Elevated Donor Troponin Levels Are Associated with a Lower Frequency of Allograft Vasculopathy

Heart transplantation and biomarkers: a review about their usefulness in clinical practice

Advanced heart failure (AdvHF) can only be treated definitively by heart transplantation (HTx), yet problems such right ventricle dysfunction (RVD), rejection, cardiac allograft vasculopathy (CAV), and primary graft dysfunction (PGD) are linked to a poor prognosis. As a result, numerous biomarkers have been investigated in an effort to identify and prevent certain diseases sooner. We looked at both established biomarkers, such as NT-proBNP, hs-troponins, and pro-inflammatory cytokines, and newer ones, such as extracellular vesicles (EVs), donor specific antibodies (DSA), gene expression profile (GEP), donor-derived cell free DNA (dd-cfDNA), microRNA (miRNA), and soluble suppression of tumorigenicity 2 (sST2). These biomarkers are typically linked to complications from HTX. We also highlight the relationships between each biomarker and one or more problems, as well as their applicability in routine clinical practice.

Donor Cardiac Troponin for Prognosis of Adverse Outcomes in Cardiac Transplantation Recipients: a Systematic Review and Meta-analysis

BACKGROUND

Cardiac troponin is a highly specific and widely available marker of myocardial injury, and elevations in cardiac transplant donors may influence donor selection. We aimed to investigate whether elevated donor troponin has a role as a prognostic biomarker in cardiac transplantation.

METHODS

In a systematic review and meta-analysis, we searched MEDLINE, Embase, and the Cochrane Library, without language restriction, from inception to December 2020. We included studies reporting the association of elevated donor troponin with recipient outcome after cardiac transplant. We generated summary odds ratios and hazard ratios for the association of elevated donor troponin with short- and long-term adverse outcomes. Methodological quality was monitored using the Quality In Prognosis Studies tool, and interstudy heterogeneity was assessed using a series of sensitivity and subgroup analyses.

RESULTS

We included 17 studies involving 15 443 patients undergoing cardiac transplantation. Elevated donor troponin was associated with increased odds of graft rejection at 1 y (odds ratio, 2.54; 95% confidence interval, 1.22-5.28). No significant prognostic relationship was found between donor troponin and primary graft failure, short- to long-term mortality, cardiac allograft vasculopathy, and pediatric graft loss.

CONCLUSIONS

Elevated donor troponin is not associated with an increased short- or long-term mortality postcardiac transplant despite increasing the risk of graft rejection at 1 y. Accordingly, an elevated donor troponin in isolation should not exclude donation.

Assessment of potential heart donors: A statement from the French heart transplant community

Assessment of potential donors is an essential part of heart transplantation. Despite the shortage of donor hearts, donor heart procurement from brain-dead organ donors remains low in France, which may be explained by the increasing proportion of high-risk donors, as well as the mismatch between donor assessment and the transplant team's expectations. Improving donor and donor heart assessment is essential to improve the low utilization rate of available donor hearts without increasing post-transplant recipient mortality. This document provides information to practitioners involved in brain-dead donor management, evaluation and selection, concerning the place of medical history, electrocardiography, cardiac imaging, biomarkers and haemodynamic and arrhythmia assessment in the characterization of potential heart donors.

Optical coherence tomography and highly sensitivity troponin T for evaluating cardiac allograft vasculopathy

