Gender differences in heart transplantation: Twenty-five year trends in the nationwide Spanish heart transplant registry

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.

Evolution of the impact of the COVID-19 pandemic on heart transplant recipients: Decreasing risk, improving perspective

BACKGROUND AND METHODS

Heart transplant recipients (HTr) have a higher probability of suffer from severe coronavirus disease-2019 (COVID-19) in comparison to general population, but their risk has changed over the course of the pandemic in relation to various factors. We conducted a prospective study including all HTr at risk of COVID-19 in a tertiary center between February 2020 and October 2022. The aim was to analyze how the prognosis (incidence of pneumonia and mortality) of COVID-19 in HTr has evolved over time, contextualizing variants, vaccination, and other treatments.

RESULTS

Of 308 HTr included, 124 got the infection (39.2%). COVID and non-COVID HTr had similar baseline characteristics. COVID-19 patients with pneumonia had a poorer prognosis than those with less severe presentations, with a higher rate of hospitalization (93.3 vs. 14.1%, p < .001) and death (41.0 vs. 1.2%, p < .001). Multivariate analysis identified age ≥60 years (odds ratio [OR] 3.65, 95% confidence interval [CI] 1.16-11.49, p = .027), and chronic kidney disease ≥3a (OR 4.95, 95% CI 1.39-17.54, p = .014) as predictors of pneumonia. Two-dose vaccination (OR 0.20, CI 95% 0.05-0.72, p = .02) and early remdesivir administration (OR 0.17, CI 0.03-0.90, p = .037) were protective factors. Over the course of the pandemic considering three periods in the follow-up (prevaccination February-December 2020, postvaccination January-December 2021, and post early remdesivir indication January-October 2022), we observed a reduction in pneumonia incidence from 62% to 19% (p < .001); and mortality (from 23% to 4%, p < .001).

CONCLUSIONS

The prognosis of COVID-19 in HTr has improved over time, likely due to vaccination and early administration of remdesivir.

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.

Association of fasting blood glucose variability with all-cause mortality in heart transplant recipients

BACKGROUND

Fasting blood glucose (FBG) variability, an emerging marker of glycemic control, has been shown to be related to the risk of cardiovascular events and all-cause mortality in subjects with or without diabetes. However, whether FBG variability is independently associated with a higher all-cause mortality in heart transplant recipients remains unknown.

METHODS

We performed a retrospective cohort study including 373 adult recipients who survived for at least 1 year after heart transplantation with a functioning graft and measured FBG more than three times within first year after transplantation. Multivariable adjusted Cox regression analyses were performed to assess the association between FBG variability and all-cause mortality.

RESULTS

Patients were categorized into three groups according to the coefficient of variation of FBG level: ≤7.0%, 7.0%-13.5%, and >13.5%. During a median follow-up of 44.4 months (interquartile range [IQR], 22.6-63.3 months), 31 (8.3%) participants died. In univariate analyses, FBG variability was associated with an increased all-cause mortality (hazard ratio [HR]: 3.00, 95% confidence interval [CI]: 1.67, 5.38; p < .001). This association remained materially unchanged in the multivariable model adjusted for components of demographics, cardiovascular history and lifestyle, hospital information, immunosuppressive therapy, and post-transplant renal function (HR: 2.75, 95% CI: 1.43, 5.28; p = .004).

CONCLUSIONS

After heart transplantation, high FBG variability is strongly and independently associated with an increased risk of all-cause mortality. Our findings suggest that FBG variability is a novel risk factor and prognostic marker for heart transplantation recipients in outpatient clinic.

The effect of sex inequality on solid organ transplantation: A systematic review and meta-analysis

BACKGROUND

Sex disparities are related to biological differences, which may have significant impact on patient and allograft outcomes. The aim was to investigate the impact of sex on clinical and safety outcomes after solid organ transplantation (SOT).

METHODS

A systematic review and meta-analysis was performed. Observational studies comparing females vs. males after SOT were considered for inclusion after a systematic search of the Pubmed, Cochrane Library, and Web of Science databases conducted from 2016 to 2021. Primary outcome was mortality. PROSPERO register number: CRD42021282615.

