Identification and Characterization of Trajectories of Cardiac Allograft Vasculopathy After Heart Transplantation: A Population-Based Study.

BACKGROUND: Cardiac allograft vasculopathy (CAV) is a major contributor of heart transplant recipient mortality. Little is known about the prototypes of CAV trajectories at the population level. We aimed to identify the different evolutionary profiles of CAV and to determine the respective contribution of immune and nonimmune factors in CAV development. METHODS: Heart transplant recipients were from 4 academic centers (Pitié-Salpêtrière and Georges Pompidou Hospital, Paris, Katholieke Universiteit Leuven, and Cedars-Sinai, Los Angeles; 2004-2016). Patients underwent prospective, protocol-based monitoring consisting of repeated coronary angiographies together with systematic assessments of clinical, histological, and immunologic parameters. The main outcome was a prediction for CAV trajectory. We identified CAV trajectories by using unsupervised latent class mixed models. We then identified the independent predictive variables of the CAV trajectories and their association with mortality. RESULTS: A total of 1301 patients were included (815 and 486 in the European and US cohorts, respectively). The median follow-up after transplantation was 6.6 (interquartile range, 4-9.1) years with 4710 coronary angiographies analyzed. We identified 4 distinct profiles of CAV trajectories over 10 years. The 4 trajectories were characterized by (1) patients without CAV at 1 year and nonprogression over time (56.3%), (2) patients without CAV at 1 year and late-onset slow CAV progression (7.6%), (3) patients with mild CAV at 1 year and mild progression over time (23.1%), and (4) patients with mild CAV at 1 year and accelerated progression (13.0%). This model showed good discrimination (0.92). Among candidate predictors assessed, 6 early independent predictors of these trajectories were identified: donor age (P<0.001), donor male sex (P<0.001), donor tobacco consumption (P=0.001), recipient dyslipidemia (P=0.009), class II anti-human leukocyte antigen donor-specific antibodies (P=0.004), and acute cellular rejection ≥2R (P=0.028). The 4 CAV trajectories manifested consistently in the US independent cohort with similar discrimination (0.97) and in different clinical scenarios, and showed gradients for overall-cause mortality (P<0.001). CONCLUSIONS: In a large multicenter and highly phenotyped prospective cohort of heart transplant recipients, we identified 4 CAV trajectories and their respective independent predictive variables. Our results provide the basis for a trajectory-based assessment of patients undergoing heart transplantation for early risk stratification, patient monitoring, and clinical trials. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04117152.

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.

Does ex vivo perfusion lead to more or less intimal thickening in the first-year post-heart transplantation?

BACKGROUND: The Organ Care System (OCS), an ex vivo heart perfusion platform, represents an alternative to the current standard of cold organ storage that sustains the donor heart in a near-physiologic state. Previous reports showed that this system had significantly shortened the cold ischemic time from standard cold storage (CS). However, the effect of reduced ischemic injury against the coronary vascular bed has not been examined by intravascular ultrasound (IVUS). METHODS: Between August 2011 and February 2013, heart transplant (HTx) candidates enrolled in the PROCEED 2 trial were randomized to either CS or OCS. IVUS was performed at 4-6 weeks (baseline) and repeated 1 year after transplantation. The change in maximal intimal thickness (MIT) and other clinical outcomes were examined. RESULTS: Thirty-nine patients were randomized and underwent HTx by OCS (n=16) or CS (n=18). Of these, 18 patients (OCS: n=5, CS: n=13) with paired IVUS were examined. There were no significant differences in the change of MIT and other clinical outcomes between the groups. CONCLUSION: The incidence of cardiac allograft vasculopathy in donor hearts preserved with the OCS versus CS was similar. These results suggest that this ex vivo allograft perfusion system is a promising and valid platform for donor heart transportation.

Acceptable Post-Heart Transplant Outcomes Support Temporary MCS Prioritization in the New OPTN|UNOS Heart Allocation Policy.

