Effects of ACE Inhibitors on Long-Term Outcome of Renal Transplant Recipients: A Randomized Controlled Trial

Antihypertensive treatment for kidney transplant recipients

BACKGROUND

The comparative effects of specific blood pressure (BP) lowering treatments on patient-important outcomes following kidney transplantation are uncertain. Our 2009 Cochrane review found that calcium channel blockers (CCBs) improved graft function and prevented graft loss, while the evidence for other BP-lowering treatments was limited. This is an update of the 2009 Cochrane review.

OBJECTIVES

To compare the benefits and harms of different classes and combinations of antihypertensive drugs in kidney transplant recipients.

SEARCH METHODS

We contacted the Information Specialist and searched the Cochrane Kidney and Transplant Register of Studies up to 3 July 2024 using search terms relevant to this review. Studies in the Register were identified through searches of CENTRAL, MEDLINE, EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs evaluating any BP-lowering agent in recipients of a functioning kidney transplant for at least two weeks were eligible.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risks of bias and extracted data. Treatment estimates were summarised using the random-effects model and expressed as relative risk (RR) or mean difference (MD) with 95% confidence intervals (CI). Evidence certainty was assessed using Grades of Recommendation, Assessment, Development and Evaluation (GRADE) processes. The primary outcomes included all-cause death, graft loss, and kidney function.

MAIN RESULTS

Ninety-seven studies (8706 participants) were included. One study evaluated treatment in children. The overall risk of bias was unclear to high across all domains. Compared to placebo or standard care alone, CCBs probably reduce all-cause death (23 studies, 3327 participants: RR 0.83, 95% CI 0.72 to 0.95; I2 = 0%; moderate certainty evidence) and graft loss (24 studies, 3577 participants: RR 0.84, 95% CI 0.75 to 0.95; I2 = 0%; moderate certainty evidence). CCBs may make little or no difference to estimated glomerular filtration rate (eGFR) (11 studies, 2250 participants: MD 1.89 mL/min/1.73 m2, 95% CI -0.70 to 4.48; I2 = 48%; low certainty evidence) and acute rejection (13 studies, 906 participants: RR 10.8, 95% CI 0.85 to 1.35; I2 = 0%; moderate certainty evidence). CCBs may reduce systolic BP (SBP) (3 studies, 329 participants: MD -5.83 mm Hg, 95% CI -10.24 to -1.42; I2 = 13%; low certainty evidence) and diastolic BP (DBP) (3 studies, 329 participants: MD -3.98 mm Hg, 95% CI -5.98 to -1.99; I2 = 0%; low certainty evidence). CCBs have uncertain effects on proteinuria. Compared to placebo or standard care alone, angiotensin-converting-enzyme inhibitors (ACEi) may make little or no difference to all-cause death (7 studies, 702 participants: RR 1.13, 95% CI 0.58 to 2.21; I2 = 0%; low certainty evidence), graft loss (6 studies, 718 participants: RR 0.75, 95% CI 0.49 to 1.13; I2 = 0%; low certainty evidence), eGFR (4 studies, 509 participants: MD -2.46 mL/min/1.73 m2, 95% CI -7.66 to 2.73; I2 = 64%; low certainty evidence) and acute rejection (4 studies, 388 participants: RR 1.75, 95% CI 0.76 to 4.04; I2 = 0%; low certainty evidence). ACEi may reduce proteinuria (5 studies, 441 participants: MD -0.33 g/24 hours, 95% CI -0.64 to -0.01; I2 = 67%; low certainty evidence) but had uncertain effects on SBP and DBP. Compared to placebo or standard care alone, angiotensin receptor blockers (ARB) may make little or no difference to all-cause death (6 studies, 1041 participants: RR 0.69, 95% CI 0.36 to 1.31; I2 = 0%; low certainty evidence), eGRF (5 studies, 300 participants: MD -1.91 mL/min/1.73 m2, 95% CI -6.20 to 2.38; I2 = 57%; low certainty evidence), and acute rejection (4 studies, 323 participants: RR 1.00, 95% CI 0.44 to 2.29; I2 = 0%; low certainty evidence). ARBs may reduce graft loss (6 studies, 892 participants: RR 0.35, 95% CI 0.15 to 0.84; I2 = 0%; low certainty evidence), SBP (10 studies, 1239 participants: MD -3.73 mm Hg, 95% CI -7.02 to -0.44; I2 = 63%; moderate certainty evidence) and DBP (9 studies, 1086 participants: MD -2.75 mm Hg, 95% CI -4.32 to -1.18; I2 = 47%; moderate certainty evidence), but has uncertain effects on proteinuria. The effects of CCBs, ACEi or ARB compared to placebo or standard care alone on cardiovascular outcomes (including fatal or nonfatal myocardial infarction, fatal or nonfatal stroke) or other adverse events were uncertain. The comparative effects of ACEi plus ARB dual therapy, alpha-blockers, and mineralocorticoid receptor antagonists compared to placebo or standard care alone were rarely evaluated. Head-to-head comparisons of ACEi, ARB or thiazide versus CCB, ACEi versus ARB, CCB or ACEi versus alpha- or beta-blockers, or ACEi plus CCB dual therapy versus ACEi or CCB monotherapy were scarce. No studies reported outcome data for cancer or life participation.

AUTHORS' CONCLUSIONS

For kidney transplant recipients, the use of CCB therapy to reduce BP probably reduces death and graft loss compared to placebo or standard care alone, while ARB may reduce graft loss. The effects of ACEi and ARB compared to placebo or standard care on other patient-centred outcomes were uncertain. The effects of dual therapy, alpha-blockers, and mineralocorticoid receptor antagonists compared to placebo or standard care alone and the comparative effects of different treatments were uncertain.

