Creatine kinase-mb fraction and cardiac troponin T to diagnose acute myocardial infarction after cardiopulmonary resuscitation

High-sensitivity troponin T for detection of culprit lesions in patients with out-of-hospital cardiac arrest

BACKGROUND

Patients with an out-of-hospital cardiac arrest (OHCA) often undergo coronary angiography, although a culprit lesion is found in only 30%-40% of patients. The aim of this study was to investigate high-sensitivity troponin T (hsTnT) levels in post cardiac arrest patients with and without coronary culprit lesions; factors affecting hsTnT levels after return of spontaneous circulation (ROSC); and the diagnostic ability of hsTnT in identifying patients with culprit lesions. We hypothesized that peak hsTnT levels were higher during the initial 48 h after cardiac arrest in patients with a coronary culprit lesion.

METHODS

This was a retrospective observational study, which included patients admitted to the Intensive Care Unit after an OHCA and who received a coronary angiography. Peak values and dynamic changes in hsTnT were analyzed in relation to the presence of a culprit lesion at coronary angiography.

RESULTS

A total of 238 patients were studied, of whom 140 had a culprit lesion. HsTnT levels during the initial 48 h were higher in patients with culprit lesions, longer time to ROSC and an unwitnessed cardiac arrest. At 6 to 12 h after ROSC, a hsTnT cut-off level of 1690 ng/L had a sensitivity of 64% and specificity of 84% to identify a culprit lesion. In patients without ST-elevations, hsTnT measured between 6 and 12 h after ROSC had a specificity above 90%, with a sensitivity of 46%.

CONCLUSION

HsTnT levels after cardiac arrest are higher in patients with coronary culprit lesions. Presence of a culprit lesion, witnessed status and the duration of CPR are important factors affecting hsTnT levels. Repeated measurement of hsTnT within the first 12 h after admission improved diagnostic accuracy but the value of hsTnT as a predictor of culprit lesions early after OHCA is limited.

Elevated Troponins and Diagnosis of Non-ST-Elevation Myocardial Infarction in the Emergency Department

Background In the emergency department (ED), the diagnosis of non-ST-elevation myocardial infarction (NSTEMI) is primarily based on the presence or absence of elevated cardiac troponin levels, ECG changes, and clinical presentation. However, limited data exist regarding the incidence, clinical characteristics, and predictive value of different cardiac diagnostic tests and outcomes in patients with non-acute coronary syndrome (ACS)-related troponin elevation. Our study aimed to determine the percentage of patients with elevated troponin levels who had true ACS and identify various risk factors associated with true ACS in these patients. Methodology This was a single-center retrospective study. We performed a chart review of patients who presented to the ED from January 1, 2016, to December 31, 2017, and were admitted to the hospital with an elevated cardiac troponin I level in the first 12 hours after ED presentation with a diagnosis of NSTEMI. True ACS was defined as (a) patients with typical symptoms of ischemia and ECG ischemic changes and (b) patients with atypical symptoms of myocardial ischemia or without symptoms of ischemia and new segmental wall motion abnormalities on echocardiogram or evidence of culprit lesion on angiography. A logistic regression model was used to determine the association between risk factors and true ACS. Results A total of 204 patients were included in this study. The mean age of the study group was 67.4 ± 14.5 years; 53.4% (n = 109) were male, and 57.4% (n = 117) were Caucasian. In our study, 51% of patients were found to have true ACS, and the remaining 49% had a non-ACS-related elevation in troponins. Most patients without ACS had alternate explanations for elevated troponin levels. The presence of chest pain (odds ratio (OR) = 3.7, 95% confidence interval (CI) = 1.8-7.7, p = 0.001), tobacco smoking (OR = 4, 95% CI = 1.06-3.8, p = 0.032), and wall motion abnormalities on echocardiogram (OR = 3.8, 95% CI = 1.8-6.5, p = 001) were associated with increased risk of true ACS in patients with elevated troponins. Conclusions Cardiac troponin levels can be elevated in hospitalized patients with various medical conditions, in the absence of ACS. The diagnosis of ACS should not be solely based on elevated troponin levels, as it can lead to expensive workup and utilization of hospital resources.

Heart-on-a-chip systems with tissue-specific functionalities for physiological, pathological, and pharmacological studies

Recent advances in heart-on-a-chip systems hold great promise to facilitate cardiac physiological, pathological, and pharmacological studies. This review focuses on the development of heart-on-a-chip systems with tissue-specific functionalities. For one thing, the strategies for developing cardiac microtissues on heart-on-a-chip systems that closely mimic the structures and behaviors of the native heart are analyzed, including the imitation of cardiac structural and functional characteristics. For another, the development of techniques for real-time monitoring of biophysical and biochemical signals from cardiac microtissues on heart-on-a-chip systems is introduced, incorporating cardiac electrophysiological signals, contractile activity, and biomarkers. Furthermore, the applications of heart-on-a-chip systems in intelligent cardiac studies are discussed regarding physiological/pathological research and pharmacological assessment. Finally, the future development of heart-on-a-chip toward a higher level of systematization, integration, and maturation is proposed.

The Prognostic Value of Troponin-T in Out-of-Hospital Cardiac Arrest Without ST-Segment Elevation: A COACT Substudy

Background

In out-of-hospital cardiac arrest (OHCA) without ST-elevation, predictive markers that can identify those with a high risk of acute coronary syndrome are lacking.

Methods

In this post hoc analysis of the Coronary Angiography after Cardiac Arrest (COACT) trial, the baseline, median, peak, and time-concentration curves of troponin-T (cTnT) (T-AUC) in OHCA patients without ST-elevation were studied. cTnT values were obtained at predefined time points at 0, 3, 6, 12, 24, 36, 28, and 72 hours after admission. All patients who died within the measurement period were not included. The primary outcome was the association between cTnT and 90-day survival. Secondary outcomes included the association of cTnT and acute thrombotic occlusions, acute unstable lesions, and left ventricular function.

