Cardiac troponin T in chest pain unit patients without ischemic electrocardiographic changes: angiographic correlates and long-term clinical outcomes

Effect of ischaemic postconditioning on markers of myocardial injury in ST-elevation myocardial infarction: a meta-analysis

OBJECTIVES

This study aimed to perform a meta-analysis of the short-term impact of ischaemic postconditioning (IPoC) on myocardial injury in ST elevation myocardial infarction (STEMI) using surrogate cardiac biomarkers.

METHODS

Eligible studies were identified using several article databases. Randomised controlled trials published between 1 January 2000 and 1 December 2021 comparing IPoC to standard of therapy in STEMI patients were included in the search. Outcomes included surrogates of myocardial injury, specifically peak troponin, creatine-kinase (CK) and CK myoglobin binding (CK-MB) enzyme levels.

RESULTS

11 articles involving 1273 patients reported on CK-MB and 8 studies involving 505 patients reported on CK. Few studies used troponin as an outcome, thus, a subanalysis of troponin dynamics was not performed. Meta-regression analysis demonstrated no significant effect of IPoC on peak CK-MB (effect size -0.41, 95% CI -1.15 to 0.34) or peak CK (effect size -0.42, 95% CI -1.20 to 0.36). Linear regression analysis demonstrated a significant correlation between a history of smoking and CK-MB in the IPoC group (p=0.038).

CONCLUSIONS

IPoC does not seem to protect against myocardial injury in STEMI, except possibly in smokers. These results resonate with some studies using imaging techniques to ascertain myocardial damage. More research using troponin and cardiac imaging should be pursued to better assess the effects of IPoC on cardiovascular outcomes in STEMI.

Association of Cardiac Troponin T Concentration on Admission with Prognosis in Critically Ill Patients without Myocardial Infarction: A Cohort Study

Purpose

To investigate the association of cardiac Troponin T (cTnT) with prognosis in critically ill patients without myocardial infarction.

Methods

Adult patients admitted to the intensive care units (ICUs) of the Beth Israel Deaconess Medical Center between 2008 and 2019 who were free of myocardial infarction with a length of ICU stay ≥24 hours and available cTnT records within 24 hours before and after ICU admission were included. The association between cTnT on ICU admission and hospital mortality was evaluated by multivariable logistic regression analysis. The discrimination capacity of cTnT on ICU admission for predicting hospital mortality was examined by receiver operating characteristic (ROC) analysis.

Results

A total of 2960 patients were included. Elevated cTnT (>0.01 ng/mL) was observed in 2730 (92.23%) patients with a higher hospital mortality compared to normal cTnT (11.21% versus 7.39%, P=0.075). There was no statistically significant association between elevated cTnT on ICU admission and hospital mortality (adjusted odds ratio 1.50, 95% confidence interval (CI) 0.88–2.57). Poor discrimination capacity was found for cTnT on ICU admission to predict hospital mortality (area under the ROC curve 0.48, 95% CI 0.44–0.53).

Conclusion

cTnT on ICU admission has limited prognostic value in critically ill patients without myocardial infarction.

Sex differences in long-term clinical outcomes of acute myocardial infarction according to the presence of diabetes mellitus

BACKGROUND/AIMS

This study compared long-term clinical outcomes between male and female acute myocardial infarction (AMI) patients with and without diabetes mellitus (DM).

METHODS

From November 2011 to December 2015, 13,104 patients with AMI were enrolled in the Korea Acute Myocardial Infarction Registry National Institutes of Health (KAMIR-NIH) (4,458 diabetic patients and 8,646 non-diabetic patients). Propensity score matching (PSM) was used to reduce bias due to confounding variables. Following PSM, 2,046 diabetic patients, 1,023 males (69.8 ± 9.4 years) and 1,023 females (69.9 ± 9.4 years); and 3,412 non-diabetic patients, 1,706 males (70.0 ± 10.4 years) and 1,706 females (70.4 ± 10.8 years) were analyzed. Clinical outcomes were compared between male and female patients with and without diabetes over a 3-year clinical follow-up.

