Sex mismatch in heart transplantation is associated with increased number of severe rejection episodes and shorter long-term survival

Sex and Gender-related Disparities in Clinical Characteristics and Outcomes in Heart Transplantation

PURPOSE OF REVIEW

Limited research has been conducted on sex disparities in heart transplant (HT). The aim of this review is to analyse the available evidence on the influence of sex and gender-related determinants in the entire HT process, as well as to identify areas for further investigation.

RECENT FINDINGS

Although women make up half of the population affected by heart failure and related mortality, they account for less than a third of HT recipients. Reasons for this inequality include differences in disease course, psychosocial factors, concerns about allosensitisation, and selection or referral bias in female patients. Women are more often listed for HT due to non-ischaemic cardiomyopathy and have a lower burden of cardiovascular risk factors. Although long-term prognosis appears to be similar for both sexes, there are significant disparities in post-HT morbidity and causes of mortality (noting a higher incidence of rejection in women and of malignancy and cardiac allograft vasculopathy in men). Additional research is required to gain a better understanding of the reasons behind gender disparities in eligibility and outcomes following HT. This would enable the fair allocation of resources and enhance patient care.

Sex Differences in Cardiac Transplantation

PURPOSE OF REVIEW

The goal of this review was to summarize contemporary evidence surrounding sex differences in heart transplantation (HT).

RECENT FINDINGS

Women have steadily comprised approximately 25% of waitlist candidates and HT recipients. This disparity is likely multifactorial with possible explanations including barriers in referral to advanced heart failure providers, implicit bias, and concerns surrounding sensitization. Women continue to experience higher waitlist mortality at the highest priority tiers. After HT, there are differences in post-transplant complications and outcomes. Future areas of study should include sex differences in noninvasive surveillance, renal outcomes after transplantation, and patient-reported outcomes. There are important sex-specific considerations that impact candidate selection, donor matching, waitlist and post-transplant outcomes. Concerted efforts are needed to improve referral patterns to ensure transplantation is allocated equally.

Understanding and Investigating Sex-Based Differences in Heart Transplantation: A Call to Action

Women represent only about 25% of heart transplant recipients annually. Although the number of women living with advanced heart failure remains unknown, epidemiologic research suggests that more women should be receiving advanced heart failure therapies. Sex differences in risk factors, presentation, response to pharmacotherapy, and outcomes in heart failure have been well described. Yet, less is known about sex differences in heart transplant candidate selection, waitlist management, donor selection, perioperative considerations, and post-transplant management and outcomes. The purpose of this review was to summarize the existing published reports related to sex differences in heart transplantation, highlighting areas in which sex-based considerations are well described and supported by available evidence, and emphasizing topics that require further study.

Choosing wisely: incorporating appropriate donor-recipient size matching in heart transplantation

Historically, transplantation of a female donor heart to male recipient has been viewed with caution given evidence of suboptimal outcomes, particularly in special populations such as patients with pulmonary hypertension or those supported by ventricular assist devices. However, the use of predicted heart mass ratio for donor-recipient size matching demonstrated that the size of the organ rather than sex of the donor was most responsible for the outcomes. With the advent of the predicted heart mass ratio, avoiding female donor hearts for male recipients is no longer justified and may result in unnecessary waste of available organs. In this review, we highlight the value of donor-recipient sizing by predicted heart mass ratio and summarize the evidence of different approaches to the donor-to-recipient size and sex matching. We conclude that the utilization of predicted heart mass is currently considered a preferred method of matching heart donors and recipients.

Sex mismatch following heart transplantation in the United States: Characteristics and impact on outcomes

BACKGROUND

Available literature indicates the possible detrimental effect of sex mismatching on mortality in patients undergoing heart transplantation. Our objective was to examine the role of sex and heart mass (predicted heart mass [PHM]) mismatch on mortality and graft rejection in patients undergoing heart transplantation in the US.

METHODS

Data on adult patients who underwent heart transplantation between January 2015 and October 2021 were queried from the United Network of Organ Sharing (UNOS) registry. The main outcomes were all-cause mortality, 1-year all-cause mortality and treated acute rejection.

RESULTS

A total of 19 805 adult patients underwent heart transplant during the study period. 92.2% of the patients in the female graft to male group had a PHM mismatch <25%, while only 38.5% had such a mismatch in the male graft to female group. In male to male and female to female groups, 79% and 76% of the patients had a PHM mismatch <25% (p = .122). Proportion of PHM mismatch was similar throughout the study period. Unadjusted analysis showed that male recipients of female grafts had increased risk for all-cause mortality (hazard ratio [HR]: 1.13; 95% confidence intervals [CI]: 1.02, 1.27; p = .026) and 1-year mortality (HR: 1.26; 95% CI: 1.09, 1.45; p = .002) compared to male recipients of male grafts. Graft failure incidence was also higher (HR: 1.12; 95% CI: 1.01, 1.25; p = .041). However, all these associations were non- significant after risk factor adjustment.

