Abstract 4144583: Beyond Acute Rejection Screening Following Pediatric Heart Transplant: In Patients Negative for Rejection, Elevated Donor-Derived Cell-Free DNA is Associated with Cardiac Allograft Vasculopathy (CAV) and Donor Specific Antibodies (DSA)

Circulation, Volume 150, Issue Suppl_1, Page A4144583-A4144583, November 12, 2024. Donor-derived cell-free DNA (dd-cfDNA) has been increasingly used to detect acute rejection (AR). We aimed to compare our institutional dd-cfDNA results to previously published adult and pediatric dd-cfDNA AR cutoffs. We also hypothesized that in the absence of AR, elevated dd-cfDNA would be associated with CAV and positive DSA.Patients (pt) < 18 years at transplant with >1 dd-cfDNA between 2021-2023 were included. Using dd-cfDNA levels from this cohort, sensitivity, specificity, NPV, and PPV were calculated. False positives and false negatives (FN) were determined using published dd-cfDNA thresholds. AR was defined as decision-to-treat with increased immunosuppression, which was independent of dd-cfDNA in our cohort. In pt without AR,t-test was used to compare the means of dd-cfDNA levels in pt with and without DSA. χ2testing was then performed to evaluate the association between dd-cfDNA levels above and below 0.2% and the presence/absence of DSA and CAV. DSA was defined as allele-specific DSA identified by single antigen bead with mean fluorescence intensity >1000, and CAV as any disease by angiography.There were 379 samples among 163 pt, a median of 2 samples per pt, and 32 samples obtained at time of AR. Performance of dd-cfDNA in our cohort vs published dd-cfDNA thresholds is shown in Table 1. The FN rate ranged from 16 to 37% as the dd-cfDNA threshold increased. Mean dd-cfDNA was higher in patients with positive DSA versus those without (0.83% vs 0.19%, p0.2% were associated with a higher prevalence of positive DSA (n=66) (48% vs 13%, p

Read More
Novembre 2024

Abstract 4146311: Cardiac Thickening, Cell Free DNA, and Rejection in the 2nd Porcine Cardiac Xenograft

Circulation, Volume 150, Issue Suppl_1, Page A4146311-A4146311, November 12, 2024. Introduction/Background:A 58-year-old man with inotrope dependent heart failure was declined for allotransplant and MCS at multiple centers and was transplanted with a 10 gene-edited porcine cardiac xenograft under FDA expanded access Investigational New Drug (eIND) approval. After requiring perioperative transfusions, by post operative day (POD) 13, endomyocardial biopsy revealed antibody and complement deposition without damage or cellular infiltrate. Hemodynamic decompensation on POD 29 prompted biopsy revealing antibody mediated rejection (AMR). The patient required ECMO support POD31 and chose comfort care POD 40.Research Questions/Hypothesis:The cardiac xenograft doubled in mass from implant to autopsy. Donor derived cell free DNA (cfDNA) correlated temporally with the rejection findings. These processes are hypothesized to correlate.Approach:Routine TTE measurements of diastolic LV posterior wall dimension (LVPWd), intraventricular septal dimension (IVSd), LV mass, and LV mass index were taken. Donor derived cfDNA was measured weekly and PRN (Care Dx Inc., Brisbane, CA). Pearson correlation coefficient analysis was conducted in GraphPad Prism 10 (Dotmatics, Boston, MA).Results/Data:POD 26 TTE measurements indicated thickening graft. POD 30 cfDNA began elevating. cfDNA correlated moderately with LVPWd (r = 0.43, p=0.4) and IVSd (r= 0.5, p=0.31) less so with LV mass (r= 0.28, p=0.59) and LV mass index (r=0.34, p=0.51)Conclusions:Xenograft cardiac thickening measured on TTE preceded elevation in cfDNA. Both were moderately correlated and temporally corresponded to biopsy diagnosed AMR and ultimate graft failure. Future xenograft surveillance will likely benefit from multimodal approach.