RESULTS

In diabetic patients, mortality (21.1% vs. 21.5%, p = 0.813) and major adverse cardiac events (MACE) (30.6% vs. 31.4%, p = 0.698) were not significantly different between males and females. However, mortality (15.8% vs. 12.0%, p = 0.002) and MACE (20.8% vs. 15.6%, p < 0.001) were significantly higher in male non-diabetic patients than in female non-diabetic patients. The predictors of mortality for both males and females in the diabetic and non-diabetic groups were old age, heart failure, renal dysfunction, anemia, and no percutaneous coronary intervention.

CONCLUSION

The long-term clinical outcomes in AMI patients with DM did not significantly differ by sex. However, the mortality and MACE in non-diabetic male patients were higher than those in females.

CCTA in patients with positive troponin and low clinical suspicion for ACS: a useful diagnostic option to exclude obstructive CAD

PURPOSE

It is uncertain whether patients with elevated troponin and non-classical presentation of acute coronary syndrome (ACS) should receive coronary CT angiography (CCTA). A proportion of these patients will have no coronary artery disease (CAD) and would benefit from non-invasive investigations and expedited discharge. Objectives were to determine most common diagnoses and rate of ACS among patients with positive troponin and low clinical suspicion of ACS who received CCTA.

METHODS

IRB approved retrospective analysis of 491 consecutive patients in a level I trauma center ED referred for CCTA between April 4, 2015 to April 2, 2017. Patients were included if there was an elevated troponin (TnI > 0.045 μg/L) and atypical chest pain within 24 h prior to imaging. One hundred one patients met inclusion criteria; 17 excluded due to technical factors or history. Scans performed on dual-source CT.

RESULTS

Eighty-four patients (47 men, 37 women) with median TnI of 0.11 ± 0.21 μg/L underwent CCTA 8.20 ± 6.41 h after first elevated Tn. Mean age was 53.2 ± 14.6 years. CCTA demonstrated absence of CAD in 39 patients (46.4%; 20 M, 19 F). CAD < 25% stenosis was observed in 24 (28.6%; 9 M, 15 F). CAD with 25-50% stenosis was observed in seven (8.3%; six M, one F). CAD > 50% stenosis was observed in 11 (13.1%; 9 M, 2 F), and non-diagnostic in three (3.6%, 3 M, 0 F). Forty-six (56.8%) were discharged directly from ED with median stay 15.82 ± 6.41 h.

CONCLUSIONS

Use of CCTA in ED patients with elevated troponin and low clinical suspicion for ACS allowed obstructive CAD to be excluded in 83%.

Acute cardiac injury events ≤30 days after laboratory-confirmed influenza virus infection among U.S. veterans, 2010-2012

BACKGROUND

Cardiac injury is a known potential complication of influenza infection. Because U.S. veterans cared for at the U.S. Department of Veterans Affairs are older and have more cardiovascular disease (CVD) risk factors than the general U.S. population, veterans are at risk for cardiac complications of influenza infection. We investigated biomarkers of cardiac injury characteristics and associated cardiac events among veterans who received cardiac biomarker testing ≤30 days after laboratory-confirmed influenza virus infection.

METHODS

Laboratory-confirmed influenza cases among veterans cared for at U.S. Department of Veterans Affairs' facilities for October 2010-December 2012 were identified using electronic medical records (EMRs). Influenza confirmation was based on respiratory specimen viral culture or antigen or nucleic acid detection. Acute cardiac injury (ACI) was defined as an elevated cardiac biomarker (troponin I or creatinine kinase isoenzyme MB) >99 % of the upper reference limit occurring ≤30 days after influenza specimen collection. EMRs were reviewed for demographics, CVD history and risk factors, and ACI-associated cardiac events.

RESULTS

Among 38,197 patients with influenza testing results, 4,469 (12 %) had a positive result; 600 of those patients had cardiac biomarker testing performed ≤30 days after influenza testing, and 143 (24 %) had one or more elevated cardiac biomarkers. Among these 143, median age was 73 years (range 44-98 years), and 98 (69 %) were non-Hispanic white. All patients had one or more CVD risk factors, and 98 (69 %) had a history of CVD. Eighty-six percent of ACI-associated events occurred within 3 days of influenza specimen collection date. Seventy patients (49 %) had documented or probable acute myocardial infarction, 8 (6 %) acute congestive heart failure, 6 (4 %) myocarditis, and 4 (3 %) atrial fibrillation. Eleven (8 %) had non-cardiac explanations for elevated cardiac biomarkers, and 44 (31 %) had no documented explanation. Sixty-eight (48 %) patients had received influenza vaccination during the related influenza season.