BACKGROUND: Temporary mechanical circulatory support (MCS) devices are generally used short term to maintain adequate organ perfusion in patients with advanced heart failure and cardiogenic shock. Unacceptably high waitlist mortality in this cohort motivated changes to heart allocation policy, which recognized the severity of illness by prioritization for temporary MCS and broader sharing in the new U.S. donor heart allocation policy. We evaluated the post-heart transplant outcomes for patients bridged with temporary MCS, a control population not bridged with MCS, and a cohort bridged with durable MCS. METHODS: The heart transplant research database was queried to identify patients bridged with temporary MCS and bridged with durable MCS who went directly to heart transplant in our center. Temporary MCS included Impella, intra-aortic balloon pump, and extracorporeal membrane oxygenation. Post-transplant endpoints were assessed at 30 days, 6 months, and 1 year. RESULTS: From 2010 to 2017, a total of 23 patients were bridged to heart transplant with temporary MCS and 548 were transplanted without MCS bridge. Patients bridged with temporary MCS had younger age, lower body mass index, and higher frequencies of prior blood transfusion and Status 1 (1A/1B) listing at transplant compared to patients not bridged with MCS (all P < .001). Despite the severity of illness in patients bridged with temporary MCS, post-transplant outcomes were indistinguishable from those in patients transplanted without MCS bridge, with no difference in 30-day, 6-month, or 1-year survival or 1-year freedom from cardiac allograft vasculopathy, nonfatal major adverse cardiac events, any-treated rejection, acute cellular rejection, or antibody-mediated rejection (P = .23-.97). Similarly, compared to 157 patients bridged with durable MCS, no differences in post-transplant outcomes were identified for the temporary MCS cohort (P = .15-.94). CONCLUSION: Temporary MCS as a bridge to transplant achieves similar post-transplant outcomes at 1 year compared to no MCS and durable MCS. These encouraging findings support recent changes in the Organ Procurement and Transplantation Network | United Network Organ Sharing (OPTN|UNOS) adult heart allocation policy.

Plasma kallikrein predicts primary graft dysfunction after heart transplant.

BACKGROUND: Primary graft dysfunction (PGD) is the leading cause of early mortality after heart transplant. Pre-transplant predictors of PGD remain elusive and its etiology remains unclear. METHODS: Microvesicles were isolated from 88 pre-transplant serum samples and underwent proteomic evaluation using TMT mass spectrometry. Monte Carlo cross validation (MCCV) was used to predict the occurrence of severe PGD after transplant using recipient pre-transplant clinical characteristics and serum microvesicle proteomic data. Putative biological functions and pathways were assessed using gene set enrichment analysis (GSEA) within the MCCV prediction methodology. RESULTS: Using our MCCV prediction methodology, decreased levels of plasma kallikrein (KLKB1), a critical regulator of the kinin-kallikrein system, was the most predictive factor identified for PGD (AUROC 0.6444 [0.6293, 0.6655]; odds 0.1959 [0.0592, 0.3663]. Furthermore, a predictive panel combining KLKB1 with inotrope therapy achieved peak performance (AUROC 0.7181 [0.7020, 0.7372]) across and within (AUROCs of 0.66-0.78) each cohort. A classifier utilizing KLKB1 and inotrope therapy outperforms existing composite scores by more than 50 percent. The diagnostic utility of the classifier was validated on 65 consecutive transplant patients, resulting in an AUROC of 0.71 and a negative predictive value of 0.92-0.96. Differential expression analysis revealed a enrichment in inflammatory and immune pathways prior to PGD. CONCLUSIONS: Pre-transplant level of KLKB1 is a robust predictor of post-transplant PGD. The combination with pre-transplant inotrope therapy enhances the prediction of PGD compared to pre-transplant KLKB1 levels alone and the resulting classifier equation validates within a prospective validation cohort. Inflammation and immune pathway enrichment characterize the pre-transplant proteomic signature predictive of PGD.

Outcomes of Heart Transplantation in Cardiac Amyloidosis Patients: A Single Center Experience.

