Redefining the molecular rejection states in 3230 heart transplant biopsies: Relationships to parenchymal injury and graft survival.

The first-generation Molecular Microscope (MMDx) system for heart transplant endomyocardial biopsies used expression of rejection-associated transcripts (RATs) to diagnose not only T cell-mediated rejection (TCMR) and antibody-mediated rejection (ABMR) but also acute injury. However, the ideal system should detect rejection without being influenced by injury, to permit analysis of the relationship between rejection and parenchymal injury. To achieve this, we developed a new rejection classification in an expanded cohort of 3230 biopsies: 1641 from INTERHEART (ClinicalTrials.gov NCT02670408), plus 1589 service biopsies added to improve the power of the machine learning algorithms. The new system used 6 rejection classifiers instead of RATs and generated 7 rejection archetypes: No rejection, 48%; Minor, 24%; TCMR1, 2.3%; TCMR2, 2.7%; TCMR/mixed, 2.7%; early-stage ABMR, 3.9%; and fully developed ABMR, 16%. Using rejection classifiers eliminated cross-reactions with acute injury, permitting separate assessment of rejection and injury. TCMR was associated with severe-recent injury and late atrophy-fibrosis and rarely had normal parenchyma. ABMR was better tolerated, seldom producing severe injury, but in later biopsies was often associated with atrophy-fibrosis, indicating long-term risk. Graft survival and left ventricular ejection fraction were reduced not only in hearts with TCMR but also in hearts with severe-recent injury and atrophy-fibrosis, even without rejection.

Molecular states associated with dysfunction and graft loss in heart transplants.

BACKGROUND: We explored the changes in gene expression correlating with dysfunction and graft failure in endomyocardial biopsies. METHODS: Genome-wide microarrays (19,462 genes) were used to define mRNA changes correlating with dysfunction (left ventricular ejection fraction [LVEF] ≤ 55) and risk of graft loss within 3 years postbiopsy. LVEF data was available for 1,013 biopsies and survival data for 779 patients (74 losses). Molecular classifiers were built for predicting dysfunction (LVEF ≤ 55) and postbiopsy 3-year survival. RESULTS: Dysfunction is correlated with dedifferentiation-decreased expression of normal heart transcripts, for example, solute carriers, along with increased expression of inflammation genes. Many genes with reduced expression in dysfunction were matrix genes such as fibulin 1 and decorin. Gene ontology (GO) categories suggested matrix remodeling and inflammation, not rejection. Genes associated with the risk of failure postbiopsy overlapped dysfunction genes but also included genes affecting microcirculation, for example, arginase 2, which reduces NO production, and endothelin 1. GO terms also reflected increased glycolysis and response to hypoxia, but decreased VEGF and angiogenesis pathways. T cell-mediated rejection was associated with reduced survival and antibody-mediated rejection with relatively good survival, but the main determinants of survival were features of parenchymal injury. Both dysfunction and graft loss were correlated with increased biopsy expression of BNP (gene NPPB). Survival probability classifiers divided hearts into risk quintiles, with actuarial 3-year postbiopsy survival >95% for the highest versus 50% for the lowest. CONCLUSIONS: Dysfunction in transplanted hearts reflects dedifferentiation, decreased matrix genes, injury, and inflammation. The risk of short-term loss includes these changes but is also associated with microcirculation abnormalities, glycolysis, and response to hypoxia.

Transcatheter tricuspid valve edge-to-edge repair after a heart transplant: a single-centre experience with a novel therapy†.