CONCLUSION

Among veterans with laboratory-confirmed influenza infection and cardiac biomarker testing ≤30 days after influenza testing, approximately 25 % had evidence of ACI, the majority within 3 days. Approximately half were myocardial infarctions. Our findings emphasize the importance of considering ACI associated with influenza infection among patients at high risk, including this older population with prevalent CVD risk factors.

Can troponin I measurement predict short-term serious cardiac outcomes in patients presenting to the emergency department with possible acute coronary syndrome?

Objective:

To determine the ability of troponin I (TnI) measurement to predict the likelihood of a serious cardiac outcome over the subsequent 72 hours in patients presenting to the emergency department (ED) with symptoms suggestive of an acute coronary syndrome.

Methods:

This prospective observational study enrolled consecutive patients presenting to 2 urban tertiary care hospital EDs over a 5-week period. Eligible patients included those for whom a TnI test was ordered within 24 hours of arrival and in whom no serious cardiac outcome occurred before the test result was available. Patients were followed for 72 hours and serious cardiac outcomes documented; these included cardiovascular death, myocardial infarction, congestive heart failure, serious arrhythmia and refractory pain. We calculated likelihood ratios (LRs) to describe the association of the TnI result with serious cardiac outcomes.

Results:

Of the 352 enrolled patients, 20 had a serious cardiac outcome within 72 hours of ED presentation. The derived LRs (and 95% confidence interval [CI]) were 0.5 (0.3–0.9) for TnI values &lt;0.5 µg/L, 1.6 (0.4–6.5) for TnI values from 0.5 to 2.0 µg/L, 5.8 (1.7–19.5) for TnI values from &gt;2.0 to 10.0 µg/L and 14.4 (4.8–42.9) for TnI values &gt;10.0 µg/L.

Conclusions:

TnI values &gt;2.0 µg/L are associated with an increased probability of serious cardiac outcomes within 72 hours. TnI values between 0.5 and 2.0 µg/L are weakly positive predictors. TnI values &lt;0.5 µg/L have LRs in the range of 0.5 and thus are weakly negative predictors, not substantially decreasing the likelihood of serious cardiac outcomes, particularly in patients with a moderate or high pretest probability.

High-sensitivity cardiac troponin T and copeptin assays to improve diagnostic accuracy of exercise stress test in patients with suspected coronary artery disease

BACKGROUND

The average diagnostic sensitivity of exercise stress tests (ESTs) is lower than that of other non-invasive cardiac stress tests. The aim of the study was to examine whether high-sensitivity cardiac troponin T (hs-cTnT) or copeptin concentrations rise in response to inducible myocardial ischaemia and may improve the diagnostic accuracy of ESTs.

METHODS AND RESULTS

An EST was performed stepwise on a bicycle ergometer by 383 consecutive patients with suspected or progression of coronary artery disease (CAD). In addition venous blood samples for measurement of hs-cTnT and copeptin were collected prior to EST, at peak exercise, and 4 h after EST. Coronary angiography was assessed for all patients. Patients with significant CAD (n = 224) were more likely to be male and older compared to patients with non-significant CAD (n = 169). Positive EST was documented in 125 (55.8%) patients with significant CAD and in 69 (43.4%) patients with non-significant CAD. Copeptin and hs-cTnT concentrations at baseline were higher in patients with significant CAD (copeptin: 10.8 pmol/l (interquartile range (IQR) 8.1-15.6) vs 9.4 pmol/l (IQR 7.1-13.9); p = 0.04; hs-cTnT: 3.0 ng/l (IQR <3.0-5.4) vs <3.0 ng/l (IQR <3.0); p = 0.006). Hs-cTnT improved sensitivity (61.6% vs 55.8%), specificity (67.7% vs 56.6%) and the positive predictive value (PPV) (72.3% vs 64.4%) and negative (55.2% vs 47.6%) predictive value (NPV) of EST. Copeptin could not improve sensitivity (55.4% vs 55.8%) and reduced specificity, PPV and NPV.