Impact of Renin-Angiotensin System Blockade on Mortality and Allograft Loss among Renal Transplant Recipients: A Systematic Review and Meta-Analysis

INTRODUCTION

The blockade of the renin-angiotensin system (RAS) has a beneficial effect on reducing the levels of proteinuria and blood pressure in patients with chronic kidney disease (CKD) and reduces the risk of developing end-stage kidney disease in CKD patients. Nonetheless, a debate persists regarding the impact of RAS inhibitors on outcomes such as mortality and graft survival in renal transplant patients. To assess the effect of RAS inhibitors on graft recipients in the past decade, we conducted a systematic review and meta-analysis.

METHODS

We searched Embase, PubMed, and the Cochrane Central Register of Clinical Trials from January 1, 2012, to August 1, 2022. We included 14 articles, comprising 5 randomized controlled trials (RCTs) and 9 cohort studies, including 45,377 patients. These studies compared patient or graft survival between an RAS inhibitor treatment arm and a control arm.

RESULTS

The meta-analysis revealed that RAS blockade was significantly associated with lower mortality in cohort studies (risk ratio [RR] = 0.66, 95% confidence interval [CI]: 0.55-0.79), reduced allograft loss in cohort studies (RR = 0.62, 95% CI: 0.54-0.71), and significant changes in systolic blood pressure in RCTs. Subgroup analysis of the groups of interest (interventions involving RAS blockade, follow-up period of ≥5 years) showed consistently reduced mortality (RR = 0.67, 95% CI: 0.56-0.81) and reduced allograft loss (RR = 0.61, 95% CI: 0.54-0.70).

CONCLUSIONS

Our results demonstrated that the application of RAS blockade among renal transplant recipients was associated with lower mortality and allograft loss in cohort studies but not in RCTs. More powered clinical trials are needed to evaluate the effects of RAS blockade in renal transplant recipients.

Renin-angiotensin-aldosterone pathway modulators in chronic kidney disease: A comparative review

Chronic kidney disease presents a health challenge that has a complex underlying pathophysiology, both acquired and inherited. The pharmacotherapeutic treatment options available today lower the progression of the disease and improve the quality of life but cannot completely cure it. This poses a challenge to the healthcare provider to choose, from the available options, the best way to manage the disease as per the presentation of the patient. As of now, the recommended first line of treatment to control the blood pressure in chronic kidney disease is the administration of renin-angiotensin-aldosterone system modulators. These are represented mainly by the direct renin inhibitor, angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers. These modulators are varied in their structure and mechanisms of action, hence showing varying treatment outcomes. The choice of administration of these modulators is determined by the presentation and the co-morbidities of the patient, the availability and affordability of the treatment option, and the expertise of the healthcare provider. A direct head-to-head comparison between these significant renin-angiotensin-aldosterone system modulators is lacking, which can benefit healthcare providers and researchers. In this review, a comparison has been drawn between the direct renin inhibitor (aliskiren), angiotensin-converting enzyme inhibitors, and angiotensin II receptor blockers. This can be of significance for healthcare providers and researchers to find the particular loci of interest, either in structure or mechanism, and to intervene as per the case presentation to obtain the best possible treatment option.

Update on Treatment of Hypertension After Renal Transplantation

PURPOSE OF REVIEW

To incorporate novel findings on pathophysiology and treatment of posttransplant hypertension.

RECENT FINDINGS

(1) The sodium retaining effects of CNIs are mediated by stimulation of the thiazide-sensitive sodium chloride co-transporter in the distal convoluted tubule and in this regard chlorthalidone was proven to be an effective antihypertensive drug in renal transplantation. (2) Local and not systemic activation of the renin-angiotensin-aldosterone system plays a crucial role in the pathogenesis of posttransplant hypertension. (3) Recent randomized controlled trials failed to prove the presumed superiority of renin-angiotensin blockers in kidney transplantation. (4) Steroid-free and mammalian target of rapamycin-based immunosuppressive drug combinations did not show favorable effects on blood pressure control. (5) In a recent report the risk of non-melanoma skin cancer was higher with thiazide diuretics. But the increased cancer risk in transplant recipients is mainly attributed to comorbidities, such as diabetes and hypertension and of course to the transplantation condition itself or the obligatory application of immunosuppression, and has little to do with the antihypertensive medication Actual recommendations about BP targets in adult renal transplant recipients are coming from a post hoc analysis of a large randomized trial with another primary endpoint. Unless convincing studies on treatment of hypertension after renal transplantation are available, the ESC/ESH Guidelines 2018 should apply for these patients.

What solid organ transplant healthcare providers should know about renin-angiotensin-aldosterone system inhibitors and COVID-19

The data on the outcomes of solid organ transplant recipients who have contracted coronavirus disease 2019 (COVID‐19) are still emerging. Kidney transplant recipients are commonly prescribed renin‐angiotensin‐aldosterone system (AAS) inhibitors given the prevalence of hypertension, diabetes, and cardiovascular disease. As the angiotensin‐converting enzyme 2 (ACE2) facilitates the entry of coronaviruses into target cells, there have been hypotheses that preexisting use of renin‐angiotensin‐aldosterone system (RAAS) inhibitors may increase the risk of developing severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection. Given the common use of RAAS inhibitors among solid organ transplant recipients, we sought to review the RAAS cascade, the mechanism of SARS‐CoV‐2 entry, and pertinent data related to the effect of RAAS inhibitors on ACE2 to guide management of solid organ transplant recipients during the COVID‐19 pandemic. At present, there is no clear evidence to support the discontinuation of RAAS inhibitors in solid organ transplant recipients during the COVID‐19 pandemic.

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.

