Utility of troponin assays for exclusion of acute cellular rejection after heart transplantation: A systematic review

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Utility of troponin assays for exclusion of acute cellular rejection after heart transplantation: A systematic review Sarah Fitzsimons, Jonathan Evans, Jayan Parameshwar, Stephen J. Pettit www.elsevier.com/locate/bios

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S1053-2498(17)32149-6 https://doi.org/10.1016/j.healun.2017.12.008 HEALUN6671

To appear in: Journal of Heart and Lung Transplantation Cite this article as: Sarah Fitzsimons, Jonathan Evans, Jayan Parameshwar and Stephen J. Pettit, Utility of troponin assays for exclusion of acute cellular rejection after heart transplantation: A systematic review, Journal of Heart and Lung Transplantation,doi:10.1016/j.healun.2017.12.008 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Utility of Troponin assays for exclusion of acute cellular rejection after heart transplantation: A systematic review Sarah Fitzsimons MBChB, FRACP Jonathan Evans, MRCP Jayan Parameshwar, MD, FRCP Stephen J Pettit, PhD, MRCP

Transplant Unit, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, UK Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK

Corresponding Author:

Dr Sarah Fitzsimons Transplant Unit, Papworth Hospital NHS Foundation Trust, Papworth Everard, Cambridge, United Kingdom, CB23 3RE

Email for correspondence:

[email protected]

Word count:

3043 (excluding references, tables and figures)

Tables:

4

Figures:

3

Key words:

transplant, rejection, troponin

Abstract

Background: Acute cellular rejection(ACR) is a common complication in the first year after heart transplantation(HT). Routine surveillance for ACR is undertaken by endomyocardial biopsy(EMB). Measurement of Cardiac troponins(cTn) in serum is an established diagnostic test of cardiac myocyte injury. This systematic review aimed to determine if cTn measurement could be used to diagnose or exclude ACR.

Methods: Pubmed, Google Scholar and the JHLT Archive were searched for studies reporting the result of a cTn assay and a paired surveillance EMB. Significant ACR was defined as ISHLT grade 3a/2R. Considerable heterogeneity between studies precluded quantitative meta-analysis. Individual study sensitivity and specificity data were examined and used to construct a pooled hierarchical summary ROC curve.

Results: Twelve studies including 993 patients and 3803 EMBs, of which 3729 were paired with cTn levels, had adequate data available for inclusion. The overall rate of significant ACR was 12%. There was wide variation in diagnostic performance. cTn assays demonstrated sensitivity 8–100% and specificity 13–88% for detection of ACR. The positive predictive value (PPV) was low but the negative predictive value (NPV) relatively high (79-100%). High sensitivity cTn assays had greater sensitivity and NPV than conventional cTn assays for detection of ACR (Sensitivity 82-100% vs 8-77%; NPV 97-100% vs 81-95%).

Conclusions: cTn assays do not have sufficient specificity to diagnose ACR in place of EMB. However, hs-cTn assays may have sufficient sensitivity and negative predictive value to exclude ACR and limit the need for surveillance EMB. Further research is required to assess this strategy.

Introduction

Acute cellular rejection(ACR) occurs in up to 30% of patients in the first year after heart transplantation(HT) and is often asymptomatic.1 However, ACR is the direct cause of at least 8% of deaths in the first 3 years post-HT and treatment for ACR is associated with adverse prognosis.2 Patients who experience repeated episodes of ACR are at increased risk of chronic immune injury that may manifest as cardiac allograft vasculopathy(CAV); a leading cause of graft failure after the first year post-HT.3

Routine surveillance for ACR is performed by endomyocardial biopsy(EMB) of the right ventricle; typically on 10-12 occasions during the first year post-HT.4 5 EMB is an invasive test and confers risk of complications including tricuspid valve injury.6-8 Reporting of EMB is subject to a high degree of inter-observer variability. Despite standardised criteria for the diagnosis of rejection, there was only 28% concordance between pathologists grading ACR in the CARGO II study.9 A non-invasive test that could identify or exclude ACR after HT would therefore have considerable clinical utility.

