Drug Therapy in the Heart Transplant Recipient

[Routine hormonal therapy in the heart transplant donor]

BACKGROUND

Successful heart transplantation depends largely on donor heart function. During brain death many hormonal changes occur. These events lead to the deterioration of the donor hearts. The 2002 Crystal Consensus advises the use of a triple hormonal scheme to rescue marginal cardiac organs.

MATERIAL AND METHODS

A prospective, longitudinal study was conducted on potential donor hearts during the period 1 July 2011 to 31 May 2013. All donor hearts received a dual hormonal rescue scheme, with methylprednisolone 15mg/kg IV and 200mcg levothyroxine by the enteral route. There was at least a 4 hour wait prior to the harvesting. The preload and afterload was optimised. The variables measured were: left ventricular ejection fraction cardiac graft recipient; immediate and delayed mortality.

RESULTS

A total of 30 orthotopic heart transplants were performed, 11 female and 19 male patients, with age range between 19 and 63 years-old (Mean: 44.3, SD 12.92 years). The donor hearts were 7 female and 23 male, with age range between 15 and 45 years-old (mean 22.5, SD 7.3 years). Immediate mortality was 3.3%, 3.3% intermediate, and delayed 3.3%, with total 30 day-mortality of 10%. Month survival was 90%. The immediate graft left ventricular ejection fraction was 45%, 60% intermediate, and 68% delayed. The causes of death were: 1 primary graft dysfunction, one massive pulmonary embolism, and one due to nosocomial pneumonia.

CONCLUSION

It was concluded that the use of double rescue scheme hormonal therapy is useful for the recovery and preservation of the donor hearts. This scheme improves survival within the first 30 days after transplantation.

Cardiac mechanics in heart transplant recipients with and without transplant vasculopathy

Evaluation of cardiac mechanics in heart transplant recipients (HTR) is of paramount importance. Assessment of strain through echocardiography is suited to describe cardiac function and might allow characterizing patients with and without transplant vasculopathy (TVP) a risk factor of impaired organ function and rejection. For this study 41 HTR immediately after and 1-3 years after transplantation were examined in a retrospective approach with 2-dimensional speckle tracking echocardiography to assess longitudinal, radial and circumferential strain and strain rate. The cohort consists of 33 men and 8 women with a median age of 54 years (1st, 3rd; 45.7, 65.3) with seven cases diagnosed with TVP during follow-up, as diagnosed by coronary angiography. The overall cohort showed an improvement of global longitudinal strain from baseline to 1 and 3 years with -14.2% (-16.9, -12.3%) to -16.1% (-17.5, -14.3%) and -16.7% (-18, -13.7%), p = 0.036. For patients developing TVP, global longitudinal strain was not different from baseline up to the maximum of 3 years -16.6% (-16.7-13.8%) to -16.4% (-17.3, -14.7%) and -17.6% (-18.7, -16.9%) with p = 0.21. Radial strain and torsion showed a trend to decrease after transplantation with time. Circumferential strain remained stable in HTR but decreased in subjects with TVP. Longitudinal Strain and strain rate showed no relevant changes in HTR with and without TVP. Radial strain and torsion declined in HTR as well as TVP patients with time. Speckle tracking imaging is useful to assess organ function in HTR, however coronary angiography is still needed to rule out TVP.

Neurobehavioral consequences of small molecule-drug immunosuppression

60 years after the first successful kidney transplantation in humans, transplant patients have decent survival rates owing to a broad spectrum of immunosuppressive medication available today. Not only transplant patients, but also patients with inflammatory autoimmune diseases or cancer benefit from these life-saving immunosuppressive and anti-proliferative medications. However, this success is gained with the disadvantage of neuropsychological disturbances and mental health problems such as depression, anxiety and impaired quality of life after long-term treatment with immunosuppressive drugs. So far, surprisingly little is known about unwanted neuropsychological side effects of immunosuppressants and anti-proliferative drugs from the group of so called small molecule-drugs. This is partly due to the fact that it is difficult to disentangle whether and to what extent the observed neuropsychiatric disturbances are a direct result of the patient's medical history or of the immunosuppressive treatment. Thus, here we summarize experimental as well as clinical data of mammalian and human studies, with the focus on selected small-molecule drugs that are frequently employed in solid organ transplantation, autoimmune disorders or cancer therapy and their effects on neuropsychological functions, mood, and behavior. These data reveal the necessity to develop immunosuppressive and anti-proliferative drugs inducing fewer or no unwanted neuropsychological side effects, thereby increasing the quality of life in patients requiring long term immunosuppressive treatment. This article is part of a Special Issue entitled 'Neuroimmunology and Synaptic Function'.

Similar survival in patients following heart transplantation receiving induction therapy using daclizumab vs. basiliximab

BACKGROUND

Induction therapy with interleukin-2 receptor antagonists has been established as an effective immunosuppressive strategy in the management of heart transplant (HTx) recipients. We compared outcomes following HTx in patients receiving basiliximab, daclizumab, or no induction therapy.

