Aplicación del algoritmo 0 h/1 h de troponina de alta sensibilidad de la ESC para la toma de decisiones en el servicio de urgencias

Diagnosis of non–ST-segment elevation acute coronary syndromes (NSTEACS) is based on 3 cornerstones: clinical presentation, 12-lead electrocardiogram, and cardiac troponin measurement. Advances in the development of high-sensitivity cardiac troponin (hs-cTn) assays have substantially improved the detection of cardiomyocyte injury in a shorter time period, and hs-cTn has consequently been established as the gold-standard biomarker for the assessment of patients with suspected NSTEACS. The implementation of these assays in clinical practice allows a faster “rule-out”, especially among low-risk patients, as well as a safer and more rapid “rule-in”, with its therapeutic consequences. Current guidelines for the diagnosis of NSTEACS recommend the use of hs-cTn applied in rapid diagnostic algorithms based on serial hs-cTn sampling within the first few hours. The current work provides an overview of the use of hs-cTn for the early detection of NSTEACS.     

Cinética temprana de troponina en pacientes con sospecha de infarto agudo de miocardio

Introduction and objectivesRelease kinetics of high-sensitivity cardiac troponin (hs-cTn) T and I in patients with acute myocardial infarction (AMI) are incompletely understood. We aimed to assess whether hs-cTnT/I release in early AMI is near linear.MethodsIn a prospective diagnostic multicenter study the acute release of hs-cTnT and hs-cTnI within 1 and 2 hours from presentation to the emergency department was quantified using 3 hs-cTnT/I assays in patients with suspected AMI. The primary endpoint was correlation between hs-cTn changes from presentation to 1 hour vs changes from presentation to 2 hours, among all AMI patients and different prespecified subgroups. The final diagnosis was adjudicated by 2 independent cardiologists, based on serial hs-cTnT from the serial study blood samples and additional locally measured hs-cTn values.ResultsAmong 2437 patients with complete hs-cTnT data, AMI was the adjudicated diagnosis in 376 patients (15%). For hs-cTnT, the correlation coefficient between 0- to 1-hour change and 0- to 2 hour change was 0.931 (95%CI, 0.916-0.944), P < .001. Similar findings were obtained with hs-cTnI (Architect) with correlation coefficients between 0- to 1-hour change and 0- to 2 hour change of 0.969 and hs-cTnI (Centaur) of 0.934 (P < .001 for both). Findings were consistent among type 1 and type 2 AMI and in the subgroup of patients presenting very early after chest pain onset.ConclusionsPatients presenting with early AMI showed a near linear release of hs-cTnT and hs-cTnI. This near linearity provides the pathophysiological basis for rapid diagnostic algorithms using 0- to 1-hour changes as surrogates for 0- to 2 hour or 0- to 3 hour changes.Registered at ClinicalTrials.gov (Identifier: NCT00470587).     

New Insights Into the Use of the 12-Lead Electrocardiogram for Diagnosing Acute Myocardial Infarction in the Emergency Department

The 12-lead electrocardiogram (ECG) remains the most immediately accessible and widely used initial diagnostic tool for guiding management in patients with suspected myocardial infarction (MI). Although the development of high-sensitivity cardiac troponin assays has improved the rule-in and rule-out and risk stratification of acute MI without ST elevation, the immediate management of the subset of acute MI with acute coronary occlusion depends on integrating clinical presentation and ECG findings. Careful interpretation of the ECG might yield subtle features suggestive of ischemia that might facilitate more rapid triage of patients with subtle acute coronary occlusion or, conversely, in identification of ST-elevation MI mimics (pseudo ST-elevation MI patterns). Our goal in this review article is to consider recent advances in the use of the ECG to diagnose coronary occlusion MIs, including the application of rules that allow MI to be diagnosed on the basis of atypical ECG manifestations. Such rules include the modified Sgarbossa criteria allowing identification of acute MI in left bundle branch block or ventricular pacing, the 3- and 4-variable formula to differentiate normal ST elevation (formerly called early repolarization) from subtle ECG signs of left anterior descending coronary artery occlusion, the differentiation of ST elevation of left ventricular aneurysm from that of acute anterior MI, and the use of lead aVL in the recognition of inferior MI. Improved use of the ECG is essential to improving the diagnosis and appropriate early management of acute coronary occlusion MIs, which will lead to improved outcomes for patients who present with acute coronary syndrome.     

