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

Geographic disparities in heart transplantation persist under the new allocation policy

BACKGROUND

This study evaluated the impact of the 2018 heart allocation policy change on geographic disparities in United States orthotopic heart transplantation (OHT).

METHODS

The United Network for Organ Sharing registry was queried to measure geographic disparity in OHT rates between pre-policy and post-policy change eras. We performed multilevel Poisson regression to measure region-level OHT rates. We derived an allocation priority-adjusted median incidence rate ratio (MIRR) for each policy era, a measure of median change in OHT rates between regions.

RESULTS

5958.78 waitlist person-years were analyzed, comprising 6596 OHT procedures (3890 pre-policy and 2706 post-policy). Median region-level OHT rate was .94 transplants/person-years before and 1.51 transplants/person-years after the policy change (P < .001). The unadjusted OHT MIRR across regions was 1.29 (95% CI 1.00-1.50) pre-policy change and 1.17 (95% CI 1.00-1.43) post-policy change, suggesting that the region-related variance in OHT rates decreased under the new allocation. After adjustment for allocation priority risk factors, the MIRR pre-policy change was 1.13 (95% CI 1.01-1.32) and post-policy change was 1.15 (95% CI 1.00-1.35).

CONCLUSIONS

Geography accounts for ∼10% of the disparity among United States OHT rates. Despite broader heart sharing, the updated allocation policy did not substantially alter the existing geographic disparities among OHT recipients.

Contemporary contribution of cardiac surgery for the treatment of cardiomyopathies and pericardial diseases

Cardiomyopathy refers to a spectrum of heterogeneous myocardial disorders characterized by morphological and structural alterations leading eventually to heart failure, by affecting cardiac filling and/or the cardiac systolic function. Heart transplantation is currently the gold standard surgical treatment for patients with heart failure, with a median survival in adults of 12 years according to international registries. However, the limited available donor pool does not allow its extensive employment. For this reason, mechanical circulatory supports are increasingly used, and in the short term are becoming as possible alternatives to heart transplantation, owing to improved technologies and increased biocompatibility. However, long-term outcomes of mechanical assist devices are still burdened with a high rate of adverse events. Conventional surgical treatments could be still considered as alternatives to heart replacement treatment when tailored both on patient clinical conditions and etiology of cardiac diseases. In particular, among patients affected by ischemic cardiomyopathy, coronary artery bypass grafting has proven to improve survival when associated to optimal medical treatment, and surgical ventricular restoration might be considered as a valid treatment in particular cases. Correction of functional mitral valve regurgitation by mitral annuloplasty, which aims to restore left ventricular geometry, has not demonstrated unambiguous results, and outcomes of this procedure are still controversial. Pericardial pathology becomes of surgical interest when it is responsible for a reduced filling capacity of the heart chambers, which can develop acutely (cardiac tamponade) or chronically (as in the case of constrictive pericarditis). This review focuses on the different surgical approaches that could be adopted to treat patients with heart failure and pericardial diseases.

Post-transplant inotrope score is associated with clinical outcomes after adult heart transplantation

BACKGROUND

Inotrope score has been proposed as a marker of clinical outcome after adult heart transplantation (HTx) but is rarely used in practice.

METHODS

Inotrope score during the first 48 h after HTx was calculated in 81 patients as: dopamine + dobutamine + amrinone + milrinone (dose × 15) + epinephrine (dose × 100) + norepinephrine (dose × 100) + enoximone + isoprenaline (dose × 100), with each drug in µg/kg/min. Determinants of inotrope score were identified with linear regression. Cox regression was used to determine the association of inotrope score with mortality.

RESULTS

The mean recipient age was 52 ± 11 years, and 32 (39.5%) patients were female. Determinants of inotrope score were preoperative C-reactive protein, serum urea, congenital heart disease, and donor cardiac arrest (R2  = .30). Inotrope score was associated with 5-year mortality, independent of recipient age and gender (HR 1.03, 95% CI 1.00-1.07). This association was attenuated when adjusting for female-to-male transplant and ischemia time. Inotrope score was also strongly associated with continuous veno-venous hemofiltration (OR 1.07, 95% CI 1.03-1.12).

CONCLUSION

High inotrope score post-HTx was observed in recipient congenital heart disease and was associated with a higher risk of mortality and acute kidney injury.

Primary Graft Dysfunction after Heart Transplantation - Unravelling the Enigma

Primary graft dysfunction (PGD) remains the main cause of early mortality following heart transplantation despite several advances in donor preservation techniques and therapeutic strategies for PGD. With that aim of establishing the aetiopathogenesis of PGD and the preferred management strategies, the new consensus definition has paved the way for multiple contemporaneous studies to be undertaken and accurately compared. This review aims to provide a broad-based understanding of the pathophysiology, clinical presentation and management of PGD.

Plasma kallikrein predicts primary graft dysfunction after heart transplant

BACKGROUND

Primary graft dysfunction (PGD) is the leading cause of early mortality after heart transplant. Pre-transplant predictors of PGD remain elusive and its etiology remains unclear.

METHODS

Microvesicles were isolated from 88 pre-transplant serum samples and underwent proteomic evaluation using TMT mass spectrometry. Monte Carlo cross validation (MCCV) was used to predict the occurrence of severe PGD after transplant using recipient pre-transplant clinical characteristics and serum microvesicle proteomic data. Putative biological functions and pathways were assessed using gene set enrichment analysis (GSEA) within the MCCV prediction methodology.

RESULTS

Using our MCCV prediction methodology, decreased levels of plasma kallikrein (KLKB1), a critical regulator of the kinin-kallikrein system, was the most predictive factor identified for PGD (AUROC 0.6444 [0.6293, 0.6655]; odds 0.1959 [0.0592, 0.3663]. Furthermore, a predictive panel combining KLKB1 with inotrope therapy achieved peak performance (AUROC 0.7181 [0.7020, 0.7372]) across and within (AUROCs of 0.66-0.78) each cohort. A classifier utilizing KLKB1 and inotrope therapy outperforms existing composite scores by more than 50 percent. The diagnostic utility of the classifier was validated on 65 consecutive transplant patients, resulting in an AUROC of 0.71 and a negative predictive value of 0.92-0.96. Differential expression analysis revealed a enrichment in inflammatory and immune pathways prior to PGD.

CONCLUSIONS

Pre-transplant level of KLKB1 is a robust predictor of post-transplant PGD. The combination with pre-transplant inotrope therapy enhances the prediction of PGD compared to pre-transplant KLKB1 levels alone and the resulting classifier equation validates within a prospective validation cohort. Inflammation and immune pathway enrichment characterize the pre-transplant proteomic signature predictive of PGD.