Several non-invasive tests have been compared to EMB but none have sufficient sensitivity and specificity to be an independent diagnostic tool.10 One exception is a gene expression profile (Allomap) which was shown to be non-inferior to EMB for surveillance of ACR in the CARGO study of 737 transplant recipients more than six months post-HT.11 Allomap had a high (99.2%) negative predictive value (NPV) and has subsequently been validated in patients 2-6 months post transplantation in the CARGO II study.12 However there are significant limitations to the utility of Allomap; in particular it has a poor positive predictive value for ACR, is relatively expensive and the test takes several days to complete.

A biomarker is a quantifiable biological parameter that is an indicator of normal physiological or pathological process.13 Cardiac troponins (cTn) are specific regulatory proteins released into the circulation when cardiac myocytes are ‘injured’.14 Myocyte damage is the pathological hallmark of

moderate to severe ACR and therefore an elevated serum cTn level would be an expected finding during a significant episode of ACR.

The association between cTn and ACR has been examined in several studies in the post-HT population. The aim of this systematic review was to determine if cTn measurement may be used for diagnosis or exclusion of ACR; particularly as a tool to rationalise EMB and hence reduce the burden and risk of EMB for suitable patients.

Methods

Search Strategy

Pubmed, Medline, Google Scholar and the JHLT Archive were searched using the key words ‘troponin’, ‘transplant’ and ‘rejection’ in August 2016. The reference lists of all relevant studies and review articles identified through the search were also examined. We included studies reported in English and studies that could be translated by Google Translate. Our study design adhered to the recommendations of PRISMA-P.15

Study selection

All studies that reported the result of a cTn assay and a paired surveillance EMB were eligible for inclusion. Studies of adult and paediatric HT recipients were included, irrespective of follow up duration or time of patient enrollment. If the same patient cohort was included in repeated manuscripts, only the most recent study was included. Studies that did not report EMB using the International Society for Heart and Lung Transplantation (ISHLT) grading system were excluded.

Data extraction

Data were extracted by SF, checked by SP and disagreement was adjudicated by JP. For each study, a standard set of data was extracted. Authors of eligible studies were contacted and asked to provide missing data if it would have led to study exclusion.

Definition of significant rejection

In line with the revised 2004 ISHLT grading system, significant ACR was defined as ISHLT grade ≥2R because augmented immunosuppression is usually instituted at this point. For studies using the 1990 ISHLT grading system, a grade of ≥3a was defined as significant ACR. We note that some centers considered ISHLT grade 1b to represent significant ACR but as this was not universal and many studies did not distinguish between grade 1a and 1b, grade 1b was not defined as significant ACR in this systematic review.

Statistical analysis and data synthesis I2 was calculated to examine the heterogeneity in ACR prevalence between studies, with a value >50% considered severe heterogeneity. Two-by-two tables for cTn and ACR were constructed for each study. Sensitivity, specificity, positive and negative predicted values were calculated. Where studies reported multiple diagnostic cut off values, the level with the greatest sensitivity was used. Sensitivity and specificity of cTn per study is presented using forest plots generated using RevMan Version5.3 (Cochrane).16 Due to differences in sensitivity of the cTn assays and diagnostic thresholds, quantitative bivariate meta-analysis to calculate pooled sensitivity and specificity was deemed inappropriate. Instead study specific sensitivity and specificity data were used to construct a pooled hierarchical summary ROC curve by means of a generalized linear mixed model with random effects using the metandi command in Stata (StataCorp, TX, USA).17

Results

Study Selection

From 88 studies identified during the database search, 38 abstracts were reviewed for eligibility resulting in full review of 23 articles. Six studies were excluded after review and one additional study was identified from reference checking. In total, 19 studies were assessed for data extraction (see figure 1). Nine of these did not report sufficient data to generate a 2x2 table. The authors of these studies were asked to provide raw data or clarify published data. Two authors did not respond to contact by email and letter.18,19 Of the seven authors that replied, three supplied raw data, two no longer had raw data available, one failed to supply the raw data and one author declined to supply their data.20-26