CONCLUSIONS

The measurement of hs-cTnT during EST improves sensitivity, specificity, and positive and negative predictive values. In contrast, measurement of copeptin does not improve diagnostic sensitivity and reduces specificity.

Stress myocardial perfusion imaging for the evaluation and triage of chest pain in the emergency department: a randomized controlled trial

BACKGROUND

Patients with acute coronary syndrome (ACS) often present atypically. In a randomized controlled trial, we studied whether adding stress myocardial perfusion imaging (SMPI) to an evaluation strategy for emergency department (ED) patients presenting with chest pain more effectively identifies patients with ACS.

METHODS

Participants were randomized to standard ED chest pain protocol (clinical assessment) or standard protocol supplemented with SMPI results. During 6 hours of electrocardiogram (ECG) monitoring and serial cardiac markers (creatine kinase-MB isoenzyme, troponin), participants developing ST segment changes or elevated cardiac markers were admitted. Those with a negative observation period underwent SMPI (N = 1,004) or clinical assessment (N = 504) based on randomization, and admitted if their SMPI scan was abnormal or senior clinicians found a high or intermediate risk for ACS.

RESULTS

SMPI participants had a significantly lower admission rate than clinical assessment participants (10.16% vs 18.45%), with no significant between-group differences in risk of cardiac events (CEs) after 30 days (0.40% vs 0.79%) or 1 year (0.70% vs 0.99%).

CONCLUSIONS

When added to a standard triage strategy incorporating clinical evaluation, serial ECGs, and cardiac markers, SMPI improved clinical decision making for chest pain patients, significantly reducing the need for hospitalization without an increase in adverse CE rates at 30 days or 1 year.

Risk factors of cardiac troponin T elevation in patients with stable coronary artery disease after elective coronary drug-eluting stent implantation

BACKGROUND

Cardiac troponin T elevation after coronary intervention has been demonstrated to be associated with the prognosis of coronary artery disease (CAD). However, there were few studies about comprehensive risk factors analysis of troponin T elevation after elective drug-eluting stent (DES) implantation.

HYPOTHESIS

The prognosis of CAD after coronary interventions was associated with clinical and procedural risk factors of CAD, such as age, hypertension, severity extent of CAD and so on.

METHODS

From March to December in 2010, patients with stable CAD were admitted for elective coronary intervention in our hospital. They were divided into an elevated troponin T group and a normal troponin T group by postprocedural troponin T. Clinical factors, laboratory-test factors, and angiographic factors (such as gender, age, cholesterol, Gensini score, and others) were analyzed.

RESULTS

A total of 209 patients with an average age of 64.0 ± 9.9 years were enrolled in the study: 70 patients with elevated troponin T (≥0.03 ng/mL) after DES implantation and 139 patients with normal troponin T (<0.03 ng/mL). After univariate analysis, we found that age, hypertension, total cholesterol, low density lipoprotein-cholesterol (LDL-C), Gensini score, number of stenosed vessels, and total implanted stents were associated with postprocedural troponin T elevation. According to the results of multivariate analysis, we found that age, total cholesterol, number of stenosed vessels, and number of implanted stents were independent risk factors of postprocedural troponin T elevation.

CONCLUSIONS

Age, serum total cholesterol, number of stenosed vessels, and number of implanted stents could be independent risk factors of troponin T elevation after elective DES implantation.

Recent advances in the management of chronic stable angina I: approach to the patient, diagnosis, pathophysiology, risk stratification, and gender disparities