CONCLUSIONS

Sex mismatching is associated with post-transplant mortality with transplantation of female donor grafts to male recipients demonstrating worse outcomes, although this association disappears after risk factor adjustment. Further research is required to elucidate the need for potential changes in clinical practice.

Impact of various sizing metrics on female donor to male recipient heart transplant outcomes

BACKGROUND

This study evaluated the impact of various sizing metrics on outcomes of female donor to male recipient orthotopic heart transplantation (OHT).

METHODS

We queried the United Network of Organ Sharing database to analyze all isolated, primary adult OHTs from January 1, 2010 to January 20, 020. Patients were stratified by donor-recipient sex pairing. Logistic regression was used to investigate risk-adjusted effects of current size matching criteria (weight ratio, body mass index [BMI] ratio, predicted heart mass [pHM] ratio) on 1-year posttransplant mortality. Kaplan-Meier analysis was used to compare posttransplant survival among cohorts.

RESULTS

A total of 22,450 patients were analyzed, of which 3019 (13.4%) underwent female-to-male transplantation. Of sex-matched pairs, female-to-male donation had the lowest proportion of undersized hearts using weight and BMI ratio metrics (10.5% and 5.2%) but had the highest proportion of undersizing using pHM metrics (48.1%) (all p < 0.001). Female-to-male recipients had the lowest rate of unadjusted 1-year survival (90.0%, p = 0.0169), and increased hazards of mortality after risk adjustment (odds ratio [OR]: 1.17, 95% confidence interval [CI]: 1.01-1.36, p = 0.034). Undersizing using pHM (donor-recipient ratio <0.85) was the only metric found to be associated in increased mortality after risk adjustment (OR: 1.32, 95% CI: 1.02-1.71, p = 0.035).

CONCLUSION

Female-to-male heart transplantation has the worst survival of all sex-matching combinations. Although female donors in this cohort are appropriately sized using traditional metrics, half are under-sized using pHM. This, combined with its strong association with mortality, underscores the importance of routine pHM assessment when evaluating female donors for male recipients.

Ventricular assist device bridging with gender-mismatch increases rejection and decreases survival following a heart transplant

OBJECTIVES

Survival is poor following an orthotopic heart transplant with gender-mismatched donors and recipients. Patients bridged to an orthotopic heart transplant with a ventricular assist device (VAD) frequently become sensitized. We hypothesized that the combination of VAD bridging and gender-mismatch may result in greater rejection and poorer survival.

METHODS

Data were obtained from the United Network of Organ Sharing database. Patients were divided into 4 groups: (i) VAD recipients who received a heart from a gender-matched donor (VAD-M); (ii) VAD recipients who received a heart from a gender-mismatched donor (VAD-MM); (iii) noVAD recipients who received a heart from a gender-matched donor (noVAD-M); and (iv) noVAD recipients who received a heart from a gender-mismatched donor (noVAD-MM). Rejection episodes within 1-year post-transplant and transplant survival were compared in VAD-M versus VAD-MM and noVAD-M versus noVAD-MM groups, respectively.

RESULTS

Between January 2000 and June 2017, of 33 401 adult patients who underwent heart transplants, 8648, 2441, 12 761 and 4992 patients were identified as VAD-M, VAD-MM, noVAD-M and noVAD-MM, respectively. Rejection within 1-year post-transplant occurred in 23.3% and 27.3% of the VAD-M and VAD-MM groups, respectively (P < 0.01) and in 21.8% and 23.6% of the noVAD-M and noVAD-MM groups (P = 0.02), respectively. In an adjusted survival analysis, the VAD-MM group showed significantly worse survival than the VAD-M group (P < 0.01), whereas there was no significant difference between the noVAD-M and noVAD-MM groups (P = 0.21).

CONCLUSIONS

Our results indicated that the combination of VAD bridging and gender-mismatch caused greater rejection and worse survival following a transplant. Further study is necessary to prove comparable post-transplant survival of gender-matched or -mismatched recipients without VAD bridging.

Influence of Sex-Mismatch on Prognosis After Heart Transplantation

The influence of donor and recipient sex on prognosis after heart transplantation has been analyzed in single, multi-center studies, and international registries. In most of them, sex-mismatch was identified as a risk factor for the worst prognosis, especially in men recipients of female heart. This could be attributed to physiological differences between women and men, differences in complications rates after heart transplantation (rejection, cardiovascular allograft vasculopathy, and primary graft failure), and pulmonary hypertension of the recipient. Confounding variables as age, urgent transplantation, and size-mismatch should also be considered. When allocating a graft, sex-mismatch should be considered but its influence in long-term survival should be further explored.