18,1918,1918,1918,1918,19

We were unable to contact authors of three studies as

there were insufficient contact details in the manuscript.27-29 In total, twelve studies had adequate raw data for inclusion in this review.23-26,29-36

Study Design

Most studies did not report their design in detail, but we deduced study design from information presented in each manuscript (refer table 1). All studies were observational. Two studies used a case-control design where patients were their own control, though only one exclusively enrolled patients with clinically significant ACR. Six studies were conducted prospectively. Seven studies specified their exclusion criteria. In one study the EMBs were graded by a pathologist who was blinded to the clinical status of the patient. One study had EMBs graded by two pathologists, one of whom was blinded. Ten studies did not report whether the pathologist was blinded.

Patient Characteristics

The 12 studies in this systematic review included 993 patients, ranging from 14–186 patients per study, enrolled between 1996-2011 (table 1). Of the studies that reported age at enrollment, the mean age of adult patients ranged from 47.4-58.5years and was 11.1years for paediatric patients. Most adult patients were male (range:70-87.5%). The reason for transplantation was recorded in four adult studies that included 322 patients; 144(45%) had ischaemic cardiomyopathy, 154(48%) dilated cardiomyopathy and 24(7%) had another cause of heart failure.

Endomyocardial biopsies

In total, there were 3803 EMBs ranging from 53-788 EMBs per study (table 2). ACR was graded using the 1990 ISHLT grading system in seven studies and the revised 2004 ISHLT grading system in five studies. The rate of significant ACR varied considerably between studies (5-21%). The I2 statistic for prevalence of significant ACR between studies was 45% demonstrating moderate but not severe heterogeneity. In the seven studies using the 1990 ISHLT grading system, there were 2799 EMBs of which 368(13%) showed significant ACR(grade≥3a). In the five studies using the 2004 grading system, there were 915 EMBs of which 89(9%) showed significant ACR(grade≥2R). This equates to a significant rejection rate for all studies of 12%. Of note if the case-control study that exclusively enrolled patients with significant ACR is excluded from the post-2004 cohort (as the 43% incidence of 2R rejection is caused by the design of the study), the diagnostic rate of significant ACR halved following the changes made to the ISHLT grading system in 2004 (6 vs 13%). Due to the case-control design this study is not included in any further pooled descriptive statistics discussed in the rest of this article.26

Troponin Assays

All studies evaluated contemporary well established cTn assays for the era of study. Nine studies measured Troponin T (TnT) and three studies measured Troponin I (TnI) (table 3). The level at which a cTn result was defined as positive varied between studies. Two studies used the cTn level recommended by the manufacturer of the assay as diagnostic for a myocardial infarction, one used the lowest detection level of the assay and two studies evaluated both. Five studies used receiveroperator curve (ROC) analysis to determine the optimum positive cTn level in their population. One study assessed multiple assays but did not use a specific level to define a positive cTn result rather an index of the observed cTn level to the ‘excepted’ cTn level. Finally, one study did not describe the method used to define a positive cTn level. There was wide variation between studies in the frequency with which cTn results were positive, ranging from 12-87%.

Association between cTn and EMB Grade

Overall there were 428 EMBs that showed significant ACR, of which 156(36%) were associated with a positive cTn. There were 3301 EMBs that showed no significant rejection, of which 1014(31%) were associated with a positive cTn level (figure 2). The sensitivity and specificity of troponin assays for ACR varied considerably between studies; sensitivity 8–100% and specificity 13–88%(table 4). In most studies the PPV for ACR was low but conversely the NPV was high ranging from 79–100%. We elected not to perform quantitative meta-analysis due to the degree of heterogeneity between included studies. This is illustrated by the hierarchical summary ROC curve (figure 3a) which demonstrates a large 95% prediction range.