Vasoplegia from Continuous Flow Left Ventricular Assist Devices

PURPOSE OF REVIEW

The contribution of continuous flow left ventricular assist devices (c-LVAD) to vasoplegic syndrome and postoperative outcomes after orthotopic heart transplant (OHT) is contested in the literature. A standardized definition of vasoplegic syndrome (VS) is needed to better recognize and manage vasoplegic shock.

RECENT FINDINGS

Vasoplegic syndrome occurs after orthotopic heart transplant more frequently than after other surgeries requiring cardiopulmonary bypass. c-LVADs lead to small vessel endothelial dysfunction and desensitized adrenal receptors; however, their contribution to the development of vasoplegia is debated in clinical studies. Pulsatility may mitigate vascular dysfunction resulting from long-term continuous flow, and should be further explored in the clinical setting when considering risk factors for vasoplegic syndrome. The incidence of vasoplegic syndrome after orthotopic heart transplant is rising with the increasing use of c-LVAD bridge to therapy. Robust clinical studies are needed to advance our understanding and approach to mitigating VS after OHT.

Pathophysiology of severe primary graft dysfunction in orthotopic heart transplantation

BACKGROUND

A series of insults on the donor heart result in pathophysiological changes that manifest as primary graft dysfunction (PGD) post-orthotopic heart transplantation. The objectives of this study were: (i) describe the pathophysiology of severe PGD using an established cardiovascular model; and (ii) the evolution of the pathophysiology during recovery from severe PGD.

METHODS

Hemodynamic data from 20 consecutive patients with severe PGD (need for mechanical circulatory support, MCS) at baseline (T0), 6 h (T6) and "recovery" (explant of support), and 20 consecutive patients without severe PGD were used to model the pathophysiology using the cardiovascular model described by Burkhoff and Dickstein.

RESULTS

There was a progressive (from T0 to T6) up- and leftward shift in the diastolic pressure-volume relationship, especially of the right ventricle (RV), resulting in reduced capacitance. RV end-systolic elastance (Ees) was significantly elevated in severe PGD but preload-recruitable stroke work (PRSW) was significantly lower compared to patients without severe PGD. "Recovery" (after liberation from MCS) was associated with improvement in RV Ees, chamber capacitance and PRSW, although they remained significantly lower than patients without severe PGD.

CONCLUSION

Severe PGD of the dominant right heart failure phenotype is characterized by reduced chamber capacitance, increased "stiffness" and impaired contractility. Complete normalization was not required for successful weaning of MCS.

Recipient and surgical factors trigger severe primary graft dysfunction after heart transplant

BACKGROUND

Primary graft dysfunction (PGD) is a major cause of early mortality following heart transplant (HT). The International Society for Heart and Lung Transplantation (ISHLT) subdivides PGD into 3 grades of increasing severity. Most studies have assessed risk factors for PGD without distinguishing between PGD severity grade. We sought to identify recipient, donor and surgical risk factors specifically associated with mild/moderate or severe PGD.

METHODS

We identified 734 heart transplant recipients at our institution transplanted between January 1, 2012 and December 31, 2018. PGD was defined according to modified ISHLT criteria. Recipient, donor and surgical variables were analyzed by multinomial logistic regression with mild/moderate or severe PGD as the response. Variables significant in single variable modeling were subject to multivariable analysis via penalized logistic regression.

RESULTS

PGD occurred in 24% of the cohort (n = 178) of whom 6% (n = 44) had severe PGD. One-year survival was reduced in recipients with severe PGD but not in those with mild or moderate PGD. Multivariable analysis identified 3 recipient factors: prior cardiac surgery, recipient treatment with ACEI/ARB/ARNI plus MRA, recipient treatment with amiodarone plus beta-blocker, and 3 surgical factors: longer ischemic time, more red blood cell transfusions, and more platelet transfusions, that were associated with severe PGD. We developed a clinical risk score, ABCE, which provided acceptable discrimination and calibration for severe PGD.

CONCLUSIONS

Risk factors for mild/moderate PGD were largely distinct from those for severe PGD, suggesting a differing pathophysiology involving several biological pathways. Further research into mechanisms underlying the development of PGD is urgently needed.

Analysis of blood parameters and molecular endometrial markers during early reperfusion in two ovine models of uterus transplantation

The dissection of the veins is the trickiest step of Uterine transplantation (UTx). Performing the anastomosis of a single uterine vein could bring a therapeutic benefit and simplification of surgery and serve for managing unilateral venous thromboses. The objectives of this project were to evaluate the expression of early markers of ischemia-reperfusion and to compare findings following one or two vein anastomoses. Orthotopic uterine auto-transplantations were performed on an ovine model with anastomosis of either two (group 1) or one utero-ovarian veins (group 2). Blood gases, histology and ischemia- reperfusion markers transcripts (PTGS2, IL6, IL8, SOD2, C3, BAX/BCL2 and TLR4) were analyzed as well as PTGS2 protein expression using Western Blot and fluorescence immunolocalization on endometrial biopsies after 3h of reperfusion. Ten ewes were included in the experimentation, 4 were in group1, 3 in group 2, the others being sham operated controls. No significant differences were observed between the two phenotypes. Based on these results, the anastomosis of one single uterine vein appears to be an approach consistent with short-term graft survival. Further experiments will be needed to confirm the reliability of this approach, especially the long-term follow-up of the uterine graft including its ability to support gestation to term.

Levosimendan for Treatment of Primary Graft Dysfunction After Heart Transplantation: Optimal Timing of Application

OBJECTIVES

Primary graft dysfunction remains a serious problem after heart transplant. Pharmacological treatment with the calcium sensitizer levosimendan may be an additive treatment for primary graft dysfunction.

MATERIALS AND METHODS

Patients undergoing heart transplant between 2010 and 2020 were retrospectively reviewed and divided depending on postoperative treatment with (n = 41) or without (n = 109) levosimendan. Recipients who received levosi mendan were further divided with regard to timing of levosimendan application (early group: started ≤48 hours posttransplant [n = 23]; late group: started >48 hours posttransplant [n = 18]).

RESULTS

Patients who received levosimendan treatment displayed a remarkable incidence (87.8%) of postoperative primary graft dysfunction with need for venoarterial extracorporeal membrane oxygenation and therefore often presented with perioperative morbidity. Patient with early application of levosimendan showed significantly decreased duration of venoarterial extracorporeal membrane oxygenation support (5.1 ± 3.5 days vs 12.6 ± 9.3 days in those with late application; P < .01) and decreased mortality during venoarterial extracorporeal membrane oxygenation support (0.0% vs 33.3% in early vs late group; P < .01). In addition, compared with patients with late levosimendan application, patients with early application needed fewer blood transfusions (P < .05), had shorter ventilation times (279 ± 235 vs 428 ± 293 h; P = .03), and showed a trend of reduced incidence of postoperative renal failure (69.6% vs 94.4%; P = .06). Moreover, survival analyses indicated an increased survival for patients with early start of levosimendan therapy within the first 48 hours after heart transplant (P = .09).

