Effect of sirolimus on left ventricular hypertrophy in kidney transplant recipients: a 1-year nonrandomized controlled trial

Effects of two immunosuppression regimens on T-lymphocyte subsets in elderly kidney transplant recipients

Background

Despite the growing number of elderly kidney transplant (Ktx) recipients, few studies have examined the effects of immunosuppression on their lymphocyte profiles.

Methods

We evaluated the early conversion from mycophenolate sodium (MPS) to everolimus (EVL) after rabbit antithymocyte globulin (rATG) 2 mg/kg induction in elderly kidney recipients. Three groups of KTx patients were compared: (a) Young (n=20, 36 ± 7 y) receiving standard immunosuppression (Group A1) (prednisone, tacrolimus, and MPS), (b) Elderly (n=35, 65 ± 3 y) receiving standard immunosuppression (Group B1), and (c) Elderly (n=16, 65 ± 3 y) with early (mean 30 d) conversion from MPS to EVL (Group B2). Naive, memory, and regulatory peripheral blood TCD4+ lymphocytes were quantified at 0, 30, and 365 d.

Results

Results are reported as [mean(p25-p75)]. Young recipients had higher lymphocyte counts at baseline [2,100(1,630-2,400) vs. 1,310 (1,000-1,600)/mm3, p<0.0001] maintained higher counts within 365 d [1,850(1,590-2,120) vs. 1,130(460-1,325)/mm3, p=0.018 and vs. 1,410(805-1,895)/mm3, p=0.268]. Elderly recipients showed a decrease in lymphocytes within 30 d [1,310(1,000-1,600) vs. 910(700-1,198)/mm3, p=0.0012] with recovery within 365 d. The same pattern was observed in total lymphocytes and TCD4+ counts. Rabbit antithymocyte globulin induced a reduction in central memory T-cell percentages at 30 d in both young recipients [6.2(3.77-10.8) vs. 5.32(2.49-7.28)% of CD4+, p=0.036] and in elderly recipients [8.17(5.28-12.88) vs. 6.74(4.36-11)% of CD4+, p=0.05] on standard immunosuppression, returning to baseline at 365 d in elderly recipients but not in young recipients. Regulatory T CD39+ cells (Treg) percentages decreased at 30 d in elderly recipients [2.1(1.23-3.51) vs. 1.69(0.8-2.66)% of CD4+, p=0.0028] and in young recipients [1.29(0.45-1.85) vs. 0.84(0.18-1.82)% of CD4+, p=0.0038], returning to baseline at 365 d in elderly recipients [2.1(1.23-3.51) vs. 2.042(0.88-2.42)% of CD4+], but not in young recipients [1.29(0.45-1.85) vs. 0.86(0.7-1.34) % of CD4+]. The elderly everolimus conversion group did not show significant changes in cell profile over time or compared to elderly recipients with standard immunosuppression.

Conclusion

Aging favored the maintenance of Treg during the late transplantation period despite ongoing immunosuppression. Lymphocyte depletion due to rATG was more prominent in elderly recipients and affected memory subsets with a temporary reduction in central memory T cells. However, conversion to everolimus did not impact Treg profile. Reducing the dose of rATG in elderly recipients seems necessary for the expected lymphocyte changes with EVL to occur.

Clinical trial registration

nEverOld Trial, identifier NTC01631058.

Advancing Treatments for Feline Hypertrophic Cardiomyopathy: The Role of Animal Models and Targeted Therapeutics

Feline HCM is the most common cardiovascular disease in cats, leading to devastating outcomes, including congestive heart failure (CHF), arterial thromboembolism (ATE), and sudden death. Evidence demonstrating long-term survival benefit with currently available therapies is lacking. Therefore, it is imperative to explore intricate genetic and molecular pathways that drive HCM pathophysiology to inspire the development of novel therapeutics. Several clinical trials exploring new drug therapies are currently underway, including those investigating small molecule inhibitors and rapamycin. This article outlines the key work performed using cellular and animal models that has led to and continues to guide the development of new innovative therapeutic strategies.

Multi-Omic, Histopathologic, and Clinicopathologic Effects of Once-Weekly Oral Rapamycin in a Naturally Occurring Feline Model of Hypertrophic Cardiomyopathy: A Pilot Study

Hypertrophic cardiomyopathy (HCM) remains the single most common cardiomyopathy in cats, with a staggering prevalence as high as 15%. To date, little to no direct therapeutical intervention for HCM exists for veterinary patients. A previous study aimed to evaluate the effects of delayed-release (DR) rapamycin dosing in a client-owned population of subclinical, non-obstructive, HCM-affected cats and reported that the drug was well tolerated and resulted in beneficial LV remodeling. However, the precise effects of rapamycin in the hypertrophied myocardium remain unknown. Using a feline research colony with naturally occurring hereditary HCM (n = 9), we embarked on the first-ever pilot study to examine the tissue-, urine-, and plasma-level proteomic and tissue-level transcriptomic effects of an intermittent low dose (0.15 mg/kg) and high dose (0.30 mg/kg) of DR oral rapamycin once weekly. Rapamycin remained safe and well tolerated in cats receiving both doses for eight weeks. Following repeated weekly dosing, transcriptomic differences between the low- and high-dose groups support dose-responsive suppressive effects on myocardial hypertrophy and stimulatory effects on autophagy. Differences in the myocardial proteome between treated and control cats suggest potential anti-coagulant/-thrombotic, cellular remodeling, and metabolic effects of the drug. The results of this study closely recapitulate what is observed in the human literature, and the use of rapamycin in the clinical setting as the first therapeutic agent with disease-modifying effects on HCM remains promising. The results of this study establish the need for future validation efforts that investigate the fine-scale relationship between rapamycin treatment and the most compelling gene expression and protein abundance differences reported here.

Cardiovascular Outcomes in De Novo Kidney Transplant Recipients Receiving Everolimus and Reduced Calcineurin Inhibitor or Standard Triple Therapy: 24-month Post Hoc Analysis From TRANSFORM Study

BACKGROUND

The comparative impact of everolimus (EVR)-based regimens versus standard of care (mycophenolic acid+standard calcineurin inhibitor [MPA+sCNI]) on cardiovascular outcomes in de novo kidney transplant recipients (KTRs) is poorly understood. The incidence of major adverse cardiac events (MACEs) in KTRs receiving EVR+reduced CNI (rCNI) or MPA+sCNI from the TRANSplant eFficacy and safety Outcomes with an eveRolimus-based regiMen study was evaluated.