OBJECTIVES: Tricuspid regurgitation (TR) in patients who had heart transplants is associated with poor outcome. The increased risk for surgical and postoperative complications might be reduced in these vulnerable patients by transcatheter therapies. METHODS: All patients with a prior heart transplant (HTX) undergoing transcatheter edge-to-edge repair in the tricuspid position (T-TEER) were prospectively enrolled in an institutional registry. RESULTS: Seven patients who had heart transplants (5/7 female) at a mean age of 53 [48; 64] and median TRI-SCORE of 14 [7; 22] underwent T-TEER to treat symptomatic TR ≥ IV in an elective (n = 6) and urgent (n = 1) setting, respectively. The median time from HTX to T-TEER was 13 years. A total of 2 (n = 4) and 3 (n = 3) clips were implanted with a technical success in 6/7 (one single- device detachment). TR reduction was effective and durable within a median echocardiographic follow-up time of 10 months (TR baseline vs last follow-up: P = 0.03). Further, significant right ventricular remodelling (right ventricular end-diastolic diameter: 50 mm-36 mm, P = 0.02), decrease in the inferior vena cava diameter (24 mm-18 mm, P = 0.04) and in the gamma-glutamyl-transferase (255 U/l-159 U/l, P = 0.04) was found. Four of 7 patients were free of cardiovascular death (n = 1, 267 days after T-TEER), cardiac redo surgery (n = 1) and heart failure hospitalization (n = 2) and had no further clinical signs of right heart failure. CONCLUSIONS: T-TEER after HTX is feasible and effective regarding TR reduction in a short-term follow-up. The initial results may pave the way for a novel approach in TR management in patients having HTX.

European multicenter study on the real-world use and clinical impact of extracorporeal photopheresis after heart transplantation.

BACKGROUND: Aim of this study was to describe the real-world use of extracorporeal photopheresis (ECP) and assess its impact on clinical outcomes in the modern era of heart transplantation. METHODS: Seven transplant centers from 5 European countries participated in this retrospective, observational, single-arm chart review study. All patients received ECP after heart transplantation in 2015 or later. Data were extracted from medical records between November 2020 and December 2021. RESULTS: Overall, 105 patients were enrolled and followed for an average of 2 years after initiation of ECP. Reasons to start ECP were acute cellular rejection (35.2%), rejection prevention (32.4%), mixed rejection (18.1%), and antibody-mediated rejection (14.3%). Rejection ISHLT grades improved from start to end of ECP treatment in 92% of patients treated with ECP for rejection. Of patients who started ECP to prevent rejection, 88% remained free from any rejection despite a reduction of calcineurin inhibitors. Overall survival was 95%, and no deaths were related to ECP. Safety events occurred in 18 patients, of which 13 experienced complications with venous access. CONCLUSIONS: This study, the largest European ECP study in heart transplantation, demonstrates that ECP can effectively be used to treat different rejection types and to prevent rejection in the modern era of immunosuppression. Patients with rejections who have received ECP have shown high response as measured by histological improvements in ISHLT classification. A high percentage of patients in the prevention group remained free from rejection despite reduction in immunosuppression, in particular calcineurin inhibitors.

Prioritizing direct heart procurement in organ donors after circulatory death does not jeopardize lung transplant outcomes.

