% and 56%, respectively. Renal dysfunction was observed in 16% of patients post-ITx. The most frequent predictors of post-ITx RD were preoperative eGFR less than 75% of normal, pre-ITx location in the intensive care unit, and high-dose tacrolimus immunotherapy. An eGFR less than 75% of normal at days 7, 28, and 365 was predictive of poor patient survival (P<0.05).

CONCLUSIONS

This study provides the first detailed analysis of renal function after ITx. We identified specific risk factors for the development of RD in the first year post-ITx and found a significant association of RD with decreased long-term survival. Given the strong correlation of RD with poor outcome, preserving renal function may be key to improving long-term outcomes in ITx recipients.

Development of proteinuria after switch to sirolimus-based immunosuppression in long-term cardiac transplant patients

Calcineurin-inhibitor therapy can lead to renal dysfunction in heart transplantation patients. The novel immunosuppressive (IS) drug sirolmus (Srl) lacks nephrotoxic effects; however, proteinuria associated with Srl has been reported following renal transplantation. In cardiac transplantation, the incidence of proteinuria associated with Srl is unknown. In this study, long-term cardiac transplant patients were switched from cyclosporine to Srl-based IS. Concomitant IS consisted of mycophenolate mofetil +/- steroids. Proteinuria increased significantly from a median of 0.13 g/day (range 0-5.7) preswitch to 0.23 g/day (0-9.88) at 24 months postswitch (p = 0.0024). Before the switch, 11.5% of patients had high-grade proteinuria (>1.0 g/day); this increased to 22.9% postswitch (p = 0.006). ACE inhibitor and angiotensin-releasing blocker (ARB) therapy reduced proteinuria development. Patients without proteinuria had increased renal function (median 42.5 vs. 64.1, p = 0.25), whereas patients who developed high-grade proteinuria showed decreased renal function at the end of follow-up (median 39.6 vs. 29.2, p = 0.125). Thus, proteinuria may develop in cardiac transplant patients after switch to Srl, which may have an adverse effect on renal function in these patients. Srl should be used with ACEi/ARB therapy and patients monitored for proteinuria and increased renal dysfunction.

Multidisciplinary insights on clinical guidance for the use of proliferation signal inhibitors in heart transplantation

Proliferation signal or mammalian target-of-rapamycin inhibitors (PSI/mTOR inhibitors), everolimus and sirolimus, provide attractive options for use in heart transplantation because they are immunosuppressive and anti-proliferative. PSI/mTOR inhibitors work synergistically with calcineurin inhibitors (CNIs) and thus permit the minimization of CNIs without compromising efficacy. This approach is advantageous for the majority of heart transplant recipients and might provide particular benefit in specific cases, such as patients with cardiac allograft vasculopathy, malignancies and renal dysfunction, or in patients intolerant to other immunosuppressive agents. Drawing on the expertise of transplant cardiologists, cardiac surgeons and nephrologists, we addressed the assessment of renal function; management of adverse events associated with this class of drugs; and clinical guidance, specifically for the use of everolimus, including patient selection, indications for treatment and practicalities of drug initiation and monitoring.

Combined heart-kidney transplantation: the University of Wisconsin experience

BACKGROUND

Combined heart-kidney transplantation (HKTx) is increasing in frequency, but long-term outcomes are unknown and appropriately comparative analysis is lacking.

METHODS

This study was a retrospective review of prospectively collected data for 19 HKTx patients. Patient and graft survival, graft rejection and coronary allograft vasculopathy (CAV) were compared for HKTx vs recipients of a heart (n = 515) or kidney alone (n = 3,188) or both organs at separate time-points (n = 8).

RESULTS

Patient and graft survival did not differ for HKTx vs any group. HKTx time to first rejection episode was significantly prolonged for both organs vs single-organ recipients. The incidence of CAV was significantly lower for HKTx.

CONCLUSIONS

HKTx provides outcomes similar to those for solitary heart or kidney transplantation. There may be an immunologic advantage to receiving organs in a combined fashion. Such allocation of organs seems medically appropriate; however, more refined strategies are needed to identify optimal recipient populations.

Chronic kidney disease after nonrenal solid-organ transplantation

Chronic kidney disease (CKD) is a common complication after nonrenal solid-organ transplantation. The risk for CKD is influenced by many factors, some of which have a direct impact on how such patients are treated in the pre-, peri-, and posttransplantation settings. This review describes hazards for acute and chronic kidney injury, with particular emphasis on calcineurin inhibitor-mediated nephrotoxicity. Rather than a detailed description of management issues that are common to the general CKD population, highlighted are aspects that are more specific to nonrenal solid-organ transplant recipients with a focus on liver, heart, and lung recipients. Strategies to minimize nephrotoxic insults and retard progressive renal injury are discussed, as are issues that are pertinent to dialysis and transplantation. Finally, future approaches to prevent and treat CKD without compromising function of the transplanted organ are addressed.

