Relation between troponin T and the risk of subsequent cardiac events in unstable coronary artery disease. The FRISC study group

Biomarkers in acute coronary syndromes and their role in diabetic patients

Diabetic patients with acute coronary syndromes are at high risk for cardiovascular complications but risk stratification in these patients remains challenging. Regularly, diabetic patients have a less typical clinical presentation, which could lead to delayed diagnosis and subsequent delayed initiation of treatment. Since diabetic patients derive particular benefit from aggressive anti-platelet therapy, early diagnostic and therapeutic risk stratification of these patients is of critical importance to improve their adverse outcome. Although the electrocardiogram remains a pivotal diagnostic tool in the evaluation of patients suspected of having an acute coronary syndrome, only significant ST-segment changes provide reasonable prognostic information. Therefore, repeated assessment of circulating protein biomarkers represents a valuable diagnostic tool for improving efficacy and safety of decision-making in these patients. The combined use of biomarkers reflecting distinct pathophysiological aspects, such as myocardial necrosis, vascular inflammation, oxidative stress and neurohumoral activation, may significantly improve triage of patients with chest pain. These tools may identify those patients that are at particularly high risk for short-term and/or long-term cardiovascular events. Eventually, tailored medical and interventional treatment of diabetic patients should help to prevent these cardiac events in a cost-effective manner.

Elevated troponin and myocardial infarction in the intensive care unit: a prospective study

INTRODUCTION

Elevated troponin levels indicate myocardial injury but may occur in critically ill patients without evidence of myocardial ischemia. An elevated troponin alone cannot establish a diagnosis of myocardial infarction (MI), yet the optimal methods for diagnosing MI in the intensive care unit (ICU) are not established. The study objective was to estimate the frequency of MI using troponin T measurements, 12-lead electrocardiograms (ECGs) and echocardiography, and to examine the association of elevated troponin and MI with ICU and hospital mortality and length of stay.

METHOD

In this 2-month single centre prospective cohort study, all consecutive patients admitted to our medical-surgical ICU were classified in duplicate by two investigators as having MI or no MI based on troponin, ECGs and echocardiograms obtained during the ICU stay. The diagnosis of MI was based on an adaptation of the joint European Society of Cardiology/American College of Cardiology definition: a typical rise or fall of an elevated troponin measurement, in addition to ischemic symptoms, ischemic ECG changes, a coronary artery intervention, or a new cardiac wall motion abnormality.

RESULTS

We screened 117 ICU admissions and enrolled 115 predominantly medical patients. Of these, 93 (80.9%) had at least one ECG and one troponin; 44 of these 93 (47.3%) had at least one elevated troponin and 24 (25.8%) had an MI. Patients with MI had significantly higher mortality in the ICU (37.5% versus 17.6%; P = 0.050) and hospital (50.0% versus 22.0%; P = 0.010) than those without MI. After adjusting for Acute Physiology and Chronic Health Evaluation II score and need for inotropes or vasopressors, MI was an independent predictor of hospital mortality (odds ratio 3.22, 95% confidence interval 1.04-9.96). The presence of an elevated troponin (among those patients in whom troponin was measured) was not independently predictive of ICU or hospital mortality.

CONCLUSION

In this study, 47% of critically ill patients had an elevated troponin but only 26% of these met criteria for MI. An elevated troponin without ischemic ECG changes was not associated with adverse outcomes; however, MI in the ICU setting was an independent predictor of hospital mortality.

Use of cardiac troponin T in diagnosis and prognosis of cardiac events in patients on chronic haemodialysis

BACKGROUND

Patients undergoing chronic haemodialysis frequently have elevated serum cardiac troponin T (cTnT) levels resulting in difficulty in diagnosing acute coronary syndromes (ACS) in these patients. We sought to determine whether: (i) cTnT concentrations were consistent over time; (ii) intradialytic changes in cTnT levels were due to haemoconcentration; (iii) baseline cTnT levels predicted subsequent mortality or ACS.

METHODS

We measured serial pre- and post-dialysis cTnT concentrations in 75 asymptomatic patients undergoing chronic haemodialysis at baseline, and at 48 h, 8 months and 15 months. At 15 months, we also measured pre- and post-dialysis haematocrit levels in order to adjust the post-dialysis cTnT concentration for the effect of ultrafiltration. Kaplan-Meier survival curves, log-rank tests and Cox models were employed to determine whether baseline cTnT levels predicted death or ACS within 18 months.

RESULTS

Thirty-five (47%) patients had a baseline pre-dialysis cTnT concentration in the diagnostic range for an ACS (cTnT > or = 0.03 microg/l). There was a strong correlation between serial cTnT concentrations in individual patients (P<0.0001 for each time point). The median cTnT concentration was significantly greater post- than pre-dialysis (P<0.01 for each serial analysis); however, there was no significant difference following correction of post-dialysis cTnT levels for the effect of haemoconcentration (P = 0.48). Elevated baseline cTnT levels were associated with an increased risk of mortality or ACS at 18 months (P = 0.0015).

CONCLUSION

In asymptomatic patients on haemodialysis, serum cTnT concentrations are frequently elevated, and they rise during dialysis due to haemoconcentration. cTnT levels fluctuate minimally in individual patients in the medium term, therefore annual measurements may be useful reference points in the diagnosis of chest pain and in the prediction of ACS and mortality.

Prognostic role of cardiac troponin I after percutaneous coronary intervention in stable coronary disease

OBJECTIVE

To assess the role of cardiac troponin I (cTnI) in predicting outcome after percutaneous coronary intervention (PCI).

METHODS AND RESULTS

cTnI was measured immediately before and at 6, 14, and 24 hours after PCI in 316 consecutive patients with stable symptoms and native coronary artery disease. The study end point was the occurrence of major adverse cardiac events (MACE) at 30 days and at 18 months after PCI: death, Q wave myocardial infarction (MI), or repeat revascularisation in hospital. Postprocedural cTnI increased in 31% of patients. The cumulative MACE rate at 18 months was 25% (17.7% due to repeat PCI procedures). There was a significant association between postprocedural cTnI increase and death, Q wave MI, or both (odds ratio (OR) 3.28, 95% confidence interval (CI) 1.7 to 6.4, p = 0.01). Post-PCI cTnI increase had a positive predictive value (PPV) for adverse events at 18 months of 0.47 and a negative predictive value (NPV) of 0.96 (OR 18.9, 95% CI 9.7 to 37, p < 0.0001). The presence of both a postprocedural cTnI rise and a procedural angiographic complication gave a PPV for adverse events of 0.69 and an NPV of 0.92 (OR 22.6, 95% CI 2.6 to 68.6, p = 0.0005).

CONCLUSIONS

cTnI increased post-procedurally in one third of this stable patient population undergoing elective PCI and was independently and significantly predictive of an increased risk of adverse events at 18 months, predominantly in the form of repeat PCI.

Use of a quantitative point-of-care test for the detection of serum cardiac troponin T in patients with suspected acute coronary syndromes

We compared a third generation quantitative cardiac troponin T (cTnT) point-of-care testing (POCT) from Roche Diagnostics with the laboratory assay (Roche Elecsys 2010 immunoassay analyser). Heparin-treated blood and serum were collected simultaneously in 133 unselected patients (mean age 62 +/- 14 years, 38% females) presenting to our hospital with possible cardiac chest pain. Results of the POCT were measured against the laboratory-based assay considered as the gold standard. There were 18 POCT positive versus 24 laboratory assay positive (> or = 0.03 ng/mL) patients. POCT was falsely negative in six patients, with values between 0.03 and 0.1 ng/mL. The POCT had a sensitivity of 75%, specificity of 100%, positive predictive value of 100%, negative predictive value of 95% and a total accuracy of 95%; kappa = 0.831 (P < 0.001). There was good correlation between the values of POCT and the laboratory assay: Y = 1.195X + 0.002, r2 = 0.94 (P < 0.0001). Whereas cTnT levels > 0.1 mg/mL were reliably detected with this current generation of POCT, cTnT levels between 0.03 and 0.10 ng/mL were not. Future generations of devices will need to improve sensitivity to reliably risk stratify patients with suspected acute coronary syndromes.