The potential importance of both prevention and personal responsibility in controlling heart disease, the leading cause of death in the USA and elsewhere, has attracted renewed attention. Coronary artery disease is preventable, using relatively simple and inexpensive lifestyle changes. The inexorable rise in the prevalence of obesity, diabetes, dyslipidemia, and hypertension, often in the risk cluster known as the metabolic syndrome, drives the ever-increasing incidence of heart disease. Population-wide improvements in personal health habits appear to be a fundamental, evidence based public health measure, yet numerous barriers prevent implementation. A common symptom in patients with coronary artery disease, classical angina refers to the typical chest pressure or discomfort that results when myocardial oxygen demand rises and coronary blood flow is reduced by fixed, atherosclerotic, obstructive lesions. Different forms of angina and diagnosis, with a short description of the significance of pain and silent ischemia, are discussed in this review. The well accepted concept of myocardial oxygen imbalance in the genesis of angina is presented with new data about clinical pathology of stable angina and acute coronary syndromes. The roles of stress electrocardiography and stress myocardial perfusion scintigraphic imaging are reviewed, along with the information these tests provide about risk and prognosis. Finally, the current status of gender disparities in heart disease is summarized. Enhanced risk stratification and identification of patients in whom procedures will meaningfully change management is an ongoing quest. Current guidelines emphasize efficient triage of patients with suspected coronary artery disease. Many experts believe the predictive value of current decision protocols for coronary artery disease still needs improvement in order to optimize outcomes, yet avoid unnecessary coronary angiograms and radiation exposure. Coronary angiography remains the gold standard in the diagnosis of coronary artery obstructive disease. Part II of this two part series will address anti-ischemic therapies, new agents, cardiovascular risk reduction, options to treat refractory angina, and revascularization.

Prevalence and Prognostic Significance of Preprocedural Cardiac Troponin Elevation Among Patients With Stable Coronary Artery Disease Undergoing Percutaneous Coronary Intervention

Background— Although cardiac troponin (cTn) elevation is associated with periprocedural complications during percutaneous coronary intervention (PCI) in the setting of acute coronary syndromes, the prevalence and prognostic significance of preprocedural cTn elevation among patients with stable coronary artery disease undergoing PCI are unknown.

Methods and Results— Between July 2004 and September 2006, 7592 consecutive patients who underwent attempted stent placement at 47 hospitals throughout the United States were enrolled in a prospective multicenter registry. We analyzed the frequency of an elevated cTn immediately before PCI and its relationship to in-hospital and 1-year outcomes among patients who underwent PCI for either stable angina or a positive stress test. Among the stable coronary artery disease population (n=2382, 31.4%), 142 (6.0%) had a cTn level above the upper limit of normal before the procedure. Compared with patients who had normal baseline cTn, patients with elevated cTn had a higher rate of in-hospital death or myocardial infarction (13.4% versus 5.6%; P <0.001) and a trend toward higher rates of urgent repeat PCI (1.4% versus 0.2%; P =0.06). In multivariable analyses adjusted for demographic, clinical, angiographic, and procedural factors, baseline cTn elevation remained independently associated with the composite of death or myocardial infarction at hospital discharge (odds ratio, 2.1; 95% confidence interval, 1.2 to 3.8; P =0.01) and at the 1-year follow-up (odds ratio, 2.0; 95% confidence interval, 1.2 to 3.3; P =0.005).

Conclusions— Baseline elevation of cTn is relatively common among patients with stable coronary artery disease undergoing PCI and is an independent prognostic indicator of ischemic complications. If these data are confirmed in future studies, consideration should be given to routine testing of cTn before performance of PCI in this patient population.

Usefulness of 201TlCl/ 123I-BMIPP dual-myocardial SPECT for patients with non-ST segment elevation myocardial infarction

OBJECTIVE

Earlier studies suggested that elevated cardiac troponin T (cTnT) might be useful for detecting less severe types of myocardial injury (i.e., non-ST segment elevation myocardial infarction). The objective of this study is to elucidate the usefulness of (201)thallous chloride ((201)TlCl) and (123)I-betamethyl-p-iodophenyl-pentadecanoic acid ((123)I-BMIPP) dual-single-photon emission computed tomography (SPECT) imaging for patients with myocardial infarction (MI) without ST segment elevation.

METHODS

Consecutive 86 patients (56 men and 30 women; mean age 66 +/- 12 years) clinically diagnosed with acute myocardial infarction (AMI) were divided into two groups according to serum creatine kinase MB (CK-MB) and cTnT levels. Group A consisted of 53 patients with increased serum CK-MB and cTnT levels, and Group B, 33 patients with increased serum cTnT without increased serum CK-MB. All patients underwent (201)TlCl and (123)I-BMIPP dual-SPECT about 8 days following the onset. The left ventricular myocardium was divided into 20 segments on each SPECT image, and tracer accumulation in those segments was scored on a five-point scoring system. The total defect scores (TDS) were calculated by summing the scores for all 20 segments, and compared between groups A and B. Group B patients were subdivided into two groups according to the TDS on (123)I-BMIPP images as groups B(S) (severe; TDS > or = 8) and B(M) (mild; TDS < or = 7), and we compared the prognosis over a period of 2 years from the onset between the three groups.