METHODS AND RESULTS

We investigated post-transplant prognosis of patients receiving basiliximab (n=67), daclizumab (n=98) or no induction therapy (n=70). Patients treated with daclizumab (50.3 ± 14.7 years) were younger than those receiving basiliximab (55.8 ± 11.2 years) or no induction therapy (54.9 ± 14.1 years; both P<0.05). Patients receiving either induction therapy showed better survival 1 year after HTx (95%) than those without induction therapy (82%; P<0.001). Survival was similar between patients receiving basiliximab and daclizumab. The incidence of acute cellular or antibody-mediated rejections did not differ among the groups. The main reason that patients did not receive induction therapy was ongoing infection (65.7%), which was more common in patients on ventricular assist device (VAD) support than those without VAD (76.1% vs. 45.8%; P=0.004). The VAD-related infection rate in the entire study cohort was 29.7% (35/118 VAD recipients).

CONCLUSIONS

Survival following HTx was worse in patients not receiving induction therapy. No differences were noted in survival or the incidence of rejection between the daclizumab- and basiliximab-treated groups. Induction therapy was less used in patients with infection, which was related to prior VAD support.

Immunosuppression following heart transplantation: prospects and challenges

Immunosuppression after heart transplantation has significantly reduced the incidence of cellular rejection and improved patient outcomes with the routine use of calcineurin inhibitors. Antimetabolites and proliferation signal inhibitors add to the improvement in patient outcomes, particularly with respect to the reduced burden of cardiac allograft vasculopathy. Patients with antibody sensitization are potentially at higher risk of postoperative complications. Sensitized patients are undergoing heart transplantation with increased frequency, in part due to the emergence of ventricular assist device use as a bridge to heart transplantation. Despite improvements in immunosuppressive therapies, many challenges face physicians and patients, which will further refine and improve care of the post-heart transplant patient.

Beyond cancer treatment - a review of total lymphoid irradiation for heart and lung transplant recipients

Immunosuppressive drugs used in the management of heart and lung transplants have a large monetary and quality of life cost due to their side effects. Total lymphoid irradiation (TLI) is one method of minimising the need for or replacing post-operative immunosuppressive drugs. A literature review was conducted on electronic databases using defined search terms. The aim was to establish the indications for the use of TLI, its advantages and disadvantages and the weaknesses associated with the methods used in related research. Eight articles were located that focused on TLI usage in combating organ rejection. These studies identified that the use of TLI resulted in a reduction in early rejection. One study reported a drop in rejection episodes from 0.46 to 0.14 episodes per patient per month once the TLI was complete. While the short-term prognosis is excellent, the long-term outlook is less positive with an increased risk of organ rejection and myelodysplasia 3.5 years post-TLI. This review reminds us that radiation therapy (RT) is not exclusively indicated for cancer treatment. While TLI cannot replace immunosuppressive drug therapy, it can offer a treatment option for people that cannot tolerate immunosuppressive drugs, or when conventional anti-rejection treatment is no longer viable. Reported long-term complications suggest that TLI should be used with caution. However, this modality should not be overlooked in cases of chronic rejection. Further research is required to establish the efficacy of RT in the treatment of transplant patients who are unsuitable for drug-based anti-rejection therapies.

Effect of everolimus on the immunomodulation of the human neutrophil inflammatory response and activation

The primary cause of mortality at 5 years following a cardiac transplantation is the development of atherosclerosis, termed coronary allograft vasculopathy (CAV). This pathology is characterized by diffused intimal hyperplasia and emanates from coronary arterial injuries caused by immune inflammatory cells. Neutrophils play an important role in this inflammatory process; however, their potential participation in the pathogenesis of CAV is poorly understood. Despite their essential contribution to the prevention of graft rejection, immunosuppressive drugs could have detrimental effects owing to their pro-inflammatory activities. Thus, we investigated the impact of different immunosuppressive drugs on the inflammatory response of neutrophils isolated from the blood of healthy volunteers. Under basal conditions, mammalian target of rapamycin (mTOR) inhibitors (sirolimus and everolimus) had the most potent anti-inflammatory effect, decreasing both IL-8 release (≈−80%) and vascular endothelial growth factor (VEGF) release (≈−65%) and preserving the release of the anti-inflammatory cytokine interleukin-1 receptor antagonist (IL-1RA). In TNF-α-treated neutrophils, pre-incubation with everolimus provided the most potent effect, simultaneously reducing the release of both VEGF and IL-8 while doubling the release of IL-1RA. This latter effect of everolimus was maintained even when administered in combination with other immunosuppressive drugs. Sirolimus and everolimus decreased the tumor necrosis factor (TNF)-α-induced adhesion of neutrophils to human endothelial cells and human extracellular matrix. This effect was largely dependent on the ability of these compounds to alter β₂-integrin/CD18 activation. Our results suggest a potential mechanism for the beneficial effect of everolimus in the prevention of CAV in heart transplant recipients.

TPMT genetic variants are associated with increased rejection with azathioprine use in heart transplantation

OBJECTIVES

Azathioprine (AZA) is an important immunosuppressant drug used in heart transplantation (HTX). Consensus guidelines recommend that patients with thiopurine S-methyltransferase (TPMT) genetic variants be started on lower AZA dose because of higher active metabolite levels and risk of adverse events. However, in-vitro lymphocyte proliferation assays performed in participants with inactive TPMT alleles have suggested that AZA use may result in decreased immunosuppressant efficacy as compared with wild-type (WT) individuals. The objective of this study was therefore to determine the effect of TPMT genetic variation on AZA efficacy or prevention of rejection in HTX recipients treated with AZA.

