New-onset graft dysfunction after heart transplantation—incidence and mechanism-related outcomes

Feasibility and prognostic value of tissue motion annular displacement in patients with heart transplantation

BACKGROUND

Tissue motion of mitral annular displacement (TMAD) assessment has proved to be an effective method for several cardiovascular diseases including hypertrophic cardiomyopathy, heart failure, non-ST-elevation myocardial infarction, etc. However, there are no studies exploring the feasibility of TMAD in heart transplantation (HT) recipients, and the predictive value of this parameter for adverse outcomes in these patients remains unknown. Consequently, this study aimed to evaluate the feasibility of TMAD in the evaluation of left ventricular (LV) systolic function in clinically well adult HT patients, and further investigate the prognostic value of TMAD.

METHODS

Echocardiography was performed in 155 adult HT patients and 49 healthy subjects. All the subjects were examined by conventional transthoracic two-dimensional echocardiography and two-dimensional speckle tracking echocardiography (2D-STE) with evaluation of the LV end-diastolic diameter, LV end-diastolic volume index, LV end-systolic volume index, interventricular septal thickness, left atrial diameter, mitral annular plane systolic excursion (MAPSE), LV ejection fraction (LVEF), TMAD and LV global longitudinal strain (LVGLS). The end point was defined as all-causes mortality or posttransplant related hospitalization during follow up. Cox proportional hazards regression was performed to evaluate the prognostic value of the parameters for predicting poor outcomes in HT patients.

RESULTS

A significant positive correlation was found between the measurements of TMAD and LVGLS (r = .714, p < .001). TMAD obtained by 2D-STE had good reproducibility. The LVGLS and TMAD were significantly lower in HT group than in control group (both p < .001). In HT patients, compared with event free group, adverse outcome group displayed reduced TMAD and LVGLS, and elevated age (p < .001, < .001, = .017, respectively). Patients with higher TMAD (> 9.1 mm) had comparatively better survival when stratified by cutoff value (log-rank p < .001). LVGLS and TMAD were independently associated with adverse outcomes in multivariable analysis (both p < .001).

CONCLUSION

Assessment of TMAD is effective for evaluating LV longitudinal systolic function and predicting adverse outcomes in clinically well adult HT patients.

Early left ventricular systolic function is a more sensitive predictor of adverse events after heart transplant

BACKGROUND

First-phase ejection fraction (EF1) is a novel measure of early changes in left ventricular systolic function. This study was to investigate the prognostic value of EF1 in heart transplant recipients.

METHODS

Heart transplant recipients were prospectively recruited at the Union Hospital, Wuhan, China between January 2015 and December 2019. All patients underwent clinical examination, biochemistry measures [brain natriuretic peptide (BNP) and creatinine] and transthoracic echocardiography. The primary endpoint was a combined event of all-cause mortality and graft rejection.

RESULTS

In 277 patients (aged 48.6 ± 12.5 years) followed for a median of 38.7 [26.8-45.0] months, there were 35 (12.6%) patients had adverse events including 20 deaths and 15 rejections. EF1 was negatively associated with BNP (β = -0.220, p < 0.001) and was significantly lower in patients with events compared to those without. EF1 had the largest area under the curve in ROC analysis compared to other measures. An optimal cut-off value of 25.8% for EF1 had a sensitivity of 96.3% and a specificity of 97.1% for prediction of events. EF1 was the most powerful predictor of events with hazard ratio per 1% change in EF1: 0.628 (95%CI: 0.555-0.710, p < 0.001) after adjustment for left ventricular ejection fraction and global longitudinal strain.

CONCLUSIONS

Early left ventricular systolic function as measured by EF1 is a powerful predictor of adverse outcomes after heart transplant. EF1 may be useful in risk stratification and management of heart transplant recipients.

Cardiac magnetic resonance imaging in detection of progressive graft dysfunction in pediatric heart transplantation

BACKGROUND

Chronic graft failure (CGF) in pediatric heart transplant (PHT) is multifactorial and may present with findings of fibrosis and microvessel disease (MVD) on endomyocardial biopsy (EMB). There is no optimal CGF surveillance method. We evaluated associations between cardiac magnetic resonance imaging (CMR) and historical/EMB correlates of CGF to assess CMR's utility as a surveillance method.

