High-sensitivity Cardiac Troponin Testing Research Articles

Diagnostic accuracy of baseline troponin and troponin change for the diagnosis of myocardial infarction complicated with heart failure

BackgroundThe diagnosis of myocardial infarction (MI) in the presence of heart failure (HF) presents a clinical problem. While diagnostic algorithms using high-sensitivity cardiac troponin have been established for suspected MI,...

Whole Blood Cardiac Troponin "Triaging" to Improve Early Detection of Myocardial Injury at a Pediatric Hospital.

The importance of offering on-site cardiac troponin (cTn) testing at pediatric hospitals may be underappreciated. We developed a rapid rule-in process for myocardial injury at a pediatric hospital experiencing delays in off-site high-sensitivity cardiac troponin T (hs-cTnT) testing. Collect-to-verify turnaround times (TATs) for off-site testing were reviewed. Pre-analytic changes to improve TATs were devised, implemented and evaluated, after which a new analyzer was selected and evaluated for on-site cTn testing. Performance of the new analyzer's assay was compared to the off-site hs-cTnT assay, and post go-live TATs for on-site testing were assessed. Median collect-to-verify TAT for short turnaround-time (STAT) priority off-site plasma hs-cTnT testing was 104 min, with 35% of orders having a TAT >120 min. Eliminating serum separator tubes and requiring a separate plasma separator tube did not significantly reduce TATs. A QuidelOrtho Triage® MeterPro whole blood cardiac troponin I (cTnI) assay was implemented to "triage" time-critical and STAT priority specimens collected for off-site hs-cTnT testing. Elevated cTnI (≥0.02 µg/L) had a sensitivity of 91% for clear elevations in hs-cTnT (≥53 ng/L) but a 0% sensitivity for modest elevations (5 to 13 ng/L, 14 to 52 ng/L). An interpretive comment was auto-appended to cTnI results indicating that clinicians should wait for the hs-cTnT result if cTnI was normal. Median collect-to-verify TAT for on-site cTnI testing was <50% the TAT for off-site hs-cTnT testing. On-site point-of-care whole blood cTn testing can rapidly confirm significant or late-presenting myocardial injury. Combined with simultaneous off-site high-sensitivity cardiac troponin (hs-cTn) testing, this workflow is a viable interim solution for pediatric hospitals without on-site hs-cTn testing.

Management of patients suspected for non-ST elevation-acute coronary syndrome in the prehospital phase.

The management of patients with suspected acute coronary syndrome, especially in prehospital settings, is challenging. This Special Report focuses on studies in emergency medical services concerning chest pain patients' triage and risk stratification. In addition, it emphasizes advancements in point-of-care cardiac troponin testing. These developments are compared with in-hospital guidelines, proposing an initial framework for a new acute care pathway. This pathway integrates a risk stratification tool with high-sensitivity cardiac troponin testing, aiming to deliver optimal care and collaboration within the acute care chain. It has the potential to contribute to a significant reduction in hospital referrals, reduce observation time and overcrowding at emergency departments and hospital admissions.

Performance of a prehospital HEART score in patients with possible myocardial infarction: a prospective evaluation

IntroductionThe History, Electrocardiogram (ECG), Age, Risk Factors and Troponin (HEART) score is commonly used to risk stratify patients with possible myocardial infarction as low risk or high risk in the...

The Incremental Value of Functional Testing for Acute Chest Pain Assessment in the Context of High-sensitivity Troponin T

Background: Functional testing for acute chest pain assessment is a common practice that has not been re-examined in the era of high-sensitivity cardiac troponin. This population poses a significant analytical dilemma for physicians to achieve accurate diagnosis, balanced against the inherent risks of hospital admission and invasive downstream testing. This single-centre study evaluated outcomes in patients who underwent chest pain assessment, whose initial diagnosis was not consistent with a MI, comparing subsequent functional testing versus no functional testing. Methods: An inverse probability propensity-matched analysis of patients who underwent chest pain assessment in the emergency department and not initially referred for coronary angiography was performed to examine whether functional testing was associated with a lower rate of death or MI at 30 days. Results: In total, 3,101 patients were included. Functional testing was performed in 986 patients, while 2,115 did not undergo functional testing. The quality of propensity matching for covariates was high. The overall event rate of all-cause mortality and MI was low, totalling at five events. There was no significant difference between those who underwent functional testing versus those who did not undergo functional testing. Conclusion: Functional testing is not likely to be associated with a reduced risk of death or MI within 30 days, and provides limited further diagnostic benefit in the acute timeframe in the context of high-sensitivity cardiac troponin testing.

