Rapid Use of High-sensitive Cardiac Troponin I for ruling-in and Ruling-out of Acute Myocardial Infarction
Conditions: Myocardial Infarction, Chest Pain
Sponsor: Aarhus University Hospital



Introduction 
Chest pain is a key symptom of acute myocardial infarction (MI), but can also represent other 
cardiac and non-cardiac disease.1, 2 Rapid identification of MI in terms of ‘rule-in’ or ‘rule-out’ is 
essential in order to minimize treatment delay or time to discharge. In the absence of ST-segment 
elevation myocardial infarction (STEMI) at initial MI evaluation, the European Society of Cardiology 
(ESC) guidelines recommend repeated measurements of high-sensitive cardiac troponin (hs-cTn) at 
presentation (0h) and 3 hours (3h) after presentation to rule-in and rule-out MI.2  
An accelerated algorithm for ruling-in and ruling-out MI after 1 hour (0h/1h algorithm) has 
been suggested by the ESC as a valid alternative to the standard approach.2 The novel 0h/1h algorithm 
has only been validated for certain hs-cTn assays.3-7 The algorithm assigns patients to three groups: 
rule-in, observational zone and rule-out of MI based on absolute troponin values and troponin 
dynamics below the 99th percentile. However, routine use of the 0h/1h algorithm is still not widely 
recommended, as further data are warranted.2, 8  
A study of patients undergoing transcoronary ablation of septal hypertrophy, a clinical model 
of MI, shows that troponin concentrations measured by a hs-cTn assay significantly increase already 
after 15 min.9 This suggests that troponin dynamics may be evaluated even sooner than the 0h/1h 
algorithm.  
 So far, the 0h/1h algorithm has only been tested in a few patient cohorts.3-7, 10 Moreover, it 
has never been investigated whether rule-in and rule-out of MI can be done safely using a diagnostic 
algorithm after 30 minutes (0h/30m algorithm).  
This study aims to derive and validate two accelerated diagnostic algorithms using a high-
sensitive cardiac troponin I (hs-cTnI) Assay: a 0h/1h algorithm and a 0h/30m algorithm. 
 
Methods 
Study methodology 
This is a prospective, observational study of 1000 patients undergoing MI evaluation using hs-
cTnI measurements at 0h, 30m, 1h and 3h in patients presenting with chest pain. 
 
Eligibility and exclusion criteria  
 
Upon admission, the admitting physician decides whether to observe for myocardial infarction 
or not based on a mandatory evaluation of all patients, including electrocardiogram as well as vital 

sign parameters (blood pressure, heart rate, peripheral oxygen saturation, respiratory rate and 
temperature). The admitting health care staff will assess the patient for study eligibility.  
Patients with chest pain suggestive of MI are eligible for inclusion. Exclusion criteria are: 
STEMI at admission, <18 years of age, pregnancy or kidney failure requiring dialysis. Patients with 
incomplete blood sampling will be excluded from the primary analysis.  
The study site is Regional Hospital Randers, Randers, Denmark. The hospital is a regional 
hospital without invasive capability. The hospital has a catchment area of approximately 230,000 
patients, 220 beds, 164,000 outpatient visits and 37,564 patients being admitted each year.  
 
Table 1: HEART risk score 
 
Patients 
Patients will be stratified according to pre-test probability of MI using HEART risk score (Table 
1), as this score is easily applicable to clinical practice.11 The HEART score divides patients into low- 
(0-3 points), intermediate- (4-6) or high-risk groups (7-10), with mean risks of an event of 0.9%, 12% 
and 65%, respectively.11 An event is defined as MI, Percutaneous Coronary Intervention (PCI), 
Coronary Artery Bypass Grafting (CABG) or death within 6 weeks after presentation. 
History 
Highly suspicious  
2 
Moderately suspicious 
1 
Slightly or non-suspicious 
0 
 
 
 
Electrocardiogram Significant ST depression 
2 
Nonspecific repolarization disturbance 
1 
Normal 
0 
 
 
 
Age 
65 years old or more 
2 
46-64 years old 
1 
45 years old or less 
0 
 
 
 
Risk Factors 
3 or more risk factors or history of significant atherosclerosis 
2 
1-2 risk factors 
1 
No risk factors known 
0 
 
 
 
Troponin 
More than or at 3x normal limit 
2 
1-<3x normal limit 
1 
Lower than or at normal limit 
0 

Oral and written consent will be obtained. The information will be given in a quiet setting, and 
the patient can ask questions. The patient will be given time to consider study participation. It will be 
possible for the patient to have a companion present (e.g. a family member). Patients will be asked 
for informed consent to have information passed on from the electronic patient journal regarding 
gender, age, medicine, previous myocardial infarction and co-morbidity for use in this study only. 
Patients declining to participate will receive standard treatment. 
 