Background: Controlled donation after circulatory death (cDCD) has become a standard in liver, kidney, and lung transplantation (LTx). Based on recent innovations in ex vivo heart preservation, heart transplant centers have started to accept cDCD heart allografts. Because the heart has very limited tolerance to warm ischemia, changes to the cDCD organ procurement procedures are needed. These changes entail delayed ventilation and prolonged warm ischemia for the lungs. Whether this negatively impacts lung allograft function is unclear. Methods: A retrospective analysis of cDCD lungs transplanted between 2012 and February 2022 at the Medical University of Vienna was performed. The heart + lung group consisted of cases in which the heart was procured by a cardiac team for subsequent normothermic ex vivo perfusion. A control group (lung group) was formed by cases where only the lungs were explanted. In heart + lung group cases, the heart procurement team placed cannulas after circulatory death and a hands-off time, collected donor blood for ex vivo perfusion, and performed rapid organ perfusion with Custodiol solution, after which the heart was explanted. Up to this point, the lung procurement team did not interfere. No concurrent lung ventilation or pulmonary artery perfusion was performed. After the cardiac procurement team left the table, ventilation was initiated, and lung perfusion was performed directly through both stumps of the pulmonary arteries using 2 large-bore Foley catheters. This study analyzed procedural explant times, postoperative outcomes, primary graft dysfunction (PGD), duration of mechanical ventilation, length of intensive care unit (ICU) stay, and early survival after LTx. Results: A total of 56 cDCD lungs were transplanted during the study period. In 7 cases (12.5%), the heart was also procured (heart + lung group); in 49 cases (87.5%), only the lungs were explanted (lung group). Basic donor parameters were comparable in the 2 groups. The median times from circulatory arrest to lung perfusion (24 minutes vs 13.5 minutes; P = .002) and from skin incision to lung perfusion (14 minutes vs 5 minutes; P = .005) were significantly longer for the heart + lung procedures. However, this did not affect post-transplantation PGD grade at 0 hours (P = .851), 24 hours (P = .856), 48 hours (P = .929), and 72 hours (P = .874). At 72 hours after transplantation, none of the lungs in the heart + lung group but 1 lung (2.2%) in lung group was in PGD 3. The median duration of mechanical ventilation (50 hours vs 41 hours; P = .801), length of ICU stay (8 days vs 6 days; P = .951), and total length of hospital stay (27 days vs 25 days; P = .814) were also comparable in the 2 groups. In-hospital mortality occurred in only 1 patient of the lung group (2.2%). Conclusions: Although prioritized cDCD heart explantation is associated with delayed ventilation and significantly longer warm ischemic time to the lungs, post-LTx outcomes within the first year are unchanged. Prioritizing heart perfusion and explantation in the setting of cDCD procurement can be considered acceptable.

Reduction ascending aortoplasty: A retrospective analysis of outcomes and risk factors.

Objectives: Indication for Reduction of Ascending Aortoplasty (RAA) and long-term outcomes remain unclear. This study analyzed the outcomes after nonreinforced RAA in two Austrian centers. Methods: Patients with RAA at two Austrian centers between 6/2,009 and 6/2,017 were retrospectively analyzed. Aortic diameters were measured by CT pre- and post-operatively. Patients were assigned according to valve morphology and imaging modality. Results: Overall, 253 patients underwent RAA [women: 30.8%; median age 74 (63-79) years] with a mean preoperative ascending diameter of 44.7 (±3.5) mm. RAA-related postoperative adverse events occurred in 1.2% (n = 3) over a follow-up of a median of 3.8 (2.4-5.5) years: One type A aortic dissection, one lethal aortic rupture at the suture line, and one suture line bleeding with cardiac tamponade and need of surgical revision. The overall survival rate was 89.7%. Aortic valve morphology itself was no risk factor for mortality (Log-Rank: 0.942). One hundred and forty patients had a tricuspid [TAV: (55.3%)] aortic valve and 113 patients had a bicuspid aortic valve [BAV: (44.7%)]. Redilatation to a diameter >50 mm according to CT follow-up occurred in 5.7% (n = 5 of 87). One patient needed reoperation with RAA and aortic valve replacement due to a prosthesis-patient mismatch after aortic valve replacement and aortic redilatation. Conclusion: Non-reinforced RAA is a safe, feasible, and reproducible procedure with low rates of perioperative complications in selected patients primarily undergoing aortic valve repair with a dilated ascending aorta. Aortic valve morphology has no impact on mortality after RAA.

Indications, Complications, and Outcomes of Cardiac Surgery After Heart Transplantation: Results From the Cash Study.

