Primary Graft Failure After Heart Transplantation: The Importance of Donor Pharmacological Management

Artificial Intelligence Approaches for Predicting the Risks of Durable Mechanical Circulatory Support Therapy and Cardiac Transplantation

Background: The use of AI-driven technologies in probing big data to generate better risk prediction models has been an ongoing and expanding area of investigation. The AI-driven models may perform better as compared to linear models; however, more investigations are needed in this area to refine their predictability and applicability to the field of durable MCS and cardiac transplantation. Methods: A literature review was carried out using Google Scholar/PubMed from 2000 to 2023. Results: This review defines the knowledge gaps and describes different AI-driven approaches that may be used to further our understanding. Conclusions: The limitations of current models are due to missing data, data imbalances, and the uneven distribution of variables in the datasets from which the models are derived. There is an urgent need for predictive models that can integrate a large number of clinical variables from multicenter data to account for the variability in patient characteristics that influence patient selection, outcomes, and survival for both durable MCS and HT; this may be fulfilled by AI-driven risk prediction models.

Donor Pericardial Interleukin and Apolipoprotein Levels May Predict the Outcome after Human Orthotopic Heart Transplantation

The proinflammatory cascade that is activated at the time of brain death plays a crucial role in organ procurement. Our aim of this study was to explore the relationship between the clinical outcome of orthotopic heart transplantation, as well as cytokine and apolipoprotein profiles of the pericardial fluid obtained at donation. Interleukin, adipokine and lipoprotein levels in the pericardial fluid, as well as clinical data of twenty donors after brain death, were investigated. Outcome variables included primary graft dysfunction, the need for posttransplantation mechanical cardiac support and International Society for Heart and Lung Transplantation grade ≥ 2R rejection. Hormone management and donor risk scores were also investigated. Lower levels of IL-6 were observed in primary graft dysfunction (median: 36.72 [IQR: 19.47–62.90] versus 183.67 [41.21–452.56]; p = 0.029) and in the need for mechanical cardiac support (44.12 [20.12–85.70] versus 247.13 [38.51–510.38]; p = 0.043). Rejection was associated with lower ApoAII (p = 0.021), ApoB100 (p = 0.032) and ApoM levels (p = 0.025). Lower adipsin levels were detected in those patients receiving desmopressin (p = 0.037); moreover, lower leptin levels were found in those patients receiving glucocorticoid therapy (p = 0.045), and higher T3 levels were found in those patients treated with L-thyroxine (p = 0.047) compared to those patients not receiving these hormone replacement therapies. IL-5 levels were significantly associated with UNOS-D score (p = 0.004), Heart Donor Score (HDS) and Adapted HDS (p < 0.001). The monitoring of immunological and metabolic changes in donors after brain death may help in the prediction of potential complications after heart transplantation, thus potentially optimizing donor heart allocation.

Primary Graft Dysfunction After Isolated Heart Transplantation - Incidence, Risk Factors, and Clinical Implications Based on a Single-Center Experience

BACKGROUND

Since the international consensus on primary graft dysfunction (PGD) following heart transplantation (HT) was reported in 2014, few clinical studies have been reported. We aimed to analyze the incidence, predictive factors, and clinical implications of PGD following the International Society of Heart and Lung Transplant criteria in a single center.Methods and Results:This study enrolled 570 consecutive adult patients undergoing isolated HT between November 1992 and December 2017. Under a new set of criteria, PGD-left ventricle (PGD-LV) occurred in 35 patients (6.1%; mild, n=1 [0.2%]; moderate, n=14 [2.5%]; severe, n=20 [3.5%]), whereas PGD-right ventricle (PGD-RV) occurred in 3 (0.5%). Multivariable analysis demonstrated that preoperative admission (odds ratio [OR] 4.20; 95% confidence interval [CI] 1.24-14.26; P=0.021), preoperative extracorporeal membrane oxygenation (OR 4.03; 95% CI 1.75-9.26; P=0.001), and prolonged total ischemic time (OR 1.09; 95% CI 1.02-1.15; P=0.006) were significant predictors of moderate to severe PGD-LV. Moderate to severe PGD-LV was an independent and significant risk factor for early death (OR 55.64; 95% CI 11.65-265.73; P<0.001), with its effects extending up to 3 months after HT.