Patient handling  
Time of first admission contact will be recorded for each patient in accordance with 
registrations in the electronic patient journal. All patients will receive routine clinical cardiac 
assessment at admission. The admitting nurse will request blood samples, which will be drawn at the 
following time points: 0h, 30m, 1h and 3h (Fig. 1). Standardized admission blood samples will 
include the first hs-cTnI (0h).  
The medical laboratory technician will set the timer when collecting the 0h blood sample. The 
timer will notify the admitting physician or a research assistant of when to obtain the blood samples 
at 30m and 1h, respectively. Time of each blood draw will be registered.  
Hs-cTnI will be measured in the central laboratory for each of the four time-points (0h, 30m, 
1h and 3h). An additional 10 mL lithium heparin and 4 mL serum will be stored in a research biobank. 
The treating physician will be blinded to test results at 30m and 1h, with the final therapeutic decision 
relying on hs-cTnI measurements at 0h and 3h only.  
 
Figure 1: study design 
 
 
 
 
 
 
 
 
 
 
Standard 
admission blood 
sampling, incl. 
Hs-cTnI 
0h 
30 min 
1h 
3h 
Hs-
cTnI 
Hs-
cTnI 
Hs-
cTnI 
Chest pain 
patients 
presenting to the 
ED 
Timeline 

Chest pain data and baseline characteristics 
A questionnaire will be distributed to all patients after admission and includes questions on: 1) 
time of chest pain onset and peak, 2) chest pain characteristics (localization, radiation, sensation), 3) 
additional symptoms at presentation (such as nausea, abdominal pain, syncope, dyspnea, 
palpitations), 4) height and weight, smoking status and family history of MI and 5) whether the patient 
believes that his or her symptoms are caused by MI (yes/no). If no, the patient will be asked to state 
what the patient believes to be the cause of hospital admittance. 
Baseline characteristics will be recorded for all patients: age, gender, vital parameters, 
admission blood samples, Hs-cTnI results, electrocardiogram description, medication, previous MI 
and co-morbidity passed on from the electronic patient journal. 
 
Final diagnosis 
Two physicians will adjudicate the final diagnosis based on data from the electronic patient 
journal (including physical examination, patient history, laboratory results, electrocardiogram, and 
other examinations). In cases of disagreement between the two physicians a consensus decision will 
be reached after a case review. All available data from each patient will be linked to the final 
diagnosis, including baseline characteristics, chest pain characteristics, blood samples and HEART 
risk score. 
 
Electrocardiogram 
ST-segment elevation is defined according to ESC guidelines.12 Ischemic electrocardiogram 
changes are defined by ST depression of ≥0.5 mm or T-wave inversion of ≥1 mm.2 
 
Biochemical analysis 
Troponin analyses will be performed in accordance with routine laboratory methodology on 
ADVIA Centaur using the high-sensitivity cardiac Troponin I (TNIH) assay (Siemens Healthcare 
GmbH, Erlangen, Germany) in an accredited clinical biochemical laboratory (DANAK ISO 15189 
accreditation standard). The limit of detection for the TNIH assay is 2.21 ng/L, the 99th percentile 
cut-off point is 47.34 ng/L and the coefficient of variation is less than 10% at 4.46 ng/L.  
 
 
 

Outcomes 
Data from the first 500 patients will be used to derive two algorithms: a 0h/30m and a 0h/1h 
algorithm. Both algorithms will subsequently be validated in the last 500 patients. For the 0h/1h 
algorithm, data from the total patient cohort will also be used to further validate already existing 
0h/1h algorithm cut-off values.  
The primary outcomes will be the negative predictive value of the 0h/30m algorithm when 
ruling-out MI at 30m and the negative predictive value of the 0h/1h algorithm when ruling-out MI at 
1h. Secondary outcomes will be positive predictive value, sensitivity and specificity at 30m and 1h. 
Results will be compared with the standard 0h/3h algorithm. 
 