METHODS

Retrospective analysis of PHT undergoing comprehensive CMR between September 2015 and January 2022 was performed. EMB within 6 months was graded for fibrosis (scale 0-5) and MVD (number of capillaries with stenotic wall thickening per field of view). Correlation analysis and logistic regression were performed.

RESULTS

Forty-seven PHT with median age at CMR of 15.7 years (11.6, 19.3) and time from transplant of 6.4 years (4.1, 11.0) were studied. Cardiac allograft vasculopathy (CAV) was present in 11/44 (22.0%) and historical rejection in 14/41 (34.2%). CAV was associated with higher global T2 (49.0 vs. 47.0 ms; p = 0.038) and peak T2 (57.0 vs. 53.0 ms; p = 0.013) on CMR. Historical rejection was associated with higher global T2 (49.0 vs. 47.0 ms; p = 0.007) and peak T2 (57.0 vs. 53.0 ms; p = 0.03) as well as global extracellular volume (31.0 vs. 26.3%; p = 0.03). Higher fibrosis score on EMB correlated with smaller indexed left ventricular mass (rho = -0.34; p = 0.019) and greater degree of MVD with lower indexed left ventricular end-diastolic volume (rho = -0.35; p = 0.017).

CONCLUSION

Adverse ventricular remodeling and abnormal myocardial characteristics on CMR are present in PHT with CAV, historical rejection, as well as greater fibrosis and MVD on EMB. CMR has the potential use for screening of CGF.

De Novo Donor-Specific Antibodies after Heart Transplantation: A Comprehensive Guide for Clinicians

Antibodies directed against donor-specific human leukocyte antigens (HLAs) can be detected de novo after heart transplantation and play a key role in long-term survival. De novo donor-specific antibodies (dnDSAs) have been associated with cardiac allograft vasculopathy, antibody-mediated rejection, and mortality. Advances in detection methods and international guideline recommendations have encouraged the adoption of screening protocols among heart transplant units. However, there is still a lack of consensus about the correct course of action after dnDSA detection. Treatment is usually started when antibody-mediated rejection is present; however, some dnDSAs appear years before graft failure is detected, and at this point, damage may be irreversible. In particular, class II, anti-HLA-DQ, complement binding, and persistent dnDSAs have been associated with worse outcomes. Growing evidence points towards a more aggressive management of dnDSA. For that purpose, better diagnostic tools are needed in order to identify subclinical graft injury. Cardiac magnetic resonance, strain techniques, or coronary physiology parameters could provide valuable information to identify patients at risk. Treatment of dnDSA usually involves plasmapheresis, intravenous immunoglobulin, immunoadsorption, and ritxumab, but the benefit of these therapies is still controversial. Future efforts should focus on establishing effective treatment protocols in order to improve long-term survival of heart transplant recipients.

Prognostic value of right ventricular three-dimensional speckle-tracking strain in adult heart transplantation patients

We aimed to investigate the prognostic value of three-dimensional right ventricular free wall longitudinal strain (3D-RV FWLS) in adult heart transplantation (HTx) patients, taking three-dimensional left ventricular global longitudinal strain (3D-LV GLS) into account. We prospectively enrolled 155 adult HTx patients. Conventional right ventricular (RV) function parameters, two-dimensional (2D) RV FWLS, 3D-RV FWLS, RV ejection fraction (RVEF), and 3D-LV GLS were obtained in all patients. All patients were followed for the endpoint of death and major adverse cardiac events. After a median follow-up of 34 months, 20 (12.9%) patients had adverse events. Patients with adverse events had higher incidence of previous rejection, lower hemoglobin, and lower 2D-RV FWLS, 3D-RV FWLS, RVEF and 3D-LV GLS (P < 0.05). In multivariate Cox regression, Tricuspid annular plane systolic excursion (TAPSE), 2D-RV FWLS, 3D-RV FWLS, RVEF and 3D-LV GLS were independent predictors of adverse events. The Cox model using 3D-RV FWLS (C-index = 0.83, AIC = 147) or 3D-LV GLS (C-index = 0.80, AIC = 156) was observed to predict adverse events more accurately than that with TAPSE, 2D-RV FWLS, RVEF or traditional risk model. Moreover, when added in nested models including previous ACR history, hemoglobin levels, and 3D-LV GLS, the continuous NRI (0.396, 95% CI 0.013 ~ 0.647; P = 0.036) of 3D-RV FWLS was significant. 3D-RV FWLS is a stronger independent predictor of adverse outcomes, and provides additive predictive value over 2D-RV FWLS and conventional echocardiographic parameters in adult HTx patients, taking 3D-LV GLS into account.