CONCLUSIONS

Moderate to severe PGD-LV, as defined by the new guidelines, is an important predictor of early mortality, with effects extending up to 3 months after HT. Efforts to reduce the occurrence of moderate to severe PGD-LV may lead to better outcomes.

Mechanically Supported Early Graft Failure After Heart Transplantation

BACKGROUND

The occurrence of early graft failure (EGF) after heart transplantation (Htx) often requires a mechanical circulatory support (MCS) therapy. The aims of our study were to identify risk factors of mechanically supported severe EGF and evaluate their impact on both early and late outcomes.

METHODS

Between January 2000 and December 2019, 499 consecutive adult patients underwent Htx at our institution. Severe EGF was defined as the need for extracorporeal life support (ECLS) within 24 hours after surgery. All available recipient and donor variables were retrospectively analyzed.

RESULTS

Overall, EGF occurred in 58 (11.6%) patients. Post-Htx peripheral or central ECLS was necessary in 32 (6.4%) cases. Independent predictors of severe EGF were, in the recipient group, preoperative transpulmonary gradient (TPG) >12 mm Hg (odds ratio [OR] 4.1, P = .013), preoperative inotropic score >10 (OR 7.3, P = .0001), and pre-Htx ECLS support (OR 5.2, P = .015), while in the donors, a Eurotransplant donor score ≥17 (OR 8.5, P = .005). The absence of EGF was related with a better survival at 1 year and 5 years (94% and 85%, respectively) compared with EGF requiring ECLS population (36% and 28% at 1 year and 5 years, respectively; P < .001). A five-year conditional survival rate did not differ significantly (85% no EGF vs 83% EGF requiring ECLS).

CONCLUSION

Both donor and recipient factors may influence EGF occurrence. Post-Htx ECLS may impact negatively early; however, patients weaned from ECLS eventually benefit from such a rescue treatment with outcomes comparable with Htx patients who did not suffer EGF.

Pediatric donor management to optimize donor heart utilization

Optimal management of pediatric cardiac donors is essential in order to maximize donor heart utilization and minimize the rate of discarded organs. This review was performed after a systematic literature review and gives a detailed overview on current practices and guidelines. The review focuses on optimal monitoring of pediatric donors, donor workup, hormonal replacement, and obliterating the adverse effects of brain death. The current evidence on catecholamine support and thyroid hormone replacement is also discussed. Recognizing and addressing this shall help in a standardized approach toward donor management and optimal utilization of pediatric heart donors organs.

ISHLT consensus statement on donor organ acceptability and management in pediatric heart transplantation

The number of potential pediatric heart transplant recipients continues to exceed the number of donors, and consequently the waitlist mortality remains significant. Despite this, around 40% of all donated organs are not used and are discarded. This document (62 authors from 53 institutions in 17 countries) evaluates factors responsible for discarding donor hearts and makes recommendations regarding donor heart acceptance. The aim of this statement is to ensure that no usable donor heart is discarded, waitlist mortality is reduced, and post-transplant survival is not adversely impacted.

Primary graft dysfunction in heart transplantation

PURPOSE OF REVIEW

Primary graft dysfunction (PGD) is common early postheart transplantation; however, use of standardized definitions remains inconsistent. This review focuses on understanding the incidence, classification, risk factors, and management of PGD.

RECENT FINDINGS

The incidence and mortality of PGD in heart transplant varies considerably in the published literature ranging from 1.0% to 31% and 3% to 75%, respectively. There is also considerable variation in management strategies with current data favoring early intervention.

SUMMARY

PGD in heart transplantation remains a challenging problem associated with significant mortality and morbidity. There is need for a consistent and accessible definition to better define associated risk factors and optimize management strategies.

Moderate-severe primary graft dysfunction after pediatric heart transplantation

BACKGROUND

PGD is a complication after heart transplantation (OHT) and a significant cause of mortality, particularly in infant recipients. Lack of standardized definition of PGD in the pediatric population makes the prevalence and magnitude of impact unclear.

METHODS

ISHLT PGD consensus guidelines, which include inotrope scores and need for MCS, were applied retrospectively to 208 pediatric OHT recipients from a single institution from 1/2005-5/2016. PGD was defined as: moderate PGD-inotrope score >10 on postoperative day 1 (24-48 hours), and severe PGD-MCS within 24 hours (in the absence of detectable rejection).