CONCLUSIONS

Pharmacotherapy with levosimendan may be a promising additive in the treatment of primary graft dysfunction after heart transplant. With administration of levosimendan within the first 48 hours posttransplant, rates of successful weaning from venoarterial extracorporeal membrane oxygenation and outcomes after heart transplant were shown to increase.

Incidence and impact of primary graft dysfunction in adult heart transplant recipients: A systematic review and meta-analysis

PURPOSE

Primary graft dysfunction (PGD) is a leading cause of early mortality after heart transplant (HTx). To identify PGD incidence and impact on mortality, and to elucidate risk factors for PGD, we systematically reviewed studies using the ISHLT 2014 Consensus Report definition and reporting the incidence of PGD in adult HTx recipients.

METHODS

We conducted a systematic search in January 2020 including studies reporting the incidence of PGD in adult HTx recipients. We used a random effects model to pool the incidence of PGD among HTx recipients and, for each PGD severity, the mortality rate among those who developed PGD. For prognostic factors evaluated in ≥2 studies, we used random effects meta-analyses to pool the adjusted odds ratios for development of PGD. The GRADE framework informed our certainty in the evidence.

RESULTS

Of 148 publications identified, 36 observational studies proved eligible. With moderate certainty, we observed pooled incidences of 3.5%, 6.6%, 7.7%, and 1.6% and 1-year mortality rates of 15%, 21%, 41%, and 35% for mild, moderate, severe and isolated right ventricular-PGD, respectively. Donor factors (female sex, and undersized), recipient factors (creatinine, and pre-HTx use of amiodarone, and temporary or durable mechanical support), and prolonged ischemic time proved associated with PGD post-HTx.

CONCLUSION

Our review suggests that the incidence of PGD may be low but its risk of mortality high, increasing with PGD severity. Prognostic factors, including undersized donor, recipient use of amiodarone pre-HTx and recipient creatinine may guide future studies in exploring donor and/or recipient selection and risk mitigation strategies.

Donor Left Ventricular Function Assessed by Echocardiographic Strain is a Novel Predictor of Primary Graft Failure After Orthotopic Heart Transplantation

OBJECTIVES

This study sought to determine the utility of donor left ventricular function assessment by echocardiographic left ventricular global longitudinal strain (LV GLS) in predicting primary graft failure (PGF) after orthotopic heart transplantation (HT).

DESIGN

Retrospective, observational study.

SETTING

Tertiary referral hospital.

PARTICIPANTS

Adult patients (>18 years) who underwent isolated HT.

INTERVENTIONS

Demographic, clinical, and echocardiographic data were collected on 100 patients who underwent HT between January 2010 and December 2019 at the authors' institution. The respective donor variables, as well as procedural factors, were reviewed and analyzed to assess their independent association with PGF. Standard donor echocardiographic measurements were supplemented by two-dimensional speckle-tracking echocardiography to obtain LV GLS. PGF was defined as per the International Society for Heart and Lung Transplantation 2014 consensus statement.

MEASUREMENTS AND MAIN RESULTS

PGF occurred in 40 of the 100 patients (40%). Initial univariate analysis found that RADIAL score, donor ejection fraction, and donor LV GLS were associated with PGF. However, in a multivariate Cox regression analysis, only RADIAL score and donor LV GLS remained significant predictors of PGF, with a p < 0.001. By receiver operating characteristic curve analysis, LV GLS at a cut-off value of -11.5% showed the greatest area under the curve (area under the curve = 0.889; 95% confidence interval, 0.826-0.952) and predicted PGF with 92.5% sensitivity and 65% specificity.

CONCLUSIONS

Impaired donor LV GLS was proven to be an independent predictor of PGF after HT.

Right Heart Failure While on Left Ventricular Assist Device Support Is Associated with Primary Graft Dysfunction

Primary graft dysfunction (PGD) is a potentially devastating complication of heart transplantation. Understanding the risk factors for PGD in the modern era of heart transplantation is of vital importance. This study investigated the relationship between post-left ventricular assist device (LVAD) right heart failure (RHF) and transplant outcomes. Patients with durable, continuous-flow LVADs who were transplanted between 2010 and 2016 at Barnes-Jewish Hospital were included in the study. Data collection was performed through retrospective chart review. The primary outcome was the incidence of PGD stratified by pretransplant incidence of RHF while on LVAD support. Among the 141 patients included in the study, 41 developed RHF. In the RHF cohort, 18 patients developed PGD as compared to 14 patients in the group without RHF (44% vs. 14%; p < 0.001). Mortality was significantly higher in the RHF group at 30 days (20% vs. 1%; p < 0.001) and 1 year (22% vs. 6%; p = 0.013). In a multivariable logistic regression model adjusted for confounding variables, RHF was associated with a nearly fourfold increased risk of PGD (odds ratio, 3.91; p = 0.003). The results of this study show that patients supported with LVADs who develop early severe RHF or late RHF are at increased risk of PGD and death following cardiac transplantation.

Veno-Arterial Extracorporeal Membrane Oxygenation for Patients Undergoing Heart Transplantation: A 7-Year Experience

Objective: Primary graft dysfunction (PGD) is the leading cause of early death after heart transplantation. Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) can provide temporary mechanical circulatory support and time for functional recovery of the transplanted heart. The purpose of this study was to analyze the timing and prognoses of VA-ECMO in patients with severe PGD after heart transplantation. Methods: A total of 130 patients underwent heart transplantation at the Zhongshan Hospital Affiliated with Fudan University between January 2014 and December 2020. All patients received basiliximab immunoinduction and a classic double vena cava anastomosis orthotopic heart transplantation. Among them, 29 patients (22.3%) developed severe PGD in the early postoperative period. VA-ECMO was performed in patients with difficulty weaning from cardiopulmonary bypass (CPB) or postoperative refractory cardiogenic shock. Patients were divided into two groups according to whether or not they were successfully weaned from VA-ECMO (patients who survived for 48 h after weaning and did not need VA-ECMO assistance again). The perioperative clinical data were recorded, and all patients were followed up until discharge. Early outcomes were compared between groups. Results: A total of 29 patients with VA-ECMO support after heart transplantation were included in this study. The proportion of patients receiving VA-ECMO was 22.3% (29/130). Nineteen patients (65.5%) needed VA-ECMO due to difficulty with weaning from CPB, and 10 patients required VA-ECMO for postoperative cardiogenic shock. Nineteen patients (65.5%) were successfully weaned from VA-ECMO. Overall, in-hospital mortality of VA-ECMO support patients was 55.2%. The main causes of death were ventricular fibrillation (four cases), major bleeding (three cases), infection (four cases), and graft failure (five cases). Conclusion: Despite advances in heart transplantation, severe PGD remains a lethal complication after heart transplantation. At present, the treatment for severe PGD after heart transplantation is a challenge. VA-ECMO provides an effective treatment for severe PGD after heart transplantation, which can promote graft function recovery.