Background: Allograft pathologies, such as valvular, coronary artery, or aortic disease, may occur early and late after cardiac transplantation. Cardiac surgery after heart transplantation (CASH) may be an option to improve quality of life and allograft function and prolong survival. Experience with CASH, however, has been limited to single-center reports. Methods: We performed a retrospective, multicenter study of heart transplant recipients with CASH between January 1984 and December 2020. In this study, 60 high-volume cardiac transplant centers were invited to participate. Results: Data were available from 19 centers in North America (n = 7), South America (n = 1), and Europe (n = 11), with a total of 110 patients. A median of 3 (IQR 2-8.5) operations was reported by each center; five centers included ≥ 10 patients. Indications for CASH were valvular disease (n = 62), coronary artery disease (CAD) (n = 16), constrictive pericarditis (n = 17), aortic pathology (n = 13), and myxoma (n = 2). The median age at CASH was 57.7 (47.8-63.1) years, with a median time from transplant to CASH of 4.4 (1-9.6) years. Reoperation within the first year after transplantation was performed in 24.5%. In-hospital mortality was 9.1% (n = 10). 1-year survival was 86.2% and median follow-up was 8.2 (3.8-14.6) years. The most frequent perioperative complications were acute kidney injury and bleeding revision in 18 and 9.1%, respectively. Conclusion: Cardiac surgery after heart transplantation has low in-hospital mortality and postoperative complications in carefully selected patients. The incidence and type of CASH vary between international centers. Risk factors for the worse outcome are higher European System for Cardiac Operative Risk Evaluation (EuroSCORE II) and postoperative renal failure.

Extracorporeal Photopheresis With Low-Dose Immunosuppression in High-Risk Heart Transplant Patients-A Pilot Study.

In severely ill patients undergoing urgent heart transplant (HTX), immunosuppression carries high risks of infection, malignancy, and death. Low-dose immunosuppressive protocols have higher rejection rates. We combined extracorporeal photopheresis (ECP), an established therapy for acute rejection, with reduced-intensity immunosuppression. Twenty-eight high-risk patients (13 with high risk of infection due to infection at the time of transplant, 7 bridging to transplant via extracorporeal membrane oxygenation, 8 with high risk of malignancy) were treated, without induction therapy. Prophylactic ECP for 6 months (24 procedures) was initiated immediately postoperatively. Immunosuppression consisted of low-dose tacrolimus (8-10 ng/ml, months 1-6; 5-8 ng/ml, >6 months) with delayed start; mycophenolate mofetil (MMF); and low maintenance steroid with delayed start (POD 7) and tapering in the first year. One-year survival was 88.5%. Three patients died from infection (POD 12, 51, 351), and one from recurrence of cancer (POD 400). Incidence of severe infection was 17.9% (n = 5, respiratory tract). Within the first year, antibody-mediated rejection was detected in one patient (3.6%) and acute cellular rejection in four (14.3%). ECP with reduced-intensity immunosuppression is safe and effective in avoiding allograft rejection in HTX recipients with risk of severe infection or cancer recurrence.

Many heart transplant biopsies currently diagnosed as no rejection have mild molecular antibody-mediated rejection-related changes.

BACKGROUND: The Molecular Microscope (MMDx) system classifies heart transplant endomyocardial biopsies as No-rejection (NR), Early-injury, T cell-mediated (TCMR), antibody-mediated (ABMR), mixed, and possible rejection (possible TCMR, possible ABMR). Rejection-like gene expression patterns in NR biopsies have not been described. We extended the MMDx methodology, using a larger data set, to define a new "Minor" category characterized by low-level inflammation in non-rejecting biopsies. METHODS: Using MMDx criteria from a previous study, molecular rejection was assessed in 1,320 biopsies (645 patients) using microarray expression of rejection-associated transcripts (RATs). Of these biopsies, 819 were NR. A new archetypal analysis model in the 1,320 data set split the NRs into NR-Normal (N = 462) and NR-Minor (N = 359). RESULTS: Compared to NR-Normal, NR-Minor were more often histologic TCMR1R, with a higher prevalence of donor-specific antibody (DSA). DSA positivity increased in a gradient: NR-Normal 24%; NR-Minor 34%; possible ABMR 42%; ABMR 66%. The top 20 transcripts distinguishing NR-Minor from NR-Normal were all ABMR-related and/or IFNG-inducible, and also exhibited a gradient of increasing expression from NR-Normal through ABMR. In random forest analysis, TCMR and Early-injury were associated with reduced LVEF and increased graft loss, but NR-Minor and ABMR scores were not. Surprisingly, hearts with MMDx ABMR showed comparatively little graft loss. CONCLUSIONS: Many heart transplants currently diagnosed as NR by histologic or molecular assessment have minor increases in ABMR-related and IFNG-inducible transcripts, associated with DSA positivity and mild histologic inflammation. These results suggest that low-level ABMR-related molecular stress may be operating in many more hearts than previously estimated. (ClinicalTrials.gov #NCT02670408).