Cardiac allograft vasculopathy (CAV) is a major impediment to long-term graft survival after heart transplantation. Intravascular ultrasound (IVUS) is more sensitive than coronary angiography for diagnosis, but the identification of specific plaque components or plaque composition is limited. In addition, there is an evident need for other noninvasive tools for diagnosing CAV. The aim of this study was to assess the utility of 2 new techniques for evaluating CAV: optical coherence tomography (OCT), and new high-sensitivity troponin T (hsTnT) assays. In 21 heart transplantation patients, coronary arteriography with IVUS and OCT were performed. Maximal intimal thickness (MIT) and luminal area at the most severe site were measured using the 2 techniques. Immediately before cardiac catheterization, blood samples were obtained and hsTnT levels measured. The evaluation of CAV by OCT showed a good correlation with IVUS measurements, with a mean difference in MIT of 0.0033 (95% confidence interval -0.049 to 0.043), taking advantage of lower interobserver variability (r = 0.94 for OCT vs r = 0.78 for IVUS) and better plaque characterization. When independent predictors of MIT were assessed in a multiple linear regression model, time after transplantation (β = 0.488, p = 0.004) and hsTnT (β = 0.392, p = 0.011) were the only independent predictors of MIT (R(2) = 0.591). In conclusion, this study is the first to evaluate 2 new techniques, OCT and hsTnT, in the challenging setting of CAV. The findings suggest that OCT provides lower interobserver variability and better plaque characterization than IVUS. Also, hsTnT could become a useful tool for ruling out CAV.

Donor cardiac troponin I levels do not predict recipient survival after cardiac transplantation

BACKGROUND

Serum levels of cardiac troponin I (cTnI) are frequently measured in the evaluation of potential heart donors. However, the utility of cTnI levels for predicting recipient outcomes remains controversial. This study was performed to determine whether donor cardiac cTnI levels exceeding 1.0 microg/liter are associated with adverse recipient outcomes.

METHODS

All donors managed by the California Transplant Donor Network between January 2001 and July 2002 with consent for donor evaluation and at least 1 measured cTnI level were included in the study if 1-year recipient mortality data were available. Each study subject was classified as having elevated cTnI if any level exceeded 1.0 microg/liter. Donor variables, recipient risk of 30-day and 1-year mortality, and recipient need for mechanical circulatory support were compared between the 2 groups.

RESULTS

A total of 263 potential donors were evaluated, and 98 had elevated cTnI levels. Of these potential donors, 139 were accepted for transplantation. The cTnI levels were normal in 96 and elevated in 43. Most donors (77%) with elevated cTnI levels had levels of less than 10 microg/liter. Donor cardiopulmonary resuscitation was associated with cTnI elevations. Donors with elevated cTnI levels did not require higher doses of inotropic drugs before transplantation and had similar hemodynamic profiles compared with donors with normal cTnI levels. Although there was a trend towards longer post-transplant hospitalization in recipients of grafts from donors with elevated cTnI levels (17 days vs 15 days, p = 0.044), there was no significant difference in the recipient need for mechanical circulatory support or 30-day and 1-year mortality between the 2 groups.

CONCLUSIONS

In this study, a modestly elevated donor cTnI was not associated with a higher risk of recipient mortality or need for post-transplant mechanical circulatory support. A potential donor heart should not be discarded solely because the troponin level is elevated.

Diagnosis of graft coronary artery disease

PURPOSE OF REVIEW

Graft coronary artery disease is the leading cardiac cause of death in patients who have undergone cardiac transplantation. Due to denervation, classic symptoms of angina are not reliable. Many transplant centers have a protocol of routine annual surveillance cardiac angiography because treatment options are limited, especially with advanced disease. Angiography is an assessment of the arterial lumen, however, and can miss nonfocal disease. This paper reviews invasive and noninvasive diagnostic tools for graft coronary artery disease. Intravascular ultrasound is the most sensitive, but the cost and lack of widespread expertise make it unpopular. Noninvasive techniques have been studied. An ideal test would be sufficiently sensitive to detect disease and allow for prognostic information. Dobutamine echocardiography is the most sensitive noninvasive test but can have a high false-positive rate. It is also not universally available. Exercise nuclear imaging is specific and can be used as a confirmatory test in patients with positive dobutamine echocardiograms.

RECENT FINDINGS

Computed tomographic imaging and cardiac magnetic resonance imaging are exciting new modalities but require further study.

SUMMARY

There is no test sensitive and specific enough yet that can be confidently used to replace coronary angiography.