DNA methyltransferase inhibitor 5-azacytidine in high dose promotes ultrastructural maturation of cardiomyocyte

Background

The adult human heart muscle cells, cardiomyocytes are not capable of regenerate after injury. Stem cells are a powerful means for future regenerative medicine because of their capacity for self-renewal and multipotency. Several studies have reported the cardiogenic potential in human adipose tissue-derived stem cells (ADSCs) differentiation, but there is still no efficient protocol for the induction of cardiac differentiation by 5-azacytidine (5-Aza). The present study involves characterization and mainly, the ultrastructure of ADSCs derived cardiomyocyte-like cells.

Methods

The cultured ADSCs were treated with 50 µM 5-Aza for 24 hours, followed by a 10-week extension. At different time points, cardiomyocyte-like cells were assessed by qRT-PCR and were evaluated by transmission electron microscopy at 10^th week.

Results

The expression of cardiac-specific markers entailing cardiac troponin I (cTnI), connexin 43, myosin light chain-2v (Mlc-2v), increased over 10 weeks and the highest expression was at 10^th week. The expression of the β-myosin heavy chain (β-MHC) increased significantly over 5 weeks and then decreased. At the ultrastructural level myofibrils, transverse tubules (T-tubules), sarcoplasmic reticular membrane, and intercalated discs were present.

Conclusions

These data suggest that treatment with 5-Aza in high dose could promote differentiation of ADSCs into cardiomyocyte-like cells. These differentiated cells could be used for regeneration of damaged cardiomyocytes with the 3D scaffold for delivery of the cells.

A modified heterotopic heart transplantation in the rat - as an important model in experimental regeneration and replacement of the failing organ

The qualification of new knowledge is one of the oldest problems in experimental medicine that provides a link between fundamental discovery, hypothesis, ‘proof of concept’ preclinical studies and development of clinical trials. The biggest challenge in animal models is the proper evaluation of all the aspects that are crucial in specific studied pathologies as well as the prediction of their progression. The aim of this review was to describe and discuss the rat animal model of heart transplant. The rat model of heart transplantation is an excellent yet underestimated method of research of prevention, monitoring and treatment of acute and chronic, immune and nonimmune response to organ transplantation. Despite being a technically and logistically demanding model, it provides a tool for reproducible experiments with longterm animal survival and excellent graft survival.

Mitigating the Impact of Using Female Donor Hearts in Male Recipients Using BMI Difference

BACKGROUND

Heart transplantation is limited by the supply of donor organs. Previous studies have associated female donor to male recipient with decreased posttransplant survival. We wanted to evaluate whether this risk can be mitigated using higher donor than recipient body mass index (BMI).

METHODS

We performed a retrospective analysis of the Organ Procurement and Transplantation Network/United Network of Organ Sharing registry encompassing years 2005 to 2018 for all male adult recipients (>18 years of age) who underwent isolated heart transplantation with grafts from female donors. The association between donor and recipient BMI difference and recipient survival was evaluated using adjusted Cox proportional hazards modeling.

RESULTS

A total of 3788 male recipients who received female donor hearts met inclusion criteria for analysis. Maximally selected rank statistics identified donor minus recipient BMI of 1.5 kg/m² as a meaningful cutoff point in the analysis of recipient survival. Multivariable Cox proportional hazards analysis demonstrated that increasing donor BMI relative to recipient BMI up to this cutoff point was associated with improved survival (hazard ratio per 5-unit difference, 0.87; 95% confidence interval, 0.77-0.99). Above this cutoff point, increasing donor BMI relative to the recipient did not improve survival more than what was achieved by adding 1.5 of BMI difference (hazard ratio per 5-unit difference, 0.97; 95% confidence interval, 0.90-1.04).

CONCLUSIONS

Increasing donor BMI relative to recipient BMI up to 1.5 kg/m² greater than recipient BMI was associated with improved survival. BMI difference may be useful as a simple surrogate for predicted heart mass difference to help mitigate the impact of sex mismatch in heart transplantation.

Sex-mismatch influence on survival after heart transplantation: A systematic review and meta-analysis of observational studies

INTRODUCTION AND OBJECTIVES

Heart transplantation (HT) is the treatment for patients with end-stage heart disease. Despite contradictory reports, survival seems to be worse when donor/recipient sex is mismatched. This systematic review and meta-analysis aims to synthesize the evidence on the effect of donor/recipient sex mismatch after HT.

METHODS

We searched PubMed and EMBASE until November 2017. Comparative cohort and registry studies were included. Published articles were systematically selected and, when possible, pooled in a meta-analysis. The primary endpoint was one-year mortality.

RESULTS

After retrieving 556 articles, ten studies (76 175 patients) were included in the quantitative meta-analysis. Significant differences were found in one-year survival between sex-matched and mismatched recipients (odds ratio (OR) 1.30, 95% confidence interval (CI) 1.25-1.35, P < .001). In female recipients, we found that sex mismatch was not a risk factor for one-year mortality (OR = 0.93, 95% CI = 0.85-1.00, P = .06). However, in male recipients, we found that it was a risk factor for one-year mortality (OR = 1.38, 95% CI = 1.31-1.44, P < .001).