Evidence-based emergency medicine at the 'coal face'

While evidence-based medicine may be trumpeted by zealots, managers and politicians, incorporating it into clinical practice is easier said than done. The present article aims to show that it can be achieved and gives some clinical examples to illustrate this. An appendix contains a summary of useful databases and websites for accessing good medical information and evidence, quickly and reliably near the bedside.

Combining different biochemical markers of myocardial ischemia does not improve risk stratification in chest pain patients compared to troponin I alone

OBJECTIVE

Early evaluation of patients with chest pain is important not only for the detection of acute myocardial infarction (AMI) but also for identification of patients at high risk for future cardiac events. A multimarker strategy applying results of early measurements of different biochemical markers of cardiac necrosis in combination may improve risk prediction in chest pain patients.

METHODS

Rapid measurements of troponin I (TnI), creatine kinase MB and myoglobin were performed in 191 consecutive patients with chest pain and a non-diagnostic electrocardiogram for AMI. The prognostic value of these markers and different multimarker strategies was evaluated and compared.

RESULTS

Ten (5.2%) patients died during follow-up, which for eight (4.2%) patients was due to cardiac causes. Myocardial reinfarctions occurred in 17 (6.8%) patients. TnI was most predictive for cardiac mortality (TnI>or=0.1 microg/l, 10.7% event rate compared with TnI<0.1 microg/l, 0%, P<0.001) and myocardial reinfarction (14.9% compared with 1.7%, P<0.001). The other markers and multimarker strategies had a lower capacity for predicting adverse events apart from myoglobin and the combination of TnI or myoglobin regarding the endpoint of total mortality.

CONCLUSION

The combinations of different markers were prognostically non-superior compared to TnI, which thus, should be preferred as a biochemical marker for risk stratification in patients with chest pain.

Association between cardiac troponin T elevation and angioscopic morphology of culprit lesion in patients with non-ST-segment elevation acute coronary syndrome

BACKGROUND

It is well known that cardiac troponin T (TnT) elevation on admission indicates a high-risk subgroup among patients with non-ST-segment elevation acute coronary syndrome (NSEACS). Although the mechanism of TnT elevation is speculated to be the microthromboembolism from unstable plaques, it has not been clarified. The aim of this study is to clarify the association between the serum TnT elevation and the angioscopically evaluated morphology of culprit lesion in the patients with NSEACS.

METHODS

Among 113 patients with NSEACS who had significant coronary stenosis, 62 patients with successful angioscopic examination were prospectively and consecutively enrolled from October 2001 to August 2002. Patients were divided into 2 groups according to the serum TnT level measured before percutaneous coronary intervention: TnT-positive or TnT-negative group. Thrombus and plaque color at culprit lesion were evaluated by angioscopy and were compared between the groups. Plaque color was determined as yellow or white, and thrombus as none, small, or large. Three different definitions for TnT-positive (> or =0.1, > or =0.03, and > or =0.01 ng/mL) were used and the sensitivity and specificity for detecting thrombus was compared.

RESULTS

Prevalence of thrombus, large thrombus, and yellow plaque were all higher in TnT-positive than in TnT-negative group for 3 different cutoff values of TnT. Angiographic slow-flow occurred more frequently after percutaneous coronary intervention in TnT-positive than in TnT-negative group for 3 different cutoff values of TnT. Sensitivity/specificity of detecting large thrombus were 33%/100%, 44%/91%, and 56%/83% when TnT-positive was defined as TnT > or = 0.1, > or =0.03, and > or =0.01 ng/mL, respectively.

CONCLUSIONS

Serum TnT level was significantly associated with the prevalence of thrombus and yellow plaque at the culprit lesions of NSEACS. Troponin T, when positive was defined as > or =0.01 ng/mL, still have a high specificity for detecting intracoronary thrombus.

Contemporary management of acute coronary syndrome

This review focuses on the modern management of the non-ST elevation acute coronary syndromes (unstable angina and non-ST elevation myocardial infarction). Patients with these syndromes are at varying degrees of risk of (re)infarction and death. This risk can be reliably predicted by clinical, electrocardiographic, and biochemical markers. Aspirin, clopidogrel, heparin (unfractionated or low molecular weight), and anti-ischaemic drugs should be offered to all patients, irrespective of the predicted level of risk. Patients at high risk should also receive a glycoprotein IIb/IIIa receptor inhibitor and should undergo early coronary arteriography with a view to percutaneous or surgical revascularisation. Lower risk patients should undergo non-invasive testing. When inducible myocardial ischaemia is exhibited coronary arteriography should follow. When non-invasive testing is negative, a conservative management strategy is safe.

Serum cardiac troponin T levels as an indicator of myocardial injury in ischemic and hemorrhagic stroke patients

Many studies in the literature have clearly shown the increase in creatine kinase-myocardial subfraction (CK-MB) levels and changes in electrocardiography (ECG) after stroke. However, the studies on cardiac troponin T (cTnT) which is more sensitive and specific to myocardium after stroke are relatively scarce. Moreover, its associations with volume of stroke lesions and type of stroke have not been investigated thoroughly. Thus, the aims of this study were to investigate a predictive value of cTnT in assessing myocardial injury and cardiac dysfunction in different types of stroke (hemorrhagic or ischemic stroke) and its relationship with stroke size and volume. This study included 62 patients (30 males and 32 females) with acute stroke confirmed by computed tomography (CT). Blood samples were obtained within 24 hours of stroke onset to measure the serum levels of creatin kinase (CK), CK-MB, lactate dehydrogenate (LDH), and cTnT. ECG and echocardiography were performed to assess myocardial function and left ventricular ejection fraction (LVEF). Of all patients included in the study, 20 patients (32%) demonstrated elevations in cTnT, while 28 patients (45%) had increased CK-MB levels. Serum levels of cTnT were positively correlated with stroke volume (r = 0.65, p < 0.0001), while inversely correlated with LVEF (r = -0.53, p < 0001). Serum levels of both CK-MB and cTnT were higher in patients with hemorrhagic stroke than those with ischemic stroke but this difference was not significant (p > 0.05). As a conclusion, cTnT has a higher specificity and sensitivity in detecting myocardial injury after stroke of both ischemic and hemorrhagic origins. Measurement of the serum levels of cTnT is of clinical importance in evaluating myocardial injury and provides a useful aid in estimating the volume of stroke lesions.

Survival among hospital in-patients with troponin T elevation below levels defining myocardial infarction

BACKGROUND

Cardiac troponin T (cTnT) has an accepted place in the management of patients presenting with suspected acute coronary syndrome (ACS). Uncertainty remains about the significance and interpretation of elevated cTnT below the cut-off levels defining myocardial infarction (0.1 microg/l).

AIM

To compare the mortality risks for elevation of cTnT in the ranges 0.01-0.029 microg/l, 0.03-0.099 microg/l and <0.01 microg/l.

DESIGN

Retrospective record study in three hospitals.

METHODS

All cTnT measurements with values in the range >0.01-0.099 microg/l analysed during January 2002 were extracted from clinical biochemistry laboratory databases. Following agreed exclusion criteria, 179 patients with cTnT in the range 0.01-0.099 microg/l and 60 patients <0.01 microg/l were selected at random from across the three sites. Six-month follow-up was completed by review of case notes and contact with the patients' GP.

RESULTS

There was a graded increase in mortality with increasing cTnT, although only achieving statistical significance for patients in the 0.03-0.099 microg/l range. The graded increase in relative risk with cTnT was weaker after adjustment for potential confounding factors

DISCUSSION

We found a trend for worse survival with increasing cTnT within the range 0.01-0.099 microg/l in unselected patient populations presenting with possible acute coronary syndrome. This suggests that the combined effects of assay imprecision and co-morbidity should be taken into account when interpreting borderline elevation of cTnT. The use of a cut-off based on current standards of assay precision should be used to define the sensitivity of cTnT as biochemical evidence of ischaemic cardiac damage and as an indicator of mortality risk. This level is likely to be between 0.03 and 0.1 microg/l.