Pharmacological interventions for heart failure in people with chronic kidney disease

BACKGROUND

Approximately half of people with heart failure have chronic kidney disease (CKD). Pharmacological interventions for heart failure in people with CKD have the potential to reduce death (any cause) or hospitalisations for decompensated heart failure. However, these interventions are of uncertain benefit and may increase the risk of harm, such as hypotension and electrolyte abnormalities, in those with CKD.

OBJECTIVES

This review aims to look at the benefits and harms of pharmacological interventions for HF (i.e., antihypertensive agents, inotropes, and agents that may improve the heart performance indirectly) in people with HF and CKD.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies through 12 September 2019 in consultation with an Information Specialist and using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials of any pharmacological intervention for acute or chronic heart failure, among people of any age with chronic kidney disease of at least three months duration.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the records to identify eligible studies and extracted data on the following dichotomous outcomes: death, hospitalisations, worsening heart failure, worsening kidney function, hyperkalaemia, and hypotension. We used random effects meta-analysis to estimate treatment effects, which we expressed as a risk ratio (RR) with 95% confidence intervals (CI). We assessed the risk of bias using the Cochrane tool. We applied the GRADE methodology to rate the certainty of evidence.

MAIN RESULTS

One hundred and twelve studies met our selection criteria: 15 were studies of adults with CKD; 16 studies were conducted in the general population but provided subgroup data for people with CKD; and 81 studies included individuals with CKD, however, data for this subgroup were not provided. The risk of bias in all 112 studies was frequently high or unclear. Of the 31 studies (23,762 participants) with data on CKD patients, follow-up ranged from three months to five years, and study size ranged from 16 to 2916 participants. In total, 26 studies (19,612 participants) reported disaggregated and extractable data on at least one outcome of interest for our review and were included in our meta-analyses. In acute heart failure, the effects of adenosine A1-receptor antagonists, dopamine, nesiritide, or serelaxin on death, hospitalisations, worsening heart failure or kidney function, hyperkalaemia, hypotension or quality of life were uncertain due to sparse data or were not reported. In chronic heart failure, the effects of angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) (4 studies, 5003 participants: RR 0.85, 95% CI 0.70 to 1.02; I² = 78%; low certainty evidence), aldosterone antagonists (2 studies, 34 participants: RR 0.61 95% CI 0.06 to 6.59; very low certainty evidence), and vasopressin receptor antagonists (RR 1.26, 95% CI 0.55 to 2.89; 2 studies, 1840 participants; low certainty evidence) on death (any cause) were uncertain. Treatment with beta-blockers may reduce the risk of death (any cause) (4 studies, 3136 participants: RR 0.69, 95% CI 0.60 to 0.79; I² = 0%; moderate certainty evidence). Treatment with ACEi or ARB (2 studies, 1368 participants: RR 0.90, 95% CI 0.43 to 1.90; I² = 97%; very low certainty evidence) had uncertain effects on hospitalisation for heart failure, as treatment estimates were consistent with either benefit or harm. Treatment with beta-blockers may decrease hospitalisation for heart failure (3 studies, 2287 participants: RR 0.67, 95% CI 0.43 to 1.05; I² = 87%; low certainty evidence). Aldosterone antagonists may increase the risk of hyperkalaemia compared to placebo or no treatment (3 studies, 826 participants: RR 2.91, 95% CI 2.03 to 4.17; I² = 0%; low certainty evidence). Renin inhibitors had uncertain risks of hyperkalaemia (2 studies, 142 participants: RR 0.86, 95% CI 0.49 to 1.49; I² = 0%; very low certainty). We were unable to estimate whether treatment with sinus node inhibitors affects the risk of hyperkalaemia, as there were few studies and meta-analysis was not possible. Hyperkalaemia was not reported for the CKD subgroup in studies investigating other therapies. The effects of ACEi or ARB, or aldosterone antagonists on worsening heart failure or kidney function, hypotension, or quality of life were uncertain due to sparse data or were not reported. Effects of anti-arrhythmic agents, digoxin, phosphodiesterase inhibitors, renin inhibitors, sinus node inhibitors, vasodilators, and vasopressin receptor antagonists were very uncertain due to the paucity of studies.

AUTHORS' CONCLUSIONS

The effects of pharmacological interventions for heart failure in people with CKD are uncertain and there is insufficient evidence to inform clinical practice. Study data for treatment outcomes in patients with heart failure and CKD are sparse despite the potential impact of kidney impairment on the benefits and harms of treatment. Future research aimed at analysing existing data in general population HF studies to explore the effect in subgroups of patients with CKD, considering stage of disease, may yield valuable insights for the management of people with HF and CKD.

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.

Waiting List and Kidney Transplant Vascular Risk: An Ongoing Unmet Concern

BACKGROUND

Chronic kidney disease (CKD) is an important independent risk factor for adverse cardiovascular events in patients waitlisted for kidney transplantation (KT). Although KT reduces cardiovascular risk, these patients still have a higher all-cause and cardiovascular mortality than the general population. This concerning situation is due to a high burden of traditional and nontraditional risk factors as well as uremia-related factors and transplant-specific factors, leading to 2 differentiated processes under the framework of CKD, atherosclerosis and arteriosclerosis. These can be initiated by insults to the vascular endothelial endothelium, leading to vascular calcification (VC) of the tunica media or the tunica intima, which may coexist. Several pathogenic mechanisms such as inflammation-related endothelial dysfunction, mineral metabolism disorders, activation of the renin-angiotensin system, reduction of nitric oxide, lipid disorders, and the fibroblast growth factor 23-klotho axis are involved in the pathogenesis of atherosclerosis and arteriosclerosis, including VC.