RESULTS

The TDS of group A derived from (201)TlCl and (123)I-BMIPP images was significantly higher than those of group B (14.5 +/- 10.8 vs. 1.5 +/- 2.4 and 20.8 +/- 13.3 vs. 9.1 +/- 6.2, respectively; P < 0.0001). The sensitivities of (201)TlCl and (123)I-BMIPP images were 94.3% (50/53) and 96.2% (51/53) to detect the culprit coronary lesions in group A (no significant difference). In contrast, the sensitivity of (123)I-BMIPP images (72.7%, 24/33) was higher than that of (201)TlCl images (27.3%, 9/33) in group B (P < 0.05). At 2 years of follow-up, the incidence of hard cardiac events in groups A, B(S), and B(M) was 24.5%, 27.8%, and 6.7%, respectively. The rate of group BS, as well as that of group A, was significantly higher than that of group B(M) (P < 0.05).

CONCLUSIONS

Of those with a clinical diagnosis of AMI accompanied by increased cTnT, the CK-MB negative patients accounted for 38% (33/86) of all patients as having non-ST segment elevation myocardial infarction such as NTMI. For such patients, (123)I-BMIPP imaging is useful not only for the detection of the culprit lesions but also for the prediction of the prognosis.

Economic analysis including long-term risks and costs of alternative diagnostic strategies to evaluate patients with chest pain

BACKGROUND

Diagnosis costs for cardiovascular disease waste a large amount of healthcare resources. The aim of the study is to evaluate the clinical and economic outcomes of alternative diagnostic strategies in low risk chest pain patients.

METHODS

We evaluated direct and indirect downstream costs of 6 strategies: coronary angiography (CA) after positive troponin I or T (cTn-I or cTnT) (strategy 1); after positive exercise electrocardiography (ex-ECG) (strategy 2); after positive exercise echocardiography (ex-Echo) (strategy 3); after positive pharmacologic stress echocardiography (PhSE) (strategy 4); after positive myocardial exercise stress single-photon emission computed tomography with technetium Tc 99m sestamibi (ex-SPECT-Tc) (strategy 5) and direct CA (strategy 6).

RESULTS

The predictive accuracy in correctly identifying the patients was 83,1% for cTn-I, 87% for cTn-T, 85,1% for ex-ECG, 93,4% for ex-Echo, 98,5% for PhSE, 89,4% for ex-SPECT-Tc and 18,7% for CA. The cost per patient correctly identified results $2.051 for cTn-I, $2.086 for cTn-T, $1.890 for ex-ECG, $803 for ex-Echo, $533 for PhSE, $1.521 for ex-SPECT-Tc ($1.634 including cost of extra risk of cancer) and $29.673 for CA ($29.999 including cost of extra risk of cancer). The average relative cost-effectiveness of cardiac imaging compared with the PhSE equal to 1 (as a cost comparator), the relative cost of ex-Echo is 1.5x, of a ex-SPECT-Tc is 3.1x, of a ex-ECG is 3.5x, of cTnI is x3.8, of cTnT is x3.9 and of a CA is 56.3x.

CONCLUSION

Stress echocardiography based strategies are cost-effective versus alternative imaging strategies and the risk and cost of radiation exposure is void.

Prognostic value of troponin after elective percutaneous coronary intervention: A meta-analysis

BACKGROUND

Although the prognostic importance of troponin in patients with anacute coronary syndrome is clear, the significance of troponin elevation after elective percutaneous coronary intervention (PCI) is a subject of debate. However, most studies up to now had a small sample size and insufficient events during follow-up.

METHODS

Electronic and manual searches were performed of studies reporting on prognosis of troponin after elective PCI. A meta-analysis was done of all suitable studies, with death in follow-up as primary endpoint and the combination of death or nonfatal myocardial infarction in follow-up as secondary endpoint.

RESULTS

20 studies involving 15,581 patients were included. These studies were published between 1998 and 2007. Overall, troponin was elevated after elective PCI in 32.9% of patients. The follow-up period varied between 3 and 67 months (mean 16.3). Increased mortality was significantly associated with troponin elevation after PCI (4.4% vs. 3.3%, P = 0.001; OR 1.35). Furthermore, the combined endpoint of mortality or nonfatal myocardial infarction also occurred more often in patients with post-procedural troponin elevation (8.1% vs. 5.2%, P < 0.001; OR 1.59).