Predictive Parameters of Decreased Left Ventricular Global Longitudinal Strain at 1 Month After Pediatric Heart Transplantation

Previous reports indicate that the decreased left ventricular global longitudinal strain (LVGLS) seen in the early postoperative period of pediatric heart transplant patients generally recovers over the course of 1-2 years. In this study, we investigate the predictive capacity of preoperative parameters on the LVGLS decline seen at 1 month post transplant. Forty-six transplant subjects with 2D echocardiographic images sufficient for speckle tracking echocardiography were enrolled. We excluded patients diagnosed with cardiac allograft vasculopathy or with an episode of rejection 1 month before or after their echocardiographic examinations. The mean LVGLS was significantly reduced at 1 month when compared to 1 year following transplant (- 15.5% vs. - 19.4%, respectively, p < 0.001). The predictors of LVGLS that decline at 1 month were the LV mass z-score [odds ratio (OR) 1.452; 95% confidence interval (CI) 1.007-2.095, p = 0.046], recipient age (OR 1.124; 95% CI 1.015-1.245, p = 0.025), and donor age (OR 1.081; 95% CI 1.028-1.136, p = 0.002) in the univariate logistic regression analyses. Although multivariate analysis yielded no significant predictors, higher LV mass z-scores showed a trend associated with the decline of LVGLS (p = 0.087). The donor/recipient weight ratio was associated with the LV mass z-score (R² = 0.412, p < 0.001).

Outcomes of mechanical support for cardiogenic shock associated with late cardiac allograft failure

BACKGROUND

Late graft failure (LGF) is an unresolved issue after orthotopic heart transplant (OHT). In this study, we report characteristics and outcomes of severe LGF requiring mechanical circulatory support (MCS).

METHODS

All patients undergoing OHT from 2000 to 2018 at our center were reviewed. Patients re-admitted to the hospital for late graft failure (>3 months after initial discharge) and developing cardiogenic shock requiring MCS were identified. Outcomes and mortality were evaluated.

RESULTS

Twenty-six patients were identified. Median age was 37.3 years (interquartile range: 28.2-47.6) and 69% were male. Median time from initial transplant to MCS was 2.9 years. Etiology of graft failure was rejection in 19 patients (73%), transplant coronary artery disease (tCAD) in 3 (12%), with mixed tCAD or rejection in 4 (15%).

Cardiac allograft vasculopathy: Incidence and predictors in a single-center cohort

INTRODUCTION AND AIMS

Cardiac allograft vasculopathy (CAV) is one of the most significant complications after orthotopic heart transplantation. We aimed to investigate the incidence and predictors of CAV in a large cohort of orthotopic heart transplantation patients.

METHODS

We conducted a retrospective analysis on a prospective cohort of 233 patients who underwent transplantation between November 2003 and May 2014. Baseline clinical data and invasive coronary angiograms (n=712) performed as part of the follow-up program were analyzed by two independent investigators.