Statistics 
The study is designed to enroll 1000 patients with complete blood samples. We expected the 
prevalence of MI in our population to be low due to pre-hospital risk-stratification conducted in the 
ambulance. Risk stratification is based on point-of-care troponin and electrocardiogram evaluation. 
Accordingly, patients with a very high risk of MI will not be admitted to the study site, as they will 
be directly transferred to a tertiary care centers with cardiac catheterization facilities.  
In order to estimate the prevalence of MI in our study cohort, a pilot study calculation was 
performed, leading to an estimated MI prevalence of 7.4%. Assuming a negative predictive value of 
99.7% in the rule-out group, and a distribution with 7% patients in the rule-in group and 20% in the 
observational zone, enrolment of at least 500 patients in each patient cohort, the derivation and the 
validation cohorts, will provide an acceptable lower boundary of 98.2% of the two-
sided 95% confidence interval. We plan to include approximately 1400 patients. This allows for 
missing blood samples, loss of follow-up and patients who withdraw themselves from the study.  
 
The diagnostic algorithms for the study will be developed using CART-tree analysis and 
receiver operating characteristic curves using baseline and absolute 30m or 1h changes in hs-cTnI 
values, respectively. The algorithms will be used to distinguish between the following diagnoses: MI 
and non-MI (such as unstable angina, non-coronary cardiac chest pain, non-cardiac chest pain and 
discharge with no diagnosis).  
 
Data will be analyzed for normality using QQ-plots and histograms. Normally distributed 
continuous variables will be presented as mean (Standard Deviation (SD)). Non-normally distributed 
data will be presented as median (Interquartile Range (IQR)). Categorical data will be presented as 

numbers and proportions. Statistical differences will be measured using appropriate parametric and 
non-parametric tests.  
All hypothesis testing will be 2-tailed with a p-value <0.05 considered to be statistically 
significant. Statistical analyses will be performed using R statistical software, version 3.4.0. 
 
Ethics 
 
Permissions from the Danish Research Ethics Committee (1-10-72-213-16) and the Danish 
Data Protection Agency (1-16-02-530-16) have been obtained. The project will be carried out 
according to the Danish Health Act.  
      
All patients will be asked specifically for informed consent to establish the research biobank. 
 
 
Risk, side effects and other disadvantages  
 
Blood samples will be obtained according to standard venous blood sampling using a 
venepuncture. When venepuncture is unsuccessful, or when a suitable cubital peripheral venous 
catheter is present, this may be used. In such cases, the first 10 mL blood obtained will discarded at 
2nd and 3rd blood draw to avoid haemolysis in the blood samples. This leads to a total of 84mL 
additional blood drawn from each patient compared to standard procedure, when adding discarded 
blood, blood for biobank establishment and hs-cTnI analysis at 30m and 1h. We believe that the extra 
volume of blood drawn will not lead to any significant adverse effects, such as fatigue or dizziness. 
Any patient discomfort during the study is small and outweighed by the information the study 
contributes. As the treating physician acts solely on the 0h/3h hs-cTnI results, the therapeutic decision 
will not be affected by the study.   
 
Feasibility 
 
The research group behind the project has carried out a retrospective audit of chest pain patients 
admitted to the emergency department at Randers Regional Hospital to ensure the feasibility of the 
project. On average, 5 eligible patients presented with chest pain per day in the emergency department 
(according to our in- and exclusion criteria). We found that approximately 7.4% of these patients 
were diagnosed with MI. To ensure study completion a 23-month data collection period is planned.  
 
The group behind the project is established within the field of cardiovascular research, has 
previously completed a randomized clinical trial at Randers Regional Hospital and has the necessary 
expertise to ensure the completion of the study.  

 
The project will be performed in close collaboration with the Emergency Department, 
Department of Internal Medicine and Department of Clinical Biochemistry at Randers Regional 
Hospital. The departments are involved to ensure that the project fits into a clinical setting and can 
be implemented properly throughout all units. Registration of patients, blood sampling etc. will be 
performed by the clinical staff in collaboration with the research group.  
 
Financial statement 
 
The project is investigator initiated. Application for study support will be send to appropriate 
funding agencies. Grant support for one of the lead investigators is provided by Randers Regional 
Hospital.  
 