SUMMARY

This review focuses on the current understanding of atherosclerosis and arteriosclerosis, both in patients on the waiting list as well as in kidney transplant recipients, emphasizing the cardiovascular risk factors in both populations and the inflammation-related pathogenic mechanisms. Key Message: The importance of cardiovascular risk factors and the pathogenic mechanisms related to inflammation in patients waitlisted for KT and kidney transplant recipients.

Comparison of the effects of standard vs low-dose prolonged-release tacrolimus with or without ACEi/ARB on the histology and function of renal allografts

Targeting the renin-angiotensin system and optimizing tacrolimus exposure are both postulated to improve outcomes in renal transplant recipients (RTRs) by preventing interstitial fibrosis/tubular atrophy (IF/TA). In this multicenter, prospective, open-label controlled trial, adult de novo RTRs were randomized in a 2 × 2 design to low- vs standard-dose (LOW vs STD) prolonged-release tacrolimus and to angiotensin-converting enzyme inhibitors/angiotensin II receptor 1 blockers (ACEi/ARBs) vs other antihypertensive therapy (OAHT). There were 2 coprimary endpoints: the prevalence of IF/TA at month 6 and at month 24. IF/TA prevalence was similar for LOW vs STD tacrolimus at month 6 (36.8% vs 39.5%; P = .80) and ACEi/ARBs vs OAHT at month 24 (54.8% vs 58.2%; P = .33). IF/TA progression decreased significantly with LOW vs STD tacrolimus at month 24 (mean [SD] change, +0.42 [1.477] vs +1.10 [1.577]; P = .0039). Across the 4 treatment groups, LOW + ACEi/ARB patients exhibited the lowest mean IF/TA change and, compared with LOW + OAHT patients, experienced significantly delayed time to first T cell-mediated rejection. Renal function was stable from month 1 to month 24 in all treatment groups. No unexpected safety findings were detected. Coupled with LOW tacrolimus dosing, ACEi/ARBs appear to reduce IF/TA progression and delay rejection relative to reduced tacrolimus exposure without renin-angiotensin system blockade. ClinicalTrials.gov identifier: NCT00933231.

Comparative effectiveness of different antihypertensive agents in kidney transplantation: a systematic review and meta-analysis

Background

We conducted a systematic review and meta-analysis to compare benefits and harms of different antihypertensive drug classes in kidney transplant recipients, as post-transplant hypertension (HTN) associates with increased cardiovascular (CV) morbidity and mortality.

Methods

The Ovid-MEDLINE, PubMed and CENTRAL databases were searched for randomized controlled trials (RCTs) comparing all main antihypertensive agents versus placebo/no treatment, routine treatment.

Results

The search identified 71 RCTs. Calcium channel blockers (CCBs) (26 trials) reduced the risk for graft loss {risk ratio [RR] 0.58 [95% confidence interval (CI) 0.38–0.89]}, increased glomerular filtration rate (GFR) [mean difference (MD) 3.08 mL/min (95% CI 0.38–5.78)] and reduced blood pressure (BP). Angiotensin-converting enzyme inhibitors (ACEIs) (13 trials) reduced the risk for graft loss [RR 0.62 (95% CI 0.40–0.96)] but decreased renal function and increased the risk for hyperkalaemia. Angiotensin receptor blockers (ARBs) (10 trials) did not modify the risk of death, graft loss and non-fatal CV events and increased the risk for hyperkalaemia. When pooling ACEI and ARB data, the risk for graft failure was lower in renin–angiotensin system (RAS) blockade as compared with control treatments. In direct comparison with ACEIs or ARBs (11 trials), CCBs increased GFR [MD 11.07 mL/min (95% CI 6.04–16.09)] and reduced potassium levels but were not more effective in reducing BP. There are few available data on mortality, graft loss and rejection. Very few studies performed comparisons with other active drugs.

Conclusions

CCBs could be the preferred first-step antihypertensive agents in kidney transplant patients, as they improve graft function and reduce graft loss. No definite patient or graft survival benefits were associated with RAS inhibitor use over conventional treatment.

Chronic kidney disease progression in kidney transplant recipients: A focus on traditional risk factors

Kidney transplant recipients are a subset of patients with chronic kidney disease (CKD) that remain at high risk for progression to dialysis and mortality. Recent advances in immunosuppression have only partially improved long-term graft and patient survival. Discovery of new immunosuppressive regimens is a slow and resource-intensive process. Hence, recognition and management of modifiable allogeneic and non-allogeneic risk factors for progression to CKD among kidney transplant recipients is of major interest for improving long-term outcomes. Graft survival is mainly determined by the quality of the allograft and by the patient's alloimmune response, which is influenced by human leukocyte antigen matching and the presence of donor-specific antibodies. Alloimmune responses manifest as acute and chronic forms of cell- and antibody-mediated rejection, which can be worsened by patient non-adherence or under-immunosuppression. However, donor and patient ages, glomerular disease recurrence, time on dialysis, pre-existing cardiovascular burden, medication side-effects and traditional risk factors, such as hypertension, proteinuria, anaemia, dyslipidaemia, diabetes and bone mineral disorder, which can ultimately lead to severe endothelial derangement, also contribute to graft loss and mortality. These traditional risk factors, common to pre-dialysis patients, often are considered of secondary importance when compared to alloimmunity and immunosuppression concerns. In this review article, we focus on the epidemiological, pathophysiological and therapeutic features of non-allogeneic traditional risk factors for CKD. We also discuss the benefit of adopting a multidisciplinary approach to pursue the same therapeutic targets recommended for pre-dialysis patients.