Results

In total, 352 patients were included in the analysis. The mean age was 64 ± 13 years (80.4% men). All cTnT measures were independent prognostic factors for mortality after adjustment for potential confounders age, sex, history of coronary artery disease, witnessed arrest, time to BLS, and time to return of spontaneous circulation (eg, for T-AUC: hazard ratio, 1.44; 95% CI, 1.06-1.94; P = .02; P value for all variables ≤.02). Median cTnT (odds ratio [OR], 1.58; 95% CI, 1.18-2.12; P = .002) and T-AUC (OR, 2.03; 95% CI, 1.25-3.29; P = .004) were independent predictors for acute unstable lesions. Median cTnT (OR, 1.62; 95% CI, 1.17-2.23; P = .003) and T-AUC (OR, 2.16; 95% CI, 1.27-3.68; P = .004) were independent predictors for acute thrombotic occlusions. CTnT values were not associated with the left ventricular function (eg, for T-AUC: OR, 2.01; 95% CI, 0.65-6.19; P = .22; P value for all variables ≥.14).

Conclusion

In OHCA patients without ST-segment elevation, cTnT release during the first 72 hours after return of spontaneous circulation was associated with clinical outcomes.

One-Stop Plasmonic Nanocube-Excited SERS Immunoassay Platform of Multiple Cardiac Biomarkers for Rapid Screening and Progressive Tracing of Acute Myocardial Infarction

Rapid and precise acute myocardial infarction (AMI) diagnosis is essential for preventing patient death. In addition, the complementary roles of creatine kinase muscle brain (CK-MB) and cardiac troponin I (cTnI) cardiac biomarkers in the early and late stages of AMI demand their simultaneous detection, which is difficult to implement using conventional fluorescence and electrochemical technologies. Here, a nanotechnology-based one-stop immuno-surface-enhanced Raman scattering (SERS) detection platform is reported for multiple cardiac indicators for the rapid screening and progressive tracing of AMI events. Optimal SERS is achieved using optical property-based, excitation wavelength-optimized, and high-yield anisotropic plasmonic gold nanocubes. Optimal immunoassay reaction efficiencies are achieved by increasing immobilized antibodies. Multiple simultaneous detection strategies are implemented by incorporating two different Raman reports with narrow wavenumbers corresponding to two indicators and by establishing a computational SERS mapping process to accurately detect their concentrations, irrespective of multiple enzymes in the human serum. The SERS platform precisely estimated AMI onset and progressive timing in human serum and made rapid AMI identification feasible using a portable Raman spectrometer. This integrated platform is hypothesized to significantly contribute to emergency medicine and forensic science by providing timely treatment and observation.

Diagnostic and prognostic utility of cardiac troponin in post-cardiac arrest care

BACKGROUND

Cardiac troponin is routinely tested in the post-cardiac arrest setting, but its utility in identifying ischaemic aetiology and predicting left ventricular systolic dysfunction (LVSD) and survival is not known.

METHODS

In a retrospective single center registry, we identified 145 consecutive patients who had achieved return of spontaneous circulation after cardiac arrest and had undergone serial cardiac troponin T (cTnT) testing, echocardiogram, and expert adjudication of aetiology. Initial and peak cTnT were evaluated for assessing ischaemic aetiology, LVSD, and survival to discharge using area under the receiver operating characteristic curve (AUROC).

RESULTS

Mean age was 61 ± 14 years and 71% were men. Of the 145 arrests, 19% had an ischaemic aetiology, 68% had LVSD post-arrest, and 55% survived to discharge. All patients had a positive initial cTnT at 0.01 ng/mL (clinical cut-off). Even at higher cut-offs of 10×, 100× and 1000×, initial cTnT performed poorly (AUROC 0.57, 0.56, and 0.56) and peak cTnT performed modestly (AUROC 0.55, 0.61, and 0.62) as diagnostic tests for ischaemic aetiology. Similarly, even at higher cut-offs, initial (AUROC 0.60, 0.62, 0.55) and peak (AUROC 0.57, 0.61, and 0.62) cTnT performed poorly to modestly at predicting LVSD. The test performed poorly for predicting survival to discharge (AUROC for all <0.6).

CONCLUSIONS

At both current and several-fold higher thresholds, cTnT does not perform sufficiently well to guide clinical decision-making or predict patient outcomes. Routine post-cardiac arrest testing of cTnT should be reevaluated.

Role of coronary angiography for out-of-hospital cardiac arrest survivors according to postreturn of spontaneous circulation on an electrocardiogram

Survivors of out-of-hospital cardiac arrest (OHCA) have high mortality and morbidity. An acute coronary event is the most common cause of sudden cardiac death. For this reason, coronary angiography is an important diagnostic and treatment strategy for patients with postcardiac arrest. This study aimed to identify the correlation between postreturn of spontaneous circulation (ROSC) on an electrocardiogram (ECG) and results of coronary angiography of OHCA survivors.We collected data from our OHCA registry from January 2010 to November 2014. We categorized OHCA survivors into 2 groups according to post-ROSC ECG results. Emergent coronary artery angiography (CAG) (CAG performed within 12 hours after cardiac arrest) was performed in patients who showed ST segment elevation or new onset of left bundle branch block (LBBB) in post-ROSC ECG. For other patients, the decision for performing CAG was made according to agreement between the emergency physician and the cardiologist.During the study period, 472 OHCA victims visited our emergency department and underwent cardiopulmonary resuscitation. Among 198 OHCA survivors, 82 patients underwent coronary artery intervention. Thirty-one (70.4%) patients in the ST segment elevation or LBBB group and 10 (24.4%) patients in the nonspecific ECG group had coronary artery lesions (P < .01). Seven (18.4%) patients in the nonspecific ECG group showed coronary spasm.OHCA survivors without ST segment elevation or new onset LBBB still have significant coronary lesions in CAG. If there is no other obvious arrest cause in patients without significant changes in post ROSC ECG, CAG should be considered to rule out the possibility of coronary artery problems, including coronary spasm.