RESULTS

We included 157 male and 45 female patients with a median age of 66 years. A third of patients had previous ischemic heart disease, 30% peripheral arterial disease, 37% hypertension and 47% dyslipidemia, and 17% were smokers. Acute moderate or severe rejection occurred in 42 patients during the first year. Over a median follow-up of 2920 days, 18% were diagnosed with CAV, with an incidence of 2.91 cases per 100 person-years. Predictors of CAV were previous ischemic heart disease (HR 2.32, 95% CI 1.21-4.45, p=0.01), carotid artery disease (HR 2.44, 95% CI 1.27-4.71, p<0.01), and donor age (HR 1.04, 95% CI 1.00-1.07, p=0.01).

CONCLUSION

In a single-center cohort of orthotopic heart transplantation patients, predictors of CAV were previous ischemic heart disease, carotid artery disease and donor age.

The meaning of donor-specific antibodies after heart transplant

PURPOSE OF REVIEW

Antibody-mediated rejection (AMR) is a major contributor of impaired long-term survival after heart transplantation (HTx). The presence of circulating donor-specific antihuman leukocyte antigen (HLA) antibodies (DSAs) is considered as a mandatory criterion for AMR after HTx. DSA are known prognostic biomarkers of outcome, for example, recipients with de-novo DSA have a three-fold increased risk of mortality.

RECENT FINDINGS

Although the awareness of the impact and prognosis of DSA on the survival has been increased in the HTx community over the last decade, the management of DSA pre and posttransplant varies among centers and is mainly based on the experience of transplant physicians. Thus, firm consensus strategies for each HTx recipient should be established by a center advisory board of experts in the field of HLA genetics, transplantation immunology, and HTx to evaluate the immunological risk preoperatively and also continuously during the posttransplant course. Consequently, the recent advances of invasive and noninvasive diagnostic tools should be applied, according to the risk, laboratory findings, and clinical events of the recipient. Such individual strategy will result in tailored therapeutic options.

SUMMARY

Novel standards for the management of DSA in HTx recipients on the basis of an interdisciplinary approach of experts will improve diagnostics for personalized medicine.

Quantitative myocardial tissue characterization by cardiac magnetic resonance in heart transplant patients with suspected cardiac rejection

Distinct histopathologic changes occur in acute cellular rejection (ACR), antibody-mediated rejection (AMR), and biopsy-negative rejection (BNR). Cardiovascular magnetic resonance (CMR)-based myocardial tissue characterization can be used to quantify these changes. We assessed T1, T2, and extracellular volume fraction (ECV) by CMR in patients with subtypes of rejection. T1, T2, and ECV were quantified at the mid-ventricular level and compared between patients with and without rejection. The association between quantitative tissue characteristics and the combined outcome of death, retransplantation, heart failure hospitalization, or myocardial infarction was evaluated with a Cox-proportional hazards model. In 46 patients, mean age 53.3 ± 13.7 years, 71.7% male, at a median of 7.4 years from transplant, average myocardial T1 was increased in BNR compared with no rejection (1057 vs 1012 msec, P = .006). Average myocardial T2 was elevated in all types of rejection, P < .05. In a cox-proportional hazards model, higher T2 values were associated with an increase in the combined clinical outcome (adjusted HR 1.21, 95% CI 1.06-1.37, P = .004) after adjusting for left ventricular mass index. Myocardial tissue characteristics are abnormal in all subtypes of rejection, and abnormal T2 quantified by CMR provides additional prognostic value.