Urine Angiotensin II Signature Proteins as Markers of Fibrosis in Kidney Transplant Recipients

BACKGROUND

Interstitial fibrosis/tubular atrophy (IFTA) is an important cause of kidney allograft loss; however, noninvasive markers to identify IFTA or guide antifibrotic therapy are lacking. Using angiotensin II (AngII) as the prototypical inducer of IFTA, we previously identified 83 AngII-regulated proteins in vitro. We developed mass spectrometry-based assays for quantification of 6 AngII signature proteins (bone marrow stromal cell antigen 1, glutamine synthetase [GLNA], laminin subunit beta-2, lysophospholipase I, ras homolog family member B, and thrombospondin-I [TSP1]) and hypothesized that their urine excretion will correlate with IFTA in kidney transplant patients.

METHODS

Urine excretion of 6 AngII-regulated proteins was quantified using selected reaction monitoring and normalized by urine creatinine. Immunohistochemistry was used to assess protein expression of TSP1 and GLNA in kidney biopsies.

RESULTS

The urine excretion rates of AngII-regulated proteins were found to be increased in 15 kidney transplant recipients with IFTA compared with 20 matched controls with no IFTA (mean log2[fmol/µmol of creatinine], bone marrow stromal cell antigen 1: 3.8 versus 3.0, P = 0.03; GLNA: 1.2 versus -0.4, P = 0.03; laminin subunit beta-2: 6.1 versus 5.4, P = 0.06; lysophospholipase I: 2.1 versus 0.6, P = 0.002; ras homolog family member B: 1.2 versus -0.1, P = 0.006; TSP1_GGV: 2.5 versus 1.9; P = 0.15; and TSP1_TIV: 2.0 versus 0.6, P = 0.0006). Receiver operating characteristic curve analysis demonstrated an area under the curve = 0.86 for the ability of urine AngII signature proteins to discriminate IFTA from controls. Urine excretion of AngII signature proteins correlated strongly with chronic IFTA and total inflammation. In a separate cohort of 19 kidney transplant recipients, the urine excretion of these 6 proteins was significantly lower following therapy with AngII inhibitors (P < 0.05).

CONCLUSIONS

AngII-regulated proteins may represent markers of IFTA and guide antifibrotic therapies.

Cardiovascular and Renal Outcomes of Renin-Angiotensin System Blockade in Renal Transplant Recipients

BACKGROUND

There is considerable controversy over the benefits of renin-angiotensin system (RAS) blockade in renal transplant recipients (RTRs). The aim of the study was to research the effects of RAS blockade on allograft and patient outcome.

METHODS

A retrospective analysis of the effects of RAS blockade on allograft and patient outcome in 53 pairs of RTRs receiving grafts from the same donor was performed. The 106 RTRs (53 pairs), transplanted from 2002 to 2012, were included in the study when 1 patient from the pair used an angiotensin converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) for a minimum period of 36 months (RAS[+]) and the second one did not use it (RAS[-]).

RESULTS

There were no differences between RAS(+) and RAS(-) subjects in terms of age, body mass index, reason of end-stage renal disease, mismatches number, total ischemic time, episodes of cytomegalovirus infections, acute rejections, and immunosuppressive treatment. The mean time of observations was 66.28 months ± 24.39 months. RAS inhibitors were given in a mean dose of 23.1% (ACEI) and 27.08% (ARB) of the maximum recommended. The main reasons for the therapy were as follows: hypertension (39.62%), nephroprotection/proteinuria (39.62%), and polyglobulia (28.3%). The composite cardiorenal endpoint was reached by 6 (11.32%) and 7 (13.21%) patients in RAS(+) and RAS(-) group, respectively. There were no differences in changes of creatinine, potassium serum level, or estimated glomerular filtration rate between RAS(+) and RAS(-) patients in the early period after RAS blockade commencement.

CONCLUSION

Agents inhibiting the RAS system neither improved nor deteriorated patients and graft survival in RTRs.

Effect of renin-angiotensin system inhibitors on survival in kidney transplant recipients: A systematic review and meta-analysis

Renin-angiotensin system inhibitors, specifically angiotensin II converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB), have confirmed renoprotective benefits in patients with proteinuria and hypertension. However, it remains controversial whether these agents are beneficial to kidney recipients. We conducted this meta-analysis to evaluate the effects of ACEI/ARB treatment on patient and allograft survival after kidney transplant. The PubMed, Embase and Cochrane Library databases were searched for eligible articles from before May 2016, and we included 24 articles (9 randomised controlled trials [RCTs] and 15 cohort studies with 54,096 patients), in which patient or graft survival was compared between an ACEI/ARB treatment arm and a control arm. Pooled results showed that ACEI/ARB was associated with decreased risks of patient death (relative risk [RR] = 0.64; 95% confidence interval [CI]:0.49-0.84) and graft loss (RR = 0.59; 95%CI:0.47-0.74). Subgroup analysis of the cohorts revealed significantly reduced patient death (RR = 0.61; 95%CI:0.50-0.74) and graft loss (RR = 0.58; 95%CI:0.46-0.73), but this was not seen in RCTs (patient survival: RR = 0.84, 95%CI:0.39-1.81; graft survival: RR = 0.70, 95%CI:0.17-2.79). Significantly less graft loss was noted among patients with biopsy-proved chronic allograft nephropathy (CAN) (RR = 0.26, 95%CI:0.16-0.44). Furthermore, the benefit of ACEI/ARB on patient survival (RR = 0.62; 95%CI:0.47-0.83) and graft survival (RR = 0.58, 95%CI:0.47-0.71) was limited to those with ≥3years' follow-up. ACEI/ARB decreased proteinuria (P < 0.001) and lowered haemoglobin (P = 0.002), but the haemoglobin change requires no additional treatment (from 119-131 g/L to 107-123 g/L). We therefore concluded that ACEI/ARB treatment may reduce patient death and graft loss, but additional well-designed prospective studies are needed to validate these findings.

