Predisposing factors for late mortality in heart transplant patients

Relationship between donor ejection fraction, left ventricular wall thickness and mortality in heart transplants recipients

This study explored the impact of donor left ventricular ejection fraction (EF) and left ventricular wall thickness (LVWT) on mortality among heart transplant (HTx) recipients. Utilizing data from the United Network for Organ Sharing (UNOS) registry, adult HTx recipients between 2006-2022 were analyzed. Patients were categorized into four groups based on donor EF(>50 % or ≤50 %) and LVWT(<1.4 cm or ≥1.4 cm). 21,012 patients were included. There were significant differences in baseline characteristics among the groups. Unadjusted mortality was 6.3 %, 6.0 %, 6.0 %, and 2.4 %(p=0.86) at 30-days; 16.2 %, 13.5 %, 16.8 %, and 7.3 %(p=0.08) at 1-year; and 32.2 %, 29.2 %, 35.4 %, and 29.0 %(p=0.18) at 5-years, respectively. In addition, adjusted mortality did not differ across the groups. There were no significant differences in recipient mortality in groups based on donor EF and LVWT. Expanding the donor selection criteria would allow for increase in the donor pool and assist in decreasing the mortality, while on the waitlist for HTx.

Acute rejection in donation after circulatory death (DCD) heart transplants

BACKGROUND

Donation after circulatory death (DCD) heart transplantation has promising early survival, but the effects on rejection remain unclear.

METHODS

The United Network for Organ Sharing database was queried for adult heart transplants from December 1, 2019, to December 31, 2021. Multiorgan transplants and loss to follow-up were excluded. The primary outcome was acute rejection, comparing DCD and donation after brain death (DBD) transplants.

RESULTS

A total of 292 DCD and 5,582 DBD transplants met study criteria. Most DCD transplants were transplanted at status 3-4 (61.0%) compared to 58.6% of DBD recipients at status 1-2. DCD recipients were less likely to be hospitalized at transplant (26.7% vs 58.3%, p < 0.001) and to require intra-aortic balloon pumping (IABP; 9.6% vs 28.9%, p < 0.001), extracorporeal membrane oxygenation (ECMO; 0.3% vs 5.9%, p < 0.001) or temporary left ventricular assist device (LVAD; 1.0% vs 2.7%, p < 0.001). DCD recipients were more likely to have acute rejection prior to discharge (23.3% vs 18.4%, p = 0.044) and to be hospitalized for rejection (23.4% vs 11.4%, p = 0.003) at a median follow-up of 15 months; the latter remained significant after propensity matching. On multivariable logistic regression, DCD donation was an independent predictor of acute rejection (odds ratio [OR] 1.47, 95% confidence interval [CI] 1.00-2.15, p = 0.048) and hospitalization for rejection (OR 2.03, 95% CI 1.06-3.70, p = 0.026). On center-specific subgroup analysis, DCD recipients continued to have higher rates of hospitalization for rejection (23.4% vs 13.8%, p = 0.043).

CONCLUSIONS

DCD recipients are more likely to experience acute rejection. Early survival is similar between DCD and DBD recipients, but long-term implications of increased early rejection in DCD recipients require further investigation.

Recent advances in biological pumps as a building block for bioartificial hearts

The field of biological pumps is a subset of cardiac tissue engineering and focused on the development of tubular grafts that are designed generate intraluminal pressure. In the simplest embodiment, biological pumps are tubular grafts with contractile cardiomyocytes on the external surface. The rationale for biological pumps is a transition from planar 3D cardiac patches to functional biological pumps, on the way to complete bioartificial hearts. Biological pumps also have applications as a standalone device, for example, to support the Fontan circulation in pediatric patients. In recent years, there has been a lot of progress in the field of biological pumps, with innovative fabrication technologies. Examples include the use of cell sheet engineering, self-organized heart muscle, bioprinting and in vivo bio chambers for vascularization. Several materials have been tested for biological pumps and included resected aortic segments from rodents, type I collagen, and fibrin hydrogel, to name a few. Multiple bioreactors have been tested to condition biological pumps and replicate the complex in vivo environment during controlled in vitro culture. The purpose of this article is to provide an overview of the field of the biological pumps, outlining progress in the field over the past several years. In particular, different fabrication methods, biomaterial platforms for tubular grafts and examples of bioreactors will be presented. In addition, we present an overview of some of the challenges that need to be overcome for the field of biological pumps to move forward.

Retrospective analysis of the impact of pre-transplant implantable cardioverter-defibrillator status on long-term prognosis in heart transplant patients

BACKGROUND

Sudden cardiac death (SCD) post-heart transplantation affects 8%-35% of patients; however, the risk profile remains to be completely elucidated. While pre-transplant ICDs are typically removed during transplantation, no information exists to suggest if this pre-transplant risk stratification is also associated with post-transplant outcomes. The objective of this study was to assess the impact of pre-transplant ICD status on long-term prognosis post-heart transplant.