BACKGROUND: Indications for heart transplantation are expanding to include amyloid light chain (AL) and transthyretin-related (TTR) amyloidosis. Previously, AL amyloid had been a contraindication to heart transplantation given inferior outcomes. These patients typically have biventricular failure requiring mechanical circulatory support (MCS). We report the outcomes of patients with end-stage cardiac amyloidosis who underwent cardiac transplantation, including some who were bridged to transplantation with a durable biventricular MCS METHODS: The records for patients with cardiac amyloidosis who underwent cardiac transplant between 2010 and 2018 were reviewed. Primary endpoint was post-transplant 1-year survival. Secondary endpoints included 1-year freedom from cardiac allograft vasculopathy (as defined by stenosis ≥ 30% by angiography), nonfatal major adverse cardiac events (myocardial infarction, new congestive heart failure, percutaneous coronary intervention, implantable cardioverter defibrillator/pacemaker implant, stroke), and any rejection. RESULTS: A total of 46 patients received heart transplantation with a diagnosis of either AL or TTR amyloidosis. Of these, 7 patients were bridged to transplantation with a durable biventricular MCS device (6 AL, 1 TTR) and 39 patients were transplanted without MCS bridging. The MCS group consisted of 5 total artificial hearts and 2 biventricular assist devices. The 1-year survival was 91% for the entire cohort, 83% for those with AL amyloidosis, 94% for those with TTR amyloidosis, and 86% for those who received MCS bridging. CONCLUSIONS: Cardiac transplantation can be safely performed in selected amyloidosis patients with reasonable short-term outcomes. Those bridged to transplantation with biventricular MCS appear to have short-term outcomes similar to those transplanted without MCS. Larger numbers and longer observation are required to confirm these findings.

HLA-DQ mismatches stimulate de novo donor specific antibodies in heart transplant recipients.

The development of donor specific antibody is associated with graft rejection and increased mortality in solid organ transplant recipients. The majority of de novo donor specific antibodies (dnDSA) are against HLA-DQ antigens, but it has not been investigated if this is caused by more mismatches in the HLA-DQ locus between the recipient and donor. Here we examined the impact of HLA mismatches in eight HLA loci on the development of dnDSA and on rejection in a large cohort of heart transplant recipients. We evaluated HLA mismatches at the antigen level, the eplet level using HLAMatchmaker, and the epitope level using the PIRCHE algorithm. We found that the majority of dnDSA were against HLA-DQ antigens, and the number of dnDSA per mismatch is highest for HLA-DQ compared to other HLA loci. Furthermore, mismatches of HLA-DQ at the epitope level were associated with antibody-mediated rejection. Our results suggest that HLA mismatches at the HLA-DQ locus are more immunogenic than mismatches at other HLA loci to stimulate the development of dnDSA and to cause graft rejection.

Association of vimentin antibody and other non-HLA antibodies with treated antibody mediated rejection in heart transplant recipients.

Non-human leukocyte antigen (HLA) antibodies have been implicated in heart transplantation rejection. However, targets of non-HLA antibodies remain elusive. Here, we utilized a panel of multiplex beads-based assay to determine the specificity of non-HLA antibodies following heart transplantation. We utilized a selected cohort of recipients who did not have HLA donor specific antibodies, but were diagnosed with antibody mediated rejection and treated for antibody mediated rejection. We found the presence of vimentin antibody was associated with treated antibody mediated rejection. Our results suggest that, in heart transplant recipients who are suspected of AMR but in the absence of HLA donor specific antibodies, non-HLA antibodies should be examined.

Dual-organ transplantation in older recipients: outcomes after heart-kidney transplant versus isolated heart transplant in patients aged ≥65 years.

OBJECTIVES: Combined heart-kidney transplantation has successful outcomes. With an increasing number of patients with end-stage heart disease, there is a high incidence of significant renal insufficiency that may necessitate combined heart-kidney transplant. Outcomes for heart-kidney transplant recipients aged ≥65 years are not well described. METHODS: Between 2010 and 2015, 163 recipients ≥65 years of age were transplanted in a single centre: 12 heart-kidney and 151 isolated heart transplants. Outcomes assessed were estimated glomerular filtration rate at 1, 6 and 12 months after transplant, the need for dialysis, 1-year survival, 1-year freedom from rejection, 1-year freedom from cardiac allograft vasculopathy and 1-year freedom from non-fatal major adverse cardiac events. RESULTS: Recipient ages were 67.8 ± 1.6 and 69.0 ± 2.8 years for heart-kidney transplant and isolated heart transplant, and pretransplant estimated glomerular filtration rates were 26.6 ± 9.4 vs 55.2 ± 18.9, respectively. At 1 month (66.3 ± 31.4 vs 67.2 ± 28.0, P = 0.92), 6 months (68.1 ± 21.3 vs 60.5 ± 19.6, P = 0.20) and 12 months (58.6 ± 21.5 vs 52.4 ± 18.5, P = 0.27) post-transplant, estimated glomerular filtration rate was similar for heart-kidney transplant versus isolated heart transplant. There was a trend towards reduced 1-year freedom from temporary dialysis after heart-kidney transplant relative to isolated heart transplant (75.0% vs 90.4%, P = 0.06) without a difference in 1-year freedom from chronic dialysis (100% vs 95.2%, P = 0.46). There were no differences in 1-year survival, 1-year freedom from any treated rejection, acute cellular rejection, antibody-mediated rejection, cardiac allograft vasculopathy and non-fatal major adverse cardiac events. CONCLUSIONS: For patients ≥65 years old, heart-kidney transplant can achieve outcomes on par with heart transplant alone.