Chronic kidney disease after liver, cardiac, lung, heart-lung, and hematopoietic stem cell transplant

Patient survival after cardiac, liver, and hematopoietic stem cell transplant (HSCT) is improving; however, this survival is limited by substantial pretransplant and treatment-related toxicities. A major cause of morbidity and mortality after transplant is chronic kidney disease (CKD). Although the majority of CKD after transplant is attributed to the use of calcineurin inhibitors, various other conditions such as thrombotic microangiopathy, nephrotic syndrome, and focal segmental glomerulosclerosis have been described. Though the immunosuppression used for each of the transplant types, cardiac, liver and HSCT is similar, the risk factors for developing CKD and the CKD severity described in patients after transplant vary. As the indications for transplant and the long-term survival improves for these children, so will the burden of CKD. Nephrologists should be involved early in the pretransplant workup of these patients. Transplant physicians and nephrologists will need to work together to identify those patients at risk of developing CKD early to prevent its development and progression to end-stage renal disease.

Renal disease in recipients of nonrenal solid organ transplantation

Worldwide, more than 250,000 individuals who have received a liver, heart, lung, or intestinal transplant are living longer. Twenty percent to 25% of these recipients experience perioperative acute renal failure, with 10% to 15% requiring renal replacement therapy. Chronic kidney disease (CKD) is also highly prevalent, affecting 30% to 50% of the nonrenal organ transplant population with an annual end-stage renal disease risk of 1.5% to 2.0%. Both acute renal failure and CKD contribute to increased morbidity and premature mortality. The dominant causative factor for renal disorders seen in nonrenal transplant recipients are the calcineurin inhibitors (CNI) and rapamycin analogues, which singly or in combination lead to a variety of nephrotoxic injury. However, 25% to 30% of nonrenal transplant recipients with CKD have other conditions such as hypertension, focal segmental glomerulosclerosis, diabetes mellitus, and hepatitis C infection as the principal underlying cause. Management strategies for renal disease in the nonrenal transplant recipients include the following: (1) delayed introduction of CNI after graft implantation, (2) withdrawal or minimization of long-term CNI therapy, (3) timely use of an appropriate dialysis modality, and (4) expeditious introduction of supportive measures such as anemia management, phosphate binding therapy, and dietary modification. Compared with maintenance dialysis, kidney transplantation reduces long-term mortality by 60% to 70% in nonrenal transplant recipients with end-stage renal disease.

Statin therapy associated with a reduced risk of chronic renal failure after cardiac transplantation

BACKGROUND

Chronic renal failure (CRF) after heart transplantation is common, although risk factors for its development and potential preventive interventions are not well established.

METHODS

In this study we retrospectively assessed the cumulative incidence of CRF and identified independent predictors of CRF in heart transplant recipients between August 1986 and January 2003.

RESULTS

Among the 218 patients included in the analysis, the cumulative incidence of CRF was 4.5% at 5 years, and 19.6% at 10 years after transplant. Multivariate Cox modeling revealed that diabetes mellitus prior to transplant was associated with an increased risk of CRF (hazards ratio [HR] 7.11, p < 0.01), whereas factors associated with a reduced risk of CRF included a pre-transplant creatinine clearance > or = 60 ml/min/1.73 m2 (HR 0.30, p = 0.01) and treatment with a statin after transplant (HR 0.25, p < 0.01). Patients who developed CRF after transplant were at higher risk of death (HR 8.5, p < 0.01).

CONCLUSIONS

CRF is common after cardiac transplantation and is associated with substantial mortality. The reduced risk of CRF observed with statin therapy warrants prospective study, with particular emphasis on the mechanisms of progression to CRF in this population.