PARTICIPANTS AND METHODS

We genotyped 93 HTX recipients treated with AZA and measured erythrocyte TPMT enzyme activity. Acute rejection was monitored by routine endomyocardial biopsies.

RESULTS

There were 83 WT and 10 heterozygote (HZ) HTX recipients. TPMT activity level was lower in HZ compared with WT (13.1±2.8 vs. 21±4.5 U/ml red blood cell, P<0.001). Despite similar AZA dose, HZ developed severe rejection earlier (P<0.001), and the total rejection score was higher (P=0.02) than WT. AZA was discontinued more frequently in HZ (P=0.01) because of rejection. The incidence of leukopenia was similar between the groups (40 vs. 43%, P=1.0).

CONCLUSION

HTX recipients with TPMT genetic variant alleles who are treated with AZA develop acute rejection earlier, more frequently, and of greater severity. These patients, despite having lower TPMT enzymatic activity, should be monitored carefully for possible increased risk of acute rejection.

Alemtuzumab for cytolytic induction of immunosuppression in heart transplant recipients

OBJECTIVE

To review available evidence about the safety and efficacy of alemtuzumab for induction of immunosuppression in heart transplant recipients.

DATA SOURCES

Searches of MEDLINE, EMBASE, and Cochrane databases were conducted. Key search terms included alemtuzumab, Campath-1H, CD52, lymphocyte, cytolytic, induction, immunosuppression, rejection, and cardiac transplantation. Additional pertinent data were identified through a search of abstracts from major transplant meetings.

STUDY SELECTION AND DATA EXTRACTION

All English-language articles and abstracts identified from the data sources were evaluated. All primary data were eligible for inclusion if they evaluated the safety or efficacy of alemtuzumab for induction of immunosuppression in heart transplant patients. One retrospective cohort, 1 case series, 1 case-control series, and 1 open-label trial were identified and included for review.

DATA SYNTHESIS

Acute cellular rejection occurs in 40% to 70% of heart transplant recipients within the first 6 months after transplant and is associated with significant morbidity and mortality. Depleting and nondepleting antibodies have displayed positive outcomes in inducing immunosuppression; however, the ideal induction strategy that balances efficacy and toxicity remains elusive. Alemtuzumab, a cytolytic anti-CD52 antibody, has been used to induce immunosuppression in kidney, pancreas, liver, intestine, and lung transplant recipients, and its use in heart transplant has been investigated. Studies of use of alemtuzumab to induce immunosuppression in heart transplant patients have shown low rates of rejection; however, it has not been directly compared with other immunosuppression-inducing agents and safety data are limited.

CONCLUSIONS

Although alemtuzumab may be a practical option for inducing immunosuppression, data are insufficient to recommend its routine use in deference to more established agents. Large, randomized clinical trials with extended durations of follow-up must be conducted to characterize its efficacy and safety further.

Postoperative care of the transplanted patient

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

Drug-related problems and hospital admissions in cardiac transplant recipients

BACKGROUND

Drug-related problems (DRPs) in the general population account for 15% of all hospital admissions, of which approximately 30% are preventable. Cardiac transplant patients may be at increased risk for DRPs because of their complicated medication regimens that include drugs with a narrow therapeutic index.

OBJECTIVE

To determine the incidence and preventability of DRPs causing hospital admission in cardiac transplant patients at a single institution.

METHODS

Between November 2009 and January 2010, a prospective longitudinal study investigated the incidence and preventability of DRPs in a single cardiac transplant center. Three independent reviewers used validated scoring systems to determine the incidence and preventability of drug-related hospital admissions. DRPs were classified by type, pharmacologic class, and impact on length of stay.

RESULTS

During the 3-month study period, 48 cardiac transplant patients were hospitalized. DRPs accounted for 40% (19/48) of these admissions and 58% (11/19) were adjudicated to be preventable. Common DRPs included supratherapeutic (32%) and subtherapeutic (16%) dosage, adverse drug reaction (32%), drug interaction (5%), and nonadherence (5%). Pharmacologic classes implicated included immunosuppressant (63%), antimicrobial (11%), electrolyte/fluid (11%), and anticoagulant (5%). Average length of stay in drug-related compared to non-drug-related admissions was 11.4 versus 8.5 days (p = 0.458). When annualized, 44 hospitalizations or 500 hospital days may have been prevented.

CONCLUSIONS

Hospital admissions following cardiac transplantation are often drug related (40%) and preventable (58%). Incorporating this insight into the multidisciplinary transplant team may improve outcomes, assist in meeting national quality mandates by the United Network for Organ Sharing and Centers for Medicare Services, and lead to new benchmarks for transplant centers.