Conventional (conv-cTn) vs. high-sensitivity (hs-cTn) Troponin assays

Sub-group analysis of studies using conventional(conv-cTn) and high-sensitivity(hs-cTn) Troponin assays was performed. Seven studies assessed conv-cTn and four studies assessed hs-cTn assays. In the conv-cTn cohort there were 704 patients who had 2799 EMBs, of which 368(13%) EMBs had

significant ACR. In the hs-cTn cohort, there were 260 patients who had 937 EMBs, of which 60(6%) EMBs had significant ACR. In the conv-cTn cohort 27% EMBs with significant ACR were paired to a positive cTn level compared to 92% of EMBs with significant ACR in the hs-cTn cohort. Sensitivity was higher in the hs-cTn cohort (range:82-100%), compared with the conv-cTn cohort (range:8-77%). NPV was also higher in the hs-cTn cohort (range: 97-100%), compared with the conv-cTn cohort (range:81-95%). Despite this, a hierarchical summary ROC curve for the hs-cTn subgroup (figure 3b) still demonstrates a large 95% prediction range, principally due to the wide variation in specificity between studies using hs-cTn assays.

Discussion

The aim of this systematic review was to determine if cTn measurement has a role in non-invasive diagnosis of ACR.

Due to significant variation between studies, quantitative meta-analysis to

generate summary sensitivity and specificity estimates was not appropriate. Despite this limitation, it is clear that cTn assays do not have sufficient specificity to replace EMB for the diagnosis of ACR. However, cTn assays may have sufficient sensitivity to exclude ACR, offering use as a tool to determine whether EMB is required. The newer generation hs-cTn assays have particular promise in this respect. Our analysis showed that the sensitivity of hs-cTn assays was higher than the sensitivity of conv-cTn assays for ACR. As a consequence of higher sensitivity and the relatively infrequent diagnosis of ACR, hs-cTn assays had an excellent NPV of 97-100%*; comparable to gene expression profiling by Allomap.12 These data raise the possibility that hs-cTn assays could be used as a ‘ruleout’ test for ACR. In this model, a patient with a negative hs-cTn would avoid the need for surveillance EMB. One major advantage of using hs-cTn as a ‘rule-out’ test is that a result is typically available within a few hours of blood draw. This type of approach would need to be tested in a clinical trial before it could be recommended for routine use.

For a ‘rule out’ hs-cTn to have clinical utility in the real world, a majority of patients must have a negative test at a time when surveillance EMB would be performed. In the studies that assessed hscTn assays, there was wide variation in the number of negative results (range:13-73%). Some of these patients may have had a borderline indication for surveillance EMB. Almost half of patients were more than 2-3 years post-HT at the time of EMB. The utility and cost-effectiveness of surveillance EMB is less certain at this stage and many transplant centers do not routinely perform surveillance EMB after one year. We intended to perform a sub-group analysis of patients within their first year post HT when the risk of ACR and need for surveillance EMB is greatest, but only four studies reported this data separately which was not sufficient for meaningful analysis. Two studies reported performance of a hs-cTn assay within the first year. One study excluded EMBs within the first month and the second study excluded EMBs within the first 3 months post-HT.24,25 Prevalence of significant ACR was 6%(15/243) and 8%(2/26) respectively. Sensitivity of the hs-cTn assays for ACR were 93% and 100% with NPVs of 99% and 100%. Importantly, 55% of hs-cTn results were negative within the first year in these two studies. The results of these studies within the first year are encouraging, but the number of included patients is small. Further work needs to be performed to determine the time points at which hs-cTn-guided surveillance EMB would be feasible.

Measurement of cTn in patients after HT raises additional questions.

Patients who have a

detectable level of cTn but do not have ACR on surveillance EMB represent an interesting group. It is likely that pathophysiological mechanisms are responsible for the detectable cTn level and further research into the nature of these may identify opportunities to mitigate against the negative prognosis of an elevated cTn level post HT.37

Limitations

All studies included in this systematic review were observational, single center cohorts and included a relatively small number of patients.

In addition, a significant proportion of studies were

retrospective or did not recruit consecutive patients resulting in significant risk of selection bias.