TIMI, PURSUIT, and GRACE risk scores: sustained prognostic value and interaction with revascularization in NSTE-ACS

AIMS

Regarding prognosis, patients with a non-ST elevation acute coronary syndrome (ACS) are a very heterogeneous population, with varying risks of early and long-term adverse events. Early risk stratification at admission seems to be essential for a tailored therapeutic strategy. We sought to compare the prognostic value of three ACS risk scores (RSs) and their ability to predict benefit from myocardial revascularization performed during initial hospitalization.

METHODS AND RESULTS

We studied 460 consecutive patients admitted to our coronary care unit with an ACS [age: 63+/-11 years, 21.5% female, 55% with myocardial infarction (MI)]. For each patient, the Thrombolysis In Myocardial Infarction (TIMI), Platelet glycoprotein IIb/IIIa in Unstable agina: Receptor Suppression Using Integrilin (PURSUIT), and Global Registry of Acute Coronary Events (GRACE) RSs were calculated using specific variables collected at admission. Their prognostic value was evaluated by the combined endpoint of death or MI at 1 year. The best cut-off value for each RS, calculated with receiver operating characteristic curves, was used to assess the impact of myocardial revascularization on the combined incidence of death or MI. Death or MI at 1 year was 15.4% (32 deaths/49 MIs). The best predictive accuracy for death or MI at 1 year was obtained by the GRACE RS (AUC) [area under the curve: 0.715; confidence interval (CI: 0.672-0.756)] but the performance of the PURSUIT RS (AUC: 0.630; CI: 0.584-0.674), and TIMI RS (AUC: 0.585; CI: 0.539-0.631) was also good. We found a statistically significant interaction between the risk stratified by the best cut-off value for the GRACE and PURSUIT RSs and myocardial revascularization, with a better prognosis for the high-risk patients. The high-risk patients represented 36.7, 28.7, and 57.8% of the population, for the GRACE, PURSUIT, and TIMI RSs, respectively.

CONCLUSION

The RSs studied demonstrated a good predictive accuracy for death or MI at 1 year and enabled the identification of high-risk subsets of patients who will benefit most from myocardial revascularization performed during initial hospital stay.

Management and outcomes of lower risk patients presenting with acute coronary syndromes in a multinational observational registry

OBJECTIVE

To document patterns of risk stratification, management practices, and outcomes among patients with acute coronary syndromes (ACS) presenting without high risk features.

PATIENTS

The study was based on 11,885 consecutive patients presenting with non-ST segment elevation ACS enrolled in GRACE (global registry of acute coronary events). Patients without dynamic ST segment changes, positive troponin (or other cardiac markers), or haemodynamic or arrhythmic instability were defined as being at lower risk.

MAIN OUTCOME MEASURES

Management and outcomes were compared with high risk presentations.

RESULTS

Of 11,885 patients presenting with unstable angina or non-ST segment elevation myocardial infarction, 4252 (36%) were regarded as being at lower risk. Functional testing for risk stratification was performed in 1163 of 4207 (28%) lower risk and 1531 of 7521 (20%) high risk patients (p < 0.0001). Coronary angiography was performed in 1930 of 4190 (46%) and 3860 of 7544 (51%), and echocardiography in 1692 of 4190 (40%) and 4348 of 7533 (58%) of lower risk and high risk patients, respectively (p < 0.0001 for both). Over one third of patients did not undergo further risk assessment with angiography or functional testing (2746 of 7437 (37%) high risk, 1499 of 4148 (36%) lower risk, not significant). Death occurring in hospital was more likely in the high risk cohort (41 of 4227 (1.0%) lower risk v 215 of 7586 (2.8%) high risk, p < 0.0001), whereas rates of recurrent angina during admission and readmission were similar in both groups (1354 of 4231 (32%) high risk, 2313 of 7587 (31%) lower risk, not significant). In the six months after discharge, death or myocardial infarction occurred in 79 of 3223 (2.5%) lower risk patients and 302 of 5451 (5.5%) high risk patients (p < 0.0001).

CONCLUSIONS

Globally, further risk stratification after ACS presentation is suboptimal, regardless of presenting characteristics. Although in-hospital death and myocardial infarction are uncommon, recurrent ischaemia is encountered often in both groups. It remains to be seen whether better outcomes may be achieved with wider application of risk stratification and appropriately directed management strategies.

Cardiac troponin I release in acute pulmonary embolism in relation to the duration of symptoms

PURPOSE

To evaluate the release of cardiac troponin I in normotensive patients with acute pulmonary embolism in relation to the duration of symptoms.

METHODS

Fifty-seven normotensive patients with acute pulmonary embolism were included in the study. Patients were divided into two groups based on the duration of symptoms at presentation: symptoms of < or =72 h, group A; symptoms of >72 h, group B. Serum cardiac troponin I levels were measured at presentation.

RESULTS

Mean age was 63+/-18 years and 23 (40%) patients were males. Thirty-three (58%) patients had symptoms of < or =72 h (group A) and 24 (42%) had symptoms of >72 h (group B). Both groups had similar prevalence of right ventricular dysfunction on echocardiography (55% [n=18] in group A vs. 42% [n=10] in group B, p=NS). Sixteen patients had elevated serum cardiac troponin I (mean+/-S.D. 3.3+/-2.3 ng/ml, range 0.6-8.3 ng/ml). Elevated serum cardiac troponin I was strongly associated with right ventricular dysfunction (p=0.015). All patients with elevated serum cardiac troponin I (n=16) were in group A (p<0.0001). Twelve of 18 (67%) patients with (p=0.0005) and 4 of 15 (27%) patients without (p=NS) right ventricular dysfunction had elevated serum cardiac troponin I. Thirteen of 16 (81%) patients with elevated serum cardiac troponin I had duration of symptoms < or =24 h at presentation.

CONCLUSIONS

The dynamics of cardiac troponin I release in acute pulmonary embolism in patients who present with symptoms of < or =72 h duration could be different from those who present with longer duration of symptoms. Therefore, the use of cardiac troponin I in risk stratification of acute pulmonary embolism might be limited to the patients presenting within 72 h of the onset of symptoms.

Cardiovascular outcome in hospitalized patients with minimal troponin I elevation and normal creatine phosphokinase

BACKGROUND

Among patients with acute coronary syndrome, elevated cardiac troponin and creatine phosphokinase MB fraction levels have both prognostic and diagnostic values. However, in hospitalized patients, cardiac biomarkers are measured in a variety of clinical situations including but not limited to acute coronary syndrome. Moreover, these patients may have elevated troponin levels with no increase in creatine phosphokinase MB fraction levels.

OBJECTIVE

To evaluate the cardiovascular outcome of acutely ill, hospitalized patients with minimal troponin I increase with normal creatine phosphokinase MB fraction.

METHODS

We identified 64 patients retrospectively from our database with minimal troponin I increase and normal creatine phosphokinase MB fraction hospitalized between November 1998 and April 2000. Discharged patients were questioned about re-hospitalization for myocardial infarction, unstable coronary syndrome, congestive heart failure and percutaneous coronary intervention by means of a structured questionnaire. For those patients who died during hospitalization, data were collected from hospital records. For patients who died at home or at a different institution, a surviving relative completed the questionnaire. Primary outcomes were death, myocardial infarction and the need for revascularization or re-hospitalization.

RESULTS

Composite endpoint of death, myocardial infarction, percutaneous coronary intervention or coronary artery bypass grafting and re-hospitalization for cardiac cause occurred in 35.95% of patients within 1 year.

CONCLUSIONS

There is a significant composite event rate of death, myocardial infarction or re-hospitalization for cardiac causes in acutely ill, hospitalized patients with normal creatine phosphokinase MB fraction and minimally elevated troponin I, regardless of the cause for hospitalization.