Acute myocardial infarction in chest pain patients with nondiagnostic ECGs: serial CK-MB sampling in the emergency department. The Emergency Medicine Cardiac Research Group.

STUDY OBJECTIVES: This study tested the hypothesis that serial creatine phosphokinase (CK)-MB sampling in the emergency department can identify acute myocardial infarction (AMI) in patients presenting to the ED with chest pain and nondiagnostic ECGs. DESIGN: Patients more than 30 years old who were evaluated initially in the ED and hospitalized for chest pain were studied. Serial CK-MB levels were analyzed prospectively using a rapid serum immunochemical assay for identification of AMI patients in the ED. Presenting ECGs showing new, greater than 1-mm ST elevation in two or more contiguous leads were considered diagnostic for AMI. All other ECGs were considered nondiagnostic ECGs. CK-MB levels were determined at ED presentation and hourly for three hours (total of four levels). Patients with at least one level of more than 7 ng/mL were considered to have a positive enzyme study. The in-hospital diagnosis of AMI was determined by the development of typical serial ECG changes or separate standard cardiac enzyme changes after admission. SETTING: Eight tertiary-care medical center hospitals. METHODS AND MAIN RESULTS: Of the 616 study patients, 108 (17.5%) were diagnosed in the hospital as AMI; 69 of these AMI patients (63.9%) had nondiagnostic ECGs in the ED. Of the patients with nondiagnostic ECGs, 55 (sensitivity, 79.7%) had a positive ED serial CK-MB enzyme study within three hours after presentation. Combining serial ED CK-MB assay results with diagnostic ECGs yielded an 88.4% sensitivity for AMI detection within three hours of ED presentation. The predictive value of a negative serial ED enzyme study for no AMI was 96.2% (specificity, 93.7%). CONCLUSION: Serial CK-MB determination in the ED can help identify AMI patients with initial nondiagnostic ECGs. Use of serial CK-MB analysis may facilitate optimal in-hospital disposition and help guide therapeutic interventions in patients with suspected AMI despite a nondiagnostic ECG.     

Multiple Thromboembolic Events from a Left Atrial Appendage Occlusion Device

Left atrial appendage occlusion devices are an alternative to oral anticoagulation in patients with nonvalvular atrial fibrillation who are at risk of ischemic stroke. Thromboprophylaxis after implantation is recommended, but the optimal regimen is unknown. We report a clinicopathologic case in which thrombus adherent to an incompletely endothelialized WATCHMAN device (Boston Scientific, Marlborough, MA) resulted in multiple thromboembolic events, contributing to a fatal outcome. This case illustrates uncertainties regarding the device's endothelialization process.     

Biochemical markers in the diagnosis of myocardial infarction

The diagnosis of myocardial necrosis due to acute myocardial infarction (AMI) and other causes has long been based on the plasma levels of cardiac troponins. Other markers of myocardial injury such as myoglobin, heart-type fatty acid binding protein, glycogen phosphorylase isoenzyme BB, or the early and sensitive total stress marker copeptin remain to be just attractive options used primarily to early rule out AMI and in risk stratification. Recent years have seen the introduction of a routine practice of the high-sensitivity cardiac troponin assays capable of detecting diagnostic elevations in plasma troponin levels as early as the first hours of myocardial injury. However, this assay tends to identify very often low plasma troponin levels in primarily noncardiac conditions and also in healthy or apparently healthy individuals. Hence, this novel technology warrants further study.     

Left Atrial Function Using Cardiovascular Magnetic Resonance Imaging Independently Predicts Life-Threatening Arrhythmias in Patients Referred to Receive a Primary Prevention Implantable Cardioverter Defibrillator