RESULTS

PGD occurred in 34 patients (16.3%); 14 of which had severe PGD (6.7%). Multivariate risk factors for PGD included CPB time (OR 10.3/10 min, 95% 10.05, 10.2, P = 0.03), Fontan palliation (OR 1.9, 95% 1.2, 3.97), and PCM (OR 5.65, 95% 1.52, 22.4); but not age, weight, ischemic time, or donor characteristics. Upon sub-analysis excluding patients with PCM, increased CPB was a significant multivariate risk factor (OR 10.09, 95% 9.89, 10.12, P = 0.003). Patients with PGD had decreased discharge survival compared to those without PGD (85% vs 96%, P < 0.01). Severe PGD was associated with the poorest 1-year survival (57% vs 91% without PGD, P = 0.04).

CONCLUSION

Patients with prolonged CPB are potentially at risk for developing PGD. Neither infant recipients nor donor characteristics were associated with an increased risk of PGD in the current era.

Complications of Cardiac Transplantation

PURPOSE OF REVIEW

Despite the improvement in medical therapy for heart failure and the advancements in mechanical circulatory support, heart transplantation (HT) still remains the best therapeutic option to improve survival and quality of life in patients with advanced heart failure. Nevertheless, HT recipients are exposed to the risk of several potential complications that may impair their outcomes. In this article, we aim to provide a practical and scholarly framework for clinicians approaching heart transplant medicine, as well as a concise update for the experienced readers on the most relevant post-HT complications.

RECENT FINDINGS

While recognizing that most of the treatments herein discussed are based more on experience than on solid scientific evidence, significant step forward has been made in particular in the recognition and management of primary graft dysfunction, antibody-mediated rejection, and renal dysfunction. Complications after HT may vary according to the time from surgery and can be related to graft function and pathology or to diseases and dysfunctions occurring in other organs or systems, mainly as side effects of immunosuppressive drugs and progression of pre-existing conditions. Future research needs to focus on improving precision diagnostics of causes of graft dysfunction and on reaching an optimal and customized balance between efficacy and toxicities of immunosuppressive strategies.

Primary graft dysfunction after heart transplantation: Incidence, trends, and associated risk factors

Changes in heart transplantation (HT) donor and recipient demographics may influence the incidence of primary graft dysfunction (PGD). We conducted a retrospective study to evaluate PGD incidence, trends, and associated risk factors by analyzing consecutive adult patients who underwent HT between January 2009 and December 2014 at our institution. Patients were categorized as having PGD using the International Society for Heart & Lung Transplantation (ISHLT)-defined criteria. Variables, including clinical and demographic characteristics of donors and recipients, were selected to assess their independent association with PGD. A time-trend analysis was performed over the study period. Three-hundred seventeen patients met inclusion criteria. Left ventricular PGD, right ventricular PGD, or both, were observed in 99 patients (31%). Risk factors independently associated with PGD included ischemic time, recipient African American race, and recipient amiodarone treatment. Over the study period, there was no change in the PGD incidence; however, there was an increase in the recipient pretransplantation use of amiodarone. The rate of 30-day mortality was significantly elevated in those with PGD versus those without PGD (6.06% vs 0.92%, P = .01). Despite recent advancements, incidence of PGD remains high. Understanding associated risk factors may allow for implementation of targeted therapeutic interventions.

Utilization and Outcomes of Temporary Mechanical Circulatory Support for Graft Dysfunction After Heart Transplantation