Weak diagnostic performance of troponin, creatine kinase and creatine kinase-MB to diagnose or exclude myocardial infarction after successful resuscitation

BACKGROUND

The aim of this study is to evaluate the diagnostic accuracy of the cardiac injury markers troponin (TNT), creatine kinase (CK) and creatine kinase-MB (CK-MB) to diagnose or exclude acute myocardial infarction after cardiac arrest.

METHODS

226 patients who underwent diagnostic coronary angiography after sudden cardiac arrest were analyzed retrospectively. Levels of TNT, CK and CK-MB on admission and 6h, 24h and 36 h later were retrieved from the files and compared with the results of coronary angiography.

RESULTS

Acute myocardial infarction (AMI) as well as non-AMI patients showed increasing levels of TNT and CK after resuscitation, although the AMI group showed significantly higher TNT and CK levels. Receiver operator curves were calculated to determine the diagnostic precision of TNT, CK and CK-MB to differentiate AMI and non-AMI patients. All analyzed markers yielded mediocre diagnostic precision with an area under the ROC curve of 0.7020, 0.6802 and 0.6508 for 6h TNT, CK and CK-MB, respectively. Applying a modified cut-off of 1 μg/l the 6h TNT measurement had a sensitivity of 70.9% and specificity of 61.2% to diagnose AMI after cardiac arrest. Using CK 800 U/l as cut-off level resulted in a sensitivity of 62.5% and specificity of 73.7%, CK-MB levels higher than 100 U/l yielded a sensitivity of 58.8% and specificity of 72.7%.

CONCLUSION

Cardiac injury markers cannot be used to reliably diagnose or rule out AMI after resuscitation. Consequently we propose that indication for coronary angiography should be extended to all patients without a certain alternative diagnosis explaining the occurrence of cardiac arrest.

Prevalence of troponin elevations in patients with cardiac arrest and implications for assessing quality of care in hypothermia centers

The prevalence of troponin elevations in patients with cardiac arrest (CA) using newer generation troponin assays when the ninety-ninth percentile is used has not been well described. We studied patients admitted with CA without ST elevation myocardial infarction (MI). Treatment included a multidisciplinary protocol that included routine use of hypothermia for appropriate patients. Serial assessment of cardiac biomarkers, including troponin I was obtained over the initial 24 to 36 hours. Patients were classified into 1 of 5 groups on the basis of multiples of the ninety-ninth percentile (upper reference limit [URL]), using the peak troponin I value: <1×, 1 to 3×, 3 to 5×, 5 to 10×, and >10×. Serial changes between the initial and second troponin I values were also assessed. A total of 165 patients with CA (mean age 58 ± 16, 67% men) were included. Troponin I was detectable in all but 2 patients (99%); all others had peak troponin I values that were greater than or equal to the URL. Most patients had peak troponin I values >10× URL, including patients with ventricular fibrillation or ventricular tachycardia (85%), asystole (50%), and pulseless electrical activity (59%). Serial changes in troponin I were present in almost all patients: ≥20% change in 162 (98%), ≥30% change in 159 (96%), and an absolute increase of ≥0.02 ng/ml in 85% of patients. In conclusion, almost all patients with CA who survived to admission had detectable troponin I, most of whom met biomarker guideline criteria for MI. Given the high mortality of these patients, these data have important implications for MI mortality reporting at CA treatment centers.

Biomarkers as predictors of outcome after cardiac arrest

Cardiac arrest (CA) is a major health and economic problem. Management of patients resuscitated from CA is challenging for clinicians, and the mortality rate of those who achieve return of spontaneous circulation remains high. Hypoxic brain injury, cardiovascular abnormalities and systemic ischemia/reperfusion response characterize the so-called 'postcardiac arrest syndrome', which could lead to multiple organ failure and poor outcome after CA. The magnitude of these disorders differs in individual patients, mainly based on the cause and duration of CA and on the severity of the ischemic episode. Prognostication of outcome after CA is of importance because it could help physicians on triage decisions and readdress the overall management. A number of factors are thought to influence the prognosis of patients after CA, but due to the heterogeneity of CA population and scenarios no single factor has been identified as a reliable predictor of outcome and the timing and optimal approach to prognostication is still controversial. Biomarkers represent a growing area of interest in this field, as they may provide clinicians with early information on the severity of organ dysfunction to make a decision on clinical strategies and prognosticate outcome. In this article, the authors will focus on cardiac, neurological and inflammatory biomarkers as potential predictors of outcome after CA.

[Post-resuscitation syndrome. Role of inflammation after cardiac arrest]

Cardiac arrest with subsequent cardiopulmonary resuscitation causes an ischemic reperfusion syndrome of the whole body resulting in localized damage of particularly sensitive organs, such as the brain and heart, together with systemic sequelae. The main factor is a generalized activation of inflammatory reactions resulting in symptoms similar in many aspects to those of sepsis. Systemic inflammation strengthens organ damage due to disorders in the macrocirculation and microcirculation due to metabolic imbalance as well as the effects of direct leukocyte transmitted tissue destruction. The current article gives an overview on the role of inflammation following cardiac arrest and presents in detail the underlying mechanisms, the clinical symptoms and possible therapeutic approaches.

Can early cardiac troponin I measurement help to predict recent coronary occlusion in out-of-hospital cardiac arrest survivors?