Financial implications of using extracorporeal membrane oxygenation following heart transplantation

OBJECTIVES

Primary graft dysfunction after heart transplant is associated with high morbidity and mortality. Extracorporeal membrane oxygenation (ECMO) can be used to wean patients from cardiopulmonary bypass. This study retrospectively reviews a single-centre experience of post-transplant ECMO in regard to outcomes and associated costs.

METHODS

Between May 2006 and May 2019, a total of 267 adult heart transplants were performed. We compared donor and recipient variables, ECMO duration and the incidence of renal failure, bleeding, infection and cost analysis between ECMO and non-ECMO groups.

RESULTS

ECMO support was required postoperatively to manage primary graft dysfunction in 72 (27%) patients. The mean duration of ECMO support was 6 ± 3.2 days. Mean ischaemic times were similar between the groups. There was a significantly higher proportion of ventricular assist device explant to transplant in the ECMO group versus non-ECMO (38.2% vs 14.1%; P < 0.0001). ECMO patients had a longer duration of stay in the intensive care unit (P < 0.0001) and total hospital stay (P < 0.0001). Greater mortality was observed in the ECMO group (P < 0.0001). The median cost of providing ECMO was £18 000 [interquartile range (IQR): £12 750-£24 000] per patient with an additional median £35 225 (IQR: £21 487.25-£51 780.75) for ITU stay whilst on ECMO. The total median cost per patient inclusive of hospital stay, ECMO and dialysis costs was £65 737.50 (IQR: £52 566.50-£95 221.75) in the non-ECMO group compared to £145 415.71 (IQR: £102 523.21-£200 618.96) per patient in the ECMO group (P < 0.0001).

CONCLUSIONS

Patients with primary graft dysfunction following heart transplantation who require ECMO are frequently bridged to a recovery; however, the medium and longer-term survival for these patients is poorer than for patients who do not require ECMO.

Extracorporeal membrane oxygenation bridge to heart transplant: Trends following the allocation change

BACKGROUND

This study compared outcomes of patients bridged with extracorporeal membrane oxygenation (ECMO) to orthotopic heart transplantation (OHT) following the recent heart allocation policy change.

METHODS

The United Network of Organ Sharing Registry (UNOS) database was queried to examine OHT patients between 2010 and 2020 that were bridged with ECMO. Waitlist outcomes and 1-year posttransplant survival were compared between patients waitlisted and/or transplanted before and after the heart allocation policy change. Secondary outcomes included posttransplant stroke, renal failure, and 1-year rejection.

RESULTS

A total of 285 waitlisted patients were included, 173 (60.7%) waitlisted under the old policy and 112 (39.3%) under the new policy. New policy patients were more likely to receive OHT (82.2% vs. 40.6%), and less likely to be removed from the waitlist due to death or clinical deterioration (15.0% vs. 41.3%; both p < .001). A total of 165 patients bridged from ECMO to OHT were analyzed, 72 (43.6%) transplanted during the old policy and 93 (56.3%) under the new. Median waitlist time was reduced under the new policy (4 days [interquartile range {IQR}: 2-6] vs. 47 days [IQR: 10-228]). Postoperative renal failure was higher in the new policy group (23% vs. 6%; p = .002), but rates of stroke and 1-year acute rejection were equivalent. One-year survival was lower the new policy but was not significant (79.8% vs. 90.3%; p = .3917).

CONCLUSIONS

The UNOS heart allocation policy change has resulted in decreased waitlist times and higher likelihood of transplant in patients supported with ECMO. Posttransplant 1-year survival has remained comparable although absolute rates are lower.

Relationship of intraoperative perfusion parameters to the need for immediate extracorporeal support following heart transplantation

PURPOSE

We sought to assess the relationship of intraoperative perfusion parameters while on cardiopulmonary bypass, including oxygen delivery (DO₂), to the need for ECMO following orthotopic heart transplantation (OHT).

METHODS

We included all adult (>18 years old) OHTs performed at our institution since implementation of an electronic perfusion record (March 2019-February 2020). Multi-organ transplants were excluded. The primary outcome was the need for immediate venoarterial ECMO in the OR following OHT. Univariable statistics were computed across demographic, clinical, operative, and perfusion variables, including oxygen delivery (DO₂) measured each minute.

RESULTS

Fifty-three OHT were included with a median age of 54 years (interquartile range, 45-61). The primary outcome occurred in eight patients (15.1%). A significantly greater proportion of patients requiring ECMO had ischemic cardiomyopathy (50.0% (4/8) vs. 15.6% (7/45), p = 0.02) and had preoperative ventricular assist devices (37.5% (3/8) vs. 8.9% (4/45), p = 0.03). Median bypass times were longer in the ECMO group (217 vs. 147 minutes, p = 0.001). Phenylephrine doses were nonsignificantly higher in ECMO patients (4.1 vs. 1.9 mg, p = 0.10). No significant differences were observed in single-point median DO₂ (275 vs. 294 mL O₂/min/m² BSA, p = 0.17) and nadir DO₂ (226 vs. 222, p = 0.94), but increasing time and depth of DO2 below a threshold of 300 mL O₂/min/m² BSA (i.e. area over the DO₂ curve (AOC) but below threshold) was significantly associated with the need for postoperative ECMO (p = 0.04).

CONCLUSION

This is the first study to examine the relationship of perfusion parameters, including oxygen delivery, to outcomes following heart transplantation. We note that DO₂ < 300-AOC was significantly associated with the need for postoperative ECMO following heart transplant. Further study will clarify whether potential DO₂ differences in patients who require post-OHT ECMO reflect vasoplegia, or a more causative relationship which might be leveraged to improve outcomes.

Successful Heart Transplantation after Cardiopulmonary Resuscitation of Donors

BACKGROUND

 Heart transplantation (HTx) is the best therapy for end-stage heart failure. Unfortunately, death on the waiting list remains a problem. Decreasing the number of rejected organs could increase the donor pool.

METHODS

 A total of 144 patients underwent HTx at our department between 2010 and 2019. Of them, 27 patients received organs of donors with cardiopulmonary resuscitation (CPR) prior to organ donation (donor CPR) and were compared with patients who received organs without CPR (control; n = 117).

RESULTS

 We did not observe any disadvantage in the outcome of the donor CPR group compared with the control group. Postoperative morbidity and 1-year survival (control: 72%; donor CPR: 82%; p = 0.35) did not show any differences. We found no impact of the CPR time as well as the duration between CPR and organ donation, but we found an improved survival rate for donors suffering from anoxic brain injury compared with cerebral injury (p = 0.04).