Chronic kidney disease in long-term survivors of hematopoietic cell transplant

We conducted a cohort study to identify risk factors of chronic kidney disease (CKD) among long-term survivors of hematopoietic cell transplant (HCT). We studied 1635 patients transplanted at the Fred Hutchinson Cancer Research Center (FHCRC) between 1991 and 2002, who survived to day +131 after transplant and had serum creatinine measured on at least two occasions after day +131. CKD was defined as a glomerular filtration rate < 60 ml/min/m(2) on two occasions separated by at least 30 days between days 100 and 540 post transplant. Cox regression models estimated hazard ratios (HRs) describing associations between demographic data, clinical variables and the risk of developing CKD. A total of 376 patients (23%) developed CKD at a median of 191 days post transplant (range 131-516 days). An increased risk of CKD was associated with acute renal failure (ARF) (HR=1.7, 95% confidence interval (CI) 1.3-2.1), acute graft-vs-host disease (aGVHD) grade II (HR=2.0, 95% CI 1.4-2.9) and grades III/IV (HR=3.1, 95% CI 2.1-4.6) and chronic GVHD (HR=1.8, 95% CI 1.4-2.2). Total body irradiation (TBI) (HR=1.0, 95% CI 0.8-1.3) was not associated with an increased risk of CKD. CKD is relatively common among survivors of HCT. The presence of ARF and GVHD, but not receipt of TBI, appears to be associated with the occurrence of CKD.

Does Renal Function Deteriorate More Rapidly in Diabetic Cardiac Transplant Recipients?

BACKGROUND

Selection criteria for cardiac transplant candidates with diabetes mellitus (DM) have been liberalized resulting in increased numbers of diabetic patients receiving organs. Calcineurin inhibition results in nephrotoxicity. Whether this nephrotoxicity is accelerated in diabetic heart transplant recipients is unknown.

METHODS

To investigate this question, we derived the glomerular filtration rate (GFR) at transplant and at multiple time intervals thereafter for adult heart transplants performed from January 1, 2000 to January 1, 2005. GFR was estimated using the Modification of Diet in Renal Disease Study equation (GFRMDRD) and the Cockcroft-Gault (GFRCG) formula.

RESULTS

In all, 257 patients were nondiabetic and 102 patients were diabetic before and after transplant. The diabetic patients were older (57+/-8 vs. 53+/-13 years; P<0.01) and had greater body mass index (27.5+/-5.1 vs. 25.5+/-4.4 kg/m; P<0.01) than nondiabetic patients. Baseline renal function was significantly reduced in diabetic patients with higher serum creatinine (1.6+/-0.5 vs. 1.4+/-0.5 mg/dL), lower GFRCG (65+/-27 vs. 73+/-35 mL/min), and lower GFRMDRD (54+/-23 vs. 65+/-32 mL/min; all P<0.01) than nondiabetic patients. All patients were treated with cyclosporine or tacrolimus posttransplant. The change in the GFRMDRD in nondiabetic and diabetic patients was constant and comparable at 1, 2, and 3 years posttransplant. In normal subjects, GFRMDRD declined from baseline by 7+/-26, 5+/-23, and 7+/-23 mL/min(2) and in the diabetic patients was 13+/-22, 9+/-26, 10+/-22 ml/min(2) at 1, 2, and 3 years, respectively (P=NS).

CONCLUSION

This data suggests that nephrotoxicity posttransplant is not accelerated in diabetic recipients.

Renal protective strategies in heart transplant patients

PURPOSE OF REVIEW

Chronic renal failure associated with long-term calcineurin inhibitor immunosuppression is a substantial clinical problem in the heart transplant population, compounded by difficulties in identifying patients likely to develop renal dysfunction. Several approaches, however, have been developed or are being investigated to preserve renal function in heart transplant patients.

RECENT FINDINGS

Approaches to identify patients with an increased risk of developing renal dysfunction are being refined, and improved calcineurin inhibitor monitoring strategies are being investigated. Novel immunosuppressive regimens including mycophenolate mofetil and/or rapamycin that lack nephrotoxicity promise new therapeutic strategies with the efficacy of calcineurin inhibitor-based combinations. Temporary ('holiday') or permanent ('retirement') calcineurin inhibitor replacement with interleukin-2 receptor monoclonal antibodies has the potential to halt progressive renal dysfunction. Finally, emerging data on the renal protection afforded by angiotensin converting enzyme inhibitors and angiotensin II receptor blockers, either singly or in combination, provide another avenue of investigation.

SUMMARY

Several strategies have demonstrated their potential to preserve or improve renal function in heart transplant patients in small studies. Large randomized controlled trials are necessary to determine the optimal strategies to prevent rejection while preserving renal function in the long-term management of heart transplant patients.