Graft dysfunction is the main cause of early mortality after heart transplantation. In cases of severe graft dysfunction, temporary mechanical circulatory support (TMCS) may be necessary. The aim of this systematic review was to examine the utilization and outcomes of TMCS in patients with graft dysfunction after heart transplantation. Electronic search was performed to identify all studies in the English literature assessing the use of TMCS for graft dysfunction. All identified articles were systematically assessed for inclusion and exclusion criteria. Of the 5,462 studies identified, 41 studies were included. Among the 11,555 patients undergoing heart transplantation, 695 (6.0%) required TMCS with patients most often supported using venoarterial extracorporeal membrane oxygenation (79.4%) followed by right ventricular assist devices (11.1%), biventricular assist devices (BiVADs) (7.5%), and left ventricular assist devices (LVADs) (2.0%). Patients supported by LVADs were more likely to be supported longer (p = 0.003), have a higher death by cardiac event (p = 0.013) and retransplantation rate (p = 0.015). In contrast, patients supported with BiVAD and LVAD were more likely to be weaned off support (p = 0.020). Overall, no significant difference was found in pooled 30 day survival (p = 0.31), survival to discharge (p = 0.19), and overall survival (p = 0.51) between the subgroups. Temporary mechanical circulatory support is an effective modality to support patients with graft dysfunction after heart transplantation. Further studies are needed to establish the optimal threshold and strategy for TMCS and to augment cardiac recovery and long-term survival.

High-dose catecholamine donor support and outcomes after heart transplantation

BACKGROUND

Higher dose norepinephrine donor support is a frequent reason for donor heart decline, but its associations with outcomes after heart transplantation are unclear.

METHODS

We retrospectively analyzed 965 patients transplanted between 1992 and 2015 in the Heart Transplant Program Vienna. Stratification was performed according to donor norepinephrine dose administered before organ procurement (Group 0: 0 µg/kg/min; Group 1: 0.01 to 0.1 µg/kg/min; Group 2: >0.1 µg/kg/min). Sub-stratification of Group 2 was performed for comparison of high-dose subgroups (Group HD 1: 0.11 to 0.4 µg/kg/min; Group HD 2: >0.4 µg/kg/min). Associations between groups and outcome variables were investigated using a multivariable Cox proportional hazards model and logistic regression analyses.

RESULTS

Donor norepinephrine dose groups were not associated with overall mortality (Group 1 vs 0: hazard ratio [HR] 1.12, 95% confidence interval [CI] 0.87 to 1.43; Group 2 vs 0: HR 1.07, 95% CI 0.82 to 1.39; p = 0.669). No significant group differences were found for rates of 30-day mortality (p = 0.35), 1-year mortality (p = 0.897), primary graft dysfunction (p = 0.898), prolonged ventilation (p = 0.133) and renal replacement therapy (p = 0.324). Groups 1 and 2 showed higher rates of prolonged intensive care unit stay (18.9% vs 28.5% vs 27.5%, p = 0.005). High-dose subgroups did not differ significantly in 1-year mortality (Group HD 1: 14.3%; Group HD 2: 17.8%; p = 0.549).

CONCLUSIONS

Acceptance of selected donor hearts supported by higher doses of norepinephrine may be a safe option to increase the donor organ pool.

Associated Clinical and Laboratory Markers of Donor on Allograft Function After Heart Transplant

Introduction

Primary graft dysfunction is a major cause of mortality after heart transplantation.

Objective

To evaluate correlations between donor-related clinical/biochemical markers and the occurrence of primary graft dysfunction/clinical outcomes of recipients within 30 days of transplant.

Methods

The prospective study involved 43 donor/recipient pairs. Data collected from donors included demographic and echocardiographic information, noradrenaline administration rates and concentrations of soluble tumor necrosis factor receptors (sTNFR1 and sTNFR2), interleukins (IL-6 and IL-10), monocyte chemoattractant protein-1, C-reactive protein and cardiac troponin I. Data collected from recipients included operating, cardiopulmonary bypass, intensive care unit and hospitalization times, inotrope administration and left/right ventricular function through echocardiography.

Results

Recipients who developed moderate/severe left ventricular dysfunction had received organs from significantly older donors (P =0.020). Recipients from donors who required moderate/high doses of noradrenaline (>0.23 µg/kg/min) around harvesting time exhibited lower post-transplant ventricular ejection fractions (P =0.002) and required longer CPB times (P =0.039). Significantly higher concentrations of sTNFR1 (P =0.014) and sTNFR2 (P =0.030) in donors were associated with reduced intensive care unit times (≤5 days) in recipients, while higher donor IL-6 (P =0.029) and IL-10 (P =0.037) levels were correlated with reduced hospitalization times (≤25 days) in recipients. Recipients who required moderate/high levels of noradrenaline for weaning off cardiopulmonary bypass were associated with lower donor concentrations of sTNFR2 (P =0.028) and IL-6 (P =0.001).