METHODS

The incidence of MACE was determined for all randomized patients receiving at least 1 dose of the study drug. Factors associated with MACEs were determined by logistic regression. Risk of MACE out to 3 y post-study was calculated using the Patient Outcome in Renal Transplantation equation.

RESULTS

MACE occurred in 81 of 1014 (8.0%; EVR+rCNI) versus 89 of 1012 (8.8%; MPA+sCNI) KTRs (risk ratio, 0.91 [95% confidence interval [CI], 0.68-1.21]). The incidence of circulatory death, myocardial infarction, revascularization, or angina was similar between the arms. Incidence of MACE was similar between EVR+rCNI and MPA+sCNI arms with a higher incidence in prespecified risk groups: older age, pretransplant diabetes (15.1% versus 15.9%), statin use (8.5% versus 10.8%), and low estimated glomerular filtration rate (Month 2 estimated glomerular filtration rate <30 versus >60 mL/min/1.73 m 2 ; odds ratio, 2.23 [95% CI, 1.02-4.86]; P = 0.044), respectively. Predicted risk of MACE within 3 y of follow-up did not differ between the treatment arms.

CONCLUSIONS

Cardiovascular morbidity and mortality were similar between de novo KTRs receiving EVR+rCNI and MPA+sCNI. EVR+rCNI is a viable alternative to the current standard of care in KTRs.

Regression of cardiac hypertrophy in health and disease: mechanisms and therapeutic potential

Left ventricular hypertrophy is a leading risk factor for cardiovascular morbidity and mortality. Although reverse ventricular remodelling was long thought to be irreversible, evidence from the past three decades indicates that this process is possible with many existing heart disease therapies. The regression of pathological hypertrophy is associated with improved cardiac function, quality of life and long-term health outcomes. However, less than 50% of patients respond favourably to most therapies, and the reversibility of remodelling is influenced by many factors, including age, sex, BMI and disease aetiology. Cardiac hypertrophy also occurs in physiological settings, including pregnancy and exercise, although in these cases, hypertrophy is associated with normal or improved ventricular function and is completely reversible postpartum or with cessation of training. Studies over the past decade have identified the molecular features of hypertrophy regression in health and disease settings, which include modulation of protein synthesis, microRNAs, metabolism and protein degradation pathways. In this Review, we summarize the evidence for hypertrophy regression in patients with current first-line pharmacological and surgical interventions. We further discuss the molecular features of reverse remodelling identified in cell and animal models, highlighting remaining knowledge gaps and the essential questions for future investigation towards the goal of designing specific therapies to promote regression of pathological hypertrophy.

The impact of mTOR inhibitors in the regression of left ventricular hypertrophy in elderly kidney transplant recipients

End-stage kidney disease is frequently associated with left ventricular hypertrophy (LVH), a condition more prevalent in the elderly, that may increase mortality after renal transplantation (RTx). Previous studies suggested that mTOR inhibitors (mTORi) can improve LVH, but this has never been tested in elderly kidney transplant recipients. In this prospective randomized clinical trial, we analyzed the impact of Everolimus (EVL) on the reversal of LVH after RTx in elderly recipients (≥60 years) submitted to different immunosuppressive regimens: EVL/lowTacrolimus (EVL group, n = 53) or mycophenolate sodium/regularTacrolimus (MPS group, n = 47). Patients performed echocardiograms (Echo) up to 3 months after RTx and then annually. At baseline, mean age was 65±3 years in both groups and LVH was observed in 63.6% of patients in EVL group and in 61.8% of MPS group. Last Echo was performed at mean time of 47 and 49 months after RTx in EVL and MPS groups, respectively (P = .34). LVH regression was observed in 23.8% (EVL group) and 19% (MPS group) of patients (P = 1.00). Mean eGFR, blood pressure, and use of RAS blockers were similar between groups throughout follow-up. EVL did not improve LVH in this cohort, and this lack of benefit may be attributed to concomitant use of TAC, senescence, or both.

Cardiovascular protection associated with cilostazol, colchicine and target of rapamycin inhibitors

ABSTRACT

An alteration in extracellular matrix production by vascular smooth muscle cells is a crucial event in the pathogenesis of vascular diseases such as aging-related, atherosclerosis and allograft vasculopathy. The human target of rapamycin (TOR) is involved in the synthesis of extracellular matrix by vascular smooth muscle cells. TOR inhibitors reduce arterial stiffness, blood pressure, and left ventricle hypertrophy and decrease cardiovascular risk in kidney graft recipients and patients with coronary artery disease and heart allograft vasculopathy. Other drugs that modulate extracellular matrix production such as cilostazol and colchicine have also demonstrated a beneficial cardiovascular effect. Clinical studies have consistently shown that cilostazol confers cardiovascular protection in peripheral vascular disease, coronary artery disease, and cerebrovascular disease. In patients with type 2 diabetes, cilostazol prevents the progression of subclinical coronary atherosclerosis. Colchicine reduces arterial stiffness in patients with Familial Mediterranean Fever and patients with coronary artery disease. Pathophysiological mechanisms underlying the cardioprotective effect of these drugs may be related to interactions between the cytoskeleton, TOR signaling and cyclic AMP synthesis that remain to be fully elucidated. Adult vascular smooth muscle cells exhibit a contractile phenotype and produce little extracellular matrix. Conditions that upregulate extracellular matrix synthesis induce a phenotypic switch toward a synthetic phenotype. TOR inhibition with rapamycin reduces extracellular matrix production by promoting the change to the contractile phenotype. Cilostazol increases the cytosolic level of cyclic AMP, which in turn leads to a reduction in extracellular matrix synthesis. Colchicine is a microtubule-destabilizing agent that may enhance the synthesis of cyclic AMP.

The Global Longitudinal Strain in Renal Transplant Recipients and Immunosuppressive Regimen

BACKGROUND

Echocardiographic global longitudinal strain (GLS) has recently been considered as a more effective assessment than the ejection fraction (EF) in detecting subtle changes of left ventricular (LV) systolic function. The aim of the study is to compare GLS in renal transplant recipients (RTrs) with preserved LVEF, depending on the recipient's immunosuppressive regimen. The impaired GLS was considered to be > -18%.

METHODS

A total of 84 RTrs were divided into 2 groups depending on immunosuppressive regimen: group 1, which included 32 patients (aged 62.3 ± 7.5) receiving mammalian target of rapamycin inhibitors, and group 2, which included 52 patients (aged 58.9 ± 13.9 treated with calcineurin inhibitors. In all patients, echocardiography was performed, including calculation of GLS, and laboratory and clinical markers of cardiovascular risk were assessed.