BackgroundIn this study we aimed to investigate left atrial (LA) function, measured from routine cine cardiovascular magnetic resonance imaging, to determine its value for the prediction of sudden cardiac death (SCD) or appropriate implantable cardioverter defibrillator (ICD) shock in patients who received primary prevention ICD implantation.MethodsWe studied 203 patients with ischemic or idiopathic nonischemic dilated cardiomyopathy who underwent cardiovascular magnetic resonance imaging before primary prevention ICD implantation. LA volumes were measured at end-diastole and end-systole from 4- and 2-chamber cine images, and LA emptying function (LAEF) calculated. Patients were followed for the primary composite end point of SCD or appropriate ICD shock.ResultsMean age was 61 ± 12 years with a mean left ventricular ejection fraction of 24 ± 7%. The mean LAEF was 27 ± 15% (range, 0.9%-73%). At a median follow-up of 1639 days, 35 patients (17%) experienced the primary composite outcome. LAEF was strongly associated with the primary outcome (P = 0.001); patients with an LAEF ≤ 30% experienced a cumulative event rate of 26.1% vs 5.7% (hazard ratio, 5.5; P < 0.001) in patients above this cutoff. This finding was maintained in multivariable analysis (hazard ratio, 4.7; P = 0.002) and was consistently shown in the ischemic and nonischemic dilated cardiomyopathy subgroups.ConclusionsLAEF is a simple, powerful, and independent predictor of SCD in patients being referred for primary prevention ICD implantation.     

超敏肌钙蛋白在急性冠状动脉综合征中的临床应用

急性心肌梗死的早期诊断和及时进行再灌注治疗为降低死亡率的关键,故对因急性胸痛就诊的患者进行快速、正确的评估以及危险分层尤为重要;而评估心肌坏死的特异性生化标记物为急性心肌梗死诊断、监测病程与评价预后的主要指标之一。近期发展的超敏肌钙蛋白(hsTn)的检测技术可更精确地测定肌钙蛋白(cTn)的浓度并可检测99%健康人群以上的异常值,其不仅可提高急性心肌梗死的诊断率,亦可进一步进行危险分层,可用于急性冠状动脉综合征患者的长期风险评估。     

Prevalence,Determinants, and Clinical Associations of High-Sensitivity Cardiac Troponin in Patients Attending Emergency Departments

Background

High-sensitivity cardiac troponin assays may improve the diagnosis of myocardial infarction but increase the detection of elevated cardiac troponin in patients without acute coronary syndrome.

Chronic Myocardial Injury and Risk for Stroke

BACKGROUNDChronic myocardial injury, defined as persistent troponin levels >99th percentile values when measured with high-sensitivity assays (hs-cTn), is common. The association between chronic myocardial injury and stroke is unknown. This study aimed to investigate the association between chronic myocardial injury and stroke.METHODSFrom 2011 to 2014, we included patients with chest pain and high-sensitivity cardiac troponin T levels measured concurrently but without acute conditions associated with elevated high-sensitivity cardiac troponin T levels. Cox regression was used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) for stroke in patients with stable high-sensitivity cardiac troponin T levels of 5-9, 10-14, 15-29, 30-49, and ≥50 ng/L, using <5 ng/L as reference group. Categories >14 ng/L were defined as chronic myocardial injury.RESULTSA total of 19,460 patients were included, among whom 1528 (7.9%) had chronic myocardial injury. During a mean follow-up of 2.1 years, there were 244 (1.2%) strokes. With increasing high-sensitivity cardiac troponin T levels yearly stroke rates increased from 0.24% to 4.0%. Adjusted hazard ratios with 95% confidence intervals for stroke were 1.83 (1.27-2.64) in patients with high-sensitivity cardiac troponin T levels of 5-9 ng/L, increasing to 1.95 (1.21-3.14), 3.38 (1.80-6.35), and 4.32 (1.89-9.91) in patients with high-sensitivity cardiac troponin T levels of 15-29, 30-49, and ≥50 ng/L, respectively.CONCLUSIONSPatients with chronic myocardial injury have up to a 4-fold increased risk of stroke compared with patients with high-sensitivity cardiac troponin T levels <5 ng/L. Our findings indicate that patients with any detectable high-sensitivity cardiac troponin T level, in particular those with chronic myocardial injury, have an increased risk of stroke and require further attention.     