CONCLUSIONS

 Donor organs should not be rejected for HTx due to resuscitation prior to donation. The need for CPR does not affect the graft function after HTx in both short- and mid-term outcomes. We encourage the use of these organs to increase the donor pool and preserve good results.

Guidelines for the Use of Transesophageal Echocardiography to Assist with Surgical Decision-Making in the Operating Room: A Surgery-Based Approach: From the American Society of Echocardiography in Collaboration with the Society of Cardiovascular Anesthesiologists and the Society of Thoracic Surgeons

Intraoperative transesophageal echocardiography is a standard diagnostic and monitoring tool employed in the management of patients undergoing an entire spectrum of cardiac surgical procedures, ranging from "routine" surgical coronary revascularization to complex valve repair, combined procedures, and organ transplantation. Utilizing a protocol as a starting point for imaging in all procedures and all patients enables standardization of image acquisition, reduction in variability in quality of imaging and reporting, and ultimately better patient care. Clear communication of the echocardiographic findings to the surgical team, as well as understanding the impact of new findings on the surgical plan, are paramount. Equally important is the need for complete understanding of the technical steps of the surgical procedures being performed and the complications that may occur, in order to direct the postprocedure evaluation toward aspects directly related to the surgical procedure and to provide pertinent echocardiographic information. The rationale for this document is to outline a systematic approach describing how to apply the existing guidelines to questions on cardiac structure and function specific to the intraoperative environment in open, minimally invasive, or hybrid cardiac surgery procedures.

Postoperative vasoactive inotropic score is predictive of outcomes in pediatric heart transplantation

Vasoactive inotrope score (VIS) is scarcely studied in pediatric orthotopic heart transplantation (pOHT). We conducted a retrospective review of pOHT (<21 years) recipients. Max VIS and mean VIS were calculated at 0-24 and 24-48 hours post-pOHT. Patients were divided into groups based on ISHLT guidelines: high (>10) and low (≤10). In our group (n = 104), patients with high max and mean VIS groups at 0-24 and 24-48 hours had longer bypass times (high: >130 minutes; low: <108 minutes; P < .05) and high max and mean VIS groups at 0-24 hours had longer ischemic times (high: >215 minutes; low: <192 minutes; P < .05). Patients with high max and mean VIS at 0-24 and 24-48 hours had longer hospital stay, ventilation, inotrope duration, more cardiac events, and acute kidney injury postoperatively (P < .05). High max VIS at 24-48 hours and high mean VIS at 24-48 hours had higher 3-year mortality (P = .04; P = .02). Multivariate analysis confirmed the association of VIS with short-term outcomes. However, VIS was not identified as an independent predictor of mortality. The ROC curve exhibits 10 as the ideal cutoff with area under the curve >0.8 for primary graft dysfunction (PGD).

Role of donor macrophages after heart and lung transplantation

Since the 1960s, heart and lung transplantation has remained the optimal therapy for patients with end-stage disease, extending and improving quality of life for thousands of individuals annually. Expanding donor organ availability and immunologic compatibility is a priority to help meet the clinical demand for organ transplant. While effective, current immunosuppression is imperfect as it lacks specificity and imposes unintended adverse effects such as opportunistic infections and malignancy that limit the health and longevity of transplant recipients. In this review, we focus on donor macrophages as a new target to achieve allograft tolerance. Donor organ-directed therapies have the potential to improve allograft survival while minimizing patient harm related to global suppression of recipient immune responses. Topics highlighted include the role of ontogenically distinct donor macrophage populations in ischemia-reperfusion injury and rejection, including their interaction with allograft-infiltrating recipient immune cells and potential therapeutic approaches. Ultimately, a better understanding of how donor intrinsic immunity influences allograft acceptance and survival will provide new opportunities to improve the outcomes of transplant recipients.

Noteworthy Literature From 2019 for Cardiothoracic Critical Care

This annual article summarizes key findings from notable studies published in 2019 relevant to the practice of cardiothoracic critical care medicine. This year's article encompasses updates to the literature on enhanced recovery after cardiac surgery, extracorporeal membranous oxygenation, delirium, and primary graft dysfunction after heart transplant.

Perioperative Low Tetraiodothyronine Levels and Adverse Outcomes After Heart Transplantation: A Retrospective, Observational Study

OBJECTIVES

Thyroid dysfunction has been shown to be associated with increased all-cause mortality and severity of chronic heart failure in critical illness and severe cardiac diseases. The present study was conducted to ascertain the relationship between perioperative free triiodothyronine and free tetraiodothyronine (fT4) levels and postoperative adverse outcomes after heart transplantation (HTX).

DESIGN

Retrospective, observational study.

SETTING

Single-center study in a quaternary care university clinical center.

PARTICIPANTS

The study comprised adult patients who underwent HTX between 2015 and 2019 and had at least 1 perioperative thyroid hormone laboratory test on the day of surgery or in the 24 hours before/after the procedure (free triiodothyronine, fT4, and thyroid-stimulating hormone).

INTERVENTIONS

No interventions were applied.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was primary graft dysfunction (PGD), defined by the consensus conference of the International Society for Heart and Lung Transplantation. A total of 151 patients were included in the final analyses. Twenty-nine (19.2%) patients had PGD. Fourteen (9.3%) patients had low fT4 levels. An independent association was found between fT4 and PGD (odds ratio 6.49; 95% confidence interval 2.26-18.61; p = 0.001), with adjusted multivariate Cox regression models.

CONCLUSION

The perioperative fT4 level could be a prognostic marker of adverse outcomes in HTX. The authors suggest appropriate perioperative monitoring of fT4 levels. Additional research is warranted to examine the optimal timing, dosage, and method of replacement.

"The Secret Life of Human Donor Hearts": An Examination of Transcriptomic Events During Cold Storage

BACKGROUND

Ischemic tolerance of donor hearts has a major impact on the efficiency in utilization and clinical outcomes. Molecular events during storage may influence the severity of ischemic injury.

METHODS

RNA sequencing was used to study the transcriptional profile of the human left ventricle (LV, n=4) and right ventricle (RV, n=4) after 0, 4, and 8 hours of cold storage in histidine-tryptophan-ketoglutarate preservation solution. Gene set enrichment analysis and gene ontology analysis was used to examine transcriptomic changes with cold storage. Terminal deoxynucleotidyl transferase 2´-Deoxyuridine, 5´-Triphosphate nick end labeling and p65 staining was used to examine for cell death and NFκB activation, respectively.

RESULTS

The LV showed activation of genes related to inflammation and allograft rejection but downregulation of oxidative phosphorylation and fatty acid metabolism pathway genes. In contrast, inflammation-related genes were down-regulated in the RV and while oxidative phosphorylation genes were activated. These transcriptomic changes were most significant at the 8 hours with much lower differences observed between 0 and 4 hours. RNA velocity estimates corroborated the finding that immune-related genes were activated in the LV but not in the RV during storage. With increasing preservation duration, the LV showed an increase in nuclear translocation of NFκB (p65), whereas the RV showed increased cell death close to the endocardium especially at 8 hours.