OBJECTIVE

Recent guidelines recommend the immediate performance of a coronary angiography when an acute myocardial infarction is suspected as a cause of out-of-hospital cardiac arrest. However, prehospital factors such as postresuscitation electrocardiogram pattern or clinical features are poorly sensitive in this setting. We searched to evaluate if an early measurement of cardiac troponin I can help to detect a recent coronary occlusion in out-of-hospital cardiac arrest.

DESIGN

Retrospective analysis of a prospective electronic registry database.

SETTING

University cardiac arrest center.

PATIENTS

Between January 2003 and December 2008, 422 out-of-hospital cardiac arrest survivors without obvious extra-cardiac cause have been consecutively studied. An immediate coronary angiography has been systematically performed. The primary outcome was the finding of a recent coronary occlusion.

INTERVENTION

First, blood cardiac troponin I levels at admission were analyzed to assess the optimum cutoff for identifying a recent coronary occlusion. Second, a logistic regression was performed to determine early predictive factors of a recent coronary occlusion (including cardiac troponin I) and their respective contribution.

MEASUREMENTS AND MAIN RESULTS

An ST-segment elevation was present in 127 of 422 patients (30%). During coronary angiography, a recent occlusion has been detected in 193 of 422 patients (46%). The optimum cardiac troponin I threshold was determined at 4.66 ng·mL(-1) (sensitivity 66.7%, specificity 66.4%). In multivariate analyses, in addition of smoking and epinephrine initial dose, cardiac troponin I (odds ratio 3.58 [2.03-6.32], p < .001) and ST-segment elevation (odds ratio 10.19 [5.39-19.26], p < .001) were independent predictive factors of a recent coronary occlusion.

CONCLUSIONS

In this large cohort of out-of-hospital cardiac arrest patients, isolated early cardiac troponin I measurement is modestly predictive of a recent coronary occlusion. Furthermore, the contribution of this parameter even in association with other factors does not seem helpful to predict recent occlusion. As a result and given the high benefit of percutaneous coronary intervention for such patients, the dosage of cardiac troponin I at admission could not help in the decision of early coronary angiogram.

Troponin elevation in conditions other than acute coronary syndromes

Acute coronary syndromes comprise a large spectrum of clinical conditions ranging from unstable angina pectoris to acute ST-elevation myocardial infarction. Chest pain is usually the major symptom of atherosclerotic heart disease; however, it may be challenging to diagnose correctly, especially in the emergency department, because of the ambiguous way that pain is characterized by some patients. Cardiac troponins are sensitive and specific biomarkers used in the diagnosis of myocardial infarction that are released into the bloodstream when cardiac myocytes are damaged by acute ischemia or any other mechanism. They are the cornerstone for the diagnosis, risk assessment, prognosis, and determination of antithrombotic and revascularization strategies. However, troponin elevation indicates the presence, not the mechanism, of myocardial injury. There are many clinical conditions other than myocardial infarction that cause troponin elevation; thus, the physician should be aware of the wide spectrum of disease states that may result in troponin elevation and have a clear understanding of the related pathophysiology to effectively make a differential diagnosis. This review focuses on causes of troponin elevation other than acute coronary syndromes.

Value of post-resuscitation electrocardiogram in the diagnosis of acute myocardial infarction in out-of-hospital cardiac arrest patients

BACKGROUND

Diagnosis of acute myocardial infarction (AMI) in out-of-hospital cardiac arrest (OHCA) patients is important because immediate coronary angiography with coronary angioplasty could improve outcome in this setting. However, the value of acute post-resuscitation electrocardiographic (ECG) data for the detection of AMI is debatable.

METHODS

We assessed the diagnostic characteristics of post-resuscitation ECG changes in a retrospective single centre study evaluating several ECG criteria of selection of patients undergoing AMI, in order to improve sensitivity, even at the expense of specificity. Immediate post resuscitation coronary angiogram was performed in all patients. AMI was defined angiographically using coronary flow and plaque morphology criteria.

RESULTS

We included 165 consecutive patients aged 56 (IQR 48-67) with sustained return of spontaneous circulation after OHCA between 2002 and 2008. 84 patients had shockable, 73 non-shockable and 8 unknown initial rhythm; 36% of the patients had an AMI. ST-segment elevation predicted AMI with 88% sensitivity and 84% specificity. The criterion including ST-segment elevation and/or depression had 95% sensitivity and 62% specificity. The combined criterion including ST-segment elevation and/or depression, and/or non-specific wide QRS complex and/or left bundle branch block provided a sensitivity and negative predictive value of 100%, a specificity of 46% and a positive predictive value of 52%.

CONCLUSION

In patients with OHCA without obvious non-cardiac causes, selection for coronary angiogram based on the combined criterion would detect all AMI and avoid the performance of the procedure in 30% of the patients, in whom coronary angiogram did not have a therapeutic role.

Low levels of the omega-3 index are associated with sudden cardiac arrest and remain stable in survivors in the subacute phase

In previous studies, low blood levels of n-3 fatty acids (FA) have been associated with increased risk of cardiac death, and the omega-3 index (red blood cell (RBC) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) expressed as weight percentage of total FA) has recently been proposed as a new risk factor for death from coronary artery disease, especially following sudden cardiac arrest (SCA). As blood samples often haven been harvested after the event, the aim of our study was to evaluate the stability of RBC fatty acids following SCA. The total FA profile, including the omega-3 index, was measured three times during the first 48 h in 25 survivors of out-of-hospital cardiac arrest (OHCA), in 15 patients with a myocardial infarction (MI) without SCA and in 5 healthy subjects. We could not demonstrate significant changes in the FA measurements in any of the groups, this also applied to the omega-6/omega-3 ratio and the arachidonic acid (AA)/EPA ratio. Furthermore, we compared the omega-3 index in 14 OHCA-patients suffering their first MI with that of 185 first-time MI-patients without SCA; mean values being 4.59% and 6.48%, respectively (p = 0.002). In a multivariate logistic regression analysis, a 1% increase of the omega-3 index was associated with a 58% (95% CI: 0.25–0.76%) reduction in risk of ventricular fibrillation (VF). In conclusion, the omega-3 index remained stable after an event of SCA and predicted the risk of VF.