Vascular function and the role of oxidative stress in heart failure, heart transplant, and beyond

Using flow-mediated vasodilation (FMD), reactive hyperemia, and an acute oral antioxidant cocktail (AOC; vitamins C and E and α-lipoic acid), this study aimed to provide greater insight into altered vascular function and the role of oxidative stress in chronic heart failure patients with reduced ejection fraction (HFrEF) and at several time points beyond heart transplantation (HTx). A total of 61 age-matched subjects (12 healthy controls, 14 New York Heart Association class II and III HFrEF, and 35 HTx recipients [<3 years post-HTx, 5-10 years post-HTx, and >14 years post-HTx]) ingested either placebo (PL) or an AOC before FMD and reactive hyperemia testing of the brachial artery. Vascular function, as measured by FMD, was not different among the controls (6.8±1.9%), recent <3-year post-HTx group (8.1±1.2%), and the 5- to 10-year post-HTx group (5.5±1.0%). However, PL FMD was lower in the HFrEF (4.5±0.7%) and in the >14-year post-HTx group (2.9±0.8%). The AOC increased plasma ascorbate levels in all of the groups but only increased FMD in the controls (PL, 6.8±1.9%; AOC, 9.2±1.0%) and >14-year post-HTx recipients (PL, 2.9±0.8%; AOC, 4.5±1.3%). There were no differences in reactive hyperemia in any of the groups with PL or AOC. This cross-sectional study reveals that, compared with controls, vascular function is blunted in HFrEF, is similar soon after HTx, but is decreased with greater time post-HTx with free radicals implicated in this progression.

Immunosuppressant nonadherence in heart, liver, and lung transplant patients: associations with medication beliefs and illness perceptions

BACKGROUND

Nonadherence to immunosuppressant medication is a significant problem among solid organ transplant recipients. Previous research suggests that patients' perceptions about their medications may be a better predictor of nonadherence than demographic factors. This study aimed to further investigate the role of patients' perceptions about their transplant and medication beliefs in nonadherence.

METHODS

This was a cross-sectional observational study. Participants were 87 heart, 46 lung, and 193 liver transplant patients. All surviving heart, lung, and liver transplant patients from Auckland City Hospital and Greenlane Hospital older than 16 years who had received their transplant at least 3 months before study commencement were mailed questionnaires. Standardized self-report measures were used to assess illness perceptions, medication beliefs, and adherence.

RESULTS

Nonadherent patients had lower perceptions about the necessity of medication, weaker beliefs that medication could prevent rejection, and higher concerns about its harms, than adherers. Nonadherers perceived that their transplant and immunosuppressant medication caused more symptoms and were more distressed about symptoms than adherers; they understood their transplant less, perceived their transplant had a larger impact on their lives, affected them more emotionally, and caused greater concern, than patients who were more adherent. A regression model that included these perceptions and demographic variables correctly classified 71% of patients as adherent or nonadherent.

CONCLUSIONS

The perceptions that patients hold about their transplant and medications are associated with adherence to immunosuppressant medications. Future research could investigate whether a psychologic intervention could change patients' perceptions to improve adherence.

Perioperative management of the pediatric cardiac transplantation patient

OPINION STATEMENT

The major diagnoses carried by children undergoing cardiac transplantation worldwide are congenital heart defects, cardiomyopathies, and retransplantation. The leading diagnosis in infancy is congenital heart disease, whereas cardiomyopathy predominates in older children. In view of this wide spectrum of diagnoses, the perioperative management of these children requires medical, interventional, and surgical expertise in treatment of complex congenital heart defects, end-stage heart failure, and cardiac transplantation. According to the Pediatric Heart Transplantation Survey database, the majority of children listed for cardiac transplantation eventually require higher levels of cardiac support before transplantation. The team caring for these children should be prepared to escalate support in a timely fashion in order to avoid end-organ dysfunction or a catastrophic event that will remove the patient from the cardiac transplantation list. The first step is advanced hemodynamic monitoring in a specialized pediatric cardiac intensive care unit and initiation of inotropic support. Further escalation of care should be based on careful analysis of the hemodynamic profile, end-organ function, and biochemical markers of perfusion and myocardial stress. A patient who continues to deteriorate in spite of inotropic support requires positive pressure ventilation, and if deterioration continues, mechanical circulatory support is initiated. Cardiac transplantation is a challenging operation, and even more so in children with complex congenital heart defects. The abnormal cardiovascular anatomy requires planning and anticipation of possible pitfalls as hypoplasia of the aortic arch, abnormal pulmonary arteries, and abnormal systemic and pulmonary venous connections. The time required to remove adhesions in children with prior cardiac operations increases the ischemic time of the graft and the risk of primary graft dysfunction. Assessment of pulmonary vascular resistance in children with congenital heart defects is problematic, and even children with a normal transpulmonary gradient and pulmonary vascular resistance are at increased risk of postoperative pulmonary hypertension and right ventricular graft failure. The postoperative course is directly linked to the patient's preoperative physical condition and perioperative course. The induction of immunosuppression and the use of plasmapheresis in children with a positive cross-match may lead to further hemodynamic compromise. If severe primary graft dysfunction evolves, early initiation of extracorporeal membranous oxygenator is indicated to avoid irreversible end-organ dysfunction.