CONCLUSIONS

Sex mismatch increases one-year mortality after HT in male recipients. Its influence in long-term survival should be further explored with high-quality studies.

Human Wharton's Jelly-Derived Mesenchymal Stem Cells Minimally Improve the Growth Kinetics and Cardiomyocyte Differentiation of Aged Murine Cardiac c-kit Cells in In Vitro without Rejuvenating Effect

Cardiac c-kit cells show promise in regenerating an injured heart. While heart disease commonly affects elderly patients, it is unclear if autologous cardiac c-kit cells are functionally competent and applicable to these patients. This study characterised cardiac c-kit cells (CCs) from aged mice and studied the effects of human Wharton’s Jelly-derived mesenchymal stem cells (MSCs) on the growth kinetics and cardiac differentiation of aged CCs in vitro. CCs were isolated from 4-week- and 18-month-old C57/BL6N mice and were directly co-cultured with MSCs or separated by transwell insert. Clonogenically expanded aged CCs showed comparable telomere length to young CCs. However, these cells showed lower Gata4, Nkx2.5, and Sox2 gene expressions, with changes of 2.4, 3767.0, and 4.9 folds, respectively. Direct co-culture of both cells increased aged CC migration, which repopulated 54.6 ± 4.4% of the gap area as compared to aged CCs with MSCs in transwell (42.9 ± 2.6%) and CCs without MSCs (44.7 ± 2.5%). Both direct and transwell co-culture improved proliferation in aged CCs by 15.0% and 16.4%, respectively, as traced using carboxyfluorescein succinimidyl ester (CFSE) for three days. These data suggest that MSCs can improve the growth kinetics of aged CCs. CCs retaining intact telomere are present in old hearts and could be obtained based on their self-renewing capability. Although these aged CCs with reduced growth kinetics are improved by MSCs via cell–cell contact, the effect is minimal.

Primary graft dysfunction after heart transplantation: Outcomes and resource utilization

BACKGROUND

A unified definition of primary graft dysfunction (PGD) after heart transplantation was adopted in 2014, with moderate and severe PGD defined as a need for mechanical circulatory support. While risk factors for PGD are well identified, outcomes and resource utilization have not been well-studied. We examined the resource utilization and associated costs with PGD.

METHODS

All adult heart transplantations (2001-2016) from a statewide Society of Thoracic Surgery database were analyzed by dividing them into two groups-with PGD (requiring mechanical circulatory support) and without PGD.

RESULTS

Of the 718 heart transplants, 110 (15.3%) patients developed PGD. Prevalence of PGD for the study duration ranged from 3.7% to 22.7% with no significant trend. The most frequently used mechanical circulatory support device was intra-aortic balloon pump (88%), followed by extracorporeal membrane oxygenation (17%), and catheter-based circulatory support devices (3%). There were no significant differences in demographics or preoperative variables between the two groups. Resource utilization such as total intensive care unit hours, ventilation hours, reoperation for bleeding, blood product transfusions, and length of stay were significantly higher in the PGD group. Postoperative complications were also higher in PGD group including operative mortality (31.8% vs 3.8%, P < .0001). The median cost of heart transplantation was significantly higher in the PGD group $229 482 ($126 044-$388 889) vs $101 788 ($72 638-$181 180) P < .0001.

CONCLUSION

Primary graft dysfunction following heart transplantation developed in 15% of patients. Patients with PGD had significantly higher complications, resource utilization, and mortality. Preventive measures to address the development of PGD would reduce resource utilization and improve outcomes.

Sex matching does not impact the outcome after simultaneous pancreas-kidney transplantation

Background

Several studies in solid organ transplantation have shown a correlation between donor and recipient sex mismatch and risk of graft loss. In this study, we aimed to analyze the impact of donor and recipient sex matching on patient and pancreas graft survival in a large single‐center cohort.

Methods

We retrospectively analyzed all first simultaneous pancreas‐kidney transplants performed between 1979 and 2017 at the Medical University of Innsbruck.

Results

Of 452 patients, 54.6% (247) received a sex‐matched transplant. Patient survival (P = .86), death‐censored pancreas graft survival (dcPGS, P = .26), and death‐censored kidney graft survival (dcKGS, P = .24) were similar between the sex‐matched and sex‐mismatched groups. Patient survival and dcPGS at 1, 5, and 15 years were 95.9%, 90.0%, and 62.1% and 86.1%, 77.1%, and 56.7% in the sex‐matched group and 93.6%, 86.2%, and 62.4% and 83.1%, 73.3%, and 54.3% in the sex‐mismatched group. Sex matching led to a lower odds of severe postoperative complications (41.2% vs 49.0%; OR 0.57, 95%CI 0.33‐0.97; P = .038); however, no increased odds of other adverse postoperative outcomes was detected.