RESULTS

The frequency of men was significantly higher in group 1 (P = .01). There were no differences between the groups in age, body mass index, frequency of diabetes, hypertension, time of hemodialysis (HD) before kidney transplantation (KTx), time after KTx, concentration of cholesterol and creatinine, echocardiographic linear parameters, and LV mass. The estimated glomerular filtration rate and triglyceride concentration were significantly higher in group 1. The mean value of GLS was similar in both groups (-19.8 [-3.5] vs -18.9 [-3.0]; P = .22). The multivariate logistic regression analysis revealed that duration of HD > 26 months is associated with GLS ≥ -18% (odds ratio 2.95, 95% CI 1.08-7.99, P = .03) CONCLUSIONS: The frequency of impaired GLS in RTr was similar regardless of the type of the immunosuppressive regimen. The impaired GLS was associated with duration of HD before KTx.

Effect of sirolimus on carotid atherosclerosis in kidney transplant recipients: data derived from a prospective randomized controlled trial

Background

In animal models, the mammalian target of rapamycin inhibitors (mTORIs) may prevent atherogenesis by the regulation of homeostasis of cholesterol and by a reduced inflammatory response. The aim of this study is to compare the carotid intima–media thickness (cIMT) between de novo tacrolimus/mycophenolate and tacrolimus/sirolimus at low doses. The cIMT is considered a surrogate marker of atherosclerosis.

Methods

We evaluated cIMT at baseline and at 6 and 12 months after kidney transplantation in a database derived from a previously published trial. That trial had prospectively randomly assigned kidney transplant recipients older than 60 years of age to one of two groups: tacrolimus/sirolimus (n = 21) or tacrolimus/mycophenolate (n = 23). The cIMT was evaluated by using ultrasound in the common carotid artery wall on both sides.

Results

The total and high-density lipoprotein cholesterol levels were higher in the sirolimus group at 6 and 12 months. The cIMT decreased over time at 6 and 12 months in the sirolimus group (P = 0.012); this decrease continued to be significant in a model adjusted for age, sex, presence of diabetes, statin use and smoking.

Conclusions

The use of sirolimus plus tacrolimus de novo in kidney transplantation is associated with a reduction in cIMT after 12 months, a decrease more significant than seen with the combination of mycophenolate plus tacrolimus. This suggests a class effect of mTORI in the prevention of atherosclerosis.

mTOR Inhibition and Cardiovascular Diseases: Cardiac Hypertrophy

Left ventricular hypertrophy (LVH) is highly prevalent in kidney transplant recipients and is associated with poor clinical outcome. Immunosuppressive agents might affect LVH behavior after kidney transplantation. This review is an appraisal of available data regarding LVH in renal transplantation and especially of studies that evaluated LVH response to treatment. In particular, the role of mammalian target of rapamycin inhibitors adopted as immunosuppressive agents in kidney transplantation is reviewed in the light of recent studies that have shown LVH regression induced by this class of medications in kidney transplant recipients with posttransplant cardiomyopathy. Larger randomized controlled trials are warranted to confirm these findings and to ascertain the impact of such LVH regression on hard endpoints in kidney transplant recipients with posttransplant cardiomyopathy.

Biomarkers of cardio-renal syndrome in uremic myocardiopathy animal model

Introduction:

Cardio-renal syndrome subtype 4 (CRS4) is a condition of primary chronic kidney disease that leads to reduction of cardiac function, ventricular hypertrophy, and risk of cardiovascular events. Objective: Our aim was to understand the mechanisms involved on the onset of CRS4.

Methods:

We used the nephrectomy 5/6 (CKD) animal model and compared to control (SHAM). Serum biomarkers were analyzed at baseline, 4, and 8 weeks. After euthanasia, histology and immunohistochemistry were performed in the myocardium.

Results:

Troponin I (TnI) was increased at 4 weeks (W) and 8W, but nt-proBNP showed no difference. The greater diameter of cardiomyocytes indicated left ventricular hypertrophy and the highest levels of TNF-α were found at 4W declining in 8W while fibrosis was more intense in 8W. Angiotensin expression showed an increase at 8W.

Conclusions:

TnI seems to reflect cardiac injury as a consequence of the CKD however nt-proBNP did not change because it reflects stretching. TNF-α characterized an inflammatory peak and fibrosis increased over time in a process connecting heart and kidneys. The angiotensin showed increased activity of the renin-angiotensin axis and corroborates the hypothesis that the inflammatory process and its involvement with CRS4. Therefore, this animal study reinforces the need for renin-angiotensin blockade strategies and the control of CKD to avoid the development of CRS4.

Cardiovascular Parameters to 2 years After Kidney Transplantation Following Early Switch to Everolimus Without Calcineurin Inhibitor Therapy: An Analysis of the Randomized ELEVATE Study

BACKGROUND

Mammalian target of rapamycin inhibitors may confer cardioprotective advantages, but clinical data are limited.

METHODS

In the open-label ELEVATE trial, kidney transplant patients were randomized at 10 to 14 weeks after transplant to convert from calcineurin inhibitor (CNI) to everolimus or remain on standard CNI therapy. Prespecified end points included left ventricular mass index and, in a subpopulation of patients, arterial stiffness as measured by pulse wave velocity.

RESULTS

The mean change in left ventricular mass index from randomization was similar with everolimus versus CNI (month 24, -4.37 g/m versus -5.26 g/m; mean difference, 0.89 [p = 0.392]). At month 24, left ventricular hypertrophy was present in 41.7% versus 37.7% of everolimus and CNI patients, respectively. Mean pulse wave velocity remained stable with both everolimus (mean change from randomization to month 12, -0.24 m/s; month 24, -0.03 m/s) and CNI (month 12, 0.11 m/s; month 24, 0.16 m/s). The change in mean ambulatory nighttime blood pressure from randomization showed a benefit for diastolic pressure at month 12 (P = 0.039) but not at month 24. Major adverse cardiac events occurred in 1.1% and 4.2% of everolimus-treated and CNI-treated patients, respectively, by month 12 (P = 0.018) and 2.3% (8/353) and 4.5% by month 24 (P = 0.145).

CONCLUSIONS

Overall, these data do not suggest a clinically relevant effect on cardiac end points after early conversion from CNI to a CNI-free everolimus-based regimen.