Serial high-sensitivity cardiac troponin testing for the diagnosis of myocardial infarction: a scoping review

ObjectivesWe aimed to assess the diversity and practices of existing studies on several assays and algorithms for serial measurements of high-sensitivity cardiac troponin (hs-cTn) for risk stratification and the diagnosis...

Identifying Very-Low-Risk Patients for Future Myocardial Infarction or Death

High-sensitivity cardiac troponin (hs-cTn) testing has enabled shorter time intervals between serial measurements when assessing patients with possible acute coronary syndrome (ACS) with a single sample strategy proposed for early risk stratification. Specifically, a rapid rule-out for myocardial infarction (MI) is suitable for a pathway if the sensitivity for 30-day cardiac events is ≥99%. At the population level [n=131,095 emergency department (ED) patients], low hs-cTn results alone yielded sensitivities <99%.

Artificial intelligence-enabled electrocardiographic algorithm for the detection of left ventricular dysfunction in emergency department patients undergoing high-sensitivity cardiac troponin T

Abstract Background Artificial intelligence-augmented electrocardiogram (AI-ECG) algorithms have been developed from the standard 12-lead ECG and validated for the recognition of left ventricular systolic dysfunction (LVSD), defined as LV ejection fraction (LVEF)≤35%. Whether AI-ECG facilitates identification of LVSD and is associated with adverse outcomes in emergency department (ED) patients undergoing high-sensitivity cardiac troponin (hs-cTnT) testing is uncertain. Purpose To investigate the diagnostic and prognostic performance of AI-ECG in ED patients undergoing hs-cTnT measurement. Methods Observational US cohort study of ED patients undergoing hs-cTnT measurement. Cases with hs-cTnT increases &amp;gt;sex-specific 99th percentiles were adjudicated following the Fourth Universal Definition of Myocardial Infarction (MI). Post-discharge major adverse cardiac events (MACE) included death, MI, heart failure (HF) hospitalization, stroke or transient ischemic attack, and new onset atrial fibrillation/flutter during 2-years follow-up. The AI-ECG network output, which is a continuous number between 0–1, that provides a probability of LVSD, was obtained for each patient from the first ECG during the index presentation. An AI-ECG threshold of ≥0.256 indicates a positive screen that correlates with a high probability of LVSD. Results Among 1977 patients, 1729 (87%) had a negative AI-ECG screen, while 248 (13%) had a positive AI-ECG screen. Patients with a positive AI-ECG screen were older and had more comorbidities. As compared to patients with hs-cTnT≤99th percentile in whom AI-ECG was positive in 5.8%, those with hs-cTnT&amp;gt;99th percentile had a positive AI-ECG in 22% of cases (p&amp;lt;0.0001). Based on adjudicated diagnoses, the frequency of a positive AI-ECG was 20% in myocardial injury, 38% in type 1 MI, and 20% in type 2 MI. At 2-years follow-up, as compared to patients with a negative AI-ECG, those with a positive AI-ECG had a higher risk for MACE (48% vs. 21%, p&amp;lt;0.0001, adjusted HR 1.39, 95% CI 1.11–1.75) (Figure 1), mainly because of more deaths (43% vs. 30%, p=0.004) and HF hospitalizations (36% vs. 13%, p&amp;lt;0.0001). A positive AI-ECG was associated with a higher risk for MACE (60% vs. 41%, p&amp;lt;0.0001, adjusted HR 1.30, 95% CI 1.02–1.64) in those with hs-cTnT increases &amp;gt;99th percentile, but not in those without hs-cTnT increases. Among patients with an echocardiogram during index presentation or within 30-days (n=452), the diagnostic accuracy of AI-ECG for LVEF ≤35% was 81.4% (95% CI 77.5, 84.9) with a negative predictive value of 96.5% (95% CI 94.0, 98.2). A normal LVEF (&amp;gt;50%) was observed in 87% of those with a negative AI ECG, whereas in those with a positive AI-ECG LVEF was reduced (&amp;lt;50%) in 60%. Conclusions Among ED patients evaluated with hs-cTnT, a positive AI-ECG screen for LVSD identifies patients at high risk of MACE. These findings are largely because of more deaths and HF hospitalizations in those with hs-cTnT increases &amp;gt;sex-specific 99th percentiles. Funding Acknowledgement Type of funding sources: None.