Conclusion

Our study demonstrates that sex matching reduced the odds of postoperative complications but did not impact other early and late outcome parameters in our cohort.

Anesthesia for Heart Transplantation

This article seeks to evaluate current practices in heart transplantation. The goals of this article were to review current practices for heart transplantation and its anesthesia management. The article reviews current demographics and discusses the current criteria for candidacy for heart transplantation. The process for donor and receipt selection is reviewed. This is followed by a review of mechanical circulatory support devices as they pertain to heart transplantation. The preanesthesia and intraoperative considerations are also discussed. Finally, management after transplantation is also reviewed.

Mortality, rehospitalization, and post-transplant complications in gender-mismatched heart transplant recipients

BACKGROUND

Limited research has been published on outcomes in heart transplant (HT) recipients with gender-mismatched donors.

OBJECTIVE

Compare 3-year post-transplant outcomes in 2 groups of gender-mismatched HT recipients and a no-mismatch group.

METHODS

Sample: 347 HT recipients: 21.3% (74) received a heart from the opposite gender: Group 1: same gender donor/recipient (273, 78.7%); Group 2: female donor/male recipient (40, 11.5%); Group 3: male donor/female recipient (34, 9.8%).

OUTCOMES

mortality, hospitalization, and complications.

RESULTS

Female patients with male heart donors had shorter 3-year survival, were rehospitalized more days after HT discharge, and had more treated acute rejection episodes and cardiac allograft vasculopathy. No differences were found in: HT length of stay, respiratory failure, stroke, cancer, renal dysfunction, steroid-induced diabetes, number of IV-treated infections, or the timing of infection and rejection.

CONCLUSION

Female HT recipients with male donors had worse 3-year outcomes as compared to male-mismatch and no-mismatch groups.

The impact of gender mismatching on early and late outcomes following heart transplantation

Aims

The role of donor/recipient gender matching on the long‐term rejection process and clinical outcomes following heart transplantation (HT) outcomes is still controversial. We aim to investigate the impact of gender matching on early and long‐term outcome HT.

Methods and results

The study population comprised 166 patients who underwent HT between 1991 and 2013 and were prospectively followed up in a tertiary referral centre. Early and late outcomes were assessed by the type of donor–recipient gender match (primary analysis: female donor–male recipient [FD–MR, n = 36] vs. male donor–male recipient [MD–MR, n = 109]). Early mortality, need for inotropic support, length of hospital stay, and major perioperative adverse events did not differ between the FD–MR and MD–MR groups. However, the FD–MR group experienced significantly higher rates of early major rejections per patient as compared with the MD–MR group (1.2 ± 1.6 vs. 0.4 ± 0.8; P = 0.001), higher rates of overall major rejections (16 vs. 5.5 per 100 person years; P < 0.05), and higher rate of cardiac allograft vasculopathy (43% vs. 20%; P = 0.01). Kaplan–Meier survival analysis showed that the cumulative probabilities of survival free of rejections and major adverse events were significantly higher in MD–MR group (P = 0.002 and 0.001, respectively). Multivariate analysis showed that FD–MR status was associated with >2.5‐fold (P = 0.03) increase in the risk for rejections and with a >3‐fold (P = 0.01) increase in the risk for major adverse events during follow‐up.

Conclusions

Donor–recipient gender mismatch is a powerful independent predictor of early and late rejections and long‐term major adverse events following HT.

Cardiac allograft vasculopathy: a donor or recipient induced pathology?

Cardiac allograft vasculopathy (CAV) is one of the main causes of late-stage heart failure after heart transplantation. CAV is characterized by concentric luminal narrowing of the coronary arteries, but the exact pathogenesis of CAV is still not unraveled. Many researchers show evidence of an allogeneic immune response of the recipient, whereas others show contrasting results in which donor-derived cells induce an immune response against the graft. In addition, fibrosis of the neo-intima can be induced by recipient-derived circulating cells or donor-derived cells. In this review, both donor and recipient sides of the story are described to obtain better insight in the pathogenesis of CAV. Dual outcomes were found regarding the contribution of donor and recipient cells in the initiation of the immune response and the development of fibrosis during CAV. Future research could focus more on the potential synergistic interaction of donor and recipient cells leading to CAV.