Combined heart and kidney transplantation-Is there a protective effect against cardiac allograft vasculopathy using intravascular ultrasound?

BACKGROUND: Because cardiac and renal disease are physiologically related and often coexist, the prevalence of combined heart and kidney transplantation (HKTx) has significantly increased over the last few years. It has been suggested that combined organ allografts modulate the immune system favorably for one or both allografts resulting in successful clinical outcomes. However, whether the addition of kidney transplantation has a protective immune effect against developing cardiac allograft vasculopathy (CAV) has not been fully investigated. METHODS: From March 2010 to September 2018, 30 HKTx recipients who had baseline (4-6 weeks) and 1-year intravascular ultrasound (IVUS) were matched with 60 isolated heart transplant (HTx-alone) recipients using propensity scores. First-year changes in maximal intimal thickness (MIT), maximal intimal area (MIA), maximal percent stenosis (MPS), percent atheroma volume (PAV), and incidence of rapid plaque progression were compared between the groups. RESULTS: First-year coronary plaque progression was significantly decreased in HKTx recipients compared with HTx-alone recipients by change in the MIT (0.11 ± 0.14 mm vs 0.40 ± 0.32 mm, p < 0.001), MIA (0.52 ± 1.52 mm2 vs 1.86 ± 2.68 mm2, p = 0.002), MPS (2.10% ± 5.64 percentage points vs 7.22% ± 8.59 percentage points, p = 0.001), and PAV (1.62% ± 3.07 percentage points vs 5.90% ± 5.92 percentage points, p < 0.001). Rapid plaque progression occurred in 2 of 30 in HKTx (6.7%) and in 22 of 60 HTx alone (36.7%), p = 0.002. CONCLUSIONS: Combined heart and kidney transplantation is associated with a decrease in CAV by coronary plaque progression on IVUS. These results suggest that HKTx may have an immune modulating benefit over HTx alone.

Use of durable mechanical circulatory support on outcomes of heart-kidney transplantation.

OBJECTIVES: Previous studies have demonstrated that preheart transplant mechanical circulatory support (MCS) can lead to a small but significant increase in mortality. However, data on outcomes of patients with MCS who require simultaneous heart-kidney transplant are limited. METHODS: A retrospective review of simultaneous heart-kidney transplantations (HKTxs) performed at a single institution over a 5-year period was performed. Patients were divided based on the preoperative use of durable MCS. Renal graft-related end points were evaluated, including glomerular filtration rate following transplantation, prevalence of delayed renal graft function and freedom from antibody and cellular-mediated graft rejection. Patient-specific outcomes, including survival and frequency of non-fatal major adverse cardiac events at 1 year, were additionally assessed. RESULTS: During the study period, 50 HKTxs were performed, 14 of which had preoperative MCS. HKTx patients with and without MCS implantations had a similar prevalence of delayed graft function (57.1% vs 50.0%; P = 0.757). A numerical trend was observed towards a reduced glomerular filtration rate 1-month post-transplant in patients without an MCS device (81.2 ± 32.8 vs 64.4 ± 27.5; P = 0.072), but no significant difference was observed at 6 and 12 months. No significant difference was observed on the need for post-transplant renal replacement therapy, non-fatal major adverse cardiac events, freedom from graft rejection and overall survival at 1 year. CONCLUSIONS: The use of preoperative MCS in patients undergoing combined HKTx was not found to affect renal graft function post-transplantation and does not seem to be associated with increase in morbidity or mortality.