Clinical Applications of High-Sensitivity Troponin Testing: From Diagnosis to Prognosis.

High-sensitivity cardiac troponin (hs-cTn) is critical in the diagnosis of acute coronary syndrome. However, it can also inform risk of cardiovascular events and mortality. Patients with unstable angina and normal-range hs-cTn have a very favorable short-term prognosis and do not appear to suffer increased risk of cardiovascular events and mortality. Such patients can often be treated in the outpatient setting.

Computed tomography coronary angiography in non-ST-segment elevation myocardial infarction.

Electrocardiography and high-sensitivity cardiac troponin testing are routinely applied as the initial step for clinical evaluation of patients with suspected non-ST-segment elevation myocardial infarction. Once diagnosed, patients with non-ST-segment elevation myocardial infarction are commenced on antithrombotic and secondary preventative therapies before undergoing invasive coronary angiography to determine the strategy of coronary revascularisation. However, this clinical pathway is imperfect and can lead to challenges in the diagnosis, management, and clinical outcomes of these patients. Computed tomography coronary angiography (CTCA) has increasingly been utilised in the setting of patients with suspected non-ST-segment elevation myocardial infarction, where it has an important role in avoiding unnecessary invasive coronary angiography and reducing downstream non-invasive functional testing for myocardial ischaemia. CTCA is an excellent gatekeeper for the cardiac catheterisation laboratory. In addition, CTCA provides complementary information for patients with myocardial infarction in the absence of obstructive coronary artery disease and highlights alternative or incidental diagnoses for those with cardiac troponin elevation. However, the routine application of CTCA has yet to demonstrate an impact on subsequent major adverse cardiovascular events. There are several ongoing studies evaluating CTCA and its associated technologies that will define and potentially expand its application in patients with suspected or diagnosed non-ST-segment elevation myocardial infarction. We here review the current evidence relating to the clinical application of CTCA in patients with non-ST-segment elevation myocardial infarction and highlight the areas where CTCA is likely to have an increasing important role and impact for our patients.

Unmasking Myocardial Dysfunction in Patients Hospitalized for Community-Acquired Pneumonia Using a 4-Chamber 3-Dimensional Volume/Strain Analysis.

Lower respiratory infection was reported as the most common fatal infectious disease. Community-acquired pneumonia (CAP) and myocardial injury are associated; yet, true prevalence of myocardial injury is probably underestimated. We assessed the rate and severity of myocardial dysfunction in patients with CAP. Admitted patients diagnosed with CAP were prospectively recruited. All the patients had C-reactive protein (CRP), brain natriuretic peptide (BNP), and high-sensitivity cardiac troponin (hs-cTnl) tests added to their routine workup. 2D/3D Doppler echocardiography was done on a Siemens Acuson SC2000 machine ≤ 24 h of diagnosis. 3D datasets were blindly analyzed for 4-chamber volumes/strains using EchobuildR 3D-Volume Analysis prototype software, v3.0 2019, Siemens-Medical Solutions. Volume/strain parameters were correlated with admission clinical and laboratory findings. The cohort included 34 patients, median age 60 years (95% CI 55–72). The cohort included 18 (53%) patients had hypertension, 9 (25%) had diabetes mellitus, 7 (21%) were smokers, 7 (21%) had previous myocardial infarction, 4 (12%) had chronic renal failure, and 1 (3%) was on hemodialysis treatment. 2D/Doppler echocardiography findings showed normal ventricular size/function (LVEF 63 ± 9%), mild LV hypertrophy (104 ± 36 g/m2), and LA enlargement (41 ± 6 mm). 3D volumes/strains suggested bi-atrial and right ventricular dysfunction (global longitudinal strain RVGLS = − 8 ± 4%). Left ventricular strain was normal (LVGLS = − 18 ± 5%) and correlated with BNP (r = 0.40, p = 0.024). The patients with LVGLS > − 17% had higher admission blood pressure and lower SaO2 (144 ± 33 vs. 121 ± 20, systolic, mmHg, p = 0.02, and 89 ± 4 vs. 94 ± 4%, p = 0.006, respectively). hs-cTnl and CRP were not different. Using novel 3D volume/strain software in CAP patients, we demonstrated diffuse global myocardial dysfunction involving several chambers. The patients with worse LV GLS had lower SaO2 and higher blood pressure at presentation. LV GLS correlated with maximal BNP level and did not correlate with inflammation or myocardial damage markers.