Post-cardiac arrest syndrome: Epidemiology, pathophysiology, treatment, and prognostication: A scientific statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke (Part 1)

AIM OF THE REVIEW

To review the epidemiology, pathophysiology, treatment and prognostication in relation to the post-cardiac arrest syndrome.

METHODS

Relevant articles were identified using PubMed, EMBASE and an American Heart Association EndNote master resuscitation reference library, supplemented by hand searches of key papers. Writing groups comprising international experts were assigned to each section. Drafts of the document were circulated to all authors for comment and amendment.

RESULTS

The 4 key components of post-cardiac arrest syndrome were identified as (1) post-cardiac arrest brain injury, (2) post-cardiac arrest myocardial dysfunction, (3) systemic ischaemia/reperfusion response, and (4) persistent precipitating pathology.

CONCLUSIONS

A growing body of knowledge suggests that the individual components of the postcardiac arrest syndrome are potentially treatable.

Elevated serum cardiac troponin in non-acute coronary syndrome

Cardiac troponins (CTn) are the most sensitive and specific biochemical markers of myocardial injury and risk stratification. The assay for troponin T (cTnI) is standardized, and results obtained from different institutions are comparable. This is not the case with troponin I (cTnT), and clinicians should be aware that each institution must analyze and standardize its own results. Elevated cTn levels indicate cardiac injury, but do not define the mechanical injury. The differentiation of cTn elevation caused by coronary events from those not related to an acute coronary syndrome (ACS) is tiresome, at times vexing, and often costly. Elevation of cTn in non-ACS is a marker of increased cardiac and all-cause morbidity and mortality. The cause of these elevations may involve serious medical conditions that require meticulous diagnostic evaluation and aggressive therapy. At present, there are no guidelines to treat patients with elevated troponin levels and no coronary disease. The current strategy of treatment of patients with elevated troponin and non-ACS involves treating the underlying causes.

Cardiac catheterization is underutilized after in-hospital cardiac arrest

BACKGROUND

Indications for immediate cardiac catheterization in cardiac arrest survivors without ST elevation myocardial infarction (STEMI) are uncertain as electrocardiographic and clinical criteria may be challenging to interpret in this population. We sought to evaluate rates of early catheterization after in-hospital ventricular fibrillation (VF) arrest and the association with survival.

METHODS

Using a billing database we retrospectively identified cases with an ICD-9 code of cardiac arrest (427.5) or VF (427.41). Discharge summaries were reviewed to identify in-hospital VF arrests. Rates of catheterization on the day of arrest were determined by identifying billing charges. Unadjusted analyses were performed using Chi-square, and adjusted analyses were performed using logistic regression.

RESULTS

One hundred and ten in-hospital VF arrest survivors were included in the analysis. Cardiac catheterization was performed immediately or within 1 day of arrest in 27% (30/110) of patients and of these patients, 57% (17/30) successfully received percutaneous coronary intervention. Of those who received cardiac catheterization the indication for the procedure was STEMI or new left bundle branch block (LBBB) in 43% (13/30). Therefore, in the absence of standard ECG data suggesting acute myocardial infarction, 57% (17/30) received angiography. Patients receiving cardiac catheterization were more likely to survive than those who did not receive catheterization (80% vs. 54%, p<.05).

CONCLUSION

In patients receiving cardiac catheterization, more than half received this procedure for indications other than STEMI or new LBBB. Cardiac catheterization was associated with improved survival. Future recommendations need to be established to guide clinicians on which arrest survivors might benefit from immediate catheterization.

Post-cardiac arrest syndrome: epidemiology, pathophysiology, treatment, and prognostication. A Scientific Statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke

AIM OF THE REVIEW

To review the epidemiology, pathophysiology, treatment and prognostication in relation to the post-cardiac arrest syndrome.

METHODS

Relevant articles were identified using PubMed, EMBASE and an American Heart Association EndNote master resuscitation reference library, supplemented by hand searches of key papers. Writing groups comprising international experts were assigned to each section. Drafts of the document were circulated to all authors for comment and amendment.

RESULTS

The 4 key components of post-cardiac arrest syndrome were identified as (1) post-cardiac arrest brain injury, (2) post-cardiac arrest myocardial dysfunction, (3) systemic ischaemia/reperfusion response, and (4) persistent precipitating pathology.

CONCLUSIONS

A growing body of knowledge suggests that the individual components of the post-cardiac arrest syndrome are potentially treatable.

Cardiac troponin I elevation in hospitalized patients without acute coronary syndromes

Increase of cardiac troponins occurs in a variety of clinical situations in the absence of an acute coronary syndrome (ACS). Few data exist regarding the incidence, clinical characteristics, and predictive value of various cardiac diagnostic tests and outcome of patients with a non-ACS-related troponin increase. We studied 883 consecutive hospitalized patients with increased cardiac troponin I levels. The discharge diagnosis was reclassified and troponin increase attributed to ACS or another process. Clinical data and results of cardiac diagnostic tests were collected. Patients were followed for a median of 30 months. Three hundred eleven patients were classified as having a non-ACS-related troponin increase (35.2%). An alternative explanation for troponin increase was found in 99% of these patients. Troponin level had poor accuracy in discriminating patients with and without ACS (area under the receiver operating characteristics curve 0.63). Coronary angiography was frequently unhelpful in excluding a non-ACS-related troponin increase because 77% of patients in the non-ACS group had significant flow-limiting coronary artery disease. Patients with non-ACS-related troponin increase had significantly higher in-hospital (hazard ratio 2.8, 95% confidence interval 2.0 to 3.8) and long-term (hazard ratio 2.0, 95% confidence interval 1.6 to 2.5) mortalities compared with patients with ACS. In conclusion, cardiac troponin level is frequently increased in hospitalized patients in the absence of an ACS and portends poor short- and long-term outcomes. Most of these patients have an alternative explanation for cardiac troponin increase. Cardiac diagnostic procedures are frequently unhelpful in excluding a non-ACS-related troponin increase.