Donor/recipient sex mismatch and survival after heart transplantation: only an issue in male recipients? An analysis of the Spanish Heart Transplantation Registry

The results of studies on the association between sex mismatch and survival after heart transplantation are conflicting. Data from the Spanish Heart Transplantation Registry. From 4625 recipients, 3707 (80%) were men. The donor was female in 943 male recipients (25%) and male in 481 female recipients (52%). Recipients of male hearts had a higher body mass index (25.9 ± 4.1 vs. 24.3 ± 3.7; P < 0.01), and male donors were younger than female donors (33.4 ± 12.7 vs. 38.2 ± 12.3; P < 0.01). No further relevant differences related to donor sex were detected. In the univariate analysis, mismatch was associated with mortality in men (hazard ratio [HR], 1.18; 95% confidence interval [CI], 1.06-1.32; P = 0.003) but not in women (HR, 0.91; 95% CI 0.74-1.12; P = 0.4). A significant interaction was detected between sex mismatch and recipient gender (P = 0.02). In the multivariate analysis, sex mismatch was associated with long-term mortality (HR, 1.14; 95% CI 1.01-1.29; P = 0.04), and there was a tendency toward significance for the interaction between sex mismatch and recipient gender (P = 0.08). In male recipients, mismatch increased mortality mainly during the first month and in patients with pulmonary gradient >13 mmHg. Sex mismatch seems to be associated with mortality after heart transplantation in men but not in women.

Donor selection in heart transplantation

There is increased scrutiny on the quality in health care with particular emphasis on institutional heart transplant survival outcomes. An important aspect of successful transplantation is appropriate donor selection. We review the current guidelines as well as areas of controversy in the selection of appropriate hearts as donor organs to ensure optimal outcomes. This decision is paramount to the success of a transplant program as well as recipient survival and graft function post-transplant.

Extracorporeal membrane oxygenation: experience in acute graft failure after heart transplantation

INTRODUCTION

Acute graft failure is the leading cause of early mortality after heart transplantation (HTx). Extracorporeal membrane oxygenation (ECMO) is an efficient therapeutic option to treat various pathologies, unburden the left and right ventricle, and allow for functional recovery of the transplanted heart. We reviewed our ECMO experience and outcomes in HTx patients.

METHODS

Retrospectively, we analyzed all patients who received an orthotopic HTx (n = 298) in our department over a 15-yr period (1997 through 2011) to assess the incidence of post-HTx ECMO implantation, perioperative complications, early and one-yr mortality as well as causes of death.

RESULTS

ECMO therapy was utilized to treat graft failure in 28 patients (10.6%) with a mean duration of ECMO support of 4.2 d (six h to 9.4 d). Multivariate analysis revealed as independent predictors for mortality low cardiac output (p = 0.028; odds ratio (OR) = 11.3) and stroke (p = 0.008; OR = 19.7). Cumulative survival rates were 46.4 ± 9.4% within 30 d and 25.0 ± 8.2% at one yr. Causes of death were multiorgan failure (n = 9), sepsis (n = 9), lung failure (n = 2), and intracerebral bleeding (n = 2). ECMO was implanted due to primary graft failure (PGF, n = 16), sepsis (n = 4), and right heart failure (n = 6).

CONCLUSION

Temporary ECMO support for postoperative output failure is an acceptable option as a last resort for otherwise doomed patients with fatal graft failure after HTx. The small fraction of patients surviving appear to have a decent long-term prognosis.

Clinical impact of H-Y alloimmunity

H-Y antigens are a group of minor histocompatibility antigens encoded on the Y-chromosome with homologous H-X antigens on the X-chromosome. The disparate regions of the H-Y antigens are highly immunogenic and play an important role in understanding human alloimmunity. In this review, we investigate the history of H-Y antigen discovery along with their critical contributions in transplantation and pregnancy. In hematopoietic cell transplantation, male recipients with female donors who become seropositive for B-cell responses as H-Y antibodies following transplantation have increased rates of chronic graft-versus-host disease and decreased rates of relapse. Conversely, female patients who receive male kidney allografts are more likely than other gender combinations to develop H-Y antibodies and reject their allografts. Finally, in the setting of pregnancy, mothers who initially gave birth to boys are more likely to have subsequent pregnancy complications, including miscarriages, in association with H-Y antibody development. H-Y antigens continue to serve as a model for alloimmunity in new clinical scenarios. Our development of more sensitive antibody detection and next-generation DNA sequencing promises to further advance our understanding and better predict the clinical consequences of alloimmunity.

Mechanical circulatory support and heart transplantation: donor and recipient factors influencing graft survival

BACKGROUND

Mechanical circulatory support is an accepted strategy to bridge patients to heart transplantation (HTx). Among mechanical circulatory support patients who go on to HTx, factors associated with improved graft survival have not been fully elucidated.

METHODS

Using the Scientific Registry for Transplant Recipients, we identified adults who were treated with a left ventricular assist device (LVAD) or total artificial heart (TAH) before HTx. Kaplan-Meier and multivariate Cox regression models were used to identify patient, donor, and device characteristics associated with graft survival.

RESULTS

Between January 1997 and February 2012, 2,785 adults underwent HTx. Before HTx, 2,674 patients were treated with a LVAD (HeartMate XVE, 724; HeartMate II, 1,882; HeartWare, 68), and 111 were treated with a TAH. Follow-up averaged 25 ± 24 months. Gender mismatch occurred in 23%. Graft survival did not differ between LVAD groups (all p > 0.168), but TAH was associated with reduced graft survival compared with LVADs (p < 0.001). After controlling for device type (LVAD vs TAH), lower recipient pulmonary vascular resistance, shorter ischemic time, younger donor age, donor-to-recipient gender match, and higher donor-to-recipient body mass index ratio were independent predictors of longer graft survival (all p < 0.05).