Strategies for tissue engineering cardiac constructs to affect functional repair following myocardial infarction

Tissue-engineered cardiac constructs are a high potential therapy for treating myocardial infarction. These therapies have the ability to regenerate or recreate functional myocardium following the infarction, restoring some of the lost function of the heart and thereby preventing congestive heart failure. Three key factors to consider when developing engineered myocardial tissue include the cell source, the choice of scaffold, and the use of biomimetic culture conditions. This review details the various biomaterials and scaffold types that have been used to generate engineered myocardial tissues as well as a number of different methods used for the fabrication and culture of these constructs. Specific bioreactor design considerations for creating myocardial tissue equivalents in vitro, such as oxygen and nutrient delivery as well as physical stimulation, are also discussed. Lastly, a brief overview of some of the in vivo studies that have been conducted to date and their assessment of the functional benefit in repairing the injured heart with engineered myocardial tissue is provided.

The Circle of Caring Model

This column employs a case study approach to examine the application of the circle of caring model in actual nursing practice as it pertains to a medication education teaching plan for a cardiac transplant patient. The circle of caring model is applied by experienced registered nurses. The tailored medication education plan is based on the patient’s conceptualized database, understanding patient responses, using a holistic/broadened approach to therapeutics, and considering the patient’s views of outcomes. Individualized teaching plans improve patient adherence to complicated medication regimens, thus improving long-term quality of life and survival in transplant recipients.

Induction treatment with monoclonal antibodies for heart transplantation

Individualization of induction therapy for heart transplantation (HT) is needed, given that only patients at significant risk for fatal rejection seem to present a favorable risk-benefit ratio. The question whether monoclonal interleukin 2 antagonists or antilymphocyte antibodies should be recommended remains unanswered. As most studies suggest that they have similar efficacy in preventing acute rejection, other variables related to safety or management costs should be taken into account. The cytokine release syndrome, associated with the use of OKT3, complicates management of HT patient. The experience in our center with 2 consecutive cohorts, treated with basiliximab (BAS) and OKT3, respectively, suggests that the use of BAS is associated, in addition to similar immunosuppressive efficacy and better safety profile than OKT3, with simpler patient management during the initial hospital stay, which could be associated with a reduction in posttransplant costs. Because few centers continue to use OKT3 as induction therapy in HT, more studies comparing cost-effectiveness of BAS vs polyclonal antilymphocyte antibodies (ATG) are needed.

Strategies to prevent cellular rejection in pediatric heart transplant recipients

Despite more than 40 years' experience in pediatric heart transplantation, cellular rejection remains a significant cause of morbidity and mortality. In this review, strategies and agents to prevent acute cellular rejection are discussed. Strategies to prevent rejection are divided into two phases - induction and maintenance therapies. Currently, the most commonly used induction agents are polyclonal antibodies (rabbit or equine antithymocyte globulin) and interleukin-2 receptor antibodies (daclizumab or basiliximab). Induction therapies have reduced early rejection, are renal sparing, and can reduce corticosteroid exposure, but have not yet been shown to have a longer term survival benefit. Multiple maintenance immunosuppressants are available. Nearly all regimens include a calcineurin inhibitor (either ciclosporin [cyclosporine] or tacrolimus). Most combinations in pediatric heart transplantation include an antiproliferative agent (azathioprine, mycophenolate mofetil or, less commonly, sirolimus). Everolimus has seen increasing use in adult heart transplant patients in Europe but, to date, its use is rare in pediatric heart transplantation. The use of corticosteroids as a third agent is still common, but strategies to avoid or minimize their use are increasing. The 'best' combination of therapies varies between studies. By gaining a better understanding of individuals' genetic and environmental risk factors, we may in the future be able to better predict the course of cardiac allografts and enhance our ability to tailor immunosuppression to individual patient variables with the ultimate goal of inducing a state of immune tolerance.

Late presentation of Pneumocystis jiroveci pneumonia after cardiac transplantation

We report the case of a 64-year-old man who had received a heart transplant 9 years previously and was on long-term immunosuppression. He was referred to the intensive care unit of our district general hospital with acute respiratory distress and was diagnosed with community-acquired pneumonia. He was treated with antimicrobials, whose spectrum was extended empirically to cover Pneumocystis jiroveci, and respiratory support was provided with continuous positive airway pressure (CPAP). PCR analysis subsequently confirmed a diagnosis of pneumocystis pneumonia (PCP). Despite appropriate therapy the patient unfortunately died 8 days after admission to the unit. To the author's knowledge, this is the first report in the literature of such a late presentation of PCP after cardiac transplantation. We discuss current diagnostic and treatment strategies for PCP.

Diagnostic performance of multisequential cardiac magnetic resonance imaging in acute cardiac allograft rejection

AIMS

We evaluated cardiac magnetic resonance imaging (CMR) as a non-invasive test for cardiac allograft rejection.