Sirolimus Associated with Tacrolimus at Low Doses in Elderly Kidney Transplant Patients: A Prospective Randomized Controlled Trial

OBJECTIVES

There is no consensus on the best immunosuppressive regimen for elderly renal transplant recipients. The objective of this study was to assess cytomegalovirus infection incidence and kidney transplant outcomes in elderly recipients treated with mammalian target of rapamycin inhibitors sirolimus/ tacrolimus at low doses compared with those receiving tacrolimus/mycophenolate sodium.

MATERIALS AND METHODS

In this single-center prospective randomized study (Trial Registration No. NCT02683291), kidney transplant recipients over 60 years of age were randomly allocated into 2 groups: tacrolimus-sirolimus (21 patients) and tacrolimus-mycophenolate (23 patients). Cytomegalovirus infection rate and patient survival, biopsy-proven acute rejection, and renal function at 12 months were assessed.

RESULTS

Cytomegalovirus infection rate was higher in the mycophenolate group (60.9%) than in the sirolimus group (16.7%; P = .004). The rates of biopsy-proven acute rejection, patient survival, graft survival, and estimated glomerular filtration rate over 12 months did not significantly differ between groups.

CONCLUSIONS

The incidence of cytomegalovirus infection was significantly lower in the sirolimus group. The use of tacrolimus combined with sirolimus in elderly kidney transplant recipients is safe.

Impact of early conversion from cyclosporin to everolimus on left ventricular mass index: A randomized controlled trial

This is an 18-month prospective, randomized controlled trial (RCT) designed to compare the effect of early conversion from cyclosporin to everolimus/mycophenolic acid (E-MPA) between 3 and 4 months post-transplant to cyclosporin/mycophenolic acid (CsA-MPA) on left ventricular mass index (LVMI) at 3 and 18 months post-transplant (primary outcome). Secondary outcomes included estimated glomerular filtration rate (eGFR), viral infection, and adverse events. Twenty-four patients were randomized in a 1:1 ratio to E-MPA or CsA-MPA groups. There were no significant differences in mean (SD) LVMI at 3 (51.6±18.5 vs 53.7±15.7 g/m^2.7 ) and 18 months (52.7±16.3 vs 51.7±16.8 g/m^2.7 ) between CsA-MPA and E-MPA groups. The incidence of viral infections was reduced in E-MPA compared to CsA-MPA treatment groups (8% vs 50%, P=.02), but the incidences of acute rejection, adverse events, and drug discontinuation were similar between groups. There was an overall increase in eGFR with time (0.04 log- mL/min/1.73 m² per 6 months, P=.012) but no significant difference between the two groups across time (0.11 log- mL/min/1.73 m² , P=.311). Immunosuppressive regimen comprising early conversion from cyclosporine to everolimus was not associated with a regression of LVMI, but a lower risk of viral infections was observed.

Renal Allograft Function Is a Risk Factor of Left Ventricular Remodeling After Kidney Transplantation

BACKGROUND

Cardiovascular disease is the leading cause of morbidity and mortality in kidney transplantation (KT) patients. The prevalence of left ventricular hypertrophy increases with the progression of renal insufficiency.

METHODS

We investigated the association between the progression of renal insufficiency and left ventricular hypertrophy after KT. We reviewed KT patients at Seoul National University Hospital from January 1973 to December 2009. The creatinine elevation ratio (CER, the percentage change in the creatinine level from 1 month to 5 years after transplant) was calculated as follows: (creatinine level at 5 years minus creatinine level at 1 month)/creatinine level at 1 month × 100.

RESULTS

The study population was classified into a high-CER group (CER ≥25%) and low-CER group (CER <25%). Mean left ventricular mass index (LVMI) values were 135.7 and 134.7 g/m² before KT and 101.7 and 123.7 g/m² at 5 years after KT in the low-CER and high-CER groups, respectively. The LVMI before or 1 year after KT was not different between the 2 groups, but the LVMI at 5 years post-transplant was higher in the high-CER group than in the low-CER group. The LVMI increased after its initial decrease in the high-CER group, whereas its reduction was maintained in the low-CER group during the 5 years after KT (P = .009, repeated-measures analysis of variance).

CONCLUSIONS

These data suggest that deterioration of renal allograft function is associated with left ventricular remodeling after KT.

Autophagy modulation: a potential therapeutic approach in cardiac hypertrophy

Autophagy is an evolutionarily conserved process used by the cell to degrade cytoplasmic contents for quality control, survival for temporal energy crisis, and catabolism and recycling. Rapidly increasing evidence has revealed an important pathogenic role of altered activity of the autophagosome-lysosome pathway (ALP) in cardiac hypertrophy and heart failure. Although an early study suggested that cardiac autophagy is increased and that this increase is maladaptive to the heart subject to pressure overload, more recent reports have overwhelmingly supported that myocardial ALP insufficiency results from chronic pressure overload and contributes to maladaptive cardiac remodeling and heart failure. This review examines multiple lines of preclinical evidence derived from recent studies regarding the role of autophagic dysfunction in pressure-overloaded hearts, attempts to reconcile the discrepancies, and proposes that resuming or improving ALP flux through coordinated enhancement of both the formation and the removal of autophagosomes would benefit the treatment of cardiac hypertrophy and heart failure resulting from chronic pressure overload.

Antianginal Therapy for Stable Ischemic Heart Disease

Chronic angina pectoris is associated with considerable morbidity and mortality, especially if treated suboptimally. For many patients, aggressive pharmacologic intervention is necessary in order to alleviate anginal symptoms. The optimal treatment of stable ischemic heart disease (SIHD) should be the prevention of angina and ischemia, with the goal of maximizing both quality and quantity of life. In addition to effective risk factor modification with lifestyle changes, intensive pharmacologic secondary prevention is the therapeutic cornerstone in managing patients with SIHD. Current guidelines recommend a multifaceted therapeutic approach with β-blockers as first-line treatment. Another important pharmacologic intervention for managing SIHD is nitrates. Nitrates can provide both relief of acute angina and can be used prophylactically before exposure to known triggers of myocardial ischemia to prevent angina. Additional therapeutic options include calcium channel blockers and ranolazine, an inhibitor of the late inward sodium current, that can be used alone or in addition to nitrates or β-blockers when these agents fail to alleviate symptoms. Ranolazine appears to be particularly effective for patients with microvascular angina and endothelial dysfunction. In addition, certain antianginal therapies are approved in Europe and have been shown to improve symptoms, including ivabradine, nicorandil, and trimetazidine; however, these have yet to be approved in the United States. Ultimately, there are several different medications available to the physician for managing the patient with SIHD having chronic angina, when either used alone or in combination. The purpose of this review is to highlight the most important therapeutic approaches to optimizing contemporary treatment in response to individual patient needs.