Heart fatty acid-binding protein offers similar diagnostic performance to high-sensitivity troponin T in emergency room patients presenting with chest pain

BACKGROUND: The aim of the present study was to evaluate the diagnostic accuracy of high-sensitivity troponin T (hsTnT) in patients with suspected acute coronary syndrome (ACS) in comparison to heart fatty acid-binding protein (H-FABP), high-sensitivity C-reactive protein, myeloperoxidase (MPO), and pentraxin 3 (PTX3). METHODS AND REsults: Patients (n=432) with chest pain were recruited for the analysis. ACS was diagnosed in 298 patients (69%). The diagnostic accuracy of measurements obtained at presentation, as quantified by the area under the receiver operating curve (AUC), was highest for hsTnT (AUC=0.82; 95% confidence interval [CI]: 0.78-0.87) and H-FABP (AUC=0.83; 95%CI: 0.78-0.87). Sensitivity (87.9%) and negative likelihood (LH; 0.2) for hsTnT were the highest and lowest, respectively, but H-FABP had the highest specificity (78.5%) and positive LH (3.6). Among patients who presented within 2h after the onset of chest pain, MPO had the highest AUC (0.82; 95%CI: 0.69-0.94). Combined use of H-FABP and MPO measurements yielded a sensitivity of 69.2%, specificity of 84.2%, positive LH of 4.4, and negative LH of 0.4. CONCLUSIONS: The hsTnT assay offers excellent diagnostic performance to rule out ACS, but it is prone to false-positive results. H-FABP offers similar overall diagnostic performance, while the combination of H-FABP and MPO assays may improve the diagnosis of ACS, particularly in patients with recent onset of chest pain.     

Discordance of High-Sensitivity Troponin Assays in Patients With Suspected Acute Coronary Syndromes

BackgroundHigh-sensitivity cardiac troponin (hs-cTn) assays have different analytic characteristics.ObjectivesThe goal of this study was to quantify differences between assays for common analytical benchmarks and to determine whether they may result in differences in the management of patients with suspected acute coronary syndrome (ACS).MethodsThe authors included patients with suspected ACS enrolled in the ROMICAT (Rule Out Myocardial Infarction/Ischemia Using Computer Assisted Tomography) I and II trials, with blood samples taken at emergency department presentation (ROMICAT-I and -II) or at 2 and 4 h thereafter (ROMICAT-II). hs-cTn concentrations were measured using 3 assays (Roche Diagnostics, Elecsys 2010 platform; Abbott Diagnostics, ARCHITECT i2000SR; Siemens Diagnostics, HsVista). Per blood sample, we determined concordance across analytic benchmarks (<limit of detection [<LOD]/LOD-99th percentile/>99th percentile). Per-patient, the authors determined concordance of management recommendations (rule-out/observe/rule-in) per the 0/2-h algorithm, and their association with diagnostic test findings (coronary artery stenosis >50% on coronary computed tomography angiography or inducible ischemia on perfusion imaging) and ACS.ResultsAmong 1,027 samples from 624 patients (52.8 ± 10.0 years; 39.4% women), samples were classified as <LOD (56.3% vs. 10.4% vs. 41.2%; p < 0.001), LOD-99th percentile (36.5% vs. 83.5% vs. 52.6; p < 0.001), >99th percentile (7.2% vs. 6.0% vs. 6.2%) by Roche, Abbott, and Siemens, respectively. A total of 37.4% (n = 384 of 1,027) of blood samples were classified into the same analytical benchmark category, with low concordance across benchmarks (<LOD 11.1%; LOD-99th percentile 29.3%; >99th percentile 43.6%). Serial samples were available in 242 patients (40.1% women; mean age: 52.8 ± 8.0 years). The concordance of management recommendations across assays was 74.8% (n = 181 of 242) considering serial hs-cTn measurements. Of patients who were recommended to discharge, 19.6% to 21.1% had positive diagnostic test findings and 2.8% to 4.3% had ACS at presentation.ConclusionsCaregivers should be aware that there are significant differences between hs-cTn assays in stratifying individual samples and patients with intermediate likelihood of ACS according to analytical benchmarks that may result in different management recommendations. (Rule Out Myocardial Infarction by Computer Assisted Tomography [ROMICAT]; NCT00990262) (Multicenter Study to Rule Out Myocardial Infarction by Cardiac Computed Tomography [ROMICAT-II]; NCT01084239)     

A change in serum myoglobin to detect acute myocardial infarction in patients with normal troponin I levels