The clinical impact of donor-specific antibodies in heart transplantation

Donor-specific antibodies (DSA) are integral to the development of antibody-mediated rejection (AMR). Chronic AMR is associated with high mortality and an increased risk for cardiac allograft vasculopathy (CAV). Anti-donor HLA antibodies are present in 3-11% of patients at the time of heart transplantation (HTx), with de novo DSA (predominantly anti-HLA class II) developing post-transplant in 10-30% of patients. DSA are associated with lower graft and patient survival after HTx, with one study suggesting a three-fold increase in mortality in patients who develop de novo DSA (dnDSA). DSA against anti-HLA class II, notably DQ, are at particularly high risk for graft loss. Although detection of DSA is not a criterion for pathologic diagnosis of AMR, circulating DSA are found in almost all cases of AMR. MFI thresholds of ~5000 for DSA against class I antibodies, 2000 against class II antibodies, or an overall cut-off of 5-6000 for any DSA, have been suggested as being predictive for AMR. There is no firm consensus on pre-transplant strategies to treat HLA antibodies, or for the elimination of antibodies after diagnosis of AMR. Minimizing the risk of dnDSA is rational but data on risk factors in HTx are limited. The effect of different immunosuppressive regimens is largely unexplored in HTx, but studies in kidney transplantation emphasize the importance of adherence and maintaining adequate immunosuppression. One study has suggested a reduced risk for dnDSA with rabbit antithymocyte globulin induction. Management of DSA pre- and post-HTx varies but typically most centers rely on a plasmapheresis or immunoadsorption, with or without rituximab and/or intravenous immunoglobulin. Based on the literature and a multi-center survey, an algorithm for a suggested surveillance and therapeutic strategy is provided.

Symptom Experience, Self-Care Adherence, and Quality of Life Among Heart Transplant Recipients in South Korea

Among heart transplant recipients, the perceived quality of life (QOL) is a key indicator of successful transplantation. QOL is affected by posttransplant treatments, including immunosuppressive therapy or self-care. However, few studies have evaluated QOL after heart transplantation in South Korea. This study aimed to investigate posttransplant symptoms associated with immunosuppressant, self-care adherence, and QOL in 105 heart transplant recipients in South Korea. Educational status (β = −1.05, p = .013), symptoms (β = −3.98, p = .004), and diet (β = 0.38, p < .001) were found to affect subjects’ overall QOL. In addition to these factors, caregivers and the duration of heart disease (years) were found to be influencing factors, depending on the individual QOL subdimension. These findings highlight the importance of controlling symptoms and managing medications as well as of self-care (particularly dietary compliance). Educational programs targeting beneficial changes in lifestyle, including diet, are needed.

Postoperative management of heart transplantation patients

Heart transplant recipients are at risk for a number of post-transplantation complications such as graft dysfunction, rejection, and infection. The rates of many complications are decreasing over time, and prognosis is improving. However, these patients continue to experience significant morbidity and mortality. This review focuses on the optimal management of heart transplant recipients in the postoperative period, based on current knowledge. More information is needed about the best ways to predict, prevent, and treat primary graft dysfunction, right ventricular failure, and cellular and antibody-mediated rejection.

Feasibility and interpretation of global longitudinal strain imaging in pediatric heart transplant recipients

Evaluation of myocardial mechanics after heart transplant is important in monitoring allograft function and identifying rejection. Speckle tracking global longitudinal strain (GLS) may be more sensitive to early regional changes from rejection. This study aimed to determine feasibility of GLS in pediatric hearts during surveillance echocardiograms, compare their GLS to published norms (-18% to -22%), and assess association of GLS with other indices of graft function. Retrospective review of transplant echocardiograms from 2013 to 2014. Philips QLAB was used for post-acquisition GLS analysis. Multiple linear regression was used to assess the association of GLS with echocardiographic/catheterization indices, and B-type natriuretic peptide (BNP). Forty-seven patients (84 studies) were included. Calculation of GLS was feasible in 82 studies (97%) with inter- and intra-observer variability of 0.71 and 0.69. Patients (n=9) with rejection had GLS of -16.4% (SD=3.5%) compared to those without [-16.8% (SD=3.7%)]. GLS worsened linearly with increasing Ln(BNP) (P=<.001), left ventricular volume in diastole (P=<.001), septal a' wave (P=<.001), and pulmonary capillary wedge pressure (P=<.001). Speckle tracking-based GLS is feasible and reproducible in pediatric heart recipients and is reduced at baseline. The role of GLS and BNP in detecting early systolic dysfunction warrants further investigation.

Correlation of Circulating Complement-Fixing Donor-Specific Antibodies Identified by the C1q Assay and Presence of C4d in Endomyocardial Biopsy Specimens

OBJECTIVES

Donor-specific antibodies (DSAs) are associated with increased cardiac graft loss. We applied a C1q solid-phase assay in parallel with the standard immunoglobulin G (IgG) single antigen bead (SAB) assay to examine the correlation of circulating complement-fixing donor-specific antibodies and the presence of C4d in endomyocardial biopsy (EMB) specimens.