Prognostic implications of serial high-sensitivity cardiac troponin testing among patients with COVID-19: A Danish nationwide registry-based cohort study

BackgroundAlthough troponin elevation is associated with worse outcomes among patients with coronavirus disease 2019 (COVID-19), prognostic implications of serial troponin testing are lacking. We investigated the association between serial troponin measurements and adverse COVID-19 outcomes. MethodsUsing Danish registries, we identified COVID-19 patients with a high-sensitivity troponin measurement followed by a second measurement within 1–24 h. All measurements during follow-up were also utilized in subsequent time-varying analyses. We assessed all-cause mortality associated with the absence/presence of myocardial injury (≥1 troponin measurement >99th percentile upper reference limit) and absence/presence of dynamic troponin changes (>20% relative change if first measurement elevated, >50% relative change if first measurement normal). ResultsOf 346 included COVID-19 patients, 56% had myocardial injury. Overall, 20% had dynamic troponin changes. In multivariable Cox regression models, myocardial injury was associated with all-cause mortality (HR = 2.56, 95%CI = 1.46–4.51), as were dynamic troponin changes (HR = 1.66, 95%CI = 1.04–2.64). We observed a low incidence of myocardial infarction (4%) and invasive coronary procedures (4%) among patients with myocardial injury. ConclusionsMyocardial injury and dynamic troponin changes determined using serial high-sensitivity troponin testing were associated with poor prognosis among patients with COVID-19. The risk of developing myocardial infarction requiring invasive management during COVID-19 hospitalization was low.

Future application of point of care high-sensitivity cardiac troponin testing in the Emergency Department.

Evaluation needs for point of care high-sensitivity cardiac troponin assays. CV, coefficient of variation; LoD, limit of detection. Evaluation needs for point of care high-sensitivity cardiac troponin assays. CV, coefficient of variation; LoD, limit of detection.

Outcomes associated with the high sensitivity cardiac troponin testing in patients presenting with non-cardiovascular disorders.

There are limited data regarding the utility of troponin testing in patients presenting with non-cardiovascular (CV) symptoms as the primary manifestation. The study population comprised 2057 patients who presented to the emergency department (ED) of a US healthcare system with non-CV symptoms as the primary manifestation between January and September 2018. We compared the effect of high-sensitivity cardiac troponin T (hs-cTnT) (n=901) after its introduction vs. 4th generation cTnT (n=1156) on the following outcomes measures: ED length of stay (LOS), coronary tests/procedures (angiography or stress test), and long-term mortality. Mean age was 64±17yrs., and 47% were female. Primary non-CV manifestations included pneumonia, obstructive pulmonary disease, infection, abdominal-complaint, and renal failure. Mean follow up was 9±4months. Patients' demographics and medical history were clinically similar between the two troponin groups. A second cTn test was obtained more frequently in the hs-cTnT than cTnT (84% vs. 32%; p<0.001), possibly leading to a longer ED stay (8.1±8.2h vs 5.6±3.4h, respectively; p<0.001). Coronary tests/procedures were performed at a significantly higher rate in the hs-cTnT than cTnT following the introduction of the hs-cTnT test (28% vs. 22%, p<0.001). Multivariate analysis showed that following the introduction of hs-cTnT testing, there was a significant 27% lower risk of long-term mortality from ED admission through follow-up (HR=0.73, 95%CI 0.54-0.98; p=0.035). In conclusion, we show that in patients presenting primarily with non-CV disorders, the implementation of the hs-cTnT was associated with a higher rate of diagnostic coronary procedures/interventions, possibly leading to improved long-term survival rates.

High-Sensitivity Troponin T Testing for Pediatric Patients in the Emergency Department.