There was significant heterogeneity in study methodology. Many studies did not specify whether serum samples were taken before or after the EMB which is an important potential confounder as procedure related injury could result in a raised cTn level. Time of enrollment relative to HT varied widely between studies. This is potentially important as ACR is most common in the first year postHT, a recognized cause of death after HT and recruiting patients at a later stage post-HT may introduce survival bias. Furthermore, ischaemic-reperfusion injury during organ procurement and implantation are known to cause Troponin release resulting in an elevated cTn level postimplantation that falls gradually during the first few months post-HT. During this time period c-Tn levels will not be useful in excluding the presence of ACR and the precise length of this time period is uncertain. Quality of the reference standard is a potential confounder. Most EMB were graded by one pathologist and this could be an explanation for heterogeneity in the incidence of ACR. The change to the ISHLT grading system for ACR made in 2004 may have further confounded the reliability of EMB as a true gold standard. Most conv-cTn studies were performed using the 1990 grading system and there was significant variability in the frequency of ≥3a rejection (5-21%). In contrast, there was much less variability in the frequency of >2R rejection in studies using 2004 grading system. Finally, all hs-cTn studies used an ROC analysis to determine the optimum positive level for their assays compared to only a single study evaluating a conv-cTn assay. This may introduce a statistical bias in favour of hs-cTn in our sub-analysis. Whilst all studies identified a hscTn cut-point with high sensitivity and NPV, these cut-points differed between studies and their external validity is uncertain.

Conclusions

The aim of this systemic review was to determine if cTn measurement has a role in the non-invasive diagnosis of ACR, particularly as a tool to reduce the need for surveillance EMB in suitable patients. It is clear that cTn assays cannot replace EMB for the diagnosis of ACR due to their low specificity. However, our analysis suggests that hs-cTn assays may be used for the exclusion of ACR and

therefore reduce the need for surveillance EMB. This would reduce exposure to the risks of an invasive procedure and may reduce healthcare costs. Further investigation with a large multi-center prospective study designed to determine the effectiveness and safety of using an hs-cTn assay in this role is required before the strategy could be recommended. *excluding case-control study26

Acknowledgements

The authors would like to acknowledge the co-operation of authors of the published literature we have drawn on for this systemic review, particularly those who supplied us with additional data not included in their published results.

Disclosure statement

The authors have no conflicts of interest to declare.

Figure legends

Figure 1. Flow diagram of study selection.

Figure 2. Summary of positive and negative cTn results according to presence or absence of significant ACR on EMB.

Figure 3. Hierarchical summary receiver-operator curve showing the diagnostic performance of cTn assays in (a) All studies, and (b) Only studies assessing hs-cTn assays.

References

1.

Hill DA, Drazner MH, de Lemos JA. Do established biomarkers such as B-type natriuretic peptide and troponin predict rejection? Current opinion in organ transplantation. 2013.

2.

Yusen RD, Edwards LB, Kucheryavaya AY, et al. The Registry of the International Society for Heart and Lung Transplantation: Thirty-second Official Adult Lung and Heart-Lung Transplantation Report-2015; Focus Theme: Early Graft Failure. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation. 2015;34(10):1264-1277.

3.

Lund LH, Edwards LB, Kucheryavaya AY, et al. The registry of the International Society for Heart and Lung Transplantation: thirty-first official adult heart transplant report--2014; focus theme: retransplantation. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation. 2014;33(10):996-1008.

4.

Winters GL, McManus BM. Consistencies and controversies in the application of the International Society for Heart and Lung Transplantation working formulation for heart transplant biopsy specimens. Rapamycin Cardiac Rejection Treatment Trial Pathologists. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation. 1996;15(7):728-735.

5.

Costanzo MR, Dipchand A, Starling R, et al. The International Society of Heart and Lung Transplantation Guidelines for the care of heart transplant recipients. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation. 2010;29(8):914-956.

6.

Deckers JW, Hare JM, Baughman KL. Complications of transvenous right ventricular endomyocardial biopsy in adult patients with cardiomyopathy: a seven-year survey of 546 consecutive diagnostic procedures in a tertiary referral center. Journal of the American College of Cardiology. 1992;19(1):43-47.

7.

Baraldi-Junkins C, Levin HR, Kasper EK, Rayburn BK, Herskowitz A, Baughman KL. Complications of endomyocardial biopsy in heart transplant patients. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation. 1993;12(1 Pt 1):63-67.

8.