CONCLUSIONS

Our results demonstrated that the LV and RV of human donor hearts have distinct responses to cold ischemic storage. Transcriptomic changes related to inflammation, oxidative phosphorylation, and fatty acid metabolism pathways as well as cell death and NFκB activation were most pronounced after 8 hours of storage.

Histidine-Tryptophan-Ketoglutarate Solution for Donor Heart Preservation Is Safe for Transplantation

BACKGROUND

Various solutions are used for donor heart preservation. We examined the outcomes in our heart transplant population where histidine-tryptophan-ketoglutarate (HTK) solution has been used for heart preservation since 2004.

METHODS

This was a retrospective review of the United Network for Organ Sharing (UNOS) database (2004-2016) comparing our heart transplant outcomes with other national centers. Propensity matching in a 1:3 ratio was performed to adjust for preoperative recipient variables.

RESULTS

After propensity matching comparing UNOS outcomes (n = 1080) with our institutional data (n = 360), there was no difference in matched preoperative variables. Donor hearts were similar for donor age, sex, donor-to-recipient size ratio, LVEF, and ischemic time. Our HTK cohort had a larger proportion with donor cardiac arrest (26.3% vs 6.1%, P < .001) and longer cardiac arrest duration (22.1 ± 16.0 vs 17.2 ± 14.0 minutes, P = .052). Our primary graft dysfunction (PGD) rate requiring mechanical support was 4.2% (n = 1). Postoperative mechanical support use for PGD included extracorporeal membrane oxygenation in 9 (60.0%), intraaortic balloon pump in 4 (26.7%), right ventricular assist device in 3 (20%), and biventricular assist device in 3 (20%). Overall survival at our institution was similar to the national average (P = .649). Survival at 1, 5, and 10 years with HTK was 92.2%, 81.3%, and 70.8%, and for the UNOS population was 91.6%, 80.3%, and 62.0%, respectively.

CONCLUSIONS

Use of HTK solution for donor hearts was associated with a low rate of severe PGD. Overall survival was not significantly different from other institutions using a variety of preservation solutions in the UNOS database during the same period. HTK solution is efficacious for preservation of donor hearts.

Role of HIF-1α in Cold Ischemia Injury of Rat Donor Heart Via the miR-21/PDCD4 Pathway

BACKGROUND

Hypoxia-inducible factor 1 alpha (HIF-1α) is a transcription factor that plays a major role under hypoxia conditions. Cold storage during heart transplantation causes the donor heart long-term hypoxia. There is some evidence indicating a conceivable HIF-1α/microRNA-21 (miR-21)/phosphatase and tensin homolog (PTEN)/programmed cell death 4 (PDCD4) pathway. We assessed the hypothesis that HIF-1α has a positive effect during donor heart cold storage by making the miR-21 upregulate to reduce the expression of PDCD4.

METHODS

We established the rat heart cold storage model and stratified it into 6-hour groups from 0 to 24 hours. Western blot and quantitative reverse transcription polymerase chain reaction were performed to detect the expression of HIF-1α, miR-21, PDCD4, and PTEN.

RESULTS

After cold storage the expression of HIF-1α increased from 0 to 6 hours and then gradually decreased, but the expression level was relatively higher compared with the control group. The miR-21 was upregulated from 0 to 12 hours then downregulated. The messenger RNA expression of PDCD4 was upregulated gradually, but the protein expression was significantly downregulated at 12th hour then continued to upregulate. Interestingly, the expression level of miR-21 was highest in the 12th hour, which indicated miR-21 could inhibit the PDCD4. We subsequently detected the messenger RNA of PTEN, which can inhibit HIF-1α and be inhibited by miR-21. The expression of PTEN was also significantly downregulated at the 12th hour.

CONCLUSION

In conclusion, there is possible interaction between HIF-1α and miR-21, and the conceivable HIF-1α/miR-21/PTEN/PDCD4 pathway plays a protective role in cold storage of the heart.

Comparison of outcomes in lung and heart transplant recipients from the same multiorgan donor

BACKGROUND

Primary graft dysfunction (PGD) and acute cellular rejection (ACR) are important causes of early morbidity and mortality following lung and heart transplantation. While many studies have elucidated donor-related risk factors of PGD and ACR, these complications often occur even with "ideal" donors. Therefore, we investigated potential associations of PGD and ACR between bilateral lung and heart transplant recipients from the same multiorgan donor, respectively.

METHODS

Between 2011 and 2017, 100 donors contributed 100 bilateral lung transplants and 100 heart transplants performed. Logistic regression analysis for PGD and Cox proportional hazards regression analysis for ACR were used to estimate the relationship of heart and lung transplants.

RESULTS

The incidence of PGD was 33% among lung and 17% among heart transplant recipients. Similarly, the incidence of ACR grade ≥ A2 for lung recipients was 38% (30/80), and the incidence of ACR grade ≥ 2R for heart recipients was 19% (15/80). There was no association between the development of PGD and ACR in lung and heart transplant recipients from the same donor, respectively.

CONCLUSIONS

These findings suggest that inherent donor factors are not critical to the development of PGD and ACR after lung and heart transplantation.

Increasing heart transplant donor pool by liberalization of size matching

BACKGROUND

The heart transplant (HT) guidelines recommendation to match recipient and donors within 30% of body weight lacks a strong evidence base and is not well established in patients bridged to transplant with left ventricular assist devices (LVAD). In light of the scarcity of donor hearts, we investigated the effect of size mismatch on hemodynamics, one-year survival and length of stay (LOS) following HT.

METHODS

Single-center retrospective analysis of consecutive HT patients from April 2007 to September 2017. Recipients were divided into 3 cohorts based on donor-to-recipient weight ratio (DRWR): (1) undersized (<0.7), (2) size-matched, (0.7-1.3); (3) oversized (>1.3).

RESULTS

288 consecutive patients were identified (mean age 53 ± 11 years; 76% male), 46 were undersized (0.61 ± 0.05), 210 size-matched (0.94 ± 0.16), and 32 oversized (1.65 ± 0.38). There was no significant difference in donor left ventricular end diastolic diameter (LVEDD) between the 3 groups (p = 0.11). The donor/recipient (D/R) predicted heart mass (PHM) was lowest in the undersized group (0.92 ± 0.13). There were no significant differences in 1-year survival in the overall and LVAD cohort (p = 0.65 and 0.59, respectively). Neither donor LVEDD nor D/R PHM differed among survivors or non-survivors. LOS was longer in the undersized group than the size-matched cohort (p = 0.004). The undersized group had hearts with the highest filling pressures and lowest cardiac index at 1 week among the remaining groups (p = 0.009, 0.017, and p = 0.05, respectively). There were no clinically significant differences in hemodynamics at 1 or 6 months.