The Konno-Rastan procedure.

The Konno-Rastan procedure is an anterior aortoventriculoplasty that has  the aim of relieving subvalvar, valvar, and supravalvar stenosis. It can be helpful for patients with aortic stenosis at any level and also for those with a prior implanted aortic and/or mitral prosthesis.  The patient presented in this video tutorial had a history of rheumatic heart disease with previously implanted mechanical prostheses in the aortic as well as the mitral position. We provide detailed insight on how to perform the Konno incision safely and demonstrate the reconstruction of the aortic root, as well as the ventricular septum and the right ventricular outflow tract using a patch of bovine pericardium.

Donor heart selection and outcomes: An analysis of over 2,000 cases.

BACKGROUND: Decision-making when offered a donor heart for transplantation is complex, and supportive data describing outcomes according to acceptance or non-acceptance choices are sparse. Our aim was to analyze donor heart acceptance decisions and associated outcomes at a single center, and after subsequent acceptance elsewhere. METHODS: This investigation was a retrospective analysis of data obtained from the University of Vienna Medical Center and Eurotransplant centers for the period 2001 to 2015. RESULTS: Our center accepted 31.8% (699 of 2,199) of donor hearts offered. Unlike other centers, the acceptance rate, with or without transplantation, did not increase over time. Of the donor hearts rejected by our center, 38.1% (572 of 1,500) were later accepted elsewhere. Acceptance rates were twice as high for donor hearts initially rejected for non-quality reasons (339 of 601, 56.4%) compared with initial rejection for quality reasons (233 of 899, 25.9%). Three-year patient survival rate was 79% at Vienna; for donor hearts initially rejected by Vienna for non-quality reasons or quality reasons, it was 73% and 63%, respectively (p < 0.001). Outcomes at other centers after transplantation of grafts rejected by Vienna varied according to the reason for rejection, with good 3-year survival rates for rejection due to positive virology (77%), high catecholamines (68%), long ischemic time (71%), or low ejection fraction (68%), but poor survival was observed for hearts rejected for hypernatremia (46%), cardiac arrest (21%), or valve pathology (50%). CONCLUSIONS: A less restrictive policy for accepting donor hearts at our center, particularly regarding rejection for non-quality reasons or for positive virology, high catecholamine levels, longer ischemic time, or low ejection fraction, could expand our donor pool while maintaining good outcomes.

High-dose catecholamine donor support and outcomes after heart transplantation.

BACKGROUND: Higher dose norepinephrine donor support is a frequent reason for donor heart decline, but its associations with outcomes after heart transplantation are unclear. METHODS: We retrospectively analyzed 965 patients transplanted between 1992 and 2015 in the Heart Transplant Program Vienna. Stratification was performed according to donor norepinephrine dose administered before organ procurement (Group 0: 0 µg/kg/min; Group 1: 0.01 to 0.1 µg/kg/min; Group 2: >0.1 µg/kg/min). Sub-stratification of Group 2 was performed for comparison of high-dose subgroups (Group HD 1: 0.11 to 0.4 µg/kg/min; Group HD 2: >0.4 µg/kg/min). Associations between groups and outcome variables were investigated using a multivariable Cox proportional hazards model and logistic regression analyses. RESULTS: Donor norepinephrine dose groups were not associated with overall mortality (Group 1 vs 0: hazard ratio [HR] 1.12, 95% confidence interval [CI] 0.87 to 1.43; Group 2 vs 0: HR 1.07, 95% CI 0.82 to 1.39; p = 0.669). No significant group differences were found for rates of 30-day mortality (p = 0.35), 1-year mortality (p = 0.897), primary graft dysfunction (p = 0.898), prolonged ventilation (p = 0.133) and renal replacement therapy (p = 0.324). Groups 1 and 2 showed higher rates of prolonged intensive care unit stay (18.9% vs 28.5% vs 27.5%, p = 0.005). High-dose subgroups did not differ significantly in 1-year mortality (Group HD 1: 14.3%; Group HD 2: 17.8%; p = 0.549). CONCLUSIONS: Acceptance of selected donor hearts supported by higher doses of norepinephrine may be a safe option to increase the donor organ pool.