Does Mineralocorticoid Receptor Antagonism Prevent Calcineurin Inhibitor-Induced Nephrotoxicity?

Calcineurin inhibitors have markedly reduced acute rejection rates in renal transplantation, thus significantly improved short-term outcome. The beneficial effects are, however, tampered by acute and chronic nephrotoxicity leading to interstitial fibrosis and tubular atrophy, which impairs long-term allograft survival. The mineralocorticoid hormone aldosterone induces fibrosis in numerous organs, including the kidney. Evidence from animal models suggests a beneficial effect of aldosterone antagonism in reducing calcineurin inhibitor-induced nephrotoxicity. This review summarizes current evidence of mineralocorticoid receptor antagonism in animal models of calcineurin inhibitor-induced nephrotoxicity and the results from studies of mineralocorticoid antagonism in renal transplant patients.

Hypertension in the Kidney Transplant Recipient: Overview of Pathogenesis, Clinical Assessment, and Treatment

Cardiovascular disease is the leading cause of death in patients with chronic renal disease and the most common cause of death and allograft loss among kidney transplant recipients. Transplant patients often have multiple cardiovascular risk factors antedating transplantation. Among the most prominent is hypertension (HTN), which affects at least 90% of transplant patients. Uncontrolled HTN is an independent risk factor for allograft loss. The etiology of HTN in transplant recipients is complex and multifactorial, including the use of essential immunosuppressive medications. Post-transplant HTN management requires a systematic and individualized approach with nonpharmacologic and pharmacologic therapies. There is no single ideal agent or treatment algorithm. Patients should regularly monitor and record their blood pressure at home. Often, multiple antihypertensive drugs are needed to achieve a goal blood pressure of 120-140/70-90 mm Hg. As transplant recipients commonly must take 8 to 12 different medications daily, adherence must be continually encouraged and monitored. Special attention must be paid to potential drug side effects and drug interactions with immunosuppressive medications.

Chlorthalidone Versus Amlodipine for Hypertension in Kidney Transplant Recipients Treated With Tacrolimus: A Randomized Crossover Trial

BACKGROUND

Chlorthalidone is a very effective antihypertensive drug, but it has not been studied prospectively in kidney transplant recipients with hypertension. Recent data indicate that calcineurin inhibitors activate the thiazide-sensitive sodium chloride cotransporter, providing further rationale to test thiazides in this population.

STUDY DESIGN

Randomized noninferiority crossover trial (noninferiority margin, -2.8mmHg).

SETTING & PARTICIPANTS

Hypertensive kidney transplant recipients using tacrolimus (median duration, 2.4 years after transplantation; mean estimated glomerular filtration rate, 63±27 [SD] mL/min/1.73m²; mean systolic blood pressure [SBP], 151±12mmHg).

INTERVENTION

Amlodipine (5-10mg) and chlorthalidone (12.5-25mg) for 8 weeks (separated by 2-week washout).

OUTCOMES

Average daytime (9 am to 9 pm) ambulatory SBP.

MEASUREMENTS

Blood pressure and laboratory parameters.

RESULTS

88 patients underwent ambulatory blood pressure monitoring, of whom 49 (56%) with average daytime SBP>140mmHg were enrolled. 41 patients completed the study. Amlodipine and chlorthalidone both reduced ambulatory SBP after 8 weeks (mean changes of 150±12 to 137±12 [SD] vs 151±12 to 141±13mmHg; effect size, -4.2 [95% CI, -7.3 to 1.1] mmHg). Despite these similar blood pressure responses, chlorthalidone reduced proteinuria by 30% (effect size, -65 [95% CI, -108 to -35] mg/g) and also reduced physician-assessed peripheral edema (22% to 10%; P<0.05 for both). In contrast, chlorthalidone temporarily reduced kidney function and increased both serum uric acid and glycated hemoglobin levels.

LIMITATIONS

Open-label design, short follow-up, per-protocol analysis.

CONCLUSIONS

Chlorthalidone is an antihypertensive drug equally effective as amlodipine after kidney transplantation.

The Effect of Renin-angiotensin System Inhibitors on Kidney Allograft Survival: A Systematic Review and Meta-analysis

Background:

The use of renin-angiotensin system (RAS) inhibitors in patients with chronic kidney disease, and especially in diabetic kidney disease, has been shown to provide renoprotective effects and slow progression to end-stage renal disease. However, this protective effect in kidney transplant patient populations is unclear.

Aim:

The objective of this systematic review and meta-analysis was to evaluate the effect of RAS inhibitors on kidney allograft survival.

Materials and Methods:

A literature search for randomized controlled trials (RCTs) was performed from inception through February 2016. Studies that reported relative risks or hazard ratios comparing the risks of renal graft loss in renal transplant recipients who received RAS inhibitors vs. controls were included. Pooled risk ratios (RRs) and 95% confidence intervals (CIs) were calculated using a random-effect, generic inverse variance method.

Results:

Five studies (3 RCTs and 2 cohort studies) with 20024 kidney transplant patients were included in the meta-analysis. Pooled RR of allograft failure in recipients who received RAS inhibitors was 0.73 (95% CI: 0.45–1.21). When meta-analysis was limited only to RCTs, the pooled RR of allograft failure in patients using RAS inhibitors was 0.59 (95%: CI 0.20–1.69). The risk for mortality (RR: 1.13 [95% CI: 0.62–2.07]) in patients using RAS inhibitors compared to controls was not significantly reduced.

Conclusion:

This meta-analysis demonstrated insignificant reduced risks of renal graft loss among renal transplant recipients who received RAS inhibitors. Future studies assessing the potential benefits of RAS inhibitors on allograft survival in specific kidney transplant patient populations are needed.