RESULTS

After retrieving 1103 studies, 22 observational studies (1,045,380 subjects) were finally deemed eligible for inclusion. Females accounted 36.3% of SOT recipients, but presented significantly lower mortality (odds ratio (OR): 0.87, 95% confidence interval (CI): 0.83-0.92, I2=78%). In subgroup analyses, mortality was significantly lower in females undergoing liver (OR: 0.89 95%CI: 0.86-0.92, I2=0%) or kidney transplantation (OR: 0.82 95%CI: 0.76-0.89, I2=72%). Male sex was consistently reported as a protective factor against hospital readmission. Among the outcomes, allograft dysfunction was influenced by a combination of donor-recipient sex and age. Data on overall infections were inconclusive. Several reports suggest a higher risk of malignancy among males.

CONCLUSIONS

Females represent one-third of SOT recipients but have higher survival rates than males after liver and kidney transplantation. The impact on graft dysfunction was heterogeneous. While further research is warranted, our findings should encourage clinicians and researchers to consider sex as a factor when taking decisions regarding SOT management.

Influence of sex on global myocardial ischemia tolerance and mitochondrial function in circulatory death donor hearts

Donation after circulatory death (DCD) donor hearts are not routinely used for heart transplantation (HTx) because of ischemic damage, which is inherent to the DCD process. HTx outcomes are suboptimal in males who received female donor hearts. The exact mechanism for suboptimal outcomes from female donor hearts has not been defined. Differential susceptibility to ischemia tolerance, which would play a significant role in DCD donation, could be a reason but has not been studied. We studied the influence of sex on global myocardial ischemia tolerance and mitochondrial function. Sprague-Dawley rats of both sexes were assigned to DCD (n = 32) or control beating-heart donor (CBD, n = 28) groups. DCD hearts underwent 25 min of in vivo global myocardial ischemia and 90 min of ex vivo Krebs-Henseleit buffer perfusion at 37°C. CBD hearts were procured without ischemia. Infarct size was determined in hearts following 90 min of reperfusion, and in another set of hearts, mitochondrial function (oxidative-phosphorylation) was studied following 60 min of reperfusion. Infarct size was increased 3.3-fold in male and 3.1-fold in female DCD hearts compared with CBD hearts. However, infarct size (%) was comparable in female and male DCD hearts (male: 25.4 ± 3.7 vs. female 19.0 ± 3.3, P = NS). Oxidative phosphorylation was similarly decreased in male and female DCD hearts' mitochondria compared with CBD hearts' mitochondria. Thus, neither infarct size nor mitochondrial dysfunction was higher in female DCD hearts. These results suggest that the susceptibility to ischemia is not the reason for suboptimal HTx outcomes with female donor hearts.NEW & NOTEWORTHY The current study shows cardiac injury is not increased in female DCD hearts following global ischemia-reperfusion compared with male DCD hearts. In addition, mitochondrial dysfunction with DCD ischemia-reperfusion is comparable in both sexes. Sex-specific immune responses and hormone receptor modulation may contribute to suboptimal outcomes in male HTx recipients with female donor hearts.

Gender differences in the assessment, decision making and outcomes for ventricular assist devices and heart transplantation: An analysis from a UK transplant centre

PURPOSE

There are marked gender differences in all aetiologies of advanced heart failure. We sought to determine whether there is evidence of gender-specific decision making for transplant assessments, and how gender effects outcomes.

METHODS

Retrospective analysis of adult heart transplant assessments at a single UK centre between April 2015 and March 2020.

RESULTS

Females were 32% of referrals (N = 137 females, 285 males), with marked differences between diagnoses - 11% ischaemics and 43% of adult congenital. Females were younger, shorter, weighed less, and had lower pulmonary pressures. Females were much less likely to receive a ventricular assist device (13%). Blood type 'O' females were relatively more likely compared to males to receive a transplant (45%). Comparing males and females who received a ventricular assist device, both had similar levels of high pulmonary pressures, indicating consistent decision making based on haemodynamics to implant a device. Overall survival was better for females (in non congenital patients), and this was due to female patients who were not accepted for transplant or a ventricular assist device being more often 'too well for transplant', rather than in males when they were more often 'unsuitable'.