Debate exists on the usefulness of high-sensitivity cardiac troponin (hs-cTn) testing in pediatric patients due to the perceived low incidence of myocardial injury and lack of data concerning its efficacy. We evaluated the contribution of an increased hs-cTnT above the 99th percentile upper-reference limit (URL) to clinical diagnoses made in pediatric patients presenting to the emergency department (ED). Retrospective cohort study including patients aged 0-18years presenting to the ED from 2018 to 2020 where hs-cTnT was measured. Sex-specific 99th percentile URLs of 15 and 10ng/L for males and females, respectively, were used, with concentrations above these thresholds considered indicative of myocardial injury. Overall, 356 patients were identified in whom hs-cTnT concentrations were measured during ED clinical evaluation. Hs-cTnT was increased above the 99th percentile on presentation in 36 patients (10.1%). Twelve patients (3.4%) had a clinical cardiac diagnosis made. Hs-cTnT was increased in 6 of these (50.0%). Serial hs-cTnT from 106 patients with an initial hs-cTnT < 99th percentile was subsequently elevated in 5 (4.6%); none of whom had a final clinical cardiac diagnosis. Hs-cTnT has high specificity, but low sensitivity when used as a screening tool for myocardial injury when the gold standard is mostly clinical assessment. In present practice, however, they do not appear to track well with clinical diagnoses. Further studies are needed to more clearly define the role of hs-cTnT in this patient population.

Pseudomyocardial Infarction: An Atypical Presentation of Chest Wall Necrotizing Fasciitis

A 75-year-old woman was admitted because of acute chest pain for one day. The electrocardiogram (ECG) showed progressive decreasing R wave amplitudes with new QS waves at precordial leads in three hours (Figure 1 A, B). Serial high-sensitivity cardiac troponin testing at baseline and three hours after admission were within normal range (8.8 pg/mL and 11.1 pg/mL respectively. Upper reference limit: 17.5 pg/mL). The white-cell count was 6800 /µL (reference range: 4800 to 10,800). The contrast-enhanced computer tomography of chest showed no aortic dissection or pulmonary embolism (Figure 3A).

Diagnostic Performance of Serial High-Sensitivity Cardiac Troponin Measurements in the Emergency Setting.

Serial high-sensitivity cardiac troponin (hsTn) testing in the emergency department (ED) and the intensive cardiac care unit may assist physicians in ruling out or ruling in acute myocardial infarction (MI). There are three major algorithms proposed for high-sensitivity cardiac troponin I (hsTnI) using serial measurements while incorporating absolute concentration changes for MI or death following ED presentation. We sought to determine the diagnostic estimates of these three algorithms and if one was superior in two different Canadian ED patient cohorts with serial hsTnI measurements. An undifferentiated ED population (Cohort-1) and an ED population with symptoms suggestive of acute coronary syndrome (ACS; Cohort-2) were clinically managed with non-hsTn testing with the hsTnI testing performed in real-time with physicians blinded to these results (i.e., hsTnI not reported). The three algorithms evaluated were the European Society of Cardiology (ESC), the High-STEACS pathway, and the COMPASS-MI algorithm. The diagnostic estimates were derived for each algorithm for the 30-day MI/death outcome for the rule-out and rule-in arm in each cohort and compared to proposed diagnostic benchmarks (i.e., sensitivity ≥ 99.0% and specificity ≥ 90.0%) with 95% confidence intervals (CI). In Cohort-1 (n = 2966 patients, 15.3% had outcome) and Cohort-2 (n = 935 patients, 15.6% had outcome), the algorithm that obtained the highest sensitivity (97.8%; 95% CI: 96.0–98.9 and 98.6%; 95% CI: 95.1–99.8, respectively) in both cohorts was COMPASS-MI. Only Cohort-2 with both the ESC and COMPASS-MI algorithms exceeded the specificity benchmark (97.0%; 95% CI: 95.5–98.0 and 96.7%; 95% CI: 95.2–97.8, respectively). Patient selection for serial hsTnI testing will affect specificity estimates, with no algorithm achieving a sensitivity ≥ 99% for 30-day MI or death.

Past, Present, and Future of Blood Biomarkers for the Diagnosis of Acute Myocardial Infarction-Promises and Challenges.

