Post-Heart Transplant Diabetes Mellitus: Incidence, Prevalence and Outcomes

Sodium glucose co-transporter 2 inhibition with empagliflozin on metabolic, cardiac and renal outcomes in recent cardiac transplant recipients (EMPA-HTx): protocol for a randomised controlled trial

INTRODUCTION

Cardiac transplantation (CTx) is a life-saving operation that can improve the quality and length of a recipient's life. Immunosuppression medication, required to prevent rejection, can result in adverse metabolic and renal effects. Clinically significant complications include metabolic effects such as diabetes and weight gain, renal impairment, and cardiac disease such as allograft vasculopathy and myocardial fibrosis. Sodium glucose co-transporter 2 (SGLT2) inhibitors are a class of oral medication that increase urinary excretion of glucose. In patients with type 2 diabetes, SGLT2 inhibitors improve cardiovascular, metabolic and renal outcomes. Similar benefits have been shown in patients with heart failure and reduced ejection fraction irrespective of diabetes status. In patients with post-transplant diabetes mellitus, SGLT2 inhibitors improve metabolic parameters; however, their benefit and safety have not been evaluated in randomised prospective studies. This study will potentially provide a novel therapy to improve or prevent complications (diabetes, kidney failure and heart fibrosis) that occur with immunosuppressive medications.

METHODS

The EMPA-HTx study is a randomised, placebo-controlled trial of the SGLT2 inhibitor empagliflozin 10 mg daily versus placebo in recent CTx recipients. One hundred participants will be randomised 1:1 and commence the study medication within 6-8 weeks of transplantation with treatment and follow-up until 12 months after transplantation. Demographic information, anthropomorphic measurements, pathology tests and cardiac magnetic resonance (CMR) scan will be recorded at baseline and follow-up. Patients will be reviewed monthly during the study until 12 months post-CTx and data will be collected for each patient at each study visit. The overall aim of the study is to assess the safety and efficacy of empagliflozin in CTx recipients. The primary outcome is glycaemic improvement measured as change in glycated haemoglobin and/or fructosamine. Key secondary outcomes are cardiac interstitial fibrosis measured by CMR and renal function measured by estimated glomerular filtration rate.

ETHICS AND DISSEMINATION

This study has been approved by St Vincent's Hospital Human Research Ethics Committee (2021/ETH12184). The findings will be presented at national and international scientific meetings and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ACTRN12622000978763.

Pregnancies After Orthotopic Heart Transplantation: A Single-Center Experience

BACKGROUND

Patients who underwent orthotopic heart transplantation have improved survival and quality of live. Some of them are women of childbearing age and have a wish to be pregnant. If the decision to have a child is made, the patient needs a multidisciplinary approach.

MATERIAL AND METHODS

We analyzed the whole cohort of patients after orthotopic heart transplantation. From the whole group we extracted women of childbearing age between 16 and 45 years and at least 1 year after transplantation (85 patients). From this group, 8 patients gave birth to children.

RESULTS

No cardiocirculatory problems were observed in the mothers during pregnancy and in follow-ups. Strong changes in immunosuppressive drug levels were observed during and directly after the pregnancies. Two children were born prematurely (at 31 and in 34 weeks of gestation). Two children developed cardiomyopathy (the same as in mother).

CONCLUSION

The decision of childbearing should be made individually considering each patient's medical history and potential risks connected with the pregnancy. Pregnancy after heart transplantation is relatively safe for the mother. Risk of transmitting cardiomyopathies to the children, especially hypertrophic cardiomyopathy, is high. The patients should be aware of this fact and be carefully counseled preconceptionally.

Outcomes of diabetic patients with end-stage heart failure listed for heart transplantation: A propensity-matched analysis

BACKGROUND

We investigated the current trends and outcomes of diabetic patients listed for heart transplants in the U.S. and provided a method for risk-stratification.

METHODS

Using data from the United Network for Organ Sharing (UNOS), we identified heart failure patients listed for heart transplants between 2010 and 2019. Diabetic patients were propensity-matched with non-diabetics, and waitlist mortality as well as post-transplant graft survival were compared between the two groups. Further risk-stratification of diabetic patients was done based on the risk factors that independently predict graft failure.

RESULTS

28,928 adult patients (30% diabetic) with end-stage heart failure were added to the waitlist over the study period. In the propensity-matched cohort, waitlist mortality was higher in diabetic patients compared to non-diabetics (HR = 1.13 (95% CI = 1.04-1.22, p = 0.002). Over the study period, 5739 patients with diabetes were transplanted. In the propensity-matched cohorts of transplant recipients, the rate of graft failure was significantly higher for diabetic patients (23.3%) compared to non-diabetics (20.4%); HR = 1.17, 95% CI = 1.08-1.26, p<0.001. We identified 12 risk factors of graft failure among diabetic patients and developed a risk score that further risk-stratify these patients. Diabetic patients at low risk (score≤4) had similar graft survival as patients without diabetes (HR = 0.91, 95% CI = 0.82-1.01, p = 0.06). On the other hand, high-risk diabetic patients had worse graft survival compared to non-diabetics (HR = 1.52, 95% CI = 1.38-1.67, P<0.001).

CONCLUSION

Among patients with end-stage heart failure, pre-existing diabetes was associated with higher waitlist mortality and worse graft survival. However, with careful patient selection, graft survival is similar to those without diabetes. This article is protected by copyright. All rights reserved.

Metabolic Consequences of Solid Organ Transplantation

Metabolic complications affect over 50% of solid organ transplant recipients. These include posttransplant diabetes, nonalcoholic fatty liver disease, dyslipidemia, and obesity. Preexisting metabolic disease is further exacerbated with immunosuppression and posttransplant weight gain. Patients transition from a state of cachexia induced by end-organ disease to a pro-anabolic state after transplant due to weight gain, sedentary lifestyle, and suboptimal dietary habits in the setting of immunosuppression. Specific immunosuppressants have different metabolic effects, although all the foundation/maintenance immunosuppressants (calcineurin inhibitors, mTOR inhibitors) increase the risk of metabolic disease. In this comprehensive review, we summarize the emerging knowledge of the molecular pathogenesis of these different metabolic complications, and the potential genetic contribution (recipient +/- donor) to these conditions. These metabolic complications impact both graft and patient survival, particularly increasing the risk of cardiovascular and cancer-associated mortality. The current evidence for prevention and therapeutic management of posttransplant metabolic conditions is provided while highlighting gaps for future avenues in translational research.