The relationship between trace elements and cardiac markers in acute coronary syndromes

Previous studies have demonstrated increased serum copper and iron levels and decreased selenium and zinc levels in patients with myocardial infarction. Furthermore, the prognostic value of the levels of trace elements in myocardial infarction has been stressed. We examined serum levels of Cu, Fe, Zn and Se, as well as glutathione peroxidase (GPx), a selenoenzyme with antioxidant properties, and C-reactive protein (CRP), a marker of inflammation, in acute coronary syndromes (ACS) regarding their relationship to cardiac troponins and creatine kinase-MB mass (CK-MBm), important prognostic markers. Serum trace elements, GPx activity and CRP were determined in 70 patients with ACS who were admitted within 12 h after the onset. Differences in these parameters were evaluated in three groups of patients divided according to the levels of cardiac markers: group III consisted of patients with high increases in cTnT, cTnI and CK-MBm (> or =0.9 ng/mL, > or =1.0 ng/mL, > or =30 ng/mL, respectively), patients with milder increases in these markers were included in groups II and I consisted of patients with values just above the upper reference limits. Serum Fe levels increased significantly in group II and even more prominently in group III compared to group I (p = 0.04, 0.002, respectively). There was no significant difference between groups II and III. The increase in serum Cu was significant in group III compared to both groups II and I (p = 0.04, 0.001, respectively). There was no significant difference between groups I and II regarding Cu and Zn. The decrease in serum Se and GPx levels was significant only between groups III and I (p = 0.004 for Se and p = 0.0001 for GPx). CRP levels showed a significant increase in group III compared to groups II and I (p = 0.03 and 0.001). CRP showed a significant positive and GPx a significant negative correlation to the cardiac markers cTnT, cTnI and CK-MBm. Cu was positively correlated to all cardiac markers, while the positive correlation between Fe and cardiac markers was significant only for cTnI. Both Zn and Se were negatively correlated to cTnT, and Se was also to cTnI. In conclusion, the increase in serum levels of Cu and Fe and the decrease in serum levels of Zn and Se in patients with higher levels of troponins and CK-MBm imply that trace element levels are related to the degree of myocardial damage and thus may play a role in the pathogenesis of ischemic heart disease. The strong correlations between cardiac markers and both CRP and GPx suggest that these parameters are promising prognostic factors in acute coronary syndromes.

Minor elevations in troponin T values enhance risk assessment in emergency department patients with suspected myocardial ischemia: analysis of novel troponin T cut-off values

BACKGROUND

A consensus document developed by a joint committee of the European Society of Cardiology and the American College of Cardiology redefines myocardial infarction (MI) using an increase of troponin I or T as compared to a reference control population (i.e., troponin T (TnT) of 0.01 microg/l). A clinical problem arises when an arbitrary cut-off point is selected for determination of MI (i.e., TnT> or =0.1 microg/l), as minor elevations of troponin are associated with increased cardiovascular risk in selected patients with acute coronary syndromes.

METHODS

We prospectively studied 420 unselected patients being evaluated for suspected myocardial ischemia in the emergency department (ED). We compared a 99th percentile MI cut-off limit for TnT, determined by constructing a standard receiver operator curve from our ED population in whom an acute coronary syndrome was excluded, to a standard MI cut-off limit of 0.1 microg/l in assessing cardiovascular risk. We also assessed the prognostic value of detectable TnT concentrations below this 99th percentile MI cut-off, but above the upper reference limit of healthy controls.

RESULTS

The diagnosis of acute coronary syndromes (ACS) was more frequent in groups with higher TnT concentrations: 16.8% with a normal TnT (<0.03 microg/l), 29.5% with detectable TnT below the 99th percentile MI limit (0.03-0.066 microg/l), 64.3% with detectable TnT between the 99th percentile and standard MI cut-offs (0.067-0.099 microg/l), and 85.4% with TnT> or =0.1 microg/l (p<0.001 for the trend). Thirty-day cardiovascular event rates increased for any detectable concentration of troponin: 1.3% with normal TnT, 4.8% with detectable TnT below the 99th percentile MI limit, 15.4% with TnT between the 99th percentile and standard MI cut-off limits, and 12.5% with TnT> or =0.1 microg/l (p<0.01 for the trend).

CONCLUSION

Using an MI cut-off concentration for TnT from a "non-ACS reference" improves risk stratification, but fails to detect a positive TnT in 11.7% of subjects with an acute coronary syndrome.

Predictors and prognostic value of myocardial injury following stent implantation

BACKGROUND

Troponin I concentrations are frequently elevated following percutaneous coronary intervention (PCI) even in procedures without complications and are considered, by some, as predictive of long-term morbidity and mortality. We assessed whether post-PCI troponin I concentrations bore any relationship to clinical, angiographic and in-laboratory minor adverse events indicative of myocardial injury and evaluated, in follow-up, whether these levels are useful as a predictive markers of adverse events.

METHODS

Patients (n=147) who were scheduled for PCI for stent placement were prospectively studied. In-laboratory events recorded were protracted chest pain, electrocardiographic changes, slow flows, dissections and lateral branch affectation. Troponin I and creatinine kinase MB fraction (CK-MB) mass were measured at baseline and post-procedure. Mean clinical follow-up was for 10.4+/-3.6 months.

RESULTS

During PCI, at least one adverse event occurred in 34% of patients and, in 38% of them, there was an elevation of troponin I as compared to 5.1% of those patients without any adverse event (relative risk=7.4; P<0.001). Elevation of troponin I concentrations occurred in 16.3% of all patients, 79.2% associated with an AE. CK-MB was elevated in 15.6% of patients. On multivariate analysis, protracted chest pain, lateral branch involvement and slow flow remained statistically significant in relation to post-procedure elevations of troponin I concentrations. Clinical follow-up showed a poorer prognosis in patients who had had elevated troponin I concentrations.

CONCLUSIONS

In-laboratory adverse event predict elevated post-procedure troponin I concentrations which are associated with myocardial injury. These elevations, in turn, predict poorer medium-term clinical outcomes.

Validated risk score predicts the development of congestive heart failure after presentation with unstable angina or non-ST-elevation myocardial infarction: results from OPUS-TIMI 16 and TACTICS-TIMI 18

BACKGROUND

Few data are available about development of congestive heart failure (CHF) in patients with unstable angina/non-ST-elevation myocardial infarction (UA/NSTEMI). We developed and validated a risk score to predict which patients will develop CHF.

METHODS

A subset of 4681 patients from the Orbofiban in Patients With Unstable Coronary Syndromes-Thrombolysis in Myocardial Infarction (OPUS-TIMI 16) trial with UA/NSTEMI and without a history of CHF were included in this analysis and stratified according to the development of CHF at 10 months. A risk score was created from significant variables and validated in the Treat Angina With Aggrastat and Determine Cost of Therapy With an Invasive or Conservative Strategy-Thrombolysis in Myocardial Infarction (TACTICS-TIMI 18) trial. B-type natriuretic peptide (BNP) was then added to the initial multivariate analysis and validated in the TACTICS-TIMI 18 trial.

RESULTS

The incidence of CHF at 30 days was 4.9%, and at 10 months it was 5.6%. Significant variables on multivariate analysis included age >65 years, heart rate >100 beats/min, history of diabetes mellitus, lateral electrocardiographic changes, and history of angiographically confirmed coronary artery disease. The risk of CHF increased 10-fold across the number of risk factors (P <.001). When validated in the TACTICS-TIMI 18 trial, the risk score was significantly associated with CHF at 6 months (P =.01). The median BNP value doubled across the number of risk factors (P <.001 for trend). The addition of BNP to the risk score improved its discriminatory capacity.

CONCLUSIONS

In patients with UA/NSTEMI, a simple clinical risk score can aid in assessing the risk of developing CHF. BNP adds to the predictive capacity of this risk score. This score may assist in identifying patients who warrant more careful monitoring and therapy for CHF prevention inhospital and during follow-up.

Classification and risk stratification of patients with acute chest pain using a low discriminatory level of cardiac troponin T

BACKGROUND

Cardiac troponins are the biochemical markers of choice for the evaluation of acute coronary syndromes (ACS). Using the first-generation test, most studies related adverse outcome to > 0.20 or 0.10 microg/l cardiac troponin T (cTnT) levels. With the highly sensitive and specific second- and third-generation assays, cTnT is undetectable in most healthy individuals.

HYPOTHESIS

We evaluated whether a lower cTnT level, within 24 h of admission, could indicate an increased risk of future complications.