METHODS AND RESULTS

We performed CMR on 50 heart-transplant recipients. Acute rejection was confirmed in 11 cases by endomyocardial biopsy (EMB) and presumed in 8 cases with a recent fall in left-ventricular ejection fraction (LVEF) not attributable to coronary allograft vasculopathy. Control patients had both normal LVEF and no significant rejection on EMB. Cardiac magnetic resonance imaging evaluated myocardial function, oedema, and early and late post-Gadolinium-DTPA contrast enhancement. Patients with confirmed rejection demonstrated elevated early relative myocardial contrast enhancement (4.1 +/- 0.3 vs. 2.8 +/- 0.2, P < 0.001) and a trend to higher oedema suggested by higher relative myocardial intensity on T(2)-weighted imaging compared to controls (2.1 +/- 0.1 vs. 1.7 +/- 0.1, P = 0.1). With rejection defined as increased early contrast enhancement or myocardial oedema, the sensitivity and specificity of CMR compared with EMB were 100 and 73%, respectively. Eight patients with presumed rejection also had elevated early myocardial contrast enhancement compared with controls, (8.7 +/- 1.9 vs. 2.8 +/- 0.2, P < 0.05), which reduced following increased immunosuppression (8.7 +/- 1.9 vs. 4.6 +/- 1.2, P < 0.05). In these patients LVEF improved following increased immunosuppression (32 +/- 5 vs. 46 +/- 5%, P < 0.05).

CONCLUSION

Cardiac magnetic resonance imaging is a promising modality for non-invasive detection of cardiac allograft rejection.

Immunosuppression armamentarium in 2010: mechanistic and clinical considerations

Effective immunosuppression is the key to successful organ transplantation, with success being defined as minimal rejection risk with concomitant minimal drug toxicities. Despite the general recognition of this fact, a paucity of appropriate clinical trials in children has contributed to lack of standardization of clinical management regimens, resulting in an extensive diversity of favored approaches. Nonetheless, although consensus has not been reached on the ideal approach to immunosuppression in pediatric transplantation, new drug therapies have contributed to a continuing improvement in graft and patient survival. Future clinical research must focus on diminishing the extensive burden of toxicities of these therapeutic agents in children.

Induction Immunosuppression for Orthotopic Heart Transplantation: A Review

Objectives

To describe the appropriateness and safety of induction immunosuppression for patients at risk for fatal rejection, and to describe the safety and effectiveness profiles of the induction regimens available in the United States.

Data Sources

MEDLINE/PubMed database, EMBASE database, Google Scholar; references from pertinent articles were also reviewed to identify additional data.

Study Selection

A systematic literature review from January 1, 1980, through June 30, 2008, was performed. Included articles ranged from case series to prospective randomized controlled double-blind placebo-controlled trials that detailed the following topics with respect to induction immunosuppression: risk of fatal rejection, renal sparing, malignancy, OKT3, rabbit or equine antithymocyte globulin, daclizumab, basiliximab, and alemtuzumab.

Results

Patients at highest risk for fatal rejection experienced a survival benefit from induction immunosuppression, whereas all other patients experienced no benefit or harm. Most of the early data detail positive experiences with polyclonal antibody regimens. Several newer trials compare the use of polyclonal strategies with the use of anti-CD25 targeted monoclonal antibodies. Few researchers have assessed the usefulness of an anti-CD52 approach. Overall, induction therapy remains a poorly studied and widely variable practice among the major US heart transplant centers.

Conclusion

At present, the unrestricted use of induction for all patients does not seem prudent. Induction should be individualized for each patient on the basis of a well-designed protocol, careful analysis of the transplant center's demographics, and the effectiveness and safety profiles of the regimens used.

Continuous infusion of thymoglobulin for induction therapy in pediatric heart transplant recipients; experience and outcomes with a novel strategy for administration

Minimal data exist on the perioperative use of TG for induction in pediatric HTx recipients. We report our experience using continuous infusion of TG on (i) perioperative adverse events, (ii) rejection, (iii) CAV, and (iv) PTLD. TG was infused via peripheral intravenous intra- and perioperatively as a continuous infusion (24 h/day). Starting dose was 1.5 mg/kg/day titrated to achieve target lymphocyte count of 0.1-0.3 x 10(9)/L. Fifty-five patients received TG; mean age at HTx was 4.4 yr (1 day-17.8 yr). The mean duration of TG was three and a half days (2-7 days). Median platelet count during TG infusion was 95 x 10(9)/L (28-228). Five patients had TG stopped for low platelets (at 4-6 days post-HTx) - all started maintenance immunosuppression. There was no perioperative mortality due to infection. Mean follow-up of 46 survivors was 2.3 yr (0.6-5.8 yr). Fifty-one percent had > or = ISHLT 2R rejection at a median time of 33 days post-HTx (7 days-2 yr). One patient developed PTLD 1.4 yr post-HTx; three patients developed mild-moderate CAV. TG as a continuous infusion appears to have a good safety profile. Though mild thrombocytopenia was prevalent, there was no bleeding attributable solely to TG. Whether early depletion of T-cell function will translate into long-term benefits remains to be determined.

Pretransplant predictors of posttransplant adherence and clinical outcome: an evidence base for pretransplant psychosocial screening

INTRODUCTION

There is growing awareness, yet scant prospective evidence that pretransplant (TX) psychosocial factors may predict post-TX outcome. We examined which pre-TX psychosocial factors predict post-TX nonadherence with immunosuppression (NA) and clinical outcomes in heart, liver, and lung TX.