Oral sirolimus: A possible treatment for refractory angina pectoris in the elderly

Refractory angina pectoris (RAP) is a clinical problem, frequently encountered in the elderly, associated with high health-care costs. Until recently, the goal of RAP treatment aimed at improving the quality of life (QoL) because it was thought that mortality rates were not different between stable angina pectoris and RAP. Our purpose was at determining whether any mortality rate difference exists and whether any novel therapeutical solution might be translated into clinical practice. We therefore performed a literature review to assess current optimal treatment of RAP patients, including all studies involving the use of oral sirolimus and stents, although no consistent evidence was found for any specific treatment to improve survival, apart from minor QoL amelioration. A large mortality difference was seen between RAP and stable angina pectoris. On the other hand, therapeutic approaches to RAP patients showed frequent complications and several contraindications, depending on the procedure. We propose to inhibit instead of stimulating angiogenesis, by giving oral sirolimus, an immunosuppressive drug, thereby decreasing the atherosclerotic process and its evolution. Sirolimus was shown to decrease left ventricular mass (thus indirectly decreasing myocardial oxygen needs and consumption). It might stop and, in some cases, even enable regression of plaque progression. Sirolimus side effects are mild to moderate and wash-out rapidly at treatment discontinuation. Compared with current therapies sirolimus treatment is more health-care cost efficient. It should be important to design a trial in RAP patients powered to reduce mortality and QoL increase.

Cardiovascular risk factors following renal transplant

Kidney transplantation is the gold-standard treatment for many patients with end-stage renal disease. Renal transplant recipients (RTRs) remain at an increased risk of fatal and non-fatal cardiovascular (CV) events compared to the general population, although rates are lower than those patients on maintenance haemodialysis. Death with a functioning graft is most commonly due to cardiovascular disease (CVD) and therefore this remains an important therapeutic target to prevent graft failure. Conventional CV risk factors such as diabetes, hypertension and renal dysfunction remain a major influence on CVD in RTRs. However it is now recognised that the morbidity and mortality from CVD are not entirely accounted for by these traditional risk-factors. Immunosuppression medications exert a deleterious effect on many of these well-recognised contributors to CVD and are known to exacerbate the probability of developing diabetes, graft dysfunction and hypertension which can all lead on to CVD. Non-traditional CV risk factors such as inflammation and anaemia have been strongly linked to increased CV events in RTRs and should be considered alongside those which are classified as conventional. This review summarises what is known about risk-factors for CVD in RTRs and how, through identification of those which are modifiable, outcomes can be improved. The overall CV risk in RTRs is likely to be multifactorial and a complex interaction between the multiple traditional and non-traditional factors; further studies are required to determine how these may be modified to enhance survival and quality of life in this unique population.

Regression of asymptomatic cardiomyopathy and clinical outcome of renal transplant recipients: a long-term prospective cohort study

BACKGROUND

Asymptomatic left ventricular hypertrophy (LVH) is highly prevalent and associated with an adverse outcome in renal transplant recipients (RTRs). Nonetheless, there are currently no available studies analyzing the effect of LVH regression on solid clinical endpoints in these patients.

METHODS

This study is the prospective observational extension of two randomized controlled trials aimed at assessing the effect of active intervention on post-transplant LVH in RTRs. We evaluated the incidence of a composite of death and any cardiovascular (CV) or renal event in 60 RTRs in whom LVH regression was observed and in 40 whose LVH remained unchanged or worsened.

RESULTS

During an 8.4 ± 3.5-year follow-up, 8 deaths, 18 CV events and 6 renal events occurred in the entire cohort. Multivariable analysis showed that age [hazard ratio (HR) 1.07, 95% confidence interval (CI) 1.03-1.12 each 1 year, P = 0.002] and LVH regression (HR 0.42, 95% CI 0.22-0.87, P = 0.019) were significant predictors of the composite endpoint. Kaplan-Meier estimates showed better survival rates in patients in whom actual LVH regression was achieved (P < 0.001, log-rank test). Age (HR 1.09, 95% CI 1.03-1.15 each 1 year, P = 0.004), better graft function (HR 0.95, 95% CI 0.91-0.99 each 1 mL/min/1.73 m(2) increase in estimated glomerular filtration rate, P = 0.03) and LVH regression (HR 0.41, 95% CI 0.22-0.79, P = 0.01) were significant predictors of the CV endpoint. Patients with a left ventricular mass index decrease also showed better cardiac event-free survival (P = 0.0022, log-rank test).

CONCLUSIONS

This is the first study to demonstrate that LVH regression, regardless of the therapeutic strategy adopted to achieve it, portends better long-term clinical outcome in RTRs.

Blockade of the acute activation of mTOR complex 1 decreases hypertrophy development in rats with severe aortic valve regurgitation

Background

Hypertrophy (H) is an adaptive response of the heart to a hemodynamic overload. Severe left ventricular (LV) volume overload (VO) from valve regurgitations (aortic (AR) or mitral regurgitation) leads to eccentric LVH. Increased protein turnover is a major event during development of LVH and the mechanistic target of rapamycin (mTOR) is a key molecule for its control. The role of mTOR inhibition in the development of LVH using rapamycin for relatively short periods of time (days to a few weeks) has been studied in the past in pressure overload models but not in VO models. We investigated if mTOR pathway was activated during LVH development in a model of severe VO (AR) in rats and if a rapamycin treatment can slow heart remodeling in this situation.

Methods and Results

Male rats with severe AR were studied acutely at 2 days, at 8 weeks (compensated phase) and 6 months (late phase) after VO induction. mTOR complex (mTORC) 1 (ribosomal S6 protein phosphorylation) was activated early after AR induction but not later in the disease whereas mTORC2 activity levels (Akt phosphorylation at Ser473) remained stable. We observed that a moderate dose of rapamycin (2 mg/kg/day; orally) for 8 weeks prevented severe LVH caused by AR (−46 %: p < 0.001). Rapamycin treatment specifically inhibited LV mTORC1 without altering mTORC2 activity at 8 weeks. Rapamycin also prevented cardiac myocyte hypertrophy caused by AR.

Conclusion

Rapamycin slows hypertrophy in LV VO by inhibiting early activation of mTORC1 without modulating mTORC2.