Managing Cardiovascular Risk in the Post Solid Organ Transplant Recipient

Solid organ transplantation is an effective treatment for patients with end-stage organ disease. The prevalence of cardiovascular diseases (CVD) has increased in recipients. CVD remains a leading cause of mortality among recipients with functioning grafts. The pathophysiology of CVD recipients is a complex interplay between preexisting risk factors, metabolic sequelae of immunosuppressive agents, infection, and rejection. Risk modification must be weighed against the risk of mortality owing to rejection or infection. Aggressive risk stratification and modification before and after transplantation and tailoring immunosuppressive regimens are essential to prevent complications and improve short-term and long-term mortality and graft survival.

Ramipril versus placebo in kidney transplant patients with proteinuria: a multicentre, double-blind, randomised controlled trial

BACKGROUND

Angiotensin-converting enzyme inhibitors have been shown to reduce the risk of end-stage renal disease and death in non-transplant patients with proteinuria. We examined whether ramipril would have a similar beneficial effect on important clinical outcomes in kidney transplant recipients with proteinuria.

METHODS

In this double-blind, placebo-controlled, randomised trial, conducted at 14 centres in Canada and New Zealand, we enrolled adult renal transplant recipients at least 3-months post-transplant with an estimated glomerular filtration rate (GFR) of 20 mL/min/1·73m(2) or greater and proteinuria 0·2 g per day or greater and randomly assigned them to receive either ramipril (5 mg orally twice daily) or placebo for up to 4 years. Patients completing the final 4-year study visit were invited to participate in a trial extension phase. Treatment was assigned by centrally generated randomisation with permuted variable blocks of 2 and 4, stratified by centre and estimated GFR (above or below 40 mL/min/1·73 m(2)). The primary outcome was a composite consisting of doubling of serum creatinine, end-stage renal disease, or death in the intention-to-treat population. The principal secondary outcome was the change in measured GFR. We ascertained whether any component of the primary outcome had occurred at each study visit (1 month and 6 months post-randomisation, then every 6 months thereafter). This trial is registered with ISRCTN, number 78129473.

FINDINGS

Between Aug 23, 2006, and March 28, 2012, 213 patients were randomised. 109 were allocated to placebo and 104 were allocated to ramipril, of whom 109 patients in the placebo group and 103 patients in the ramipril group were analysed and the trial is now complete. The intention to treat population (placebo n=109, ramipril n=103) was used for the primary analysis and the trial extension phase analysis. The primary outcome occurred in 19 (17%) of 109 patients in the placebo group and 14 (14%) of 103 patients in the ramipril group (hazard ratio [HR] 0·76 [95% CI 0·38-1·51]; absolute risk difference -3·8% [95% CI -13·6 to 6·1]). With extended follow-up (mean 48 months), the primary outcome occurred in 27 patients (25%) in the placebo group and 25 (24%) patients in the ramipril group (HR 0·96 [95% CI 0·55-1·65]); absolute risk difference: -0·5% (95% CI -12·0 to 11·1). There was no significant difference in the rate of measured GFR decline between the two groups (mean difference per 6-month interval: -0·16 mL/min/1·73m(2) (SE 0·24); p=0·49). 14 (14%) of patients died in the ramipril group and 11 (10%) in the placebo group, but the difference between groups was not statistically significant (HR 1·45 [95% CI 0·66 to 3·21]). Adverse events were more common in the ramipril group (39 [38%]) than in the placebo group (24 [22%]; p=0·02).

INTERPRETATION

Treatment with ramipril compared with placebo did not lead to a significant reduction in doubling of serum creatinine, end-stage renal disease, or death in kidney transplant recipients with proteinuria. These results do not support the use of angiotensin-converting enzyme inhibitors with the goal of improving clinical outcomes in this population.

FUNDING

Canadian Institutes of Health Research.

Impact of recipient ACE I/D genotype on kidney function in renal transplant patients: a meta-analysis of cross-sectional and longitudinal studies

Aim: To perform a systematic review and meta-analysis of studies evaluating the influence of recipient angiotensin-converting enzyme insertion/deletion (ACE I/D) polymorphism on kidney function in renal transplant recipients. Materials & methods: A comprehensive search was performed through PubMed, Web of Knowledge and Cochrane databases up to December 2014. The methodological quality of identified studies was assessed using the MINORS criteria. Results: A total of 15 studies evaluating the role of recipient ACE I/D were included in the meta-analysis. In overall analyzes and subsequent subgroup and sensitivity analyzes, no evidence emerged of an effect of ACE I/D on serum creatinine levels, creatinine clearance or glomerular filtration rate. Conclusion: Although further investigation is still needed to determine the role of donor ACE genotype, recipient ACE I/D does not play a significant role on kidney function in renal transplant patients.

Effect of left atrial and ventricular abnormalities on renal transplant recipient outcome-a single-center study

Background

Premature cardiovascular (CV) death is the commonest cause of death in renal transplant recipients. Abnormalities of left ventricular (LV) structure (collectively termed uremic cardiomyopathy) and left atrial (LA) dilation, a marker of fluid status and diastolic function, are risk factors for reduced survival in patients with end stage renal disease (ESRD). In the present analysis, we studied the impact of pre-transplant LA and LV abnormalities on survival after successful renal transplantation (RT).

Methods

One hundred nineteen renal transplant recipients (first transplant, deceased donors) underwent cardiovascular MRI (CMR) as part of CV screening prior to inclusion on the waiting list. Data regarding transplant function and patient survival after transplantation were collected.