Use and Misuse of Cardiac Troponins in Clinical Practice

Cardiac troponins are very sensitive and specific markers of myocardial injury. Elevated troponin levels in the setting of acute coronary syndrome are diagnostic of acute myocardial infarction and provide guidance to clinicians with regard to appropriate use of intensive medical and revascularization therapies. However, elevated troponin levels are commonly seen in several noncoronary ischemia presentations and create considerable confusion among clinicians in these settings. In this review article, we discuss the utility of troponins in various clinical settings and present a "common sense" approach to interpreting troponin elevation outside the setting of acute coronary syndrome.

Retrospective diagnosis of hypoxic myocardial injury in premature newborns

Perinatal asphyxia has a high impact on neonatal mortality, morbidity, and neurological outcome. The hypoxic effects on brain, kidney and gastrointestinal system are well recognized in newborns. While it is known that hypoxia also effects cardiac function, there are few studies of quantitative myocardial injury in premature infants who suffered hypoxia.

AIM

To investigate usefulness of cardiac troponin (cTnT) and creatinine kinase MB (CK-MB) in the diagnosis of myocardial injury due to birth hypoxia and to correlate these markers with cardiac functions as measured by echocardiogram.

METHODS

We studied 43 preterm infants: 21 with birth asphyxia and 22 controls. Echocardiographic studies and quantitative determination of cTnT and CK-MB in blood serum was performed between the 12(th) and the 24(th) h of life.

RESULTS

cTnT and CK-MB levels were higher in asphyxiated infants compared to controls (0.287 +/- 0.190 vs. 0.112 +/- 0.099 ng/mL, P < 0.001) and (18.35 +/-14.81 vs. 11.09 +/- 5.17 ng/L, P < 0.05). Among controls, we observed an elevated value of cTnT in those with respiratory distress syndrome (RDS). We found a decrease in fractional shortening (P < 0.05) and an increase in tricuspid insufficiency (P < 0.01) in asphyxiated newborns.

CONCLUSIONS

cTnT and CK-MB levels are strong indicators of myocardial injury due to perinatal hypoxia. The cTnT level was most strongly related to RDS.

Intensive care after resuscitation from cardiac arrest: a focus on heart and brain injury

Less than 3% of all patients who have out-of-hospital cardiac arrests have return of spontaneous circulation (ROSC), survive the hospitalization, and have a reasonable functional recovery. The fact that many patients who have ROSC ultimately die or fail to have favorable neurologic recovery suggests that processes that occur after hospitalization, especially in the ICU, have an impact on survival and neurologic recovery. This article addresses the acute care, with emphasis on the cardiac and neurologic aspects,that patients who have post cardiac arrest are provided in the cardiac ICU.

The influence of cardiopulmonary resuscitation without defibrillation on serum levels of cardiac enzymes: A time course study of out-of-hospital cardiac arrest survivors

BACKGROUND

The serum concentration of cardiac enzymes may be influenced by mechanical and electrical trauma due to cardiopulmonary resuscitation (CPR) attempts. This could complicate the determination of whether an acute myocardial infarction (AMI) had occurred. In this study, only patients without any of the known confounding factors affecting cardiac enzyme release were included, and the specific time course and patterns of serum cardiac enzyme levels after resuscitation were evaluated. The purpose is to help clinicians distinguish between spontaneous myocardial damage and that induced by CPR.

METHODS AND RESULTS

This prospective, observational study was performed in the emergency department on eight patients surviving cardiac arrest. They were selected for not having heart disease, chest trauma or septic shock; and not receiving defibrillation. The median (range) duration of return of spontaneous circulation (ROSC) was 13 min (5-30 min). Cardiac enzyme measurements were taken immediately after ROSC and every 6h thereafter. Although cardiac troponin I (cTnI) level reached as high as 62.6 ng/ml at 24 h in one patient, five of the eight (62.5%) patients had their cTnI level fall below the normal reference range (i.e. 2 ng/ml) by 30 h. The time to maximum and peak concentration of cTnI was 16.50+/-10.99 h and 16.85+/-21.50 ng/ml, respectively. Both MB creatine kinase (CKMB) and total creatine kinase (CK) levels were above their normal reference ranges. In addition, the CKMB/CK ratio exceeded 5% in all patients at any time point during this study.

CONCLUSION

In this study, the influence of resuscitative procedures - defibrillation excluded - on the release of cardiac enzymes were examined. During 30 h after ROSC cTnI level exhibited a bell-shaped configuration, which is distinct from that after AMI; whereas the enzymatic activities of CKMB and CK, as well as CKMB/CK ratio, were constantly higher than normal. This chronological pattern of cardiac enzyme levels may help physicians differentiate primary cardiac disease from other aetiologies in out-of-hospital cardiac arrests.