METHODS

During 1998-1999, clinical data were collected in 260 patients with ACS. Cardiac troponin T was measured at arrival, and 4, 8, and 12-24 h thereafter. The maximum cTnT value was then used to assess, over a 15-month follow-up period, the cumulative risk of death or myocardial infarction (MI), as well as rates of events according to quartiles of cTnT values.

RESULTS

Patients with < or = 0.03 microg/l cTnT levels had the lowest rate of adverse events and the best Kaplan-Meier event-free survival curve. Increasing cTnT levels were associated with stepwise increases in mortality rates and with a constant 10-fold increase in MI rates during follow-up.

CONCLUSIONS

A low threshold cTnT elevation is recommended to assess the risk of ACS. All cTnT elevations > 0.03 microg/l predict a higher risk of MI during follow-up, whereas increasing values predict mortality in relation to the amount of elevation.

Diagnostic efficacy of biochemical markers in diagnosis post-mortem of ischaemic heart disease

In forensic medicine, there is a need for more sensitive biochemical markers for the post-mortem diagnosis of acute myocardial infarction. A study of the distribution of biochemical markers in different fluids is of great significance in post-mortem diagnosis, because their distribution depends on the location of tissue damage and release kinetics. The aim of this study is to compare the sensitivities and specificities of creatine kinase-MB (CK-MB), myoglobin and cTnI in serum and pericardial fluid for the post-mortem diagnosis of acute myocardial infarction (AMI). We studied 188 cadavers selected during 1 year from medicolegal autopsies. The groups were as follows: (1) myocardial infarction (n = 52); (2) asphyxia (n = 59); (3) multiple trauma (n = 41); (4) natural deaths excluding myocardial infarction (n = 36). We obtained statistically significant differences in pericardial fluid for all the biochemical markers, the highest levels being obtained in the group of cadavers who had died from myocardial infarction. A common factor is the high negative predictive value found in biochemical markers, which is contrary to the findings obtained in clinical practice, when the percentages of sensitivity are very high.

Impact of the recommendations for the redefinition of myocardial infarction on diagnosis and prognosis in an unselected United Kingdom cohort with suspected cardiac chest pain

We prospectively and blindly assessed the diagnostic and prognostic impact of implementation of the European Society of Cardiology/American College of Cardiology recommendations for redefinition of myocardial infarction (MI) in an unselected cohort of patients with suspected cardiac chest pain, with particular attention to prespecified clinical groups. All patients admitted to our institute with suspected cardiac chest pain were enrolled. Physicians provided usual care using serial electrocardiograms/creatine kinase (CK)/aspartate transaminase according to World Health Organization (WHO) criteria for MI, while blinded to additional measurements of cardiac troponin T (cTnT) and CK-MB mass. After discharge, diagnoses based on WHO and new criteria were compared, and major adverse cardiac events monitored for 6 months. Implementation of the new recommendations classified an additional 26.1% of patients as having MI compared with WHO criteria, and produced an overall diagnostic alteration in 11.5%. Two thirds of the additional patients with MI were previously diagnosed with unstable angina, whereas one third had "other cardiac" or "noncardiac" diagnoses. A similar MI cohort to the cTnT diagnosis was identified using a CK-MB mass discriminator value of 5 microg/L, but not 10 microg/L. The 6-month prognosis was similar in patients diagnosed with MI by new (cTnT) and WHO criteria, with the new criteria thus identifying a further high-risk cohort in the WHO negative group. In our cohort, the new Joint European Society of Cardiology/American College of Cardiology recommendations identify one fourth more patients as having MI. The 6-month prognosis of those patients reclassified as having MI was similar to those diagnosed with MI by both criteria.

Do we need additional markers of myocyte necrosis: the potential value of heart fatty-acid-binding protein

Heart fatty-acid-binding protein (FABP) is a small cytosolic protein that is abundant in the heart and has low concentrations in the blood and in tissues outside the heart. It appears in the blood as early as 1.5 h after onset of symptoms of infarction, peaks around 6 h and returns to baseline values in 24 h. These features of H-FABP make it an excellent potential candidate for the detection of acute myocardial infarction (AMI). We review the strengths and weaknesses of H-FABP as a clinically applicable marker of myocyte necrosis in the context of acute coronary syndromes.

Implication of different cardiac troponin I levels for clinical outcomes and prognosis of acute chest pain patients

OBJECTIVES

We compared outcomes in patients with non-ST-segment elevation acute coronary syndromes (ACS) according to the degree of cardiac troponin I (cTnI) elevation.

BACKGROUND

Controlled trials of high-risk patients have found that troponin elevations identify an even higher risk subset. It is unclear whether outcomes are similar among a lower risk, heterogeneous patient group. Also, few studies have reported outcomes other than myocardial infarction (MI) or death, based on the peak troponin value.

METHODS

Consecutively, admitted patients without ST-segment elevation on the initial electrocardiogram underwent serial marker sampling using creatine kinase (CK), CK-MB fraction, and cTnI. Patients were grouped according to peak cTnI: negative = no detectable cTnI; low = peak greater than the lower limit of detectability but less than the optimal diagnostic value; intermediate = peak greater than or equal to the optimal diagnostic value but less than the manufacturer's suggested upper reference limit (URL); and high = peak greater than or equal to the URL. Thirty-day outcomes included cardiac death, MI based on CK-MB, revascularization, significant disease, and a reversible defect on stress testing. Six-month mortality was also determined. Negative evaluations for ischemia included nonsignificant disease, no reversible stress defect, and negative rest perfusion imaging.

RESULTS

Of the 4,123 patients admitted, 893 (22%) had detectable cTnI values. Cardiac events and positive test results at 30 days and 6-month mortality increased significantly with increasing cTnI values. Negative evaluations for ischemia were significantly and inversely related to peak cTnI values. Although adverse events were significantly more common in patients with a low cTnI value than in those with negative cTnI, negative evaluations for ischemia were frequent.

CONCLUSIONS

Increased cTnI values are associated with worse outcomes. Although low cTnI values are associated with adverse events, they do not have the same implication as higher cTnI values, and nonischemic evaluations are frequent.

A rapid troponin I assay is not optimal for determination of troponin status and prediction of subsequent cardiac events at suspicion of unstable coronary syndromes

BACKGROUND

Troponin is a specific marker of myocardial damage. For early prediction of coronary events in patients with suspicion of acute coronary syndromes the assay also needs to be highly sensitive.

METHODS AND RESULTS

A rapid troponin I assay was performed prior to inclusion in 4447 acute coronary syndrome patients in the GUSTO-IV trial. A quantitative troponin T analysis was later performed on blood samples obtained at randomization by a central laboratory. There was an agreement between the rapid troponin I assay and troponin T (< or =/>0.1 microg/l) in 3596 (80.9%) patients. A positive rapid troponin I was identifying any elevation of troponin T (>0.01 microg/l) in 1990 patients (90.4%) whereas a negative rapid troponin I was corresponding to negative troponin T (< or =0.01 microg/l) in only 1217 patients (54.2%). Patients with a positive versus negative rapid troponin I had an increased risk of death or myocardial infarction at 30 days (9.3 vs. 5.9%; odds ratio, O.R. 1.64; 95% confidence interval, 1.31-2.06). Troponin T elevation (>0.1 microg/l) provided a better (10.5 v. 4.9%, O.R. 2.26; C.I. 1.79-2.85) risk stratification. Regardless of a positive or a negative rapid troponin I, the troponin T result (>0.1 vs. < or =0.1 microg/l) stratified the patients into high and low risk of events at 30 days, (10.3 vs. 5.7%, P=0.002) and (11.5 vs. 4.8%, P<0.001), respectively.