METHODS

The United Network for Organ Sharing registry was queried for all adult heart transplant recipients from 2010 to 2018. Patients were categorized as with versus without ICD prior to heart transplantation. Survival was compared using Kaplan-Meier analysis. Proportional hazards regression analysis assessed the impact of ICDs adjusting for clinical and demographic covariates.

RESULTS

Of 19 026 patients included, 78.6% (n = 14 960) had received an ICD at time of registration. Patients with an ICD were older [54.9 (±11.6) years vs. 48.6 (±15.3) years, p < .001], less likely to be female [25.7% (n = 3842) vs. 31.2% (n = 1269), p < .001], and more commonly diabetic [29.3% (n = 4376) vs 23.5% (n = 954), p < .001]. Kaplan-Meier analysis showed no difference in unadjusted survival trajectory by ICD status (chi-square = .48, p = .49). Survival was unrelated to ICD status in the multivariable model (HR = .98; 95% CI .90-1.07).

CONCLUSIONS

Patients receiving an ICD pre-transplant had a higher prevalence of risk factors for SCD than non-ICD patients, yet ICD status prior to heart transplantation was not associated with a change in long-term prognosis post-heart transplantation.

Clonal hematopoiesis confers an increased mortality risk in orthotopic heart transplant recipients

Novel risk stratification and non-invasive surveillance methods are needed in orthotopic heart transplant (OHT) to reduce morbidity and mortality post-transplant. Clonal hematopoiesis (CH) refers to the acquisition of specific gene mutations in hematopoietic stem cells linked to enhanced inflammation and worse cardiovascular outcomes. The purpose of this study was to investigate the association between CH and OHT. Blood samples were collected from 127 OHT recipients. Error-corrected sequencing was used to detect CH-associated mutations. We evaluated the association between CH and acute cellular rejection, CMV infection, cardiac allograft vasculopathy (CAV), malignancies, and survival. CH mutations were detected in 26 (20.5%) patients, mostly in DNMT3A, ASXL1, and TET2. Patients with CH showed a higher frequency of CAV grade 2 or 3 (0% vs. 18%, p < .001). Moreover, a higher mortality rate was observed in patients with CH (11 [42%] vs. 15 [15%], p = .008) with an adjusted hazard ratio of 2.9 (95% CI, 1.4-6.3; p = .003). CH was not associated with acute cellular rejection, CMV infection or malignancies. The prevalence of CH in OHT recipients is higher than previously reported for the general population of the same age group, with an associated higher prevalence of CAV and mortality.

Diltiazem as a cyclosporine A-sparing agent in heart transplantation: Benefits beyond dose reduction

Diltiazem (DZ) is widely prescribed in transplant recipients because of its drug-drug interactions with calcineurin inhibitors (CNI). However, these interactions have been primarily investigated in renal transplantation, and data regarding the long-term efficacy and safety of DZ in orthotopic heart transplantation (OHT) are still sparse. Our study aimed to elucidate the extent to which the co-prescription of DZ reduces the dose required to maintain adequate blood levels of cyclosporine A (CsA) and the resulting effect on morbidity and mortality in OHT recipients. We performed a retrospective single-center analysis of OHT recipients on a long-term immunosuppressive regimen based on CsA and mycophenolate mofetil (MMF). The study population consisted of 95 adult OHT recipients with a mean follow-up of 15.8 ± 6.7 years. DZ was co-prescribed in 39 subjects (41.1%) and was associated with a 28.6% reduction of the mean CsA daily dose (P < .001). Patients on DZ had less frequent rejection episodes (P = .002), better renal function (P = .009) and a lower rate of end-stage renal disease (P = .008). Additionally, they developed later cardiac allograft vasculopathy (CAV). We observed no prognostic relevance of DZ co-prescription in univariate and multivariate Cox-regression analyses. In addition to reducing the CsA dose required to maintain adequate blood through levels, DZ may have nephroprotective properties in OHT. The co-administration of DZ may decelerate the development of CAV and reduce the frequency of the rejection episodes. However, the beneficial influence on morbidity has no impact on mortality.

Implications of obesity across the heart failure continuum

The obesity paradox, which suggests a survival advantage for the obese in heart failure (HF) has sparked debate in the medical community. Studies demonstrate a survival advantage in obese patients with HF, including those with advanced HF requiring continuous inotropic support for palliation or disease modifying therapy with a left ventricular assist device (LVAD) or heart transplantation (HT). Importantly, the obesity paradox is affected by the level of cardiorespiratory fitness (CRF). It is now recommended that HF patients with body mass index ≥35 kg/m² achieve at least 5-10% weight loss, in order to improve symptoms and cardiac function, though more robust data are urgently needed. CRF may be the single best predictor of overall health and small improvements in fitness levels may lead to improved outcomes in HF. In addition to implications of obesity in chronic HF, we also discuss management of obese patients with advanced HF and their implications for therapies such as LVAD implantation and HT.