CONCLUSIONS

Marked gender differences exist at all stages of the heart transplant assessment pathway. Appropriate decision making based on clinical grounds is shown with less transplants in male blood type 'O's and haemodynamic criteria for ventricular assist device implantation in both genders. Further studies are need to determine if there is a wider community bias in advanced heart failure treatments for females. This article is protected by copyright. All rights reserved.

Spanish Heart Transplant Registry. 32nd Official Report of the Heart Failure Association of the Spanish Society of Cardiology

INTRODUCTION AND OBJECTIVES

The present report updates the main characteristics and outcomes of heart transplants in Spain to 2020.

METHODS

We describe the main features of recipients, donors, surgical procedure, and immunosuppression in 2020. We also analyze the temporal trends of these characteristics and outcomes (survival) for the period 2011 to 2019.

RESULTS

In 2020, 278 heart transplants were performed (7.3% decrease vs 2019). The findings in 2020 confirmed previous observations of an increase in pretransplant sternotomy, a slight decrease in urgent transplants carried out with ventricular assist devices, a slight decrease in donor age, an increase in the use of allografts with previous arrest, and a decrease in ischemia time. Survival continued to improve in recent triennia, reaching 82.0% at 1 year in the period 2017 to 2019.

CONCLUSIONS

The slight decrease in the number of heart transplants performed in 2020 in Spain, most likely due to the SARS-CoV-2 pandemic, did not change the main characteristics of the procedure. No change was observed in the tendency to improved survival.

Influence of Gender in Advanced Heart Failure Therapies and Outcome Following Transplantation

Biological differences between males and females change the course of different diseases and affect therapeutic measures' responses. Heart failure is not an exception to these differences. Women account for a minority of patients on the waiting list for heart transplantation or other advanced heart failure therapies. The reason for this under-representation is unknown. Men have a worse cardiovascular risk profile and suffer more often from ischemic heart disease. Conversely, transplanted women are younger and more frequently have non-ischemic cardiac disorders. Women's poorer survival on the waiting list for heart transplantation has been previously described, but this trend has been corrected in recent years. The use of ventricular assist devices in women is progressively increasing, with comparable results than in men. The indication rate for a heart transplant in women (number of women on the waiting list for millions of habitants) has remained unchanged over the past 25 years. Long-term results of heart transplants are equal for both men and women. We have analyzed the data of a national registry of heart transplant patients to look for possible future directions for a more in-depth study of sex differences in this area. We have analyzed 1-year outcomes of heart transplant recipients. We found similar results in men and women and no sex-related interactions with any of the factors related to survival or differences in death causes between men and women. We should keep trying to approach sex differences in prospective studies to confirm if they deserve a different approach, which is not supported by current evidence.

Survival and Nutritional Status of Male and Female Heart Transplant Patients Based on the Nutritional Risk Index

Malnutrition among heart-transplant patients may affect survival. The aim was to investigate the survival and nutrition status among male and female heart transplant patients who underwent transplantation, before and 1 year after surgery based on the nutritional risk index (NRI). The medical records of ninety heart-transplant patients (2009–2014) from the King Faisal Specialist Hospital, Riyadh, were reviewed. The assessment included demographic data, anthropometric measurements, and NRI calculation. Moreover, postoperative data included the length of stay and survival. Paired t-test and survival analysis by Kaplan–Meier (KM) curves were used. A total of 90 patients (males 77.78%) were included. The prevalence of malnutrition in the preoperative phase by NRI was 60% (7.78% as severe; 40% as moderate, and 12.22% mild NRI scores). After 1 year, body mass index (BMI) and NRI increased significantly (p < 0.001). Furthermore, NRI was significantly different between men and women (p < 0.01), while KM survival curves were insignificantly different (p = 0.67). Recipients with postoperative moderate or severe nutritional risk (NRI < 97.5) had significantly shorter survival in the first-year post-transplantation (HR = 0.82; 95% CI, 0.75–0.89; p < 0.001). Our findings indicate that the NRI after 1 year of transplant correlated significantly with mortality. Besides, there was no significant gender difference regarding survival; however, malnutrition and low survival were more prominent among women.