Cardiac response to early conversion from calcineurin inhibitor to everolimus in renal transplant recipients--a three-yr serial echocardiographic substudy of the randomized controlled CENTRAL trial

BACKGROUND

In transplant recipients, calcineurin inhibitors (CNIs) are associated with adverse cardiac effects while mTOR inhibitors have been reported to be beneficial. We performed a randomized controlled trial (RCT) in de novo renal transplant recipients examining cardiac responses of everolimus vs. CNI.

METHODS

This was a substudy of the three-yr CENTRAL study, an RCT on safety and efficacy of early (week 7 post-engraftment) conversion from cyclosporine A (CsA) to everolimus vs. continued CsA. Thirty-nine recipients [median age 64 yr, (range 31-81)] completed echocardiographic evaluations at baseline, one, and three yr.

RESULTS

After three yr, there was no difference between groups in left ventricle (LV) diastolic function, LV systolic function, LV morphology, and blood pressure response. We observed a relevant decrease in LV mass (CsA; 9.6%, p = 0.008, vs. everolimus; 7.0% reduction, p = 0.15), stabilized LV diastolic function, and a trend toward lower systolic blood pressure with 6 mmHg decrease in both arms (CsA, p = 0.08; everolimus, p = 0.14). Diastolic blood pressure was significantly reduced (8 mmHg decrease, p = 0.002) only in everolimus patients.

CONCLUSIONS

After three-yr follow-up, no clinically relevant effect on cardiac function of an early conversion from CsA to an everolimus-based immunosuppressive regimen was detected in de novo renal transplant recipients.

Impact of caloric restriction on myocardial ischaemia/reperfusion injury and new therapeutic options to mimic its effects

Caloric restriction (CR) is the most reliable intervention to extend lifespan and prevent age-related disorders in various species from yeast to rodents. Short- and long-term CR confers cardio protection against ischaemia/reperfusion injury in young and even in aged rodents. A few human trials suggest that CR has the potential to mediate improvement of cardiac or vascular function and induce retardation of cardiac senescence also in humans. The underlying mechanisms are diverse and have not yet been clearly defined. Among the known mediators for the benefits of CR are NO, the AMP-activated PK, sirtuins and adiponectin. Mitochondria, which play a central role in such complex processes within the cell as apoptosis, ATP-production or oxidative stress, are centrally involved in many aspects of CR-induced protection against ischaemic injury. Here, we discuss the relevant literature regarding the protection against myocardial ischaemia/reperfusion injury conferred by CR. Furthermore, we will discuss drug targets to mimic CR and the possible role of calorie restriction in preserving cardiovascular function in humans.

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.

The impact of arteriovenous fistulae on the myocardium: the impact of creation and ligation in the transplant era

Cardiac hypertrophy is a relatively common complication seen in patients with advanced chronic kidney disease (CKD) and end-stage renal disease (ESRD). Moreover, cardiac hypertrophy is even more frequently seen in patients with ESRD who have an arteriovenous (AV) access. There has been substantial evidence pertaining to the effects of AV access creation on the heart structure and function. Similarly, there is increasing evidence on the effects of AV access closure, flow reduction, transplantation, and immunosuppressive medication on both endpoints. In this review, we present the evidence available in the literature on these topics and open the dialog for further research in this interesting field.

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.

Rapamycin attenuated cardiac hypertrophy induced by isoproterenol and maintained energy homeostasis via inhibiting NF-κB activation

Rapamycin, also known as sirolimus, is an immunosuppressant drug used to prevent rejection organ (especially kidney) transplantation. However, little is known about the role of Rapa in cardiac hypertrophy induced by isoproterenol and its underlying mechanism. In this study, Rapa was administrated intraperitoneally for one week after the rat model of cardiac hypertrophy induced by isoproterenol established. Rapa was demonstrated to attenuate isoproterenol-induced cardiac hypertrophy, maintain the structure integrity and functional performance of mitochondria, and upregulate genes related to fatty acid metabolism in hypertrophied hearts. To further study the implication of NF-κB in the protective role of Rapa, cardiomyocytes were pretreated with TNF-α or transfected with siRNA against NF-κB/p65 subunit. It was revealed that the upregulation of extracellular circulating proinflammatory cytokines induced by isoproterenol was able to be reversed by Rapa, which was dependent on NF-κB pathway. Furthermore, the regression of cardiac hypertrophy and maintaining energy homeostasis by Rapa in cardiomyocytes may be attributed to the inactivation of NF-κB. Our results shed new light on mechanisms underlying the protective role of Rapa against cardiac hypertrophy induced by isoproterenol, suggesting that blocking proinflammatory response by Rapa might contribute to the maintenance of energy homeostasis during the progression of cardiac hypertrophy.

Regression of cardiac growth in kidney transplant recipients using anti-m-TOR drugs plus RAS blockers: a controlled longitudinal study

BACKGROUND

Left ventricular hypertrophy (LVH) is common in kidney transplant (KT) recipients. LVH is associated with a worse outcome, though m-TOR therapy may help to revert this complication. We therefore conducted a longitudinal study to assess morphological and functional echocardiographic changes after conversion from CNI to m-TOR inhibitor drugs in nondiabetic KT patients who had previously received RAS blockers during the follow-up.

METHODS

We undertook a 1-year nonrandomized controlled study in 30 non-diabetic KT patients who were converted from calcineurin inhibitor (CNI) to m-TOR therapy. A control group received immunosuppressive therapy based on CNIs. Two echocardiograms were done during the follow-up.

RESULTS

Nineteen patients were switched to SRL and 11 to EVL. The m-TOR group showed a significant reduction in LVMi after 1 year (from 62 ± 22 to 55 ± 20 g/m2.7; P=0.003, paired t-test). A higher proportion of patients showing LVMi reduction was observed in the m-TOR group (53.3 versus 29.3%, P=0.048) at the study end. In addition, only 56% of the m-TOR patients had LVH at the study end compared to 77% of the control group (P=0.047). A significant change from baseline in deceleration time in early diastole was observed in the m-TOR group compared with the control group (P=0.019).

CONCLUSIONS

Switching from CNI to m-TOR therapy in non-diabetic KT patients may regress LVH, independently of blood pressure changes and follow-up time. This suggests a direct non-hemodynamic effect of m-TOR drugs on cardiac mass.