METHODOLOGY

We prospectively followed 141 patients (28 heart, 61 liver, and 52 lung) from pre-TX until 1 year post-TX. Multivariable analyses determined which pre-TX factors (i.e., anxiety, depression, personality traits, social support, adherence with medication, and smoking status) predict poor post-TX outcome (i.e., NA, late acute rejection, graft loss, and resource utilization), controlling for medical predictors of poor outcome.

RESULTS

Pre-TX self-reported medication nonadherence (odds ratio [OR]=7.9), lower received social support (OR=0.9), a higher education (OR=2.7), and lower "conscientiousness" (OR=0.8) were independent predictors of post-TX NA. Not living in a stable relationship predicted graft loss (OR=4.9). Pre-TX medication NA was the only predictor for presence of late acute rejection (OR=4.4). No other pre-TX predictors for poor outcome could be found.

CONCLUSION

This is the first prospective study demonstrating that selected pre-TX psychosocial factors predict post-TX NA and poor clinical outcome, implying that pre-TX screening should include this set of factors in addition to traditional medical criteria.

Inadequate immune regulatory function of CD4+CD25bright+FoxP3+ T cells in heart transplant patients who experience acute cellular rejection

BACKGROUND

CD4CD25FoxP3 regulatory T cells are suppressors of antigen-activated immune reactivity. Here, we assessed the clinically relevant role of these cells in the control of immune responses directed to a transplanted heart.

METHODS

We investigated the phenotype and function of peripheral CD4CD25FoxP3 T cells in heart transplant patients free from acute rejections (n=9) and in rejectors (n=12) before and during acute cellular rejection.

RESULTS

Between rejectors and nonrejectors, the proportion of CD4CD25 T cells and of FoxP3 cells within this population was comparable. Yet, CD4CD25FoxP3 T cells of rejectors had a higher CD127 expression than those of nonrejectors (P<0.0001). Depletion of CD4CD25 T cells from peripheral blood mononuclear cells increased the antidonor proliferative response of both nonrejectors (P=0.0005) and rejectors (P=0.03). In rejectors, however, only a 2-fold increase was measured, whereas the nonrejectors' response became 14 times higher (P=0.002). Reconstitution of CD4CD25 T cells only suppressed the overall antidonor proliferative response of CD25 responder cells of nonrejectors significantly (P=0.001). Moreover, the percentage inhibition of the response was higher in nonrejectors than in rejectors (P=0.02). Analyses of pretransplant samples revealed that CD4CD25 T cells of rejectors already had a lower suppressive capacity than those of nonrejectors before transplantation (P=0.04).

CONCLUSION

CD4CD25FoxP3 T cells of heart transplant patients who experience acute rejection had an up-regulated CD127 expression and an inadequate regulatory function compared with those of nonrejecting patients. Our observations suggest that the function of circulating CD4CD25FoxP3 regulatory T cells may be pivotal for the prevention of acute cellular rejection after clinical heart transplantation.

Cardiovascular magnetic resonance in the diagnosis of acute heart transplant rejection: a review

BACKGROUND

Screening for organ rejection is a critical component of care for patients who have undergone heart transplantation. Endomyocardial biopsy is the gold standard screening tool, but non-invasive alternatives are needed. Cardiovascular magnetic resonance (CMR) is well suited to provide an alternative to biopsy because of its ability to quantify ventricular function, morphology, and characterize myocardial tissue. CMR is not widely used to screen for heart transplant rejection, despite many trials supporting its use for this indication. This review summarizes the different CMR sequences that can detect heart transplant rejection as well as the strengths and weaknesses of their application.

RESULTS

T2 quantification by spin echo techniques has been criticized for poor reproducibility, but multiple studies show its utility in screening for rejection. Human and animal data estimate that T2 quantification can diagnose rejection with sensitivities and specificities near 90%. There is also a suggestion that T2 quantification can predict rejection episodes in patients with normal endomyocardial biopsies.T1 quantification has also shown association with biopsy proven rejection in a small number of trials. T1 weighted gadolinium early enhancement appeared promising in animal data, but has had conflicting results in human trials. Late gadolinium enhancement in the diagnosis of rejection has not been evaluated.CMR derived measures of ventricular morphology and systolic function have insufficient sensitivity to diagnose mild to moderate rejection. CMR derived diastolic function can demonstrate abnormalities in allografts compared to native human hearts, but its ability to diagnose rejection has not yet been tested.There is promising animal data on the ability of iron oxide contrast agents to illustrate the changes in vascular permeability and macrophage accumulation seen in rejection. Despite good safety data, these contrast agents have not been tested in the human heart transplant population.

CONCLUSION

T2 quantification has demonstrated the best correlation to biopsy proven heart transplant rejection. Further studies evaluating diastolic function, late gadolinium enhancement, and iron oxide contrast agents to diagnose rejection are needed. Future studies should focus on combining multiple CMR measures into a transplant rejection scoring system which would improve sensitivity and possibly reduce, if not eliminate, the need for endomyocardial biopsy.