Despite important advancements in acute myocardial infarction (AMI) management, it continues to represent a leading cause of mortality worldwide. Fast and reliable AMI diagnosis can significantly reduce mortality in this high-risk population. Diagnosis of AMI has relied on biomarker evaluation for more than 50 years. The upturn of high-sensitivity cardiac troponin testing provided extremely sensitive means to detect cardiac myocyte necrosis, but this increased sensitivity came at the cost of a decrease in diagnostic specificity. In addition, although cardiac troponins increase relatively early after the onset of AMI, they still leave a time gap between the onset of myocardial ischemia and our ability to detect it, thus precluding very early management of AMI. Newer biomarkers detected in processes such as inflammation, neurohormonal activation, or myocardial stress occur much earlier than myocyte necrosis and the diagnostic rise of cardiac troponins, allowing us to expand biomarker research in these areas. Increased understanding of the complex AMI pathophysiology has spurred the search of new biomarkers that could overcome these shortcomings, whereas multi-omic and multi-biomarker approaches promise to be game changers in AMI biomarker assessment. In this review, we discuss the evolution, current application, and emerging blood biomarkers for the diagnosis of AMI; we address their advantages and promises to improve patient care, as well as their challenges, limitations, and technical and diagnostic pitfalls. Questions that remain to be answered and hotspots for future research are also emphasized.

Acute Phase Response and Non-Reproducible Elevated Concentrations with a High-Sensitivity Cardiac Troponin I Assay.

High-sensitivity cardiac troponin (hs-cTn) testing has enabled physicians to make earlier diagnostic and prognostic decisions in the hospital setting than previous cardiac troponin assays. Analytical improvements have permitted one to measure cardiac troponin precisely in the nanogram per litre (ng/L) range with hs-cTn assays which has resulted in fast 0/1-h and 0/2-h algorithms for ruling-in and ruling-out myocardial infarction. Although analytical interferences that affect the reporting of hs-cTn are uncommon, not all hs-cTn assays are designed the same nor have undergone the same clinical and analytical validations. Here, after investigating an initial case of discrepant hs-cTnI results, we report that patients with an acute phase response (e.g., patients with inflammatory or infectious illnesses) can yield high and non-reproducible results with the Ortho Clinical Diagnostics hs-cTnI assay. Compared to Abbott Diagnostics hs-cTnI, Ortho Clinical Diagnostics hs-cTnI assay misclassifies biochemical injury in approximately 10% of the population being assessed for myocardial injury with imprecise results in approximately half of this population (i.e., 5%). In conclusion, caution is warranted in interpreting Ortho Clinical Diagnostics hs-cTnI alone in patients being evaluated for myocardial injury, especially in patients whose primary presentation is related to an acute phase response and not an acute coronary syndrome symptom.

High-sensitivity cardiac troponin concentrations at presentation in patients with ST-segment elevation myocardial infarction

Abstract Background The widespread adoption of high-sensitivity cardiac troponin testing has encouraged the use of pathways to accelerate the rule-out and rule-in myocardial infarction in the Emergency Department. These pathways are not recommended for patients with ST-segment elevation, but there is a risk they may be applied incorrectly given that interpretation of the electrocardiogram is subjective, dependent on experience, and signs may be masked in those with posterior myocardial infarction. Methods Consecutive patients with suspected acute coronary syndrome were enrolled in a stepped-wedge cluster randomized controlled trial across ten hospitals in Scotland. The index diagnosis was adjudicated two clinicians independently in all patients with high-sensitivity cardiac troponin I concentrations above the sex-specific 99th centile on serial testing and abnormalities on the electrocardiogram recorded. The proportion of patients with ST-segment elevation myocardial infarction and concentrations below the rule-out threshold (&amp;lt;5 ng/L), 99th centile (&amp;lt;16 ng/L and &amp;lt;34 ng/L for women and men) and rule-in threshold (&amp;lt;52 ng/L) at presentation were determined. Results In total 48,282 patients were recruited between June 2013, and March 2016 of which 22% (10,360/48,282) had peak cardiac troponin concentrations above the 99th centile. The adjudicated diagnosis was type 1 myocardial infarction in 55% (4,981/9,115) of patients and 10% (925/9,115) had ST-segment elevation myocardial infarction (age 65 [14] years, 68% men). The majority presented within 6 hours of symptom onset (67%, 619/925), and 84% (772/925) had cardiac troponin concentrations above the 99th centile at presentation. However, troponin concentrations were below the rule-out threshold in 2% (20/925) and the rule-in threshold in 26% (240/925) of patients with ST-segment elevation myocardial infarction. Discussion In patients with suspected acute coronary syndrome who have a final diagnosis of ST-segment elevation myocardial infarction, high-sensitivity cardiac troponin concentrations are below the rule-out and rule-in threshold at presentation in 1 in 50 and 1 in 4 patients, respectively. Clinicians should not rely on cardiac troponin concentrations to guide initial treatment decisions in patients with possible ST-segment elevation myocardial infarction. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): British Heart Foundation