Impact of Rabbit Antithymocyte Globulin Dose on Long-term Outcomes in Heart Transplant Patients.

BACKGROUND: Optimal dosing strategies have not been established for rabbit antithymocyte globulin (rATG) after heart transplantation, and there is currently wide variability in rATG regimens with respect to both dose and duration. METHODS: In a retrospective, single-center analysis, 523 patients undergoing heart transplantation during 1996 to 2009 were stratified by cumulative rATG dose: less than 4.5 mg/kg (group A), 4.5 to 7.5 mg/kg (group B) or greater than 7.5 mg/kg (group C). RESULTS: Survival at 1 year after transplantation was 80% in group A, 90% in group B, and 88% in group C (P = 0.062). Incidence of acute rejection per 1000 patient-years was significantly higher in group A (hazards ratio [HR], 54.8; 95% confidence interval [95% CI], 33.9-83.8) compared to groups B (19.6; 95% CI, 11.4-31.4) and C (23.6; 95% CI, 17.5-31.3). Incidence of severe infection 10 years after transplantation was higher in group C (45%) than groups A (37%) or B (23%) (P < 0.001); cytomegalovirus infection rates were 35%, 20% and 23%, respectively (P = 0.009). Multivariable Cox regression showed an HR of 0.51 (95% CI, 0.25-1.02) for acute rejection with group B versus group A, and 0.54 (95% CI, 0.33-0.88; P = 0.013) for severe infection. The rate of malignancy per 1000 patient-years was higher in groups B (13.85) and C (14.95) than group A (7.83). CONCLUSIONS: These retrospective data suggest that a cumulative rATG dose of 4.5 to 7.5 mg/kg may offer a better risk-benefit ratio than lower or higher doses, with acceptable rates of infection and posttransplant malignancy. Prospective trials are needed.

Lack of donor and recipient age interaction in cardiac transplantation.

BACKGROUND: The proportion of older donors and recipients is constantly rising in heart transplantation (HTX). The impact of age on different outcomes after HTX has been studied; however, effects of interaction between donor and recipient age remain elusive. METHODS: This retrospective cohort study comprised 1,190 patients who underwent HTX between 1984 and 2011 at the Medical University Vienna. Multivariable models consisted of a basic set that included donor age, recipient age, and transplant eras and were adjusted for 2 sets of 6 possible confounders and 3 mediator variables. Cox models were used to estimate the risk of death. To search for age-related effects on the development of cardiac allograft vasculopathy (CAV), we applied cause-specific Cox models and proportional sub-distribution hazard models for competing risk data. RESULTS: Survival was 80%, 77%, 69%, and 56% after 1, 2, 5, and 10 years, respectively. Donor age (hazard ratio [HR], 1.1; 95% confidence interval [CI], 1.0-1.2), recipient age (HR, 1.1; 95% CI, 1.0-1.2), admission from intensive care unit to HTX (HR, 1.5; 95% CI, 1.2-1.9), and diabetes (HR, 1.4; 95% CI, 1.1-1.7) were identified as significant independent risk factors for death. Significant risk factors for CAV were donor age (HR, 1.4; 95% CI, 1.3-1.5) and male recipient sex (HR, 1.5; 95% CI, 1.0-2.2). Recipient age was inversely associated with initiation of CAV (HR, 0.8; 95% CI, 0.8-1.0). Analysis of the interaction between donor and recipient age was not significant for death (p = 0.8) or CAV (p = 0.6). CONCLUSIONS: We found no interaction between donor and recipient age negatively affecting mortality and CAV. The identified independent risk factors may have implications for allocation strategies in elderly recipients.