METHODS

We retrospectively studied the relationship of C1q+ DSAs and C4d immunofluorescence (IF) in 49 EMB specimens from 44 heart transplant recipients who had concurrent EMB, C4d IF, and DSA measurements. We applied a C1q SAB in parallel with the standard IgG SAB assay to examine the DSA profiles in heart transplant patients posttransplant.

RESULTS

A better concordance is observed between C1q+ DSAs with C4d IF+ compared with IgG DSAs with C4d IF + (40% vs 24%, P = .02). However, the correlation of C1q DSAs with C4d IF is not statistically significant (P = .24). Importantly, C1q+ DSAs were observed in 16 of 17 cases with C4d IF+; 24 cases had circulating C1q+ DSAs without detectable C4d staining, suggesting that that the presence of C1q+ DSAs may precede the detection of C4d deposition in EMB specimens and/or the development of antibody-mediated rejection.

CONCLUSIONS

In this cohort of 44 patients, no significant correlation was observed between circulating C1q DSAs and C4d IF in EMB specimens. Additional studies are needed to further evaluate the association of C1q DSAs with EMB specimens and C4d staining.

Comparison of whole blood and peripheral blood mononuclear cell gene expression for evaluation of the perioperative inflammatory response in patients with advanced heart failure

BACKGROUND

Heart failure (HF) prevalence is increasing in the United States. Mechanical Circulatory Support (MCS) therapy is an option for Advanced HF (AdHF) patients. Perioperatively, multiorgan dysfunction (MOD) is linked to the effects of device implantation, augmented by preexisting HF. Early recognition of MOD allows for better diagnosis, treatment, and risk prediction. Gene expression profiling (GEP) was used to evaluate clinical phenotypes of peripheral blood mononuclear cells (PBMC) transcriptomes obtained from patients' blood samples. Whole blood (WB) samples are clinically more feasible, but their performance in comparison to PBMC samples has not been determined.

METHODS

We collected blood samples from 31 HF patients (57±15 years old) undergoing cardiothoracic surgery and 7 healthy age-matched controls, between 2010 and 2011, at a single institution. WB and PBMC samples were collected at a single timepoint postoperatively (median day 8 postoperatively) (25-75% IQR 7-14 days) and subjected to Illumina single color Human BeadChip HT12 v4 whole genome expression array analysis. The Sequential Organ Failure Assessment (SOFA) score was used to characterize the severity of MOD into low (≤ 4 points), intermediate (5-11), and high (≥ 12) risk categories correlating with GEP.

RESULTS

Results indicate that the direction of change in GEP of individuals with MOD as compared to controls is similar when determined from PBMC versus WB. The main enriched terms by Gene Ontology (GO) analysis included those involved in the inflammatory response, apoptosis, and other stress response related pathways. The data revealed 35 significant GO categories and 26 pathways overlapping between PBMC and WB. Additionally, class prediction using machine learning tools demonstrated that the subset of significant genes shared by PBMC and WB are sufficient to train as a predictor separating the SOFA groups.

CONCLUSION

GEP analysis of WB has the potential to become a clinical tool for immune-monitoring in patients with MOD.

Correlations of lymphocyte subset infiltrates with donor-specific antibodies and acute antibody-mediated rejection in endomyocardial biopsies

BACKGROUND

Acute antibody-mediated rejection (AMR) is a major complication after heart transplantation, posing a significant risk for allograft failure, cardiac allograft vasculopathy, and poor survival. While the inflammatory milieu of cellular rejection and Quilty lesions is well known, the immunologic components of AMR are not well understood. Our aim was to better define the immunophenotype of infiltrating lymphocytes in biopsies with AMR, specifically in relation to donor-specific antibodies to human leukocyte antigen (HLA) class I, II, or both.