Evans RW, Williams GE, Baron HM, et al. The economic implications of noninvasive molecular testing for cardiac allograft rejection. American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons. 2005;5(6):1553-1558.

9.

Crespo-Leiro MG, Zuckermann A, Bara C, et al. Concordance among pathologists in the second Cardiac Allograft Rejection Gene Expression Observational Study (CARGO II). Transplantation. 2012;94(11):1172-1177.

10.

Miller CA, Fildes JE, Ray SG, et al. Non-invasive approaches for the diagnosis of acute cardiac allograft rejection. Heart (British Cardiac Society). 2013;99(7):445-453.

11.

Pham MX, Teuteberg JJ, Kfoury AG, et al. Gene-expression profiling for rejection surveillance after cardiac transplantation. The New England journal of medicine. 2010;362(20):18901900.

12.

Crespo-Leiro MG, Stypmann J, Schulz U, et al. Clinical usefulness of gene-expression profile to rule out acute rejection after heart transplantation: CARGO II. European heart journal. 2016;37(33):2591-2601.

13.

Vasan RS. Biomarkers of cardiovascular disease: molecular basis and practical considerations. Circulation. 2006;113(19):2335-2362.

14.

White H, Thygesen K, Alpert JS, Jaffe A. Universal MI definition update for cardiovascular disease. Current cardiology reports. 2014;16(6):492.

15.

Shamseer L, Moher D, Clarke M, et al. Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015: elaboration and explanation. BMJ (Clinical research ed.). 2015;349:g7647.

16.

RevMan Version 5.3 Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2014. [computer program]. Version 5.3. Copenhagen2014.

17.

metandi: Stata module for meta-analysis of diagnostic accuracy. Statistical Software Components, Boston College Department of Economics. Revised 15 Apr 2008. [computer program]2008.

18.

Mullen JC, Bentley MJ, Scherr KD, et al. Troponin T and I are not reliable markers of cardiac transplant rejection. European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery. 2002;22(2):233-237.

19.

Ogawa T, Veinot JP, Davies RA, et al. Neuroendocrine profiling of humans receiving cardiac allografts. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation. 2005;24(8):1046-1054.

20.

Moran AM, Lipshultz SE, Rifai N, et al. Non-invasive assessment of rejection in pediatric transplant patients: serologic and echocardiographic prediction of biopsy-proven myocardial rejection. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation. 2000;19(8):756-764.

21.

Balduini A, Campana C, Ceresa M, et al. Utility of biochemical markers in the follow-up of heart transplant recipients. Transplantation proceedings. 2003;35(8):3075-3078.

22.

Battes LC, Caliskan K, Rizopoulos D, et al. Repeated measurements of NT-pro-B-type natriuretic peptide, troponin T or C-reactive protein do not predict future allograft rejection in heart transplant recipients. Transplantation. 2015;99(3):580-585.

23.

Ahn KT, Choi JO, Lee GY, Park HD, Jeon ES. Usefulness of high-sensitivity troponin I for the monitoring of subclinical acute cellular rejection after cardiac transplantation. Transplantation proceedings. 2015;47(2):504-510.

24.

Patel PC, Hill DA, Ayers CR, et al. High-sensitivity cardiac troponin I assay to screen for acute rejection in patients with heart transplant. Circulation. Heart failure. 2014;7(3):463-469.

25.

Dyer AK, Barnes AP, Fixler DE, et al. Use of a highly sensitive assay for cardiac troponin T and N-terminal pro-brain natriuretic peptide to diagnose acute rejection in pediatric cardiac transplant recipients. American heart journal. 2012;163(4):595-600.

26.

Munoz-Esparza C, Garrido IP, Blanco R, et al. [Usefulness of high sensitivity troponin T assay in detecting acute allograft rejection after heart transplantation]. Revista espanola de cardiologia. 2011;64(12):1109-1113.

27.

Hossein-Nia M, Mascaro J, McKenna WJ, Murday AJ, Holt DW. Troponin T as a non-invasive marker of cardiac allograft rejection. Lancet (London, England). 1993;341(8848):838.

28.