The outcome of heart transplant recipients following the development of end-stage renal disease: analysis of the Canadian Organ Replacement Register (CORR)

End-stage renal disease is a significant complication of heart transplantation (HTx), but our understanding of dialysis outcomes in HTx recipients remains limited. We performed a retrospective analysis looking at dialysis mortality in HTx recipients as compared to a matched dialysis cohort. We also examined outcomes with respect to kidney transplantation (KTx) in these cohorts. 2709 incident HTx recipients were captured from the Canadian Organ Replacement Register between 1981 and 2002. The incidence of dialysis after HTx was 3.9% (n = 105) and carried a greater crude mortality compared to HTx recipients not requiring dialysis (56.2% vs. 35.9%, p < 0.001). Compared to the matched dialysis cohort, survival of HTx patients on dialysis was also significantly worse (19% vs. 40%, p = 0.003). In those receiving a KTx, survival did not differ between the two cohorts; however, in those that did not receive a KTx the survival was significantly lower in the dialysis post-HTx group compared to the matched dialysis cohort (15.7% vs. 35.2%, p < 0.025). Our analysis suggests mortality on dialysis following HTx is greater than would be expected from a similar dialysis population, and KTx may abrogate some of this increased risk. Attention should be placed on preventing chronic kidney disease progression following HTx.

Risks and Outcomes of Acute Kidney Injury Requiring Dialysis After Cardiac Transplantation

BACKGROUND

Risk factors for postoperative acute kidney injury (AKI) are well described in nontransplantation settings. Data regarding risks and consequences of AKI after cardiac transplantation are unclear.

METHODS

We analyzed 756 cardiac transplant recipients between 1993 and 2004. The primary outcome is postoperative AKI requiring dialysis therapy. Secondary outcomes are hospital mortality and postoperative morbidities, including cardiac, neurological, and serious infection. Wilcoxon rank-sum, chi-square, or Fisher exact tests were used for univariable comparison. A bootstrap-bagging procedure (1,000 repetitions) and multivariable logistic analysis with multiple imputation were used for the final model.

RESULTS

AKI frequency was 5.8% (44 of 756 patients). By means of univariable analysis, preoperative risk factors for AKI were diabetes, prior cardiac surgery, intra-aortic balloon pump use, albumin level, creatinine level, clinical severity score, and cold ischemia time. Intraoperative risk factors were cardiopulmonary bypass time and transfusion requirement. By means of multivariate analysis, serum creatinine level (odds ratio [OR], 2.7; 95% confidence interval [CI], 1.6 to 4.6), serum albumin level (OR, 0.34; 95% CI, 0.21 to 0.54), insulin-requiring diabetes (OR, 3.5; 95% CI, 1.4 to 9.0), and cardiopulmonary bypass time (OR, 1.29; 95% CI, 1.02 to 1.64) were independent predictors of postoperative AKI. The overall postoperative mortality rate was 4.2%; it was 50% in patients with AKI compared with 1.4% in patients without AKI. AKI was associated with greater frequencies of cardiac, neurological, and serious infection morbidities (43.2%, 18.2%, and 54.6% versus 5.5%, 2.3%, and 7.2%, respectively; P < 0.001).

CONCLUSION

AKI is associated with significant morbidity and mortality after cardiac transplantation. Predictors of AKI can be used to risk-stratify patients to ameliorate further kidney injury and offer a survival benefit.

Determination of renal function in long-term heart transplant patients by measurement of urinary retinol-binding protein levels

Significant improvements have been noted in heart transplantation with the advent of cyclosporine. However, cyclosporine use is associated with significant side effects, such as chronic renal failure. We were interested in evaluating the incidence of long-term renal dysfunction in heart transplant recipients. Fifty-three heart transplant recipients were enrolled in the study. Forty-three patients completed the entire evaluation and follow-up. Glomerular (serum creatinine, creatinine clearance measured, and creatinine clearance calculated) and tubular functions (urinary retinol-binding protein, uRBP) were re-analyzed after 18 months. At the enrollment time, the prevalence of renal failure ranged from 37.7 to 54% according to criteria used to define it (serum creatinine > or = 1.5 mg/dL and creatinine clearance <60 mL/min). Mean serum creatinine was 1.61 +/- 1.31 mg/dL (range 0.7 to 9.8 mg/dL) and calculated and measured creatinine clearances were 67.7 +/- 25.9 and 61.18 +/- 25.04 mL min-1 (1.73 m(2))-1, respectively. Sixteen of the 43 patients who completed the follow-up (37.2%) had tubular dysfunction detected by increased levels of uRBP (median 1.06, 0.412-6.396 mg/dL). Eleven of the 16 patients (68.7%) with elevated uRBP had poorer renal function after 18 months of follow-up, compared with only eight of the 27 patients (29.6%) with normal uRBP (RR = 3.47, P = 0.0095). Interestingly, cyclosporine trough levels were not different between patients with or without tubular and glomerular dysfunction. Renal function impairment is common after heart transplantation. Tubular dysfunction, assessed by uRBP, correlates with a worsening of glomerular filtration and can be a useful tool for early detection of renal dysfunction.