CONCLUSIONS

TAH was associated with reduced graft survival after transplant, and survival did not differ between the LVAD device groups. Additional variables that were independently associated with graft survival were donor age, recipient peripheral vascular resistance, ischemic time, gender match, and donor-to-recipient body mass index ratio. Recognition of these factors may inform decisions regarding device support and donor suitability.

First-year clinical outcomes in gender-mismatched heart transplant recipients

BACKGROUND

Research indicates that gender mismatch of organ donor and recipient may adversely affect outcomes in heart transplant (HT) patients. However, there is a paucity of literature on gender-mismatched outcomes in patients receiving an HT, and only a few outcomes have been investigated.

OBJECTIVES

Objectives were to (1) determine if gender-mismatched HT recipients experienced decreased survival, more posttransplantation complications, and more days of hospitalization during the first postoperative year as compared with gender-matched recipients and (2) identify risk factors for decreased survival.

METHODS

Patients were 347 HT recipients; 21.3% (74) received a heart from the opposite gender. Three groups were compared: group 1: same gender donor-recipient (273 [78.7%]: 36 women, 237 men); group 2: female donor-male recipient (40 [11.5%]); group 3: male donor-female recipient (34 [9.8%]). Ten outcomes were compared with Kaplan-Meier survival analysis, logistic regression, and multivariate analysis of covariance, using a Bonferroni-adjusted P ≤ .005. Risk factors for decreased survival were examined with Cox regression.

RESULTS

Gender-mismatched HT patients with a male donor and a female recipient (group 3) had more treated acute rejections and were rehospitalized for more days after HT discharge during the first postoperative year as compared with gender-matched patients. No significant differences were found in 8 other first-year outcomes: number of deaths, survival time, hospital length of stay for HT surgery, cardiac allograft vasculopathy, severe renal dysfunction, new-onset steroid-induced diabetes, nonskin cancers, or the number of infections treated with an intravenous antibiotic. Risk factors for decreased year 1 survival were higher year 1 cholesterol, earlier intravenous-treated infection, severe renal dysfunction, earlier treated rejection, and diabetes (both preexisting and new-onset steroid-induced diabetes).

CONCLUSION

Gender-mismatched HT recipients had more complications due to rejection and higher resource utilization due to more rehospitalization during the first postoperative year as compared with gender-matched recipients. Therefore, these problem areas may provide targets for possible interventions.

A GENS-based approach to cardiovascular pharmacology: impact on metabolism, pharmacokinetics and pharmacodynamics

Pharmacological outcomes depend on many factors, with many of them being sexually dimorphic. Thus, physiological gender/sex (GENS) differences can influence pharmacokinetics, pharmacodynamics and, thus, bioavailability and resulting in efficacy of treatment, meaning GENS differences should be an important consideration in therapeutics. In particular, drug response can change according to different hormonal environments. Therefore, GENS-specific differences have a particular clinical relevance in terms of drug delivery, especially for those substances with a narrow therapeutic margin. Since adverse effects are more frequent among women, safety is a key issue. Overall, the status of women, from a pharmacological point of view, is often different and less studied than that of men and deserves particular attention. Further studies focused on women's responses to drugs are necessary in order to make optimal pharmacotherapeutic decisions.

Mechanical circulatory support after heart transplantation

OBJECTIVE

Mechanical circulatory support (MCS) may be used for severe graft failure after heart transplantation, but the degree to which it is lifesaving is uncertain.

METHODS

Between June 1990 and December 2009, 53 patients after 1417 heart transplants (3.7%) required post-transplant MCS for acute rejection (n=17), biventricular failure (n=16), right ventricular failure (n=16), left ventricular failure (n=1), or respiratory failure (n=3). Although support was occasionally instituted remotely post-transplant (5>1 year), in 39 (73%) instances it was required within 1 week. Initial mode of support was extracorporeal membrane oxygenation in 43 patients (81%), biventricular assist device in 4 (7.5%), and right ventricular assist device in 6 (11%).

RESULTS

Risk of requiring respiratory support was highest in those with restrictive cardiomyopathy as indication for transplant, women, and those with elevated pulmonary pressure or renal failure. Complications of support, which increased progressively with its duration, included stroke in two patients (3.8%), infection in two (3.8%), and reoperation for bleeding (seven instances) in four (7.0%). Nineteen patients (36%) recovered and were removed from support, five (9.4%) underwent retransplantation (four after biventricular failure and one after acute rejection), and 29 died while on support (55%). Overall survival after initiating support was 94%, 83%, 66%, and 43% at 1, 3, 7, and 30 days, respectively. Patients requiring support for biventricular failure had better survival than those having acute rejection or other indications (P=0.03). Survival after retransplantation or removal from support following recovery was 88% at 1 year and 61% at 10 years.