Vazquez-Rodriguez JM, Crespo-Leiro MG, Pampin-Conde MF, et al. Cardiac troponin T is not a marker of biopsy-proven cellular rejection. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation. 1999;18(2):172.

29.

Anderson JR, Holt DW. The role of cardiac troponin T to predict heart transplant rejection. The Annals of thoracic surgery. 1999;68(3):1121-1122.

30.

Alexis JD, Lao CD, Selter JG, et al. Cardiac troponin T: a noninvasive marker for heart transplant rejection? The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation. 1998;17(4):395-398.

31.

Dengler TJ, Zimmermann R, Braun K, et al. Elevated serum concentrations of cardiac troponin T in acute allograft rejection after human heart transplantation. Journal of the American College of Cardiology. 1998;32(2):405-412.

32.

Forni A, Faggian G, Luciani GB, et al. Correlation between troponin I serum level and acute cardiac allograft rejection: a preliminary report. Transplantation proceedings. 2000;32(1):167-168.

33.

Chance JJ, Segal JB, Wallerson G, et al. Cardiac troponin T and C-reactive protein as markers of acute cardiac allograft rejection. Clinica chimica acta; international journal of clinical chemistry. 2001;312(1-2):31-39.

34.

Gleissner CA, Zehelein J, Sack FU, Schnabel P, Haass M, Dengler TJ. Extended experience and subgroup analysis using cardiac troponin T for rejection monitoring after heart transplantation. Transplantation proceedings. 2002;34(6):2178-2180.

35.

Wahlander H, Kjellstrom C, Holmgren D. Sustained elevated concentrations of cardiac troponin T during acute allograft rejection after heart transplantation in children. Transplantation. 2002;74(8):1130-1135.

36.

Mendez AB, Cardona M, Ordonez-Llanos J, Mirabet S, Perez-Villa F, Roig E. Predictive value of high-sensitive troponin T to rule out acute rejection after heart transplantation. Revista espanola de cardiologia (English ed.). 2014;67(9):775-776.

37.

Erbel C, Taskin R, Doesch A, et al. High-sensitive Troponin T measurements early after heart transplantation predict short- and long-term survival. Transplant international : official journal of the European Society for Organ Transplantation. 2013;26(3):267-272.

TABLES Table 1. Study Design and Patient Characteristics

Study

Alexis

Study Design

30

29

Anderson

Forni

32

Chance

Wang

33

38

Gleissner

34

Includes 31 Dengler

Wåhlander 35

Muñoz26 Esparza

Dyer

Patel

25

24

Méndez

36

Prospective, observational Consecutive patients March 1996 – October 1996 Design uncertain Enrolment uncertain Time uncertain Prospective, observational Consecutive patients August 1998 – February 1999 Prospective, observational Enrolment uncertain Jan 1997 – January 1999 Prospective, observational Consecutive patients Timeframe unknown Retrospective, cohort but analysed as case-control Patients with ACR 2R compared with patients with no ACR 1992 - 1999 Retrospective, observational Patients with 3 EMB at >1 month post-HT May 1995 – October 1999 Retrospective, casecontrol Patients with ACR compared with self (when no ACR) 2000-2008 Prospective, observational Patients at >3 months’ post HT October 2009 – April 2010 Retrospective, observational Enrolment uncertain January 2003 - December 2010 Prospective, observational Enrollment uncertain Time uncertain

Patients, n

Male gender (%)

Age, years (mean  SD)

Reason for Transplant (%)

Time from HT to EMB

90

74

48  1.6

NS

Range 1 week – 6 years

23

70

Not stated

NS

Range 0 – 1 year

52  6

ICM: 44 DCM: 46 Other: 10

Mean  SD: 640  95 days Range 15 –1740 days

114

87.5

145

NS

NS

NS

Median 29 months Range 3 days – 17.2 years

186

NS

NS

NS

NS

8.5  9.4

ICM: 59 DCM:36 Other: 5

Range 0-3 years, 518 EMB Range > 3 years, 278 EMB

132

86

14

36

Paediatric

CHD:36 DCM/HCM: 50 Other: 14

29

77

Median 57 IQR 49-62

ICM: 37 DCM:46 Other: 17

Range 0 – 1 year

42

52

Paediatric

NS

Median 24 months

NS

Range 1-12 months, 243 EMB Range >1yr, 165 EMB

NS

Range 0-3 months, 183 EMB Range 3-12

98

73

83

73

53.2  12.7

54  14

NS

months, 25 EMB Range >12 months, 16 EMB

Ahn

23

Retrospective, casecontrol Patients with ACR compared with self (when no ACR) June 2009 – September 2011