Predictive role of pretransplant serum CXCL10 for cardiac acute rejection

BACKGROUND

The detection of acute rejection in heart transplantation remains an important feature of transplant management, especially in the early phase. Frequent surveillance with endomyocardial biopsy is necessary, even though it is an invasive procedure and carries a certain risk. Hence, noninvasive biomarkers able to predict acute rejection could be a further helpful tool in patient management. The interferon-gamma-inducible chemokine CXCL10 is required for initiation and development of graft failure caused by acute or chronic rejection. It has been reported that CXCL10 serum level is predictive of graft loss in kidney graft recipients. In the present study, we investigated whether pretransplant CXCL10 serum level may be a predictive noninvasive biomarker in heart transplant (HTx) recipients, as well.

METHODS

Sera from 143 patients undergoing orthotopic heart transplantation were collected before surgery and tested for CXCL10 and CCL22 and compared with serum samples from healthy subjects.

RESULTS

We found that basal CXCL10 serum levels in HTx recipients were significantly higher than in healthy subjects, whereas no difference was seen in CCL22 levels. Among HTx recipients, CXCL10 serum levels of rejectors were significantly higher than in nonrejectors. Our results showed that CXCL10 was a significant independent risk factor of several variables and had the highest predictive value for early acute heart rejection, with 160 pg/mL cutoff value.

CONCLUSIONS

In HTx recipients, measurement of pretransplant CXCL10 serum levels could be a clinically useful tool for predicting cardiac acute rejection, especially in the early posttransplant period.

Immunomodulatory effects of BXL-01-0029, a less hypercalcemic vitamin D analogue, in human cardiomyocytes and T cells

Current immunosuppressive protocols have reduced rejection occurrence in heart transplantation; nevertheless, management of heart transplant recipients is accompanied by major adverse effects, due to drug doses close to toxic range. In allograft rejection, characterized by T-helper 1 (Th1) cell-mediated response, the CXCL10-CXCR3 axis plays a pivotal role in triggering a self-promoting inflammatory loop. Indeed, CXCL10 intragraft production, required for initiation and development of graft failure, supports organ infiltration by Th1 cells. Thus, targeting the CXCL10-CXCR3 axis while avoiding generalized immunosuppression, may be of therapeutic significance. Based on preclinical evidence for immunoregulatory properties of vitamin D receptor agonists, we propose that a less hypercalcemic vitamin D analogue, BXL-01-0029, might have the potential to contribute to rejection management. We investigated the effect of BXL-01-0029 on CXCL10 secretion induced by proinflammatory stimuli, both in human isolated cardiomyocytes (Hfcm) and purified CD4+ T cells. Mycophenolic acid (MPA), the active agent of mycophenolate mofetil, was used for comparison. BXL-01-0029 inhibited IFNgamma and TNFalpha-induced CXCL10 secretion by Hfcm more potently than MPA, impairing cytokine synergy and pathways. BXL-01-0029 reduced also CXCL10 protein secretion and gene expression by CD4+ T cells. Furthermore, BXL-01-0029 did not exert any toxic effect onto both cell types, suggesting its possible use as a dose-reducing agent for conventional immunosuppressive drugs in clinical transplantation.

The first year post-heart transplantation: use of immunosuppressive drugs and early complications

A large number of heart transplants are performed annually in different transplant centers in the United States. This is partly because of the improved survival of patients who undergo cardiac transplantation, thus making it a more viable option in the management of end-stage heart failure. The survival benefit after heart transplantation is a result of newer immunosuppressive drug regimens and a better understanding of their effects and interactions. Several studies, mostly involving a small number of patients, describe use and comparison of the many distinct immunosuppressive drugs available to date. Interestingly, many transplant centers perform in-house typical induction treatment regimens because of their own experience and intra-institutional preference. This review summarizes current practices of immunosuppressive drug therapy in the first year post-heart transplant based on the available clinical evidence and discusses future options of heart transplant immunosuppressive drug therapies.

Influence of immunosuppressive regimens on short-term morbidity and mortality in heart transplantation

BACKGROUND

The goal of immunosuppressive therapy in heart transplantation is to maximize safety and efficacy while minimizing morbidity and mortality. We now have numerous drug combinations, but few have been compared with each other.

AIM

To compare various immunosuppressive regimens assessing morbidity and mortality at one yr.

METHODS

A total of 351 patients transplanted between 1989 and 2005 were included and grouped by immunosuppressive regimen into group 1 (n = 52): Muronomab (OKT3) 10 d, cyclosporine (CSA), azathioprine (AZA), steroids; group 2 (n = 193): OKT3 seven d, CSA, AZA, steroids; group 3 (n = 22): OKT3 seven d, CSA, mycophenolate mofetil (MMF), steroids; and group 4 (n = 84): interleukin-2 antagonists (IL-2), CSA, MMF, steroids.

RESULTS

The incidence of acute graft failure and treated rejection was similar between groups (17% and 78% respectively). We found a statistically significant difference in the incidence of infections (p < 0.001), renal dysfunction (p = 0.011) and in diabetes mellitus (p = 0.023). There were no differences in survival at 30 d (97%), but differences were found at one yr (p = 0.011). The multivariate analysis showed a strong association between mortality and infection (p = 0.001) and between survival and the group 4 regimen (p < 0.001).

CONCLUSION

There are differences in survival at one yr of heart transplant patients depending on the immunosuppressive regimen used. The best combination was induction with IL-2 antagonists, followed by CSA, MMF and steroids.