CONCLUSION

Severe refractory heart failure after transplantation is a rare catastrophic event for which MCS offers the possibility of recovery or bridge to retransplantation, particularly for patients with biventricular failure in the absence of rejection. Early retransplantation should be considered in patients who show no evidence of graft recovery on MCS.

Primary graft failure after heart transplantation

Primary graft failure (PGF) is a devastating complication that occurs in the immediate postoperative period following heart transplantation. It manifests as severe ventricular dysfunction of the donor graft and carries significant mortality and morbidity. In the last decade, advances in pharmacological treatment and mechanical circulatory support have improved the outlook for heart transplant recipients who develop this complication. Despite these advances in treatment, PGF is still the leading cause of death in the first 30 days after transplantation. In today's climate of significant organ shortages and growing waiting lists, transplant units worldwide have increasingly utilised "marginal donors" to try and bridge the gap between "supply and demand." One of the costs of this strategy has been an increased incidence of PGF. As the threat of PGF increases, the challenges of predicting and preventing its occurrence, as well as the identification of more effective treatment modalities, are vital areas of active research and development.

Donor-recipient sex mismatch portends poor 10-year outcomes in a single-center experience

BACKGROUND

Several studies have indicated that survival after heart transplantation is affected by donor-recipient sex matching. In most studies, male recipients of a female heart have the poorest survival rates, whereas survival of female recipients is not affected by donor sex. The purpose of the current study was to determine the long-term outcomes of recipients at a large single center on uniform immunosuppression therapy in the current era.

METHODS

We reviewed the records of 857 patients transplanted at a single center between 1994 and 2008. Patients were divided into 4 groups based on donor-recipient sex: male donor to male recipient (male/male, n = 506); female donor to female recipient (female/female, n = 113); male donor to female recipient (male/female, n = 106); and female donor to male recipient (female/male, n = 132). Ten-year outcomes were assessed for: survival; freedom from cardiac allograft vasculopathy (CAV); and freedom from non-fatal major adverse cardiac events (NF-MACE).

RESULTS

Ten-year actuarial survival was comparable in male/male and female/female groups, at 69% and 71%, respectively (p > 0.05). Compared with the male/male group, 10-year actuarial survival was significantly lower in the sex-mismatch groups: 58% in the male/female group (p = 0.03) and 59% in the female/male group (p = 0.01). There was no significant difference in 10-year freedom from CAV or NF-MACE among the groups.

CONCLUSIONS

Heart transplant patients with donor-recipient sex mismatch have lower survival, extending the results of prior studies to suggest that sex mismatch is undesirable in female, as well as male, recipients. This may impact donor selection and recipient wait time to transplantation.

Gender differences in liver donor quality are predictive of graft loss

Some studies have found that donor-recipient gender mismatch predicts posttransplant outcomes but whether this is independent of donor quality is unknown. To evaluate the association between gender mismatch and graft loss, 11 508 females (F) and 16 714 males (M) who underwent liver transplant from March 1, 2002 to December 31, 2007 were studied. Of 11 donor characteristics, clinically relevant differences between F and M donors were median age (47 vs. 39 years), height (165 vs. 178 cm) and proportion dying of stroke (59 vs. 35%) (p < 0.001 for all). The donor risk index was significantly lower for F than M donors (1.3 vs. 1.6, p < 0.001). Recipients of gender-mismatched grafts had an 11% higher risk of graft loss (p < 0.001). Compared to M→M donor-recipient-matched transplants in univariable analysis, F→M mismatch was associated with a 17% increased risk of graft loss (95% CI = 1.11-1.24, p < 0.001), whereas M→F mismatch was not (HR = 1.02; 95% CI = 0.96-1.09; p = 0.46). However, adjustment for significant recipient and donor factors eliminated the association between F→M mismatch and graft loss (HR = 0.95; 95% CI = 0.89-1.02; p = 0.18). In conclusion, donor quality differs significantly between female and male donors-female donors are older, shorter and die more frequently of stroke-and gender differences in donor quality, rather than gender mismatch are predictive of graft loss.

Heart transplantation

PURPOSE OF REVIEW

This paper briefly and subjectively reviews a number of the modest or tentative, but noteworthy, advances in heart transplantation that have been made during the past 18 months or so.

RECENT FINDINGS

The advances reviewed concern the selection of recipients, the management of the heart transplantation waiting list, the management of donors, post-heart transplant monitoring of immunological status, the early diagnosis of rejection, the role of mammalian target of rapamycine inhibitors and induction agents, and the definition and grading of cardiac allograft vasculopathy.

SUMMARY

The findings reviewed indicate progress in the clarification of issues that were in most cases already being investigated. Further studies will in general be needed before corresponding measures are adopted in clinical practice.