Cardiac response to early conversion from calcineurin inhibitor to everolimus in renal transplant recipients: an echocardiographic substudy of the randomized controlled CENTRAL trial

BACKGROUND

Calcineurin inhibitors are associated with adverse cardiac effects. Mammalian target of rapamycin inhibitors have been reported to have beneficial effects on cardiac function. We used advanced echocardiographic techniques in a randomized controlled trial to examine cardiac responses to an everolimus-based arm versus a calcineurin inhibitor-based arm in de novo kidney transplant recipients.

METHODS

This was a substudy of the Certican Nordic Trial in Renal Transplantation study, a randomized controlled trial on safety and efficacy of early (week 7 after renal transplantation) conversion from cyclosporine A (CsA) to everolimus versus continued CsA during 1-year follow-up. A total of 44 patients (66% men; median [range] age, 61 [28-78] years) were included. All participants had a complete echocardiographic evaluation at baseline and at 1-year follow-up.

RESULTS

Left ventricular (LV) systolic function, LV mass, left atrial volumes, and blood pressure response did not differ between groups during 1-year follow-up. There was, however, a difference between the groups in change in peak early mitral velocity after 1 year (P=0.02), and E/e' ratio trended higher in the everolimus group (P=0.09).

CONCLUSIONS

Early conversion from CsA-based to everolimus-based immunosuppressive treatment in de novo renal transplant recipients caused marginal changes in LV diastolic function but no effect on LV systolic function or LV mass.

Association of a change in immunosuppressive regimen with hemodynamic and inflammatory markers of cardiovascular disease after kidney transplantation

BACKGROUND

Although rejection rates and short-term graft survival have significantly improved in kidney transplantation with the introduction of calcineurin inhibitor (CNI), cardiovascular disease (CVD) and metabolic complications are being increasingly recognized as important causes of morbidity and mortality. We hypothesize that non-CNI proliferation signal inhibitor (PSI)-based immunosuppressive regimen is associated with improved arterial stiffness after kidney transplantation compared with CNI-based immunosuppressive regimens.

METHODS

This is a prospective, single-center study of renal transplant (RT) recipients comparing the metabolic, cardiovascular (pulse wave velocity and aortic augmentation index (AI) adjusted for heart rate (AI × 75)), inflammatory cytokines (interleukins (ILs) 6, 12, and 18) and graft-related outcomes at 3 and 15 months posttransplantation between RT recipients maintained on CNI- (CNI-CNI) or PSI-based (CNI-PSI) regimens including sirolimus and everolimus.

RESULTS

Fifty and 17 RT recipients maintained on CNI-CNI and CNI-PSI, respectively, were included in this study. Median time to PSI conversion from CNI was 5 months. Compared with CNI-CNI recipients, CNI-PSI recipients had significantly lower fasting blood glucose in nondiabetics (coefficient = -16.2; 95% confidence interval (CI) = -14.4 to -18.0; P < 0.01), lower IL-18 levels (coefficient = -229.16; 95% CI = -343.94 to -114.38; P < 0.01), and lower AI × 75 (coefficient = -5.14; 95% CI = -9.99 to -0.28; P = 0.04) at 15 months posttransplant in the multivariable models.

CONCLUSIONS

Our study suggests from the elimination of CNI for PSI may lower AIx75 and IL-18, both surrogate markers of CVD, but adequately powered, randomized, controlled studies are required to establish the causal relationship between immunosuppressive agents and CVD risk.

Target of rapamycin (TOR)-based therapy for cardiomyopathy: evidence from zebrafish and human studies

Rapamycin is a U.S. Food and Drug Administration-approved drug for the prevention of immunorejection following organ transplantation. Pharmacological studies suggest a potential new application of rapamycin in attenuating cardiomyopathy, but the potential for this application is not yet supported by genetic studies of genes in target of rapamycin (TOR) signaling in rodents. Recently, supporting genetic evidence was presented in zebrafish using two adult cardiomyopathy models. By characterizing a heterozygous zebrafish target of rapamycin (ztor) mutant, the therapeutic effect of long-term TOR signaling inhibition was demonstrated. Dose- and stage-dependent functions of TOR signaling provide an explanation for the seemingly contradictory results obtained in genetic studies of TOR components in rodents. The results from the zebrafish studies, together with the supporting preliminary clinical studies, suggested that TOR signaling inhibition should be further pursued as a novel therapeutic strategy for cardiomyopathy. Future directions for developing TOR-based therapy include assessing the long-term benefits of rapamycin as a candidate drug for heart failure patients, defining the dynamic activity of TOR, exploring the impacts of TOR signaling manipulation in different models of cardiomyopathies, and elucidating the downstream signaling branches that confer the therapeutic effects of TOR signaling inhibition.

Effect of everolimus on left ventricular hypertrophy of de novo kidney transplant recipients: a 1 year, randomized, controlled trial

BACKGROUND

Although conversion from calcineurin inhibitors to mammalian target of rapamycin inhibitors proved to be effective in regressing left ventricular hypertrophy (LVH) in renal transplant recipients (RTRs) with chronic allograft dysfunction, there are currently no reports of randomized trials on this issue involving de novo RTRs administered everolimus (EVL).

METHODS

This randomized, open-label, controlled trial evaluated the effect of EVL on the left ventricular mass index (LVMi) of 30 nondiabetic RTRs (21 men; age 28-65 years). Ten were allocated to EVL plus reduced-exposure cyclosporine A (CsA), and 20 to standard dose CsA. LVMi was assessed by echocardiography both at baseline and 1 year later. Blood pressure (BP), hemoglobin, serum creatinine, lipids, trough levels of immunosuppressive drugs, and daily proteinuria were also evaluated twice monthly. Antihypertensive therapy that did not include renin-angiotensin system blockers was administered to achieve BP less than or equal to 130/80 mm Hg.

RESULTS

Changes in BP were similar in the two groups (between group difference 1.2 ± 5.7 mm Hg, P=0.84 for systolic, and -1.5 ± 3.7, P=0.69, for diastolic BP), whereas LVMi significantly decreased in the EVL group alone (between group difference 9.2 ± 3.1 g/m(2.7), P=0.005), due to a reduction in both the interventricular septum and the left ventricular posterior wall thickness. EVL therapy together with baseline LVMi were the only significant predictors of LVH regression according to a multivariate model that explained 49% of the total LVMi variance (P=0.0015).

CONCLUSIONS

An immunosuppressive regimen consisting of EVL plus reduced exposure CsA proved to be effective in regressing LVH in RTRs regardless of BP, mainly by reducing left ventricular wall thickness.