CONCLUSION

In a population with non-ST elevation acute coronary syndrome a positive rapid troponin I assay is a specific indicator of troponin elevation and a predictor of early outcome. However, a negative rapid troponin I is not a reliable indicator of the absence of myocardial damage and does not indicate a low risk of subsequent cardiac events. A rapid troponin I assay was performed prior to inclusion in 4447 acute coronary syndrome patients in the GUSTO-IV trial and related to a centrally analyzed quantitative troponin T test. A positive rapid troponin I was well corresponding to any elevation of troponin T (>0.01 microg/l) and predicted an unfavorable outcome at 30 days. However, a negative rapid troponin I was corresponding to troponin T < or =0.01 microg/l in only half of the patients. Troponin T >0.1 microg/l vs. < or =0.1 microg/l provided a better risk stratification than the rapid troponin I result. For patients with troponin T elevation (>0.1 microg/l) the 30 day event rate was high regardless of the rapid troponin I result.

Office Cardiologists Cooperative Study on Whole Blood Rapid Panel Tests in Patients With Suspicious Acute Myocardial Infarction

BACKGROUND

The whole blood rapid troponin T test, used to determine the early diagnosis of acute myocardial infarction (AMI), is effective only for 3-4 h after onset.

METHODS AND RESULTS

The present office cardiologists cooperative study compared the diagnostic efficacy of a newly developed whole blood rapid panel test for heart-type fatty acid-binding protein (H-FABP) with that of the rapid troponin T test in 129 consecutive patients with suspicious AMI according to certain time-frames from onset to presentation. Thirty-one patients (24.0%) had a final diagnosis of AMI. The respective sensitivities of the rapid H-FABP and troponin T tests were 100% vs 50% (p<0.05) for patients presenting within 3 h of onset; 75% vs 0% for those between 3 and 6 h; 100% vs 60% for those between 6 and 12 h; and 100% vs 100% for those presenting later than 12 h. The respective specificities were 63% vs 96.3% (p<0.05); 93.8% vs 93.8%; 72.7% vs 100%; and 75.0% vs 87.5%. Negative predictive value was 100% vs 86.7%; 93.8% vs 78.9%; 100% vs 84.6%; and 100% vs 100%, respectively. Patients with non-AMI myocardial damage associated with unstable angina or severe heart failure showed positive H-FABP test results and blunted the specificity.

CONCLUSIONS

When using the novel rapid H-FABP test, cardiac emergency triage to exclude non-AMI patients should be effectively organized within 3 h of onset.

Risk stratification in patients with unstable angina and non-ST-elevation myocardial infarction

Risk stratification in acute coronary syndromes is important both for prognosis and for treatment. Consistently, using any of a variety of clinical predictors of risk, patients at highest risk for poor outcomes derive the greatest benefit from aggressive therapy with early coronary angiography, glycoprotein IIb/IIIa antagonists, or low molecular weight heparins. By contrast, patients at low risk may be managed conservatively without long-term impact on their risk of death or myocardial infarction. Several clinical and laboratory parameters have been identified as independent, powerful predictors of poor outcome, helping to distinguish high-risk from low-risk patients. Although not a substitute for astute clinical judgment, risk prediction scores may help clinicians to synthesize the relevant clinical data at presentation into an overall assessment of risk, allowing for cost-effective utilization of therapies that add significant expense and morbidity. With the ever-expanding range of pharmacologic and interventional therapies that impact the treatment of patients with unstable angina and non-ST-elevation myocardial infarction (NSTEMI), risk stratification will become increasingly important in targeting therapies to those who are likely to achieve the most benefit. In this review, we first consider the identifiable components of risk in patients presenting with unstable angina or NSTEMI and then evaluate the emerging information regarding differential response to treatment based on the presence of these risk factors.

Sensitivity of acute rest myocardial perfusion imaging for identifying patients with myocardial infarction based on a troponin definition

BACKGROUND

Myocardial perfusion imaging (MPI) is often used to identify low-risk chest pain patients who have myocardial infarction (MI). A recent recommendation is that patients with increased troponin levels be diagnosed as having MI. The sensitivity and characteristics of patients who have elevated troponin levels who also underwent early MPI are unknown.

METHODS AND RESULTS

Patients considered at low risk for MI underwent rest gated tomographic MPI and serial marker assessment as part of a standard chest pain evaluation protocol. Patients with cardiac troponin I (cTnI) elevations were analyzed further for this study. MPI results were considered positive if there was a perfusion defect in association with abnormal wall motion or thickening. Short-axis images were divided into 17 segments and graded on a 4-point scale (0, normal; 3, high-grade or absent perfusion), and a summed rest score was derived. Of the 319 patients who had MPI and cTnI elevations, 78 had negative MPI results (sensitivity, 75%). Patients with negative MPI results had lower peak creatine kinase (CK)-MB values (15 +/- 25 ng/mL vs 45 +/- 78 ng/mL, P <.0001) and higher ejection fractions (56% +/- 15% vs 47% +/- 13%, P <.0001) and were less likely to have significant disease (55% vs 72%, P =.04) than those with positive MPI results. Increasing summed rest score was associated with larger MIs as estimated by peak CK and CK-MB values.

CONCLUSIONS

Patients with negative MPI results have smaller MIs and less extensive coronary disease. MPI and cTnI offer complementary data for assessing patients with possible MI.

C-reactive protein and myocardial infarction during percutaneous coronary intervention

OBJECTIVE

To evaluate the prognostic information of preprocedural C-reactive protein (CRP) levels in serum to predict myocardial infarction during percutaneous coronary interventions (PCI).

DESIGN

Prospective study.

SETTING

University hospital.

PATIENTS

A total of 400 consecutive patients with normal serum troponin T levels (</=0.03 microg L-1) presenting with stable or unstable angina pectoris.

INTERVENTIONS

PCI.

MAIN OUTCOME MEASURES

C-reactive protein levels in serum measured by a high sensitive method. Myocardial infarction defined as a serum troponin T elevation the day after PCI to a level >0.05 microg L-1.

RESULTS

Eighty-three patients (21%) experienced a myocardial infarction during PCI. The median value of CRP before the procedure was 1.83 (0.12-99.7) mg L-1. No difference was seen in CRP levels before PCI between patients without or with myocardial infarction during PCI. Multivariate analysis identified stent implantation (OR 2.68, 95% CI 1.18-7.28, P = 0.03), procedure time (OR 2.15, 95% CI 1.28-3.67, P < 0.005) and complications during the procedure (OR 3.62, 95% CI 1.72-7.58, P < 0.001) as independent predictors of myocardial infarction during PCI.

CONCLUSION

Increased CRP levels in serum before PCI were not associated with myocardial infarction during the procedure. Furthermore, patients with an expected long procedure and a high probability of stent implantation have an increased risk of developing myocardial infarction during PCI. This finding may be useful to help the operator to decide the antithrombotic regime before, during and after the procedure and the need for observation after the procedure.

Prognostic Importance of Predischarged Troponin T Levels in Acute Anterior Myocardial Infarction

The baseline cardiac troponin T (cTnT) level strongly predicts short-term mortality in acute coronary syndromes, but the added value of predischarged (7th day) measures to predict short-term outcome and left ventricular (LV) remodeling in patients with ST elevation myocardial infarction (MI) is controversial. Baseline, peak and predischarged cTnT results were evaluated in 52 patients (15 females, 37 males, mean age, 54.4 +/- 8.8 years) with first acute anterior MI. There were 4 deaths (all cardiac origin) during the 30 day follow up period. Kaplan-Meier analysis revealed patients with a predischarged serum cTnT level higher than the median level (1.2 ng/mL) had a higher mortality rate than those with submedian levels (P < 0.05). Additionally, the highest correlation rate was found between predischarged cTnT values and LV ejection fraction (LV-EF, r = -0.58, P < 0.002). There were no differences between the groups in the 7th day left ventricular diastolic parameters, but the 30th day isovolumetric relaxation time and mitral E wave deceleration time were shorter (146.9 +/- 30.1 vs 129 +/- 23.4 msec, P = 0.025 and, 185.8 +/- 51.8 vs 144.6 +/- 58.1 msec, P = 0.012) in patients with higher predischarged cTnT level. High levels of predischarged cTnT levels in patients admitted with first acute anterior MI defines a subgroup. These patients have poor systolic and diastolic functions and are at increased risk of short term mortality. This group of patients may have benefit from early intensive treatment strategies before discharge.