CONCLUSIONS

HT undersizing affects hemodynamics early but not later in the course and does not impact 1-year survival. The liberalization of size matching may increase the HT donor pool significantly.

Early Graft Dysfunction Following Heart Transplant: Prevention and Management

Heart transplant can be considered as the “gold standard” treatment for end-stage heart failure, with nearly 5.7 million adults in the United States carrying a diagnosis of heart failure. According to the International Society for Heart and Lung Transplantation registry, nearly 3300 orthotopic heart transplants were performed in 2016 in North America. In spite of significant improvements in overall perioperative care of heart transplant recipients for the past few decades, the risk of 30-day mortality remains 5% to 10%, primarily related to early failure of the allograft. Early graft dysfunction (EGD) occurs within 24 hours after transplant, manifesting as left ventricular dysfunction, right ventricular dysfunction, or biventricular dysfunction. EGD is further classified into primary and secondary graft dysfunction. This review focus on describing overall incidences of EGD, potential risk factors associated with EGD, perioperative preventive measures, and various management options.

Perioperative ischaemic reperfusion injury and allograft function in the early post-transplantation period

OBJECTIVES

Ischaemic reperfusion injury (IRI) is an inevitable complication of heart transplantation (HTX) and is observed as a pathological finding in biopsies from transplanted allografts. The aim of this study was to evaluate the severity of IRI and determine the clinical outcomes of HTX in patients with severe IRI.

METHODS

We enrolled 74 consecutive patients who had undergone HTX since 2007. Endomyocardial biopsy samples were obtained from the right ventricle of the transplanted heart. IRI was graded as 'trivial', 'mild', 'moderate' or 'severe' according to the extent of IRI-specific findings in the samples. The cohort was divided into a moderate-to-severe IRI group with 21 patients [IRI(+)] and a low-grade group with 53 patients [IRI(-)].

RESULTS

The frequency of mechanical circulatory support and duration of catecholamine dependence in the early postoperative period were significantly higher in the IRI(+) group compared to the IRI(-) group. However, overall survival after HTX and mid-term cardiac allograft function were not significantly different between the groups. Among perioperative factors, cardiac ischaemic time was significantly different between the groups [IRI(-) vs IRI(+), 199 ± 38 min vs 239 ± 39 min; P < 0.001]. Incremental increases in cardiac ischaemic time were correlated with increases in IRI severity. Serum troponin T levels 3 h after donor heart reperfusion was significantly correlated with cardiac ischaemic time (r = 0.418, P = 0.0007).

CONCLUSIONS

IRI is associated with a complicated clinical course in the early post-HTX period due to temporary deterioration of allograft function. This may be attributable to myocardial stunning caused by long donor heart ischaemic time during HTX.

Impact of Bridge to Transplantation With Continuous-Flow Left Ventricular Assist Devices on Posttransplantation Mortality

BACKGROUND

Bridge to transplantation (BTT) with left ventricular assist devices (LVADs) is a mainstay of therapy for heart failure in patients awaiting heart transplantation (HT). Criteria for HT listing do not differ between patients medically managed and those mechanically bridged to HT. The objectives of the present study were to evaluate the impact of BTT with LVAD on posttransplantation survival, to describe differences in causes of 1-year mortality in medically and mechanically bridged patients, and to evaluate differences in risk factors for 1-year mortality between those with and those without LVAD at the time of HT.

METHODS

Using the United Network of Organ Sharing database, we identified 5486 adult, single-organ HT recipients transplanted between 2008 and 2015. Patients were propensity matched for likelihood of LVAD at the time of HT. Kaplan-Meier survival estimates were used to assess the impact of BTT on 1- and 5-year mortality. Logistic regression analysis was used to evaluate the odds ratio of 1-year mortality for patients BTT with LVAD compared with those with medical management across clinically significant variables at various thresholds.

RESULTS

Early mortality was higher in mechanically bridged patients: 9.5% versus 7.2% mortality at 1 year (P<0.001). BTT patients incurred an increased risk of 1-year mortality with an estimated glomerular filtration rate of 40 to 60 mL·min^-1·1.73 m^-2 (odds ratio, 1.69; P=0.003) and <40 mL·min^-1·1.73 m^-2 (odds ratio, 2.16; P=0.005). A similar trend was seen in patients with a body mass index of 25 to 30 kg/m² (odds ratio, 1.88; P=0.024) and >30 kg/m² (odds ratio, 2.11; P<0.001). When patients were stratified by BTT status and the presence of risk factors, including age >60 years, estimated glomerular filtration rate <40 mL·min^-1·1.73 m^-2, and body mass index >30 kg/m², there were significant differences in 1-year mortality between medium- and high-risk medically and mechanically bridged patients, with 1-year mortality in high-risk BTT patients at 17.6% compared with 10.4% in high-risk medically managed patients.

CONCLUSIONS

Bridge to HT with LVAD, although necessary because of organ scarcity and capable of improving wait list survival, confers a significantly higher risk of early posttransplantation mortality. Patients bridged with mechanical support may require more careful consideration for transplant eligibility after LVAD placement.

Noteworthy Literature Published in 2018 for Thoracic Organ Transplantation

Publications of note from 2018 are reviewed for the cardiothoracic transplant anesthesiologist. Strategies to expand the availability of donor organs were highlighted, including improved donor management, accumulating experience with increased-risk donors, ex vivo perfusion techniques, and donation after cardiac death. A number of reports examined posttransplant outcomes, including outcomes other than mortality, with new data-driven risk models. Use of extracorporeal support in cardiothoracic transplantation was a prominent theme. Major changes in adult heart allocation criteria were implemented, aiming to improve objectivity and transparency in the listing process. Frailty and prehabilitation emerged as targets of comprehensive perioperative risk mitigation programs.

Management of primary graft failure after heart transplantation: Preoperative risks, perioperative events, and postoperative decisions

Primary graft failure (PGF) after heart transplantation (HT) is a devastating and unexpected event characterized by failure of the graft to adequately support recipient circulation necessitating high doses of vasopressors and inotropes and/or temporary mechanical circulatory support. Although it represents an increasingly common event in the current era, there remains a high degree of variability in prevalence, reported risk factors, and approach to this clinical entity. The purpose of the current review is to highlight preoperative considerations including known incidence and risk factors, perioperative issues involving the identification and management of PGF, and postoperative decisions related to weaning of mechanical circulatory support and titration of immunosuppressive therapy. Lastly, we highlight future directions in PGF research, involving basic and translational research, that have the potential to uncover novel strategies of risk stratification and treatment. CASE: Our patient is a 53-year-old man with end-stage non-ischemic dilated cardiomyopathy complicated by ventricular tachycardia (VT), post-capillary pulmonary hypertension, and renal insufficiency. After progressing to NYHA Class IV symptoms, he underwent implantation of a durable left ventricular assist device (LVAD) as bridge to transplant (BTT). On device support, he developed recurrent VT resulting in multiple defibrillator discharges and hospital admission for intravenous anti-arrhythmic therapy. He is subsequently upgraded to a higher status on the waiting list. A suitable donor is identified, with an appropriate predicted heart mass and an anticipated ischemic time of <4 hours. He is taken to the operating room, where at the time of anesthesia induction he develops vasodilatory shock, requiring high-dose vasopressors, and cardiopulmonary bypass (CPB) support for dissection. After surgical anastomosis, cross clamp removal and reperfusion, graft function is extremely poor, there is significant bradycardia requiring pacing, and the patient is unable to be weaned successfully from CPB. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) is initiated, and the patient is transferred to the intensive care unit. Retrospective flow crossmatch is negative. This patient is suffering from severe primary graft failure.