Read More
Novembre 2024

Abstract 4145247: Optimal threshold of donor-derived cell-free DNA for detection of cardiac transplant rejection: a meta-analysis

Circulation, Volume 150, Issue Suppl_1, Page A4145247-A4145247, November 12, 2024. Background:Plasma donor-derived cell-free DNA (dd-cfDNA) has emerged as a biomarker for acute heart transplant rejection as a potential adjunct to endomyocardial biopsy (EMBx). However, an established threshold for dd-cfDNA in acute cardiac transplant rejection is lacking, with prior studies employing different study specific thresholds. This meta-analysis aims to assess the overall diagnostic accuracy of dd-cfDNA across various cutoffs and provide an optimal threshold.Method:PubMed and Web of Science were searched for relevant publications reporting on the use of dd-cfDNA for the detection of acute cardiac transplant rejection defined as acute cellular rejection (ACR) and/or antibody-mediated rejection (AMR), with EMBx as the reference standard. Pooled sensitivity and specificity were estimated across different thresholds of dd-cfDNA across studies. The optimal dd-cfDNA threshold was estimated by specificity and 1-sensitivity in each data point pooled with fractional polynomial models, maximizing the Youden index between these models.Results:Out of 247 screened papers, 13 studies were included, comprising 12,017 samples from 3,723 patients. Twelve studies used both ACR and AMR and one study used only ACR for the definition of transplant rejection. The thresholds of dd-cfDNA varied across studies, ranging from 0.1 to 0.35 (Figure A). The overall pooled sensitivity and specificity for detecting acute transplant rejection were 0.68 (95% CI: 0.58-0.77) and 0.82 (95% CI: 0.74-0.88) respectively. The areas under the hierarchical modeling-based summary receiver-operating characteristics (sROC) curves were 0.82 (95% CI: 0.78-0.85). Specificity increased with higher thresholds while sensitivity decreased (Figure A and B). The optimal dd-cfDNA threshold derived from combining all included studies was 0.218.Conclusion:Dd-cfDNA assay demonstrates high diagnostic accuracy for acute cardiac transplant rejection, particularly notable for its high specificity. However, there exists significant inconsistency in dd-cfDNA thresholds across studies. Increasing the threshold leads to a trade-off between increased specificity and decreased sensitivity. A cutoff of 0.22 may be considered for dd-cfDNA screening for heart transplant rejection.

Read More
Novembre 2024

Abstract 4132149: Elevated Levels of Plasma Mitochondrial DNA Damage-Associated Molecular Patterns (DAMPS) in Humans and Dogs with Heart Failure and Reduced Ejection Fraction

Circulation, Volume 150, Issue Suppl_1, Page A4132149-A4132149, November 12, 2024. Background:Heart failure (HF) with reduced ejection fraction (HFrEF) is associated with increased inflammatory response that contributes to progressive worsening of the HF state. Potential endogenous triggers of this process include damage-associated molecular patterns (DAMPs). DAMPs originate from within cells following tissue stress or injury and activate pattern recognition receptors of the immune system, triggering an inflammatory response. Mitochondria are the major cell organelles that release DAMPs into the circulation. Chronic HF is associated with multi-organ mitochondrial dysfunction and cell injury and death.Purpose:The present study sought to quantify differences in mitochondrial DNA (mtDNA) DAMPs in the setting of HFrEF in humans and dogs compared to normal humans and dogs.Methods:Plasma samples were obtained from 9 HFrEF patients with left ventricular ejection fraction (LVEF) ≤35% and 9 age-matched healthy subjects, and from 6 dogs with coronary microembolization-induced HF (LVEF ≤35%) and 6 normal dogs. DNA fragments were isolated from 1 ml of plasma using a commercially available kit. Quantitative PCR and specifically designed primers were used to measure the amount of DNA in plasma fromCOX1(cytochrome c oxidase subunit 1),ND1(NADH dehydrogenase subunit 1) andND6(NADH dehydrogenase subunit 6) using an Applied Biosystems 7500 Fast-PCR unit. The relative abundances of plasma mtDNA DAMPs were expressed as threshold cycles (CT).Results:Compared to normal human subjects, mtDNA DAMPs levels ofCOX1,ND1andND6in plasma of HFrEF patients was 4-fold, 9-fold and 8-fold greater, respectively. Similarly, compared to normal dogs, mtDNA DAMPs levels ofCOX1,ND1andND6in plasma of HFrEF dogs was increased 48-fold, 12-fold and 4-fold, respectively.Conclusions:These findings indicate a marked increase of mtDNA DAMPs in plasma of humans and dogs with HFrEF. The increase of mtDNA DAMPs is consistent with the elevated systemic inflammatory state of HFrEF. The results underscore mitochondrial abnormalities as integral players in the progressive worsening of HFrEF.