Sources of diagnostic inaccuracy of conventional versus new diagnostic criteria for myocardial infarction in an unselected UK population with suspected cardiac chest pain, and investigation of independent prognostic variables

OBJECTIVE

To assess the degree and sources of current diagnostic inaccuracy of serial conventional cardiac markers and ECGs compared with the new diagnostic criteria for myocardial infarction, with specific reference to physician specialty and the prognostic value of troponin T.

DESIGN

Prospective, blinded observational study.

SETTING

University hospital.

PATIENTS AND INTERVENTIONS

All suspected cardiac chest pain admissions for six months, with additional blinded measurement of CK-MB mass and troponin T. World Health Organization and new criteria myocardial infarction diagnoses were made by an expert panel.

MAIN OUTCOME MEASURES

Diagnostic adjustment by expert panel; completeness of serial measurements; six months prognosis.

RESULTS

A complete set of serial cardiac markers was not taken in 38.7% of patients, this being twice as likely when managed by non-cardiologists than by cardiologists (p < 0.0001). The WHO myocardial infarction diagnosis was adjusted by the expert panel in 4% of cases, this being 90% more likely in patients admitted under non-cardiologists (p = 0.026). The new criteria for myocardial infarction identified an additional 27.3% of infarcts, with a diagnostic alteration in 12.0% of the cohort; 45.2% of these cases had a potentially preventable cause for diagnostic adjustment. Only troponin T (p = 0.0004), ST depression (p = 0.003), and heart failure (p = 0.016) were independently predictive of prognosis.

CONCLUSIONS

Chest pain patients appear less likely to be fully and accurately assessed by non-cardiologists than by cardiologists. The new criteria for myocardial infarction identify approximately 25% of additional patients as MI, with potential additional advantages related to simplicity of diagnostic protocols. Troponin T was the most potent predictor of six month prognosis in an unselected cohort of chest pain admissions.

Cardiac troponin T and I and creatine kinase-MB as markers of myocardial injury and predictors of outcome following percutaneous coronary intervention

AIMS

This study was performed to determine the most sensitive biochemical marker for the detection of cardiac myocyte damage potentially sustained during percutaneous coronary intervention (PCI) and to assess whether such a marker can be used to identify patients at increased risk of poor subsequent clinical outcome.

METHODS AND RESULTS

We studied 109 consecutive patients presenting with clinical stable and unstable angina and undergoing PCI at our institution. Blood was sampled for creatine kinase-MB (CK-MB), cardiac Troponin T (cTnT) and I (cTnI) immediately before and at 6, 14 and 24 h post-PCI. Five patients with raised cardiac markers pre-PCI were excluded from further analysis. The occurrence of major adverse cardiac events (MACE) was documented in-hospital, at 30 days and at long-term clinical follow up of up to 20 months. MACE occurred in 26/109 (24%) patients: death=1, QWMI=4, NQWMI=5, repeat PCI=16 (nine target vessel revascularisations and seven de-novo lesions), CABG=5. cTnI had the highest detection rate for myocardial damage, with 58 cTnI-positive patients, 38 cTnT-positive patients and 28 CK-MB-positive patients in the 24 h following PCI (Pearson's Chi square test, P<0.01). The type of interventional strategy per se was not significantly associated with post-procedural cardiac marker concentrations (Kruskal-Wallis ANOVA, P>0.05). There was a significant association between post-procedural cardiac marker concentrations of CK-MB, cTnT and cTnI and the occurrence of procedural angiographic complications (P=0.0003, 0.0002, 0.001, respectively). All three markers, at each sampling time point between 6 and 24 h post-PCI, showed a significant predictive relationship with MACE in-hospital and at long-term follow up (ROC curve AUC analysis, P<0.05). All three markers provided equally predictive information at each of the three post-procedural sampling time points between 6 and 24 h following PCI. All levels of cardiac marker elevation above the clinically discriminant cut-off values were significantly predictive of outcome at long-term follow up.

CONCLUSIONS

cTnI proved to be the most sensitive marker in detecting myocardial necrosis following PCI. CK-MB, cTnT and cTnI all provided similarly reliable prognostic information, with cTnT and cTnI being marginally superior in predicting MACE at follow up.

Clinical Predictors of 30-day Cardiac Events in Patients with Acute Coronary Syndrome at a Community Hospital

OBJECTIVE

We sought to determine predictors of coronary events (cardiac death, acute myocardial infarction, and urgent revascularization) within 30 days after admission.

METHODS

We prospectively collected data on 400 patients admitted through our emergency room for unstable angina and acute coronary syndromes. Patients with ST-segment elevation myocardial infarction and those who required thrombolysis were excluded.

RESULTS

Of 383 patients who were eligible, 120 patients had coronary events within 30 days. Statistically significant variables associated with coronary events were advanced age, male sex, family history of premature coronary artery disease (CAD), diabetes mellitus, tobacco abuse, prior congestive heart failure, prior myocardial infarction, and history of CAD. Symptoms at presentation associated with cardiac events were typical angina and shortness of breath. Objective measures of ischemia associated with cardiac events were elevated troponin T, elevated creatine kinase MB, and ischemic electrocardiographic changes. Using forward stepwise regression analysis, we generated a model to predict 30-day major adverse cardiac events. The strongest predicting variable was serum troponin T (accounting for 33% of predicting r2, P < 0.001) followed by typical angina (r2 increasing to 37%), ischemic electrocardiographic changes (40%), prior CAD (42%), family history of premature CAD (44%), shortness of breath (46%), and positive creatine kinase MB (48%). The positive predictive power of the complete model was r2 = 48%, P < 0.001.

CONCLUSION

Our model incorporating elements from the patient's demographic, medical history, presentation, and ischemic assessment identified 48% of patients presenting with unstable angina and acute coronary syndromes who will suffer a major adverse cardiac event within 30 days of admission. Although the strongest predictor was identified as serum troponin T, other clinical criteria offered improvement in our predictive abilities. Therefore, good initial clinical evaluation in addition to simple tests such as serum cardiac markers and electrocardiography are valuable in risk stratification of patients presenting with acute coronary syndromes and cardiac chest pain. Additional testing may be necessary to improve the positive predictive value of the model. Cardiac enzymes and electrocardiographic changes have the highest negative predictive value for occurrence of major adverse cardiac events. Identification of high-risk patients is essential to direct resources toward these patients and to avoid unnecessary costs and risk to the low-risk population.

Evaluation of patients with suspected acute coronary syndromes in the emergency department

Patients complaining of chest pain (CP) who visit the emergency department (ED) represent the second cause of consultation in this department, and 20-30% of hospital admissions for medical reasons. These patients form a somewhat heterogeneous group with many different aetiologies and degrees of severity. In this setting, the clinical objectives include the prompt identification of patients with acute coronary syndromes (ACSs), the prompt evaluation of the immediate risk (i.e., initial risk stratification) of cardiovascular complications in order to tailor the treatment for each individual patient and to make the best use of hospital resources, and the prompt identification of patients with other potentially severe diseases. The diagnosis of ACS in patients coming to the ED for CP or any equivalent angina is one of the most difficult diagnostic challenges facing physicians in the ED. The correct diagnosis and risk stratification of these patients has clinical consequences, as well as very important legal and economic implications. The only methodology with a clear clinical impact on diagnosis, risk stratification and initial management is clinical evaluation based on data obtained by questioning the patient, carrying out a physical examination, and interpreting the results of a standard 12-lead electrocardiogram (ECG). Nevertheless, its combined diagnostic efficiency for ACS is imperfect and additional strategies are emerging which include serial ECG, the detection of serum biochemical markers of myocardial necrosis, exercise testing, and radionuclide myocardial perfusion imaging.