Epidemiology and stratification of risk for sudden cardiac death

Sudden cardiac death (SCD) is a major cause of mortality in the United States. Approximately 65% of cases of SCD occur in patients with underlying acute or chronic ischemic heart disease. The incidence of SCD increases 2- to 4-fold in the presence of coronary disease and 6- to 10-fold in the presence of structural heart disease. Ventricular fibrillation (VF) precipitated by ventricular tachycardia (VT) is a common mechanism of cardiac arrest leading to SCD. Triggers for SCD include electrolyte disturbances, heart failure, and transient ischemia. Although a large percentage of patients with out-of-hospital SCD do not survive, successful resuscitation to hospitalization has improved in recent years. One of the challenges for preventing SCD lies in identifying individuals at highest risk for SCD within a lower-risk population. The progression from conventional risk factors of coronary artery disease to arrhythmogenesis and SCD can be represented as a cascade of changes associated with levels of increasing risk. At the first level is atherogenesis, followed by changes in atherosclerotic plaque anatomy, which may be mediated by inflammatory processes. Disruption of active plaque formed during a transitional state initiates the thrombotic cascade and acute occlusion, after which acute changes in myocardial electrophysiology become the immediate trigger for arrhythmogenesis and SCD. Each level of the cascade offers different opportunities for risk prediction. Among the classes of risk predictors are clinical markers, such as ECG measures and ejection fraction. Transient risk markers, such as inflammatory markers, are potentially useful for identifying triggers for SCD. In the future, genetic profiling is expected to allow better assessment of individual risks for SCD.

Recommended guidelines for reviewing, reporting, and conducting research on post-resuscitation care: The Utstein style

The aim of this report is to establish recommendations for reviewing, reporting, and conducting research during the post-resuscitation period in hospital. It defines data that are needed for research and more specialised registries and therefore supplements the recently updated Utstein template for resuscitation registries. The updated Utstein template and the out-of-hospital "Chain of Survival" describe factors of importance for successful resuscitation up until return of spontaneous circulation (ROSC). Several factors in the in-hospital phase after ROSC are also likely to affect the ultimate outcome of the patient. Large differences in survival to hospital discharge for patients admitted alive are reported between hospitals. Therapeutic hypothermia has been demonstrated to improve the outcome, and other factors such as blood glucose, haemodynamics, ventilatory support, etc., might also influence the result. No generally accepted, scientifically based protocol exists for the post-resuscitation period in hospital, other than general brain-oriented intensive care. There is little published information on this in-hospital phase. This statement is the result of a scientific consensus development process started as a symposium by a task force at the Utstein Abbey, Norway, in September 2003. Suggested data are defined as core and supplementary and include the following categories: pre-arrest co-morbidity and functional status, cause of death, patients' quality of life, in-hospital system factors, investigations and treatment, and physiological data at various time points during the first three days after admission. It is hoped that the publication of these recommendations will encourage research into the in-hospital post-resuscitation phase, which we propose should be included in the chain-of-survival as a fifth ring. Following these recommendations should enable better understanding of the impact of different in-hospital treatment strategies on outcome.

Influence of acute resistance exercise on cardiac biomarkers in untrained women

This study was conducted to determine if an initial bout of resistance (weight lifting) exercise by untrained women results in any alterations in indicators of acute myocardial infarction (AMI). Untrained women performed 4 resistance exercises at 70% of their 1 repetition maximum. Blood samples were obtained during the 12 h post-exercise and analyzed for total creatine kinase (CK)-MB, CK-MB subforms 1 and 2, and the relative lymphocyte percentage. Exercise resulted in significant increases in total CK-MB, CK-MB(1), CK-MB(2), and the CK-MB(2)/CK-MB(1) ratio, total leukocyte count, and lymphocyte count. Using several criteria for the assessment of AMI, 22-25% of subjects completing the protocol demonstrated increases in CK-MB(2), CK-MB(2)/CK-MB(1) ratio, and relative lymphocyte percentages that were suggestive of AMI. Thus, our data suggest that moderate resistance exercise can significantly alter blood indicators of AMI, emphasizing the need to determine recent exercise history in patients with possible AMI.

The prognostic value of high-sensitive C-reactive protein and cardiac troponin T in young and middle-aged patients with chest pain without ECG changes

BACKGROUND: There is growing evidence of the prognostic importance of inflammatory markers in angina pectoris. However, the independent value of high-sensitive C-reactive protein (hsCRP), cardiac troponin T (cTnT), or their combination has not been established in young patients with angina pectoris without ECG changes. Therefore, we assessed the 6-month prognostic values of serum hsCRP and cTnT in young and middle-aged patients who were admitted to the hospital with chest pain but without ECG changes. METHODS: Forty young or middle-aged patients (45+/-10 years old; two females) were included in the study. All had chest pain for the first time without ST-T changes or any other ECG changes and with normal CPK-MB levels. Blood was drawn on admission, separated, and serum was frozen at -80 degrees C for 1 year until thawed and studied as one batch in order to measure hsCRP and cTnT levels. A clinical follow-up was done for 6 months. RESULTS: Our findings showed that the strongest independent marker of an adverse outcome was the hsCRP level on admission (sensitivity 66.7%; specificity 94.1%); cTnT level added a little to the specificity (97.1%), but did not add to the sensitivity that was found by hsCRP level. CONCLUSIONS: hsCRP level on admission could be an independent prognostic marker in young and middle-aged patients with angina pectoris without ECG changes and without CPK-MB elevation.

Clinical application of rapid quantitative determination of cardiac troponin-T in an emergency department setting

OBJECTIVES

We analysed the clinical use of Troponin-T compared to creatine kinase MB in a non-trauma emergency department setting.

BACKGROUND

A newly established single specimen quantitative Troponin T assay allows the clinical application of this parameter. METHODS. Five-hundred Troponin T tests were provided for use by emergency physicians who could combine them with the routine laboratory tests without restriction as to the indication or number of tests per patient. The number of tests per patient, time frame, final diagnosis and additional clinical information gained were recorded. All patients were followed for at least 6 months to verify the diagnosis and to assess the occurrence of cardiac events (nonfatal AMI or cardiac death). The ability of Troponin T and creatine kinase MB tests to predict cardiac events within 6 months were compared.