Regression of left ventricular hypertrophy in kidney transplant recipients: the potential role for inhibition of mammalian target of rapamycin

Left ventricular hypertrophy (LVH) contributes to elevated cardiac mortality with graft function in renal transplant recipients. Antihypertensive therapy, and especially angiotensin-converting enzyme (ACE) inhibitors, proved to be effective in regressing the LVH of renal transplant recipients, at least in part by interacting with immunosuppressive agents, thus raising the possibility that immunosuppressive therapy might affect changes in the left ventricular mass (LVM) of recipients. This review mainly focuses on the potential role of mammalian target of rapamycin (mTOR) inhibition to regress cardiac hypertrophy in both experimental models and in the clinical setting. We comment on the results of experimental studies conducted on animal models, which showed regression of cardiac hypertrophy by sirolimus (SRL). We also discuss clinical studies that show that conversion from calcineurin inhibitors to SRL is effective to achieve regression of LVH in both kidney and cardiac transplant recipients, mainly by reducing the true left ventricular wall hypertrophy.

MTORC1 regulates cardiac function and myocyte survival through 4E-BP1 inhibition in mice

Mechanistic target of rapamycin (MTOR) plays a critical role in the regulation of cell growth and in the response to energy state changes. Drugs inhibiting MTOR are increasingly used in antineoplastic therapies. Myocardial MTOR activity changes during hypertrophy and heart failure (HF). However, whether MTOR exerts a positive or a negative effect on myocardial function remains to be fully elucidated. Here, we show that ablation of Mtor in the adult mouse myocardium results in a fatal, dilated cardiomyopathy that is characterized by apoptosis, autophagy, altered mitochondrial structure, and accumulation of eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1). 4E-BP1 is an MTOR-containing multiprotein complex-1 (MTORC1) substrate that inhibits translation initiation. When subjected to pressure overload, Mtor-ablated mice demonstrated an impaired hypertrophic response and accelerated HF progression. When the gene encoding 4E-BP1 was ablated together with Mtor, marked improvements were observed in apoptosis, heart function, and survival. Our results demonstrate a role for the MTORC1 signaling network in the myocardial response to stress. In particular, they highlight the role of 4E-BP1 in regulating cardiomyocyte viability and in HF. Because the effects of reduced MTOR activity were mediated through increased 4E-BP1 inhibitory activity, blunting this mechanism may represent a novel therapeutic strategy for improving cardiac function in clinical HF.

Left ventricular mass in chronic kidney disease and ESRD

Chronic kidney disease (CKD) and ESRD, treated with conventional hemo- or peritoneal dialysis are both associated with a high prevalence of an increase in left ventricular mass (left ventricular hypertrophy [LVH]), intermyocardial cell fibrosis, and capillary loss. Cardiac magnetic resonance imaging is the best way to detect and quantify these abnormalities, but M-Mode and 2-D echocardiography can also be used if one recognizes their pitfalls. The mechanisms underlying these abnormalities in CKD and ESRD are diverse but involve afterload (arterial pressure and compliance), preload (intravascular volume and anemia), and a wide variety of afterload/preload independent factors. The hemodynamic, metabolic, cellular, and molecular mediators of myocardial hypertrophy, fibrosis, apoptosis, and capillary degeneration are increasingly well understood. These abnormalities predispose to sudden cardiac death, most likely by promotion of electrical instability and re-entry arrhythmias and congestive heart failure. Current treatment modalities for CKD and ESRD, including thrice weekly conventional hemodialysis and peritoneal dialysis and metabolic and anemia management regimens, do not adequately prevent or correct these abnormalities. A new paradigm of therapy for CKD and ESRD that places prevention and reversal of LVH and cardiac fibrosis as a high priority is needed. This will require novel approaches to management and controlled interventional trials to provide evidence to fuel the transition from old to new treatment strategies. In the meantime, key management principles designed to ameliorate LVH and its complications should become a routine part of the care of the patients with CKD and ESRD.

Mammalian target of rapamycin is a critical regulator of cardiac hypertrophy in spontaneously hypertensive rats

Evidence exists that protein kinase C and the mammalian target of rapamycin are important regulators of cardiac hypertrophy. We examined the contribution of these signaling kinases to cardiac growth in spontaneously hypertensive rats (SHRs). Systolic blood pressure was increased (P<0.001) at 10 weeks in SHRs versus Wistar-Kyoto controls (162+/-3 versus 128+/-1 mm Hg) and was further elevated (P<0.001) at 17 weeks in SHRs (184+/-7 mm Hg). Heart:body weight ratio was not different between groups at 10 weeks but was 22% greater (P<0.01) in SHRs versus Wistar-Kyoto controls at 17 weeks. At 10 weeks, activation of Akt and S6 ribosomal protein was greater (P<0.01) in SHRs but returned to normal by 17 weeks. In contrast, SHRs had protein kinase C activation only at 17 weeks. To determine whether mammalian target of rapamycin regulates the initial development of hypertrophy, rats were treated with rapamycin (2 mg/kg per day IP) or saline vehicle from 13 to 16 weeks of age. Rapamycin inhibited cardiac mammalian target of rapamycin in SHRs, as evidenced by reductions (P<0.001) in phosphorylation of S6 ribosomal protein and eukaryotic translation initiation factor-4E binding protein 1. Rapamycin treatment also reduced (P<0.001) heart weight and hypertrophy by 47% and 53%, respectively, in SHRs in spite of increased (P<0.001) systolic blood pressure versus untreated SHRs (213+/-8 versus 189+/-6 mm Hg). Atrial natriuretic peptide, brain natriuretic peptide, and cardiac function were unchanged between SHRs treated with rapamycin or vehicle. These data show that mammalian target of rapamycin is required for the development of cardiac hypertrophy evoked by rising blood pressure in SHRs.

Reducing the risk of left ventricular hypertrophy in kidney transplant recipients: the potential role of mammalian target of rapamycin

Persistence of left ventricular hypertrophy (LVH) following renal transplantation is associated with unfavorable outcomes in renal transplant recipients. This review presents clinical data on LVH after renal transplantation and the role of antihypertensive therapy, especially ACE inhibitors, to reduce left ventricular mass, as well as the effects of interactions between antihypertensive medications acting on the renin-angiotensin system and immunosuppressive agents to regress LVH among renal transplant recipients. The effectiveness of sirolimus (SRL) to reduce posttransplantation LVH is also discussed in light of both animal model studies and 2 clinical trials in transplant recipients that showed the efficacy of this immunosuppressive agent to treat LVH in both kidney and heart transplant recipients.