METHOD

We performed a retrospective analysis of cardiac transplant patients with concurrent endomyocardial biopsies (EMB), donor-specific antibody (DSA) measurements, and immunofluorescence for C4d at our institution (2005-2011). DSA was evaluated against HLA class I and class II specificities pre- and posttransplant using flow cytometry and/or Luminex bead assays. Acute cellular rejection (ACR) and pathologic AMR (pAMR) were based on the International Society for Heart and Lung Transplantation 2005/2013 reports. Immunohistochemical analysis for CD3, CD4, CD8, and CD79a was performed using standard immunohistochemical protocols on one formalin-fixed, paraffin-embedded EMB from each patient. The number of lymphocytes expressing each protein was enumerated microscopically at 400×. Ratios of T:B cells and CD4:CD8 T cells were then calculated for each EMB.

RESULTS

Seventy-nine cardiac transplant patients who had pre- and posttransplant DSA measurements were analyzed. Of these 79 patients, 37 had DSA against HLA class I, HLA class II, or both. Of patients with DSA, the average CD4:CD8 ratio in the EMB was 0.80, while those with only ACR had a CD4:CD8 ratio of 1.49. Interestingly, the T:B cell ratio in patients with and without DSA was 5.7 and 5.5, respectively.

CONCLUSION

Cardiac transplant patients with DSA against HLA have more CD8 cytotoxic T cells than CD4 helper T cells in the EMB lymphocytic infiltrate compared with patients without DSA against HLA. The inflammatory infiltrate T:B cell ratio was similar in patients both with and without DSA. The relative increase of cytotoxic T cells in EMB while the patient has DSA suggests a possible pathogenic role of these cells and may aid in the diagnosis and treatment of AMR.

The role of donor-specific antibodies in acute cardiac allograft dysfunction in the absence of cellular rejection

BACKGROUND

Acute allograft dysfunction (AAD) is an important cause of morbidity among heart transplant recipients. The role of donor-specific antibodies (DSAs) in AAD, with the increasing use of single antigen bead (SAB) assays that have improved the ability to detect DSA, remains unclear.

METHODS

We retrospectively reviewed 329 heart transplant recipients followed up at our institution. AAD was defined as an acute decline in left ventricular ejection fraction to less than 50% and a decrement of 10% or higher compared to baseline in the absence of cellular rejection. Patients with AAD were compared with matched 30 heart transplant controls.

RESULTS

There were 10 (3%) patients with AAD, 4 (40%) had DSA detectable by SAB assay compared to 16 (53%) controls (P=0.43). Peak DSA mean fluorescent intensity (MFI) levels were significantly higher at baseline (class I and class II) in AAD compared to controls. DSA MFI values increased at the time of AAD and returned to baseline values during follow-up for these patients with AAD (P<0.05) but remained unchanged over time for controls. Six (60%) patients with AAD and 1 (3%) control had antibody-mediated rejection (AMR) by endomyocardial biopsy (P<0.01). There were 4 (40%) patients with AAD with no DSA or AMR.

CONCLUSIONS

AAD after heart transplant is a heterogeneous process characterized by 1) AMR and DSA, 2) AMR but no DSA, and 3) no AMR or DSA. The presence of DSA is not associated with AAD, but the quantity assessed by MFI levels may play a role.

Cost-Effectiveness of Routine Surveillance Endomyocardial Biopsy After 12 Months Post–Heart Transplantation

Background—

Despite low risk of late rejection after heart transplant (HT), surveillance endomyocardial biopsies (EMBs) are often continued for years. We assessed the cost-effectiveness of routine EMB after 12 months post-HT.