RESULTS

The 500 Troponin T tests were used in 249 patients (median two tests per patient (range 1-5)) within 41 days. The final diagnosis revealed coronary heart disease in 85, non-coronary heart disease in 39, non-cardiac chest pain in 86 and other diagnoses in 39 of the patients. In 14 patients with an elevated creatine kinase MB, myocardial damage could safely be ruled out by a negative Troponin T, in six patients with a normal creatine kinase MB minor myocardial damage could be detected by a positive Troponin T. During follow up 28 cardiac events were recorded. Troponin T had a significantly higher specificity, positive predictive value and proportion of correct prediction for cardiac events within 6 months compared to creatine kinase MB.

CONCLUSIONS

Troponin T has proved to be an useful method for diagnosing myocardial damage in routine clinical use in the non-trauma emergency department.

Measurement of myocardial contractility following successful resuscitation: quantitated left ventricular systolic function utilising non-invasive wall stress analysis

After successful resuscitation from cardiac arrest, prolonged contractile failure has been demonstrated in animal experiments. No systematic evaluation of myocardial contractility following successful resuscitation after human cardiac arrest exists. The aim of this study was to assess left ventricular contractility following human cardiac arrest with successful resuscitation. In 20 adult patients after cardiac arrest and in four control patients, the relation between meridional wall stress (MWS) and rate-corrected mean velocity of circumferential fibre shortening (Vcf(c)), a load independent and rate corrected index of left ventricular contractility was measured within 4 h after return of spontaneous circulation and after 24 h by means of transoesophageal echocardiography. As the normal values of Vcf(c) depend on MWS, a normal deviate (z) was calculated. A normal z-score is defined as 0+/-2, < -2 indicates reduced contractility, > + 2 increased contractility. Data are presented as median and the interquartile range (IQR). For the comparison of related samples the Wilcoxon sign test was used. In most patients after cardiac arrest contractility was severely impaired within 4 h after successful resuscitation [z - 7.0 (IQR - 8.9 - (-2.5))]. Contractility did not significantly improve within the observational period [z after 24 h - 3.7 (IQR - 7.9 - (-1.8))] (P = 0.3). The four control patients had normal left ventricular contractility on arrival (z 0.0, range - 0.9-0.8) and after 24 h (z 0.7, range - 1.5-2.7). In conclusion non-invasive wall stress analysis can be applied to quantitate systolic left ventricular function, which was severely compromised in most patients within the first 24 h after successful resuscitation. Whether depression of left ventricular function is caused by cardiac arrest itself or by the underlying disease remains speculative.

The influence of chest compressions and external defibrillation on the release of creatine kinase-MB and cardiac troponin T in patients resuscitated from out-of-hospital cardiac arrest

OBJECTIVES

This study sought to determine the influence of resuscitative procedures, such as chest compressions and external defibrillation, on the release of creatine kinase (CK)-MB and cardiac troponin T (cTnT).

METHODS

In 87 patients with out-of-hospital cardiac arrest and successful cardiopulmonary resuscitation (CPR), the initial ECG rhythm, the duration of cardiac arrest and CPR, and the number of defibrillations were assessed on arrival in the hospital. The serum CK-MB and cTnT were measured 12 h after the event. We also assessed whether the patient developed cardiogenic shock within 12 h, and if the patient had acute myocardial infarction (AMI), which was confirmed or eliminated by of typical ECG findings, thallium-201 myocardial scintigraphy, or autopsy within the hospital stay. A backward stepwise linear regression model was applied to assess the association between the markers of myocardial injury (CK-MB and cTnT) and the above clinical variables.

RESULTS

CK-MB concentrations were independently associated with the presence of AMI [B 68.5 (SE 28.5, P = 0.018)], the duration of CPR (as a measure of trauma to the chest by means of chest compressions) [B 2.07 (SE 1.01, P = 0.045)] and cardiogenic shock [B 52.3 (SE 23.4, P = 0.03)]. The remaining clinical variables listed were excluded by the model. Cardiac troponin T concentrations were only associated with the presence of AMI [B 4.86 (SE 1.34, P = 0.0005)]. There was a non-significant association between increasing serum cTnT concentrations and the presence of cardiogenic shock [B 2.51 (SE 1.46, P = 0.09)]. The remaining clinical variables were excluded by the model.

CONCLUSION

The release of CK-MB appears to be influenced by the duration of resuscitation and the presence of cardiogenic shock. This has to be considered when interpreting serum CK-MB concentrations after CPR. The release of cTnT seems to be only associated with acute myocardial infarction, but not with the duration of chest compressions, or with the number of defibrillations administered.

Bedside troponin T testing is not useful for early out-of-hospital diagnosis of myocardial infarction

BACKGROUND

A new commercially available rapid qualitative bedside immunoassay for cardiac troponin T has been developed. The aim of the study was to investigate whether this new rapid bedside cardiac troponin T assay facilitates diagnosing myocardial infarction in a pre-hospital setting.

METHODS

We evaluated the sensitivity and specificity of the new rapid bedside troponin T assay for myocardial infarction. In 68 patients with acute, central, crushing chest pain, who were strongly suspected of having myocardial infarction, the emergency doctor performed preclinically a bedside cardiac troponin T test. The results were compared with the diagnosis after admission to hospital, using the criteria of the World Health Organization.

RESULTS

The diagnosis of myocardial infarction was confirmed in 16/68 (24%) patients after admission to hospital, but only in 4/16 (25%) patients with myocardial infarction was a positive result observed preclinically with this test. The result was false positive in 1/5 patients (20%).

CONCLUSIONS

In contrast to an excellent specificity (0.98), sensitivity (0.25) of the rapid troponin T assay was poor. Thus, we conclude that this test cannot improve the distinction between myocardial infarction and angina pectoris in a pre-hospital setting.