We sought to determine the sensitivity of a change in myoglobin for acute myocardial infarction (AMI) in patients who had normal levels of troponin I at presentation. Myoglobin increases as soon as 1 to 2 hours after symptom onset in AMI. The change in myoglobin may help identify AMI in patients with normal cardiac levels of troponin I on admission. A total of 817 consecutive patients who were examined in the emergency department for possible AMI were studied. In patients whose electrocardiograms were nondiagnostic, we measured levels of myoglobin and cardiac troponin I at presentation, at 90 minutes, and at 3 and 9 hours. Patients whose initial levels of myoglobin (<200 ng/ml) and cardiac troponin I (<0.4 ng/ml) were normal underwent receiver-operating characteristic curve analysis to determine the best cutpoint for a myoglobin increase from 0 to 90 minutes. Overall, 75 patients (9%) were diagnosed with AMI, including 27 patients with normal cardiac levels of troponin I at presentation. An increase of 20 ng/ml of myoglobin from 0 to 90 minutes provided maximal diagnostic utility in patients who did not have increased levels of myoglobin or cardiac troponin I at presentation. In the absence of an increased level of cardiac troponin I or myoglobin at presentation in the emergency department, a change >or=20 ng/ml of myoglobin at 90 minutes produced 83.3% sensitivity, 88.6% specificity, and 99.5% negative predictive value for AMI. The combined sensitivity of levels of cardiac troponin I and myoglobin and a change >or=20 ng/ml of myoglobin over 90 minutes was 97.3%. In emergency department patients with normal cardiac levels of troponin I at presentation, a change in myoglobin provides a highly accurate diagnosis of AMI within 90 minutes.     

The Erlanger chest pain evaluation protocol: a one-year experience with serial 12-lead ECG monitoring,two-hour delta serum marker measurements,and selective nuclear stress testing to identify and exclude acute coronary syndromes

STUDY OBJECTIVE: We determine the overall use of a 6-step accelerated chest pain protocol to identify and exclude acute coronary syndrome (ACS) and to confirm previous findings of the use of serial 12-lead ECG monitoring (SECG) in conjunction with 2-hour delta serum marker measurements to identify and exclude acute myocardial infarction (AMI). METHODS: A prospective observational study was conducted over a 1-year period from January 1, 1999, through December 31, 1999, in 2,074 consecutive patients with chest pain who underwent our accelerated evaluation protocol, which includes 2-hour delta serum marker determinations in conjunction with automated SECG for the early identification and exclusion of AMI and selective nuclear stress testing for identification and exclusion of ACS. In patients not undergoing emergency reperfusion therapy, physician judgment was used to determine patient disposition at the completion of the 2-hour evaluation period: admit for ACS, discharge or admit for non-ACS condition, or immediate emergency department nuclear stress scan for possible ACS. A positive protocol was defined as a positive result in 1 or more of the 6 incremental steps in our chest pain evaluation protocol: (1) initial ECG diagnostic of acute injury or reciprocal injury; (2) baseline creatine kinase (CK)-MB level of 10 ng/mL or greater and index of 5% or greater or cardiac troponin I level of 2 ng/mL or greater; (3) new/evolving injury or new/evolving ischemia on SECG; (4) increase in CK-MB level of +1.5 ng/mL or greater or cardiac troponin I level of +0.2 ng/mL or greater in 2 hours; (5) clinical diagnosis of ACS despite a negative 2-hour evaluation; and (6) reversible perfusion defect on stress scan compared with on resting scan. All patients were followed up for 30-day ACS, which was defined as myocardial infarction (MI), percutaneous coronary intervention/coronary artery bypass grafting, coronary arteriography revealing stenosis of major coronary artery of 70% or greater not amenable to percutaneous coronary intervention/coronary artery bypass grafting, life-threatening complication, or cardiac death within 30 days of ED presentation. RESULTS: Discharge diagnosis in the 2,074 study patients consisted of 179 (8.6%) patients with AMI, 26 (1.3%) patients with recent AMI (decreasing curve of CK-MB), and 327 (15.8%) patients with 30-day ACS. At 2 hours, sensitivity and specificity for MI (AMI or recent AMI) of SECG plus delta serum marker measurements was 93.2% and 93.9%, respectively (positive likelihood ratio 15.3; negative likelihood ratio 0.07). At the completion of the full ED evaluation protocol (positive result in >or=1 of the 6 incremental steps), sensitivity and specificity for 30-day ACS was 99.1% and 87.4%, respectively (positive likelihood ratio 7.9; negative likelihood ratio 0.01). CONCLUSION: An accelerated chest pain evaluation strategy consisting of SECG, 2-hour delta serum marker measurements, and selective nuclear stress testing in conjunction with physician judgment identifies and excludes MI and 30-day ACS during the initial evaluation of patients with chest pain.     