Methods and Results—

Markov model compared the following surveillance EMB strategies to baseline strategy of stopping EMB 12 months post-HT: (1) every 4 months during year 2 post-HT, (2) every 6 months during year 2, (3) every 4 months for years 2 to 3, and (4) every 6 months for years 2 to 3. Patients entered the model 12 months post-HT and were followed until 36 months. In all strategies, patients had EMB with symptoms; in biopsy strategies after 12 months, EMB was also performed as scheduled regardless of symptoms. One-way and Monte Carlo sensitivity analyses were performed. Stopping EMB at 12 months was dominant (more effective, less costly), saving $2884 per patient compared with the next best strategy (every 6 months for year 2) and gaining 0.0011 quality-adjusted life-years. Increasing the annual risk of asymptomatic rejection in years 2 to 3 from previously reported 2.5% to 8.5% resulted in the biopsy every 6 months for year 2 strategy gaining 0.0006 quality-adjusted life-years, but cost $4 913 599 per quality-adjusted life-year gained. EMB for 12 months was also no longer dominant when mortality risk from untreated asymptomatic rejection approached 11%; competing strategies still cost >$200 000 per quality-adjusted life-year as that risk approached 99%.

Conclusions—

Surveillance EMB for 12 months post-HT is more effective and less costly than EMB performed after 12 months, unless risks of asymptomatic cellular rejection and its mortality are strikingly higher than previously observed.

Correlation of circulating donor-specific anti-HLA antibodies and presence of C4d in endomyocardial biopsy with heart allograft outcomes: a single-center, retrospective study

BACKGROUND

Donor-specific antibodies (DSA) are associated with increased cardiac graft loss and cardiac vasculopathy (CAV). Detection of antibody-mediated rejection (AMR) relies on graft dysfunction, C4d immunofluorescence (IF) and DSA.

METHODS

We retrospectively studied the relationship of DSA, endomyocardial biopsy (EMB) and C4d IF to cardiac transplant outcomes. DSA were evaluated against HLA class I and II specificities, both pre- and post-transplant, using microbead-based assays.

RESULTS

Of 626 cardiac transplant patients, 109 with concurrent EMBs and C4d IF and DSA measurement were included in this study. In patients with and without DSA, CAV occurred in 31% and 13% and acute cellular rejection (ACR) in 100% and 84%, respectively. One hundred ten of 170 EMBs procured during episodes of graft dysfunction had concurrent DSA. In these patients, C4d IF correlated better with DSA to class I or both class I and II and less so in patients with DSA to class II. Graft failure (GF) rates of 40%, 29% and 58% with average times to GF of 33, 77 and 48 months were seen in patients with DSA to class I, II or both, respectively.

CONCLUSIONS

Patients with DSA to class I or to both class I and II showed a correlation with C4d IF and had higher GF rates compared to patients with DSA to only class II or no DSA; patients with DSA to class II remained at risk for CAV. Episodes of ACR and CAV, but not AMR, appeared to be more frequently associated with graft dysfunction in patients with circulating DSA.

Gene Expression Signatures of Peripheral Blood Mononuclear Cells during the Early Post-Transplant Period in Patients Developing Cardiac Allograft Vasculopathy

Background. Cardiac allograft vasculopathy (CAV) is a major cause of graft loss and death after heart transplantation. Currently, no diagnostic methods are available during the early post-transplant period to accurately identify patients at risk of CAV. We hypothesized that PBMC gene expression profiles (GEP) can identify patients at risk of CAV. Methods. We retrospectively analyzed a limited set of whole-genome PBMC microarrays from 10 post-transplant patients who did (n = 3) or did not (n = 7) develop advanced grade CAV during their long-term follow-up. We used significance analysis of microarrays to identify differentially expressed genes and High-Throughput GoMiner to assess gene ontology (GO) categories. We corroborated our findings by retrospective analysis of PBMC real-time PCR data from 33 patients. Results. Over 300 genes were differentially expressed (FDR < 5%), and 18 GO-categories including “macrophage activation”, “Interleukin-6 pathway”, “NF-KappaB cascade”, and “response to virus” were enriched by these genes (FDR < 5%). Out of 8 transcripts available for RT-PCR analysis, we confirmed 6 transcripts (75.0%) including FPRL1, S100A9, CXCL10, PRO1073, and MMP9 (P < .05). Conclusion. Our pilot data suggest that GEP of PBMC may become a valuable tool in the evaluation of patients at risk of CAV. Larger prospectively designed studies are needed to corroborate our hypothesis.