Prior Amiodarone Exposure Reduces Tacrolimus Dosing Requirements in Heart Transplant Recipients

Introduction:

Amiodarone use prior to heart transplant is independently associated with a higher rate of severe primary graft dysfunction and in-hospital mortality. Amiodarone may also alter the pharmacokinetics of medications metabolized via cytochrome P450. No data exist regarding the interaction between pretransplant amiodarone and tacrolimus concentrations.

Design:

Single-center retrospective study of transplant patients between January 1, 2014, and June 30, 2016. A therapeutic tacrolimus concentration was defined as a trough level between 8 and 15 ng/mL for 2 consecutive days. The primary outcome was the tacrolimus therapeutic weight-based dosing requirements (mg/kg/day) for patients receiving amiodarone prior to transplant when compared to those without prior receipt of amiodarone. Secondary outcomes include the incidence of cellular rejection and mortality within 6 months posttransplant.

Results:

Multi-organ transplant recipients (n = 3), retransplants (n = 9), those who died prior to a therapeutic level (n = 1), and those receiving amiodarone posttransplant (n = 7) were excluded from the analysis. Of the 80 patients included, 34 (42%) received amiodarone prior to transplant. Patient characteristics were similar, with the exception of primary graft dysfunction incidence (38% in amiodarone vs 8.5% in control, P = .001). The median therapeutic dose was 0.1 (interquartile range [IQR]: 0.07-0.12) versus 0.13 (IQR: 0.09-0.17) in the amiodarone and control groups, respectively, ( P < .01). No significant difference in mortality or rejection was noted.

Conclusion:

Patients receiving amiodarone prior to transplant require a lower weight-based dose of tacrolimus.

Ferroptotic cell death and TLR4/Trif signaling initiate neutrophil recruitment after heart transplantation

Non-apoptotic forms of cell death can trigger sterile inflammation through the release of danger-associated molecular patterns, which are recognized by innate immune receptors. However, despite years of investigation the mechanisms which initiate inflammatory responses after heart transplantation remain elusive. Here, we demonstrate that ferrostatin-1 (Fer-1), a specific inhibitor of ferroptosis, decreases the level of pro-ferroptotic hydroperoxy-arachidonoyl-phosphatidylethanolamine, reduces cardiomyocyte cell death and blocks neutrophil recruitment following heart transplantation. Inhibition of necroptosis had no effect on neutrophil trafficking in cardiac grafts. We extend these observations to a model of coronary artery ligation-induced myocardial ischemia reperfusion injury where inhibition of ferroptosis resulted in reduced infarct size, improved left ventricular systolic function, and reduced left ventricular remodeling. Using intravital imaging of cardiac transplants, we uncover that ferroptosis orchestrates neutrophil recruitment to injured myocardium by promoting adhesion of neutrophils to coronary vascular endothelial cells through a TLR4/TRIF/type I IFN signaling pathway. Thus, we have discovered that inflammatory responses after cardiac transplantation are initiated through ferroptotic cell death and TLR4/Trif-dependent signaling in graft endothelial cells. These findings provide a platform for the development of therapeutic strategies for heart transplant recipients and patients, who are vulnerable to ischemia reperfusion injury following restoration of coronary blood flow.

Perioperative Management of the Cardiac Transplant Recipient

Management of the cardiac transplant recipient includes careful titration of inotropes and vasopressors. Recipient pulmonary hypertension and ventilatory status must be optimized to prevent allograft right ventricular failure. Vasoplegia, coagulopathy, arrhythmias, and renal dysfunction also require careful management to achieve an optimal outcome. Primary graft dysfunction (PGD) can be an ominous problem after cardiac transplantation. Although mild degrees of PGD may be managed medically, mechanical circulatory support with extracorporeal membrane oxygenation or temporary ventricular assist devices may be required. Retransplantation may be necessary in some cases.

Risk of severe primary graft dysfunction in patients bridged to heart transplantation with continuous-flow left ventricular assist devices

BACKGROUND

Primary graft dysfunction (PGD) remains a significant cause of post-transplant morbidity and mortality. The exact mechanism and risk factors for this phenomenon remain unknown in the contemporary era.

METHODS

In this study we reviewed adult patients undergoing heart transplantation (HT) at our institution between 2009 and 2017. Severe PGD was defined as the need for mechanical circulatory support (MCS) within the first 24 hours after HT. Multivariate logistic regression analysis was used to identify risk factors for severe PGD, focusing on those bridged to transplant (BTT) with a continuous-flow left ventricular assist device (CF-LVAD).

RESULTS

Fifty-six of 480 (11.7%) HT patients experienced severe PGD. Eighty percent of the severe PGD patients were BTT with a CF-LVAD (odds ratio [OR] 3.86, 95% confidence interval [CI] 1.94 to 7.68, p < 0.001). Among the BTT patients, significant associations between >1 year of CF-LVAD support (OR 2.48, 95% CI 1.14 to 5.40, p = 0.022), pre-HT creatinine (OR 3.35, 95% CI 1.42 to 7.92, p = 0.006), elevated central venous pressure/pulmonary capillary wedge pressure (CVP/PCWP) ratio (OR 3.32, 95% CI 1.04 to 10.60, p = 0.043), use of amiodarone before HT (OR 2.69, 95% CI 1.20 to 6.20, p = 0.022), and severe PGD were identified. RADIAL score did not accurately predict severe PGD in this contemporary cohort. Those patients who developed severe PGD had decreased 1-year post-transplant survival (78.3% vs 91.8%, p = 0.007).

CONCLUSIONS

Use of CF-LVAD as BTT is associated with an increased risk of severe PGD. Increased time on device support, renal dysfunction, right ventricular dysfunction as assessed by CVP/PCWP ratio, and pre-transplant amiodarone may identify those patients at high risk. Further research is warranted focusing on optimal timing of device implantation and transplantation, as well as the underlying mechanisms of PGD.