Early detection of acute myocardial infarction in patients presenting with chest pain and nondiagnostic ECGs: serial CK-MB sampling in the emergency department

STUDY OBJECTIVES: Patients presenting to the emergency department with chest discomfort are a difficult problem for emergency physicians. Nearly 50% of patients with acute myocardial infarction (AMI) will initially have nondiagnostic ECGs on ED presentation. The purpose of this study was to determine if patients with AMI having nondiagnostic ECGs could be identified using new immunochemical assays for serial CK-MB sampling in the ED. DESIGN: Chest pain patients, more than 30 years old, with pain not caused by trauma or explained by radiographic findings, were eligible for the study. Serial serum samples were drawn on ED presentation (zero hours) and three hours after presentation, then analyzed for CK-MB using four immunochemical methods and electrophoresis. Standard World Health Organization criteria were used to establish the diagnosis of AMI, including new Q-wave formation or elevation of standard in-hospital serum cardiac enzyme markers. SETTING: A tertiary cardiac care community hospital. MEASUREMENTS AND MAIN RESULTS: The serum from 183 patients hospitalized for possible ischemic chest pain was collected and analyzed. Thirty-one of 183 patients (17%) were found to have AMI by standard in-hospital criteria. Sixteen of the 31 patients (52%) with AMI had nondiagnostic ECGs on presentation. Immunochemical determination of serial CK-MB levels provided a sensitive and specific method for detecting AMI in patients within three hours after ED presentation compared with standard electrophoresis. The four immunochemical methods demonstrated a range in sensitivity from 50% to 62.1% on ED presentation versus 92% to 96.7% three hours later. The immunochemical tests demonstrated specificities ranging from 83.0% to 96.4% at three hours, with three of the four tests having specificities of 92% or greater. Electrophoresis had a sensitivity of 34.5% on ED presentation, increasing to 76.9% at three hours, with a specificity of 98.6%. CONCLUSIONS: Immunochemical CK-MB methods allowed rapid, sensitive detection of AMI in the ED. Early detection of AMI offers many potential advantages to the emergency physician. Early detection of AMI, while the patient is in the ED, could direct disposition of this potentially unstable patient to an intensive care setting. Such information may prevent the ED discharge of patients with AMI having nondiagnostic ECGs. The diagnosis of AMI within a six-hour period after symptom onset may allow thrombolytic therapy to be given to patients with AMI not having diagnostic ECGs. This study served as a pilot trial for a multicenter study of the Emergency Medicine Cardiac Research Group, which is currently ongoing.     

Cardiac biomarkers and acute coronary syndromes--the Euro Heart Survey of Acute Coronary Syndromes Experience.

AMIS: To examine the application of the redefinition of acute myocardial infarction (AMI) published on 4 September 2000. METHODS AND RESULTS: The Euro Heart Survey of Acute Coronary Syndromes (ACS) prospectively surveyed 10484 patients in 103 hospitals across 25 European and Mediterranean basin countries during 4 September 2000 to 15 May 2001. We evaluated the use of cardiac troponin assays and whether the diagnosis of unstable angina (UA) or AMI was in accordance with the results of biomarker assays (cardiac troponins, CK-MB mass, CK-MB%, or CK). Troponin assays were used in 6036 (63.3%) of the 9538 patients with available biomarker levels; of whom elevated troponin levels were recorded in 648 of 2307 (28.1%) patients with UA and in 2957 of 3729 (79.3%) patients with AMI. Of the 8871 patients with available creatine kinase values, levels above the upper limit of normal were recorded in 848 of 3625 (23.4%) patients with UA and in 3948 of 5246 (75.3%) patients with AMI. CONCLUSIONS: Cardiac troponin assays are still not universally available for the evaluation of ACS patients. A substantial proportion of ACS patients receive a diagnosis of UA or AMI, irrespective of the result of biomarker assays, indicating that the redefinition of AMI has not yet been universally adopted, and that additional efforts are warranted to ensure its appropriate implementation.     