Conclusion

High levels of sTNFR1, sTNFR2, IL-6 and IL-10 in donors were associated with enhanced evolution in recipients. Allografts from older donors, or from those treated with noradrenaline doses >0.23 µg/kg/min, were more frequently affected by primary graft dysfunction within 30 days of surgery.

Clinical Factors Implicated in Primary Graft Dysfunction After Heart Transplantation: A Single-center Experience

BACKGROUND

Primary graft dysfunction (PGD) is a frequent complication after cardiac transplantation and remains one of the leading causes of mortality in these patients. The objective of this case-control study is to identify donor and surgical procedure's factors associated with PGD, and further guide possible strategies to prevent PGD.

METHODS

Retrospective analysis of the medical records of patients who underwent cardiac transplantation at Memorial Hermann Hospital at Texas Medical Center between October 2012 and February 2015.

RESULTS

The study population included 99 patients, of which 18 developed PGD. Univariate analysis of donor characteristics revealed opioid use (P = .049) and death owing to anoxia (P = .021) were associated with PGD. The recipient/donor blood type match AB/A was significantly associated with PGD (P = .031). Time from brain death to aortic cross clamp (TBDACC) of ≥3 and ≥5 days were also found to be associated with PGD (P = .0011 and .0003, respectively). Multivariate analysis confirmed that patients with a time from brain death to aortic cross clamp ≥3 and ≥5 days had lesser odds of developing PGD (odds ratio, 0.098 [P = .0026] and OR, 0.092 [P = .0017], respectively].

CONCLUSIONS

Our study showed that a longer time from brain death to aortic cross clamp was associated with lower odds of developing PGD. Therefore, postponing heart procurement for a few days after brain death seems to be beneficial in preventing PGD.

Biomarkers of cellular apoptosis and necrosis in donor myocardium are not predictive of primary graft dysfunction

Primary graft dysfunction (PGD) is a life-threatening complication among heart transplant recipients and a major cause of early mortality. Although the pathogenesis of PGD is still unclear, ischemia/reperfusion injury has been identified as a predominant factor. Both necrosis and apoptosis contribute to the loss of cardiomyocytes during ischemia/reperfusion injury, and this loss of cells can ultimately lead to PGD. The aim of our prospective study was to find out whether cell death, necrosis and apoptosis markers present in the donor myocardium can predict PGD. The prospective study involved 64 consecutive patients who underwent orthotopic heart transplantation at our institute between September 2010 and January 2013. High-sensitive cardiac troponin T (hs-cTnT) as a marker of minor myocardial necrosis was detected from arterial blood samples before the donor's pericardium was opened. Apoptosis (caspase-3, active + pro-caspase-3, bcl-2, TUNEL) was assessed from bioptic samples taken from the right ventricle prior graft harvesting. In our study, 14 % of transplant recipients developed PGD classified according to the standardized definition proposed by the ISHLT Working Group. We did not find differences between the groups in regard to hs-cTnT serum levels. The mean hs-cTnT value for the PGD group was 57.4+/-22.9 ng/l, compared to 68.4+/-10.8 ng/l in the group without PGD. The presence and severity of apoptosis in grafted hearts did not differ between grafts without PGD and hearts that subsequently developed PGD. In conclusion, our findings did not demonstrate any association between measured myocardial cell death, necrosis or apoptosis markers in donor myocardium and PGD in allograft recipients. More detailed investigations of cell death signaling pathways in transplanted hearts are required.

A review of cardiac transplantation

Perioperative anesthetic management for cardiac transplantation is reviewed. Recent developments in adult cardiac transplantation are noted. This review includes demographics and historical results, recipient and donor selection and evaluation, mechanical circulatory support and heart transplantation techniques, and patient management immediately postimplantation.

Postoperative care of the transplanted patient

The successful delivery of optimal peri-operative care to pediatric heart transplant recipients is a vital determinant of their overall outcomes. The practitioner caring for these patients must be familiar with and treat multiple simultaneous issues in a patient who may have been critically ill preoperatively. In addition to the complexities involved in treating any child following cardiac surgery, caretakers of newly transplanted patients encounter multiple transplant-specific issues. This chapter details peri-operative management strategies, frequently encountered early morbidities, initiation of immunosuppression including induction, and short-term outcomes.

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.