Investigators and publication 
 
Camilla Bang, MD, and Camilla Hansen, MD, are the lead investigators of the outlined study. 
Professor Bo Løfgren, MD, PhD, FESC (PI) has committed himself as main supervisor and scientific 
mentor. Kasper Glerup Lauridsen, MD, PhD student, Christian Alcaraz Frederiksen MD, PhD, 
Morten Schmidt, MD, PhD, consultant Tage Jensen, MD and associate professor, consultant Nete 
Hornung, MD, PhD, have committed themselves as co-supervisors. 
The results, whether positive, negative or inconclusive, will be submitted to an international 
peer-reviewed journal. 
 
Perspectives 
 
This study challenges existing time limits for MI evaluation by investigating the diagnostic 
value of hs-cTnI measurements at 30m. If our study shows that rule-in and rule-out of MI can be 
performed safely at 30m, MI evaluation can potentially be accelerated even further.  
 
The study results can change clinical practice for patients presenting with chest pain in the 
future. Implementation of the algorithm can lead to improved patient outcomes, as a decrease in time 
to clinical decision-making favours early initiation of treatment. In addition, bed availability may rise 
in emergency departments to the benefit of patient safety. 
 
 
 
 

References  
1.  
Cohn JK, Cohn PF. Cardiology Patient Page – Chest Pain. Circulation. 2002;106:530-531  
2.  
Roffi M, Patrono C, Collet JP, et al. ESC Guidelines for the management of acute coronary 
syndromes in patients presenting without persistent ST-segment elevation: Task Force for the 
management of acute coronary syndromes in patients presenting without persistent ST-
segment elevation of the European Society of Cardiology (ESC). European Heart Journal. 
2016;37;267-315. 
 
3.  
Giménez M, Twerenbold R, Jaeger C. et al. One-hour Rule-in and Rule-out of Acute 
Myocardial Infarction Using High-sensitivity Cardiac Troponin I. Am J Med. 2015; 128; 861-
870. 
 
4.  
Reichlin T, Schindler C, Drexler B, et al. One-Hour Rule-out and Rule-in of Acute 
Myocardial Infarction Using High-Sensitivity Cardiac Troponin T. Arch Intern Med. 2012; 
172. 
5.  
Reichlin T, Twerenbold R, Wiren K, et al. Prospective validation of a 1-hour algorithm to 
rule-out and rule-in acute myocardial infarction using a high-sensitivity cardiac troponin T 
assay. CMAJ. 2015;187. 
6.  
Mueller C, Giannitsis E, Christ. Multicenter Evaluation of a 0-Hour/1-Hour Algorithm in the 
Diagnosis of Myocardial Infarction With High-Sensitivity Cardiac Troponin T. Ann Emerg 
Med. 2015;-:1-12. 
 
7.  
Jaeger C, Wikli K, Twerenbold R, Reichlin T, Gimenez MR, Mueller C. One-hour rule-in and 
rule-out of acute myocardial infarction using high-sensitivity cardiac troponin I. Am Heart J 
2016;171:92-102.e5. 
8.  
Amsterdam EA, Wenger NK, Brindis RG, et al. 2014 AHA/ACC Guideline for the 
Management of Patients With Non–ST-Elevation Acute Coronary Syndromes: A Report of 
the American College of Cardiology/American Heart Association Task Force on Practice 
Guidelines. Circulation. 2014; 64:2645-87.  
9.  
Liebetrau C, Möllmann H, Nef H, et. al. Release Kinetics of Cardiac Biomarkers in Patients 
Undergoing Transcoronary Ablation of Septal Hypertrophy. Clin Chem. 2012;58:1049-1054.  
10. 
Shiozaki M, Inoue K, Suwa S, et al. Utility of the 0-hour/1-hour high-sensitivity cardiac 
troponin T algorithm in Asian patients with suspected non-ST elevation myocardial infarction. 
Int J Cardiol. 2017;249:32-35.  
 

 
 
 
11.  Backus BE, Six AJ, Kelder JC, et. al. Chest Pain in the Emergency Room: A Multicenter 
Validation of the HEART Score. Crit Pathways in Cardiol. 2010;9:164-169.  
12.    Steg G, et al. 2012 ESC Guidelines for the management of acute coronary infarction in 
patients presenting wit persistent ST-segment elevation. European Heart Journal.