The International Consortium on Primary Graft Dysfunction: Redefining Clinical Risk Factors in the Contemporary Era of Heart Transplantation

BACKGROUND

Primary Graft Dysfunction (PGD) is the leading cause of morbidity and mortality early after heart transplant (HT). The International Consortium on PGD is a multicenter collaboration dedicated to identifying the clinical risk factors for PGD in the contemporary era of HT. The objectives of the current report were to 1) assess the incidence of severe PGD in an international cohort, 2) evaluate the performance of the most validated PGD risk tool, the RADIAL score, in a contemporary cohort, and 3) redefine clinical risk factors for severe PGD in the current era of HT.

METHODS

This is a retrospective, observational study of consecutive adult HT recipients between 2010 and 2020 in 10 centers in the United States, Canada, and Europe. Patients with severe PGD were compared to those without severe PGD (comprising those with no, mild and moderate PGD). The RADIAL score was calculated for each transplant recipient. The discriminatory power of the RADIAL score was evaluated using receiver operating characteristic (ROC) analysis and its calibration was assessed by plotting the percentage of PGD predicted versus observed. To identify clinical risk factors associated with severe PGD, we performed multivariable mixed-effects logistic regression modeling to account for among-center variability.

RESULTS

A total of 2,746 patients have been enrolled in the registry to date, including 2,015 (73.4%) from North America, and 731 (26.6%) from Europe. 215 participants (7.8%) met the criteria for severe PGD. There was an increase in the incidence of severe PGD over the study period (p-value for trend by difference sign test = 0.004). The Kaplan Meier estimate for 1-year survival was 75.7% [95%CI 69.4-80.9%] in patients with severe PGD as compared to 94.4% [95% CI 93.5-95.2%] in those without severe PGD (log-rank p-value <0.001). The RADIAL score performed poorly in our contemporary cohort and was not associated with severe PGD with an AUC of 0.53 (95%CI 0.48-0.58). In the multivariable regression model, acute preoperative dialysis (OR 2.41, 95% CI 1.31 - 4.43), durable LVAD support (OR 1.77, 95% CI 1.13 - 2.77), and total ischemic time (OR 1.20 for each additional hour, 95% CI 1.02 - 1.41) were associated with an increased risk of severe PGD.

CONCLUSIONS

Our consortium has identified an increasing incidence of PGD in the modern transplant era. We identified contemporary risk factors for this early post-transplant complication, which confers a high mortality risk. These results may enable the identification of patients at high risk for developing severe PGD in order to inform peri-transplant donor and recipient management practices.

Predictors of early renal dysfunction after heart transplantation: a report from the International Consortium on Primary Graft Dysfunction

Background

Renal dysfunction is a common complication after heart transplantation (HT). Renal replacement therapy (RRT) after HT has been associated with increased risk of death. Long-term renal dysfunction is associated mainly to immunosuppressive therapy but is also strongly related to post-transplant renal failure. Predictors of early renal dysfunction after HT have not been clearly identified.

Purpose

We aimed to define predictors of early renal dysfunction after HT.

Methods

Our consortium includes 10 centers in the US, Canada and Europe. We collected data on all consecutive single-organ HT recipients from 2010 to 2020. The primary outcome was early renal dysfunction (ERD), defined as a composite of need for RRT or creatinine ≥2.5 mg/dL 24 hours after HT. We assessed the incidence of early renal dysfunction and performed univariate and multivariate analyses to identify the recipient and transplant characteristics associated with its development.

Results

We included 2,764 HT recipients: 282 (10.2%) presented early renal dysfunction and 2482 (89.8%) did not. Recipients who presented postoperative renal dysfunction were more frequently male, Caucasian, with previous sternotomy, higher baseline creatinine, longer ischemic time and worse donor LVEF. They were also more likely to be under RRT, intravenous inotropes or ECMO support and there was more incidence of severe primary graft dysfunction (PGD) (Table 1). Multi-variable logistic regression demonstrated that the strongest predictors for post-transplant renal dysfunction were development of severe PGD (OR 5.26, 2.88–9.62, p&lt;0,001) and RRT prior to HT (OR 5.80, 2.93–11.5, p&lt;0.001). Other predictors were male sex, previous sternotomy, long ischemic time and need for inotropes prior to HT.

Conclusions

Early renal dysfunction is a common complication after HT with an incidence around 10% in a large and contemporary cohort. The presence of PGD and need for RRT pre-transplant were the strongest predictors for its development. Interestingly, emergent transplantation or need for MCS were not independently associated with ERD. Further studies are needed to identify patients at high risk of early and late kidney dysfunction that may benefit from combined transplantation.

Funding Acknowledgement

Type of funding sources: None.

Perfusion Cardiac Magnetic Resonance Imaging as a Rule-Out Test for Cardiac Allograft Vasculopathy

Cardiac allograft vasculopathy (CAV) is a leading cause of mortality after heart transplantation. Noninvasive imaging techniques used in CAV evaluation have important limitations. In a cross-sectional study, we investigated perfusion cardiac magnetic resonance (CMR) imaging to determine an optimal myocardial perfusion reserve index (MPR) cutoff for detecting CAV using receiver operating characteristic curve analysis. We evaluated CMR performance using sensitivity, specificity and likelihood ratio analysis. We included 29 patients (mean 5 ± 4 years after transplant) scheduled for coronary angiography with intravascular ultrasound (IVUS) who completed CMR. CAV was defined as maximal intimal thickness (MIT) >0.5 mm by IVUS of the left anterior descending artery. CAV was evident in 19 patients (70%) on IVUS (mean MIT 0.82 ± 0.42 mm). MPR was significantly lower in patients with MIT ≥0.50 mm (1.35 ± 0.23 vs. 1.71 ± 0.45, p = 0.013). There was moderate inverse correlation between MPR and MIT (r = -0.36, p = 0.075). The optimal MPR cutoff ≤1.68 for predicting CAV showed sensitivity of 100%, specificity of 63%, a negative predictive value of 100%, a positive predictive value of 86% and a positive likelihood ratio of 2.7. An MPR ≤1.68 has high negative predictive value, suggesting its potential as a test to rule out CAV.

A survey of current practice for antibody-mediated rejection in heart transplantation

No evidence based management guidelines exist for antibody mediated rejection (AMR) in heart transplantation. The International Society for Heart and Lung Transplantation (ISHLT) recently introduced standardized pathologic based diagnostic criteria for AMR (pAMR 0-3). We evaluated international practice for the management of AMR focusing on pAMR grade, donor specific antibody (DSA) and allograft function. On-line survey data were analyzed from 184 ISHLT members (physicians-78%, surgeons-20%). The majority were from adult-transplant (84%), medium-large volume centres (transplants/year: 10-25, 61%; 25-50, 19%) across North America (60%) and Europe (26%). Irrespective of pAMR grade and DSA, 83-90% treated a drop in ejection fraction (EF≤45% or >25% decrease). In the presence of stable EF, an increasing number elected treatment for progressively severe pAMR grade (p<0.001) and for accompanying DSA (p<0.05, pAMR 1-3). Intravenous steroid was the most commonly used therapy followed by intravenous immunoglobulin (IVIG) or plasmapheresis, rituximab and thymoglobulin. Plasmapheresis and rituximab were favored for positive versus negative DSA (p<0.05). Using a threshold of ≥70% consensus among respondents, treatment for AMR may be considered for a drop in EF, asymptomatic pAMR 3 or asymptomatic pAMR 2 with DSA. Combination steroid, IVIG and plasmapheresis are suggested as initial therapies.