Introduction: The Shift Toward Long-term Survivorship Challenges
Heart transplantation (HT) remains the gold-standard intervention for end-stage heart failure, offering a dramatic extension of life for patients who would otherwise have few options. However, as surgical techniques, immunosuppression protocols, and post-operative monitoring have improved, the clinical focus has shifted. It is no longer enough to simply ensure immediate graft survival; clinicians must now manage the long-term, multi-systemic complications that arise from chronic immunosuppression, pre-existing comorbidities, and the physiological stress of the transplant itself.
A burgeoning area of concern is the Cardiovascular-Kidney-Metabolic (CKM) syndrome—a complex interplay of metabolic dysfunction, renal impairment, and cardiovascular disease. While the link between these factors is well-established in the general population, their specific burden and progression in the heart transplant population have been less clearly defined until now.
Study Rationale and Methodology
A recent comprehensive retrospective observational study published in JACC: Heart Failure (Huang et al., 2025) sought to characterize the incidence and prevalence of CKM risk factors in both adult and pediatric HT recipients. Conducted at a high-volume single center, the study analyzed data from 860 adults and 84 children who underwent HT between January 1, 2015, and June 30, 2024.
The researchers extracted longitudinal clinical and laboratory data from electronic health records to calculate incidence rates (IRs) for type 2 diabetes mellitus (DM2), overweight/obesity, hypertension, chronic kidney disease (CKD), and dyslipidemia. Furthermore, the study investigated the real-world impact of newer pharmacological agents—specifically sodium-glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide-1 receptor agonists (GLP1RAs)—on renal function and body mass index (BMI) in this specific cohort.
The Alarming Burden of CKM in Adult HT Recipients
The findings for adult recipients underscore a high-intensity burden of metabolic and renal disease. The incidence rates, reported as cases per 100 person-years, were strikingly high:
Metabolic and Renal Incidence Rates:
Adult recipients experienced dyslipidemia at a rate of 139.1 per 100 person-years, followed by overweight or obesity at 77.3, CKD at 69.7, and DM2 at 28.6. These figures suggest that metabolic derangement is almost an expected outcome rather than a rare complication in the post-transplant setting.
The Early Post-Transplant Window:
The first 12 months following transplantation appear to be a critical period for the onset of CKM dysfunction. The study found that 99% of adults developed stage 1 or 2 hypertension within the first year. Even more concerning, 22.1% of all adults manifested hemoglobin A1c (HbA1c) levels of 6.5% or higher within that first year, regardless of whether they had a pre-existing diagnosis of diabetes. This suggests a significant incidence of post-transplant diabetes mellitus (PTDM), likely exacerbated by corticosteroid use and calcineurin inhibitors.
Lipid and Renal Deterioration:
Dyslipidemia was rampant, with 37.5% of adults developing moderate to severe hypertriglyceridemia and 31.1% showing worsened low-density lipoprotein cholesterol (LDL-C) control. Renal health was equally fragile; among those with relatively healthy pre-transplant kidney function (eGFR ≥45 mL/min/1.73 m2), a staggering 86.2% experienced a decline to below that threshold within 12 months post-HT.
Pediatric Recipients: A Different but Significant Profile
The pediatric cohort (n=84) presented a different CKM profile, generally showing lower incidence rates than adults but still significantly higher risks than the general pediatric population. The IRs for children were 2.8 for DM2, 26.9 for overweight/obesity, 5.5 for dyslipidemia, and 3.6 for CKD. While the absolute numbers are lower, the early onset of obesity and metabolic risk factors in children is particularly concerning for their long-term cardiovascular health over decades of expected survival.
Impact on Clinical Outcomes: Mortality and Vasculopathy
The study utilized time-varying Cox regression models to link these CKM comorbidities with clinical outcomes. One of the most critical findings was the association between DM2 and survival. Adult recipients with DM2 faced a significantly increased risk of mortality (Hazard Ratio [HR]: 1.84; 95% CI: 1.04-3.25). This highlights DM2 not just as a metabolic nuisance, but as a primary driver of post-transplant mortality.
Interestingly, the study did not find a significant association between the examined CKM comorbidities and the development of cardiac allograft vasculopathy (CAV). This suggests that while CKM factors drive overall mortality and systemic morbidity, the pathogenesis of CAV may be more heavily influenced by immunologic factors or specific transplant-related mechanisms not fully captured by traditional CKM metrics.
The Role of SGLT2 Inhibitors and GLP1RAs
A major highlight of this research is the evaluation of modern therapeutic agents in the HT population. Historically, clinicians have been cautious about using SGLT2 inhibitors and GLP1RAs in transplant recipients due to concerns about drug-drug interactions with immunosuppressants or potential adverse effects like urinary tract infections or gastrointestinal distress.
SGLT2 Inhibitors and Renal Function:
In 242 adults initiated on SGLT2 inhibitors post-HT, the study observed a nonlinear improvement in eGFR during the following 12 months. This mirrors findings in the non-transplant heart failure and CKD populations, suggesting that the nephroprotective benefits of SGLT2 inhibitors extend to the unique physiological environment of the heart transplant recipient.
GLP1RAs and Weight Management:
For the 168 individuals initiated on GLP1RAs, there was a predominantly linear reduction in BMI. Given the high incidence of obesity and its subsequent impact on metabolic health and graft strain, GLP1RAs represent a potent tool for managing the weight gain often associated with post-transplant steroid use.
Expert Commentary and Clinical Implications
The CKM framework provides a holistic lens through which to view the post-transplant patient. The data from Huang et al. suggest that CKM dysfunction is not a late-stage complication but an early and aggressive phenomenon. The 99% incidence of hypertension and the rapid decline in renal function within the first year indicate that screening and intervention must begin immediately after the patient leaves the operating room.
The mortality risk associated with DM2 (84% increase in risk) underscores the need for aggressive glycemic control. Furthermore, the positive signals from SGLT2 inhibitors and GLP1RAs provide a roadmap for updating post-transplant care guidelines. These agents may offer a double benefit: protecting the kidneys from calcineurin inhibitor-induced nephrotoxicity while simultaneously managing the metabolic fallout of immunosuppression.
Limitations
As a single-center retrospective study, the findings may reflect specific institutional practices regarding immunosuppression and patient selection. While the longitudinal nature of the data is a strength, prospective randomized controlled trials are still needed to definitively establish the safety and efficacy of SGLT2 inhibitors and GLP1RAs in the heart transplant population, particularly regarding their interaction with various immunosuppressive regimens.
Conclusion
The evolution of heart transplantation from a life-saving surgery to a chronic disease management challenge is highlighted by the high burden of CKM dysfunction. With nearly all adult recipients developing hypertension and a significant portion facing diabetes and renal decline within a year, the post-HT period must be treated as a high-risk metabolic state. The association of DM2 with increased mortality serves as a call to action for earlier, more aggressive metabolic management. The promising data on SGLT2 inhibitors and GLP1RAs offer a new therapeutic horizon, potentially allowing clinicians to mitigate the very complications that threaten the long-term success of the transplant.
References
Huang S, Tamaroff J, Farber-Eger E, et al. Cardiovascular-Kidney-Metabolic Disease Burden in Children and Adults Following Heart Transplantation. JACC Heart Fail. 2025 Dec;13(12):102710. doi: 10.1016/j.jchf.2025.102710. Epub 2025 Oct 20. PMID: 41117724.