47

ICM: 11 DCM: 87 Other: 2

47.4  15.8

68

Range 0 – 60 days, 69 EMB Range 60 days – 2 years, 183 EMB

ACR = Acute Cellular Rejection, CHD = Congenital Heart Disease, DCM = Dilated Cardiomyopathy, EMB = Endomyocardial biopsy, HT = Heart Transplant, HCM = Hypertrophic Cardiomyopathy, ICM = Ischaemic Cardiomyopathy, NS = Not Stated

Table 2. Endomyocardial biopsies ISHLT grade Study

Patients, n

EMB, n

1990 system

2004 system

0

1

2

3a

0R

1R

2R

Patients with significant rejection

EMB with significant rejection

Alexis

90

256

120

107

17

12

9%

5%

Anderson

23

223

161

37

9

16

NS

7%

Forni

114

385

360

12

13

NS

3%

Chance

145

704

169

101

142

NS

20%

Wang

186

365

290

75

NS

21%

Gleissner

132

788

268

280

139

101

NS

13%

Wåhlander

14

78

46

7

16

9

50%

12%

Muñoz-Esparza*

29

67

38

29

100%

43%

Dyer

42

53

46

7

12%

13%

Patel

98

408

258

19

37%

5%

Méndez

73

224

208

16

NS

7%

Ahn

47

252

234

18

NS

7%

TOTAL

993

3803

915

89

2431

292

368

131

12%

EMB = Endomyocardial biopsy, NS = Not stated, ISHLT = International Society of Heart and Lung Transplantation. *True case-control study

Table 3. Troponin Assays Study

cTn

Assay

Positive level as defined in study

Positive cTn n (%)

Conventional troponin (Conv-cTn) Assays Alexis

TnT

Enzymun Test R System, Boehringer Mannheim

0.1ng/ml

30 (12)

Anderson

TnT

NS

0.5ng/ml

50 (22)

Forni

TnI

Dimension Rx L

0.04 mmol/L

301 (78)

Chance

TnT

Elecsys 2010 3rd gen immunoassay System, Roche

0.1ng/ml

78 (11)

0.01ng/ml (detect)

269 (38)

TnT 0.07ng/ml

TnT: 62 (17)

TnI 1.7 ng/ml

TnI: 27 (8)

ELIZA based on Enzymun-Test R System, Boehringer Mannheim

140ng/l established by ROC analysis

163 (21)

STAT Elecsys 2010, Roche

0.1ng/ml

21 (27)

Wang

TnT

Gleissner

TnI TnT

Wåhlander

TnT

Enzymun Test R System, Boehringer Mannheim Stratus Cardiac

High Sensitivity Troponin (hs-cTn) Assays Muñoz-Esparza

TnT

Elecsy analyzer, Roche

0.035ng/ml established by ROC analysis

45 (67)

Dyer

TnT

Elecsy analyzer, Roche

14pg/ml established by ROC analysis

19 (36)

Patel

TnI

Architect i2000, Abbott

15ng/L established by ROC analysis

182(45)

Méndez

TnT

Roche

Several levels evaluated by ROC analysis including 17ng/l

195 (87)

Ahn

TnI TnI

Architect stat, Abbott Architect stat analysed on Architect i2000, Abbott

hs-cTnI ratio index 1.17 Used a ratio index of observed: expected levels**

69* (27)

EMB = Endomyocardial Biopsy, TnT = Troponin T, TnI = Troponin I, ROC = Receiver Operator Curve, NS = Not Stated, HT = Heart Transplantation, ** Observed = result at current time: Expected = mean value of TnI measurements sampled at –ve EMB >60days post HT

Table 4: Results