Read More
Novembre 2024

Abstract 4147025: Obesity as an Underlying Driver of Differences in Racial and Socioeconomic Disparity Associated Cardiac DNA Methylation Among Men with End-stage Heart Failure

Circulation, Volume 150, Issue Suppl_1, Page A4147025-A4147025, November 12, 2024. Heart failure (HF) treatment advances have improved outcomes but HF heterogeneity leads to ~50% response to standard therapies, emphasizing a need to further study mechanisms of disparate outcomes. One serious disparity is increased cardiovascular disease risk and mortality in African Americans (AA) compared to Caucasian Americans (CA). Race is a social construct and thus poor proxy for physiology; hence, our lab studies epigenetics, stable yet reversible changes to DNA serving as a possible interface of how environment impacts gene regulation. We’ve previously implicated cardiac DNA methylation as a new indicator of socio-economic disparities in HF outcomes. Related to HF, US adult obesity rates are 40% and similar disparities exist with AA having higher rates, and studies on obesity show how inequity leads to disparate rates. Thus, our secondary analysis investigates the role of obesity, through its impact on cardiac epigenetics and transcription, as an underlying environment/molecular driver within HF disparities.Multi-omics data of left ventricular assist device placement biopsies of age-matched males were from our previous publication’s public dataset. Cardiac DNA methylation (850k-array) analyzed via minfi, and differential gene expression (RNA-seq) via DESeq2.Two-year survival is decreased in non-obese (NO) vs. obese (OB) patients (p

Read More
Novembre 2024

Abstract 4143732: Mitochondrial DNA heteroplasmy and incident cardiovascular disease

Circulation, Volume 150, Issue Suppl_1, Page A4143732-A4143732, November 12, 2024. Background:Variants of mitochondrial DNA (mtDNA) may exist in heteroplasmy and have been associated with increased risk of mortality and cancer. While variation in mtDNA has been associated with cardiomyopathy in mitochondrial disease, the association between mtDNA heteroplasmy and cardiovascular disease (CVD) in the general population has not been well studied.Methods:We quantified mtDNA heteroplasmy from whole genome sequencing data in 476,434 participants in the UK Biobank. We defined a variant allele frequency of 5–95% as heteroplasmic. We functionally characterized mtDNA single nucleotide variants using a constraint-based score, mitochondrial local constraint score sum (MSS). We evaluated the associations of MSS and incident CVD, defined as fatal or non-fatal myocardial infarction (MI) or ischemic stroke (IS), using Cox proportional hazards models adjusted for demographic, lifestyle, and clinical factors in 463,705 participants free of CVD. We further tested the interactions with clonal hematopoiesis of indeterminant potential (CHIP) and leukocyte telomere length (LTL) in the association between heteroplasmy and CVD. We performed additional analysis stratified by MSS for each complex/region in the mtDNA, and subgroup analysis by sex and C-reactive protein (CRP; ≥3mg/L). Lastly, we performed analysis separately for MI and IS.Results:During a median (1stand 3rdquartiles) follow-up of 13.6 (13.1–14.5) years, there were 24,723 incident CVD events (16,959 MI and 9671 IS cases). 28.3% of the study population had 1 or more heteroplasmies. We found that higher MSS was associated with CVD (adjusted hazard ratio [aHR] for a 1-unit increase in MSS 1.08; 95% confidence interval 1.00–1.17). In particular, a higher MSS was associated with MI (aHR 1.13; 1.02–1.24) but not with IS (aHR 1.03; 0.90–1.17). The association between MSS and MI was stronger for fatal MI (aHR 1.52; 1.10–2.10) than for non-fatal MI (aHR 1.10; 0.99–1.21). When stratified by complex/region, higher MSS in Complex I increased the risk of MI by 27% (aHR 1.27; 1.06–1.53) but not in other complexes/regions. Although LTL was inversely associated with CVD outcomes, there were no associations with CHIP. Furthermore, there was no interactions by LTL, CHIP, sex, and CRP in the association between MSS and CVD outcomes.Conclusion:These results indicate that mitochondria may have a functional role in the development of CVD, particularly MI, and MSS may serve as a biomarker for CVD risk.

Read More
Novembre 2024