High-sensitive cardiac troponin T

Cardiac troponin is the preferred biomarker for the diagnosis of acute myocardial infarction (AMI). The recent development of a high-sensitive cardiac troponin T (hs-cTnT) assay permits detection of very low levels of cTnT. Using the hs-cTnT assay improves the overall diagnostic accuracy in patients with suspected AMI, while a negative result also has a high negative predictive value. The gain in sensitivity may be particularly important in patients with a short duration from symptom onset to admission. Measurement of cardiac troponin T with the hs-cTnT assay may provide strong prognostic information in patients with acute coronary syndromes, stable coronary artery disease, heart failure and even in the general population; however, increased sensitivity comes at a cost of decreased specificity. Serial testing, as well as clinical context and co-existing diseases, are likely to become increasingly important for the interpretation of hs-cTnT assay results.     

Diagnosis and management of patients with acute cardiac symptoms, troponin elevation and culprit-free angiograms

Patients with acute cardiac symptoms, elevated cardiac troponin and culprit-free angiograms comprise a significant proportion of patients admitted with presumed acute coronary syndromes (ACS). International guidelines recommend that these patients receive lifelong secondary prevention under the presumption that angiographically undetectable coronary artery disease is the likeliest cause for their presentation. Recent studies using cardiac MRI suggest myocarditis to be the most common cause of these presentations. Emerging data also suggest that myocarditis presenting like an ACS may not be benign. In this article the current literature on patients presenting with acute cardiac symptoms, elevated cardiac troponins but culprit-free angiograms is reviewed, focusing on the diagnostic utility of cardiac MRI in this cohort, and the importance of diagnosing acute myocarditis. The development of higher sensitivity troponin assays will undoubtedly lead to an increase in the number of patients with presumed ACS but culprit free angiography. Robust management pathways including cardiac MRI are vital for cardiac centres dealing with these patients in order to achieve cost-effective, individualised patient care.     

Telehealth for Remote Stroke Management

Stroke is a leading cause of adult disability and the fourth leading cause of death in Canada. Most strokes are ischemic and functional outcome is highly time-dependent, making fast diagnosis and treatment initiation crucial. This poses a challenge in vast geographical areas where stroke neurology expertise is only available in urban centres. In this article we review the rationale for telestroke networks and their current implementation in Canada. Telestroke networks enable stroke-specific procedures to be performed by less experienced physicians under the guidance of stroke neurology experts. We also present evidence that the safety and effectiveness of intravenous alteplase in community hospitals in a telestroke network seems to be comparable with that achieved in dedicated stroke centres. It is thus a viable option to guarantee an aging population access to stroke care across large geographic regions with faster treatment and access to more advanced treatment options by means of transfer to a comprehensive centre if necessary. Although telestroke networks have an upfront implementation cost, they can lead to reduced direct and indirect costs for the health care system by reducing days spent in the hospital as well as disability with the need for long-term care. Telestroke networks can also be used for identification and enrollment of patients into emergency stroke trials and thus provide a more representative sample of the population and increase recruitment. Standardization of regional telestroke networks could lead to collaborations with larger data acquisitions for research purposes and quality control in the future.     

High-sensitivity cardiac troponins in everyday clinical practice

High-sensitivity cardiac troponin(hs-cTn) assays are increasingly being used in many countries worldwide,however,a generally accepted definition of high-sen-sitivity is still pending.These assays enable cTn mea-surement with a high degree of analytical sensitivity with a low analytical imprecision at the low measuring range of cTn assays(coefficient of variation of 10% at the 99th percentile upper reference limit).One of the most important advantages of these new assays is that they allow novel,more rapid approaches to rule in or rule out acute coronary syndromes(ACSs) than with previous cTn assay generations which are still more commonly used in practice worldwide.hs-cTn is also more sensitive for the detection of myocardial damage unrelated to acute myocardial ischemia.Therefore,the increase in early diagnostic sensitivity of hs-cTn assays for ACS comes at the cost of a reduced ACS specificity,because more patients with other causes of acute or chronic myocardial injury without overt myocardial isch-emia are detected than with previous cTn assays.As hs-cTn assays are increasingly being adopted in clinical practice and more hs-cTn assays are being developed,this review attempts to synthesize the available clinical data to make recommendations for their everyday clini-cal routine use.