Myocardial perfusion imaging versus biochemical markers in acute coronary syndromes

The assessment and appropriate clinical management of patients with acute chest pain and non-diagnostic electrocardiograms remain a continuing clinical problem. Accordingly, there is considerable interest in evaluating new strategies to improve early diagnostic accuracy in patients with possible acute myocardial ischaemia. Cardiac troponins (T and I) and acute rest myocardial perfusion imaging have similar sensitivities for detecting acute myocardial infarction. Whereas cardiac markers require 6-12 h to become positive, acute rest myocardial perfusion imaging immediately reflects the status of regional myocardial blood flow at the time of radiopharmaceutical injection. The measurement of cardiac troponins is particularly useful in the diagnosis and estimation of the degree of myocardial injury in those patients with a high likelihood of coronary artery disease and myocardial necrosis and for prognostication of adverse cardiac events in those patients with unstable angina. In contrast, the most appropriate use of acute rest myocardial perfusion imaging is in the setting of patients with acute ischaemic symptoms, non-diagnostic electrocardiogram and a low likelihood of myocardial necrosis, in which early imaging will assist in effective triage decisions.

Impact of the troponin standard on the prevalence of acute myocardial infarction

BACKGROUND

Recent recommendations are that troponin should replace creatine kinase (CK)-MB as the diagnostic standard for myocardial infarction (MI). The impact of this change has not been well described. Our objective was to determine the impact of a troponin standard on the prevalence of acute non-ST-elevation MI.

METHODS

The current study was a retrospective analysis of consecutive patients without ST-segment elevation admitted for exclusion of myocardial ischemia to an inner city urban tertiary care center. All patients underwent serial marker sampling (CK, CK-MB, and cardiac troponin I [cTnI]). Patients with ST elevation consistent with acute MI (n = 130) or who did not have an 8 hour cTnI (n = 124) were excluded. The impact of 3 different cTnI diagnostic values were examined in 2181 patients: the lower limit of detectability (LLD); an optimal diagnostic value (OPT), chosen using receiver operator characteristic curve analysis; and the manufacturer's suggested upper reference level (URL), when compared to a gold standard CK-MB MI definition. In addition, MI prevalence was assessed using different CK-MB MI definitions and evaluated in patients with ischemic changes only.

RESULTS

The prevalence CK-MB MI was 7.8%. Using the various cTnI diagnostic values, the incidence of MI increased the prevalence by 28% to 195%. Using the optimal diagnostic value for cTnI, patients with cTnI elevations not meeting CK-MB MI criteria had an intermediate 30-day mortality (5.4%) compared to those with CK-MB MI (7.1%). Grouping the cTnI positive, CK-MB MI negative patients with the CK-MB MI patients rather than the non-CK-MB MI patients reduced mortality for both the MI (to 5.9%) and non-MI groups (from 1.9% to 1.6%).

CONCLUSIONS

Changing to a troponin standard will have a substantial impact on the number of patients diagnosed with MI. The revised definition for MI will have important clinical and health care implications.

A new scoring system to stratify risk in unstable angina

BACKGROUND

We performed this study to develop a new scoring system to stratify different levels of risk in patients admitted to hospital with a diagnosis of unstable angina (UA), which is a complex syndrome that encompasses different outcomes. Many prognostic variables have been described but few efforts have been made to group them in order to enhance their individual predictive power.

METHODS

In a first phase, 473 patients were prospectively analyzed to determine which factors were significantly associated with the in-hospital occurrence of refractory ischemia, acute myocardial infarction (AMI) or death. A risk score ranging from 0 to 10 points was developed using a multivariate analysis. In a second phase, such score was validated in a new sample of 242 patients and it was finally applied to the entire population (n = 715).

RESULTS

ST-segment deviation on the electrocardiogram, age > or = 70 years, previous bypass surgery and troponin T > or = 0.1 ng/mL were found as independent prognostic variables. A clear distinction was shown among categories of low, intermediate and high risk, defined according to the risk score. The incidence of the triple end-point was 6 %, 19.2 % and 44.7 % respectively, and the figures for AMI or death were 2 %, 11.4 % and 27.6 % respectively (p < 0.001).

CONCLUSIONS

This new scoring system is simple and easy to achieve. It allows a very good stratification of risk in patients having a clinical diagnosis of UA. They may be divided in three categories, which could be of help in the decision-making process.

Use of a whole blood rapid panel test for heart-type fatty acid-binding protein in patients with acute chest pain: comparison with rapid troponin T and myoglobin tests

PURPOSE

We sought to determine the clinical utility of a newly developed qualitative test to measure heart-type fatty acid-binding protein levels in blood for the early identification of myocardial infarction.

METHODS

We measured heart-type fatty acid-binding protein levels in 371 consecutive patients with acute chest pain and suspected myocardial infarction, and compared the performance of this test with those of troponin T and myoglobin tests. Levels of heart-type fatty acid-binding protein >or=6.2 ng/mL were considered as positive results.

RESULTS

A final diagnosis of acute myocardial infarction was made in 181 patients (49%). Of the 68 patients who presented within 2 hours of the onset of symptoms, 37 (54%) had a final diagnosis of myocardial infarction. The sensitivity of the rapid heart-type fatty acid-binding protein test was 89% (33/37), significantly higher than for troponin T (22% [8/37]; P<0.001) and myoglobin (38% [14/37]; P<0.001). However, the specificity of troponin T (94% [29/31]) was significantly better than for heart-type fatty acid-binding protein (52% [16/31]; P= 0.002) within 2 hours. The area under the receiver operating characteristic curve for heart-type fatty acid-binding protein levels was greater than that for myoglobin (0.72 vs. 0.61, P = 0.01) among patients who presented within 2 hours.

CONCLUSION

A novel whole blood rapid heart-type fatty acid-binding protein test can be useful in the early evaluation of patients who present with acute chest pain.

Troponin T levels and risk of 30-day outcomes in patients with the acute coronary syndrome: prospective verification in the GUSTO-IV trial

BACKGROUND

A third-generation troponin T assay with improved precision and a lower detection limit has been developed. However, the appropriate cutoff for identifying patients with the acute coronary syndrome who are at low risk of subsequent mortality has not been established.

METHODS

A retrospective evaluation of data from the Fragmin and fast Revascularization during InStability in Coronary artery disease II (FRISC-II) trial suggested that a cutoff below 0.1 microg/L for troponin T levels might be more useful in risk stratification. A prospective validation of two cutoff levels (0.03 microg/L and 0.01 microg/L) was performed in 7115 patients with non-ST-elevation acute coronary syndrome from the Global Utilization of Strategies To open Occluded arteries IV (GUSTO-IV) trial.

RESULTS

Patients with troponin T levels >0.1 microg/L had greater 30-day mortality (5.5% [201/3679]) than did those with levels <or=0.1 microg/L (2.2% [75/3436], P <0.001). A cutoff value of 0.03 microg/L provided better discrimination between high and low risk: 5.1% (234/4552) versus 1.6% (42/2563). However, a cutoff value at the lower limit of detection, 0.01 microg/L, provided the best discrimination: 5.0% (254/5123) versus 1.1% (22/1992) (P<0.001). This cutoff level had the highest negative predictive value; it also discriminated best for the combined endpoint of death and myocardial infarction.

CONCLUSION

Using a cutoff of <or=0.01 microg/L for the third-generation troponin T assay, the detection level of the assay, is useful for identifying patients with the acute coronary syndrome who are at low risk of subsequent mortality.

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.

The increasing impact of laboratory medicine on clinical cardiology

The practice of cardiology continues to evolve along with a better understanding of the pathophysiology of cardiovascular disease and the development of new therapeutic procedures. Consequently, new demands are being made on the in vitro diagnostics industry to improve the performance of existing cardiac markers and to develop novel markers for new cardiac disease indications. Indeed, in the last 20 years there has been a progressive increase in new laboratory tests for markers of cardiac diseases. Several highly sensitive and/or specific assays for the detection of myocardial ischemic damage as well as some immunoassays for cardiac natriuretic hormones, now considered a reliable marker of myocardial function, have become commercially available. In parallel, a growing number of some novel risk factors, which can be assessed and monitored by laboratory methods, have been added to the classical risk factors for cardiovascular disease. Finally, the recent explosion of genetic analysis may soon place at the clinical cardiologist's disposal many laboratory tests for defining the diagnosis at the molecular level, assessing new risk factors, and better targeting the pharmaceutical approaches in patients with cardiovascular disease. In the present article, after a brief description of the analytical tests included in these four groups, each group's impact on clinical cardiology is discussed in detail.