Results

Median post-transplant follow-up was 4.3 years (interquartile range (IQR) 1.9, 6.2). During the post-transplant period, 13 patients returned to dialysis after graft failure and 23 patients died with a functioning graft. Survival analyses, censoring for patients returning to dialysis, showed that pre-transplant LV hypertrophy and elevated LA volume were significantly associated with reduced survival after transplantation. Multivariate Cox regression analyses demonstrated that longer waiting time, poorer transplant function, presence of LV hypertrophy and higher LA volume on screening CMR and female sex were independent predictors of death in patients with a functioning transplant.

Conclusions

Presence of LVH and higher LA volume are significant, independent predictors of death in patients who are wait-listed and proceed with renal transplantation.

Cardiovascular morbidity and mortality after kidney transplantation

Kidney transplantation is the optimal treatment for patients with end stage renal disease (ESRD) who would otherwise require dialysis. Patients with ESRD are at dramatically increased cardiovascular (CV) risk compared with the general population. As well as improving quality of life, successful transplantation accords major benefits by reducing CV risk in these patients. Worldwide, cardiovascular disease remains the leading cause of death with a functioning graft and therefore is a leading cause of graft failure. This review focuses on the mechanisms underpinning excess CV morbidity and mortality and current evidence for improving CV risk in kidney transplant recipients. Conventional CV risk factors such as hypertension, diabetes mellitus, dyslipidaemia and pre-existing ischaemic heart disease are all highly prevalent in this group. In addition, kidney transplant recipients exhibit a number of risk factors associated with pre-existing renal disease. Furthermore, complications specific to transplantation may ensue including reduced graft function, side effects of immunosuppression and post-transplantation diabetes mellitus. Strategies to improve CV outcomes post-transplantation may include pharmacological intervention including lipid-lowering or antihypertensive therapy, optimization of graft function, lifestyle intervention and personalizing immunosuppression to the individual patients risk profile.

Calcineurin inhibitors and hypertension: a role for pharmacogenetics?

Hypertension is a common side effect of calcineurin inhibitors (CNIs), which are drugs used to prevent rejection after transplantation. Hypertension after kidney transplantation has been associated with earlier graft failure and higher cardiovascular mortality in the recipient. Recent data indicate that enzymes and transporters involved in CNI pharmacokinetics and pharmacodynamics, including CYP3A5, ABCB1, WNK4 and SPAK, are also associated with salt-sensitive hypertension. These insights raise the question whether polymorphisms in the genes encoding these proteins increase the risk of CNI-induced hypertension. Predicting who is at risk for CNI-induced hypertension may be useful for when selecting specific interventions, including dietary salt restriction, thiazide diuretics or a CNI-free immunosuppressive regimen. This review aims to explore the pharmacogenetics of CNI-induced hypertension, highlighting the knowns and unknowns.

Hypertension after kidney transplantation: a pathophysiologic approach

Post-transplant hypertension is associated with decreased graft and patient survival and cardiovascular morbidity. Unfortunately, post-transplant hypertension is often poorly controlled. Important risk factors include immunosuppressive medications, complications of the transplant surgery, delayed graft function, rejection, and donor and recipient risk factors. The effects of immunosuppressive medications are multifactorial including increased vascular and sympathetic tone and salt and fluid retention. The immunosuppressive agents most commonly associated with hypertension are glucocorticoids and calcineurin inhibitors. Drug therapy for hypertension should be based on the comorbidities and pathophysiology. Evidence-based approaches to defining and treating hypertension in renal transplant recipients are predominantly extrapolated from large-scale studies performed in the general population. Thus, there continues to be a need for larger studies examining the pathophysiology, diagnosis and treatment of hypertension in renal transplant recipients.

Cardiovascular death in kidney recipients treated with renin-angiotensin system blockers

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) are widely prescribed after kidney transplantation, but evidence for an improvement in outcomes is mixed. A recent trial demonstrated a significantly lower incidence of major cardiovascular events in ACEI-treated recipients.

METHODS

Collaborative Transplant Study data on cardiovascular death during years 2 to 10 after kidney transplantation in patients with a functioning graft were analyzed according to whether ACEI/ARB or other antihypertensive therapy (excluding diuretics) was administered at year 1.

RESULTS

Of 39,251 transplants analyzed, 15,250 (38.9%) received ACEI/ARB and 24,001 (61.1%) received other antihypertensive therapy at year 1 after transplantation. The mean duration of follow-up was 5.8 years. During years 2 to 10 after transplantation, cardiovascular death occurred in 918 patients (cumulative incidence=4.7%) with a functioning graft. The rate of cardiovascular death was similar in patients who received ACEI/ARB therapy or other antihypertensive treatment overall and in subpopulations of patients who were considered by the transplant center to be at an increased cardiovascular risk, had no pretransplant risk factors, were aged 60 years and older, were treated for diabetes at year 1, or had serum creatinine of 130 μmol/L or higher at year 1. Multivariable Cox regression analysis confirmed that treatment with ACEI/ARB did not confer a beneficial effect beyond that conferred by other antihypertensive treatments on the cumulative incidence of cardiovascular death during years 2 to 10 (hazard ratio=1.1, P=0.24).

CONCLUSIONS

This large-scale retrospective analysis of prospectively collected data shows that the rate of cardiovascular death in kidney transplant recipients receiving ACEI/ARB or other antihypertensive medications is virtually identical.

Cardiovascular complications after transplantation: treatment options in solid organ recipients

Premature cardiovascular disease is the commonest cause of death in solid organ transplant recipients, with coronary artery disease, sudden cardiac death and heart failure being highly prevalent. There are unique factors leading to CV disease in organ transplant recipients that include underlying comorbidities, and metabolic effects of immunosuppression. As a consequence management strategies developed in the general population may have limited benefit. In this review, we will focus on renal transplantation, where most research has been carried out and, despite incomplete understanding of the disease process, the incidence of cardiovascular disease appears to be falling.