CONCLUSIONS

According to this meta-analysis, troponin elevation after elective PCI provides important prognostic information.

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.

Prognostic importance of troponin T and creatine kinase after elective angioplasty

BACKGROUND

The prognostic importance of elevated cardiac enzymes after elective percutaneous coronary intervention has been debated. Therefore, we performed a prospective observational study to evaluate the prognostic value of postprocedural rise of troponin T and creatine kinase.

METHODS

Troponin T (cut-off value 0.05 ng/ml) and creatine kinase (cut-off value 180 IU/l with muscle-brain fraction >4%) were measured 12 h after elective percutaneous coronary intervention in 713 consecutive patients without elevated troponin before the procedure. Primary endpoint was the combined incidence of death, myocardial infarction, stroke, repeat angiography or re-admission because of anginal symptoms during the follow-up period.

RESULTS

Troponin was elevated after the procedure in 150 patients (21%) and creatine kinase in 66 pts (9%), with a strong association between increased troponin and creatine kinase. After a mean follow-up of 10.9 months, mortality was low (1%) and not associated with increased troponin or creatine kinase. There was, however, a strong relation between postprocedural troponin and re-admission for angina (p=0.001) or myocardial infarction (p=0.001). Furthermore, troponin rise was significantly associated with an increased risk of the primary endpoint (relative risk 1.55 95% confidence interval 1.01-2.38). After multivariate analysis, troponin elevation but not increased creatine kinase was associated with an increased risk of the primary endpoint (relative risk 1.59 95% confidence interval 1.02-2.47 for troponin elevation versus 1.16 95% confidence interval 0.62-2.15 for increased creatine kinase).

CONCLUSION

Increase of troponin T after elective percutaneous coronary intervention has stronger prognostic implication when compared to increased creatine kinase.

The use of biomarkers for the evaluation and treatment of patients with acute coronary syndromes

The advent of inexpensive, highly accurate, and predictive markers of myocardial injury, inflammation, and hemodynamic stability has revolutionized the evaluation and treatment of patients who have acute coronary syndromes (ACSs). These blood biomarkers require small sample volumes, can be run expeditiously, and provide important information concerning the diagnosis, risk stratification, and treatment of these patients. To understand the use of these markers, one must have some knowledge about what elevations in these markers imply, how they have to be collected and measured to provide reliable information, when to suspect analytic confounds, and what the key values are that impart the diagnostic, prognostic, and therapeutic information. This article discusses these issues, emphasizing what clinicians must know for optimal test use, and then addresses the practical use of these markers in patients who have ACS.

A practical approach with outcome for the prognostic assessment of non-ST-segment elevation chest pain and normal troponin

Patients with non-ST-elevation chest pain constitute a heterogeneous population. Our aim is to compare the outcome of patients with chest pain, non-ST-segment deviation, and normal troponin, categorized using a risk score, with that of patients with ST depression or troponin increase. A total of 1,449 patients with non-ST-elevation chest pain were evaluated. A validated risk score (using pain characteristics and risk factors) was applied to patients without ST depression or troponin increase. Accordingly, 4 risk categories were defined: group 1, no troponin increase, no ST depression, and risk score <3 points (n = 633); group 2, no troponin increase, no ST depression, but risk score > or = 3 points (n = 158); group 3, no troponin increase, ST depression (n = 106); and group 4, troponin increase (n = 552). Median follow-up was 26 months, and the end point was death or myocardial infarction. Group 1 experienced fewer events at 30 days (1.7%, p = 0.0001) and long-term follow-up (9.4%, p = 0.0001) than groups 2 (10.8% and 26%), 3 (6.6% and 30%), and 4 (9.5% and 25%). Kaplan-Meier curves overlapped among groups 2, 3, and 4, whereas group 1 showed a flatter curve (p = 0.0001). Using multivariate analysis, risk group (group 1 vs remaining groups) predicted 30-day (p = 0.0003) and long-term (p = 0.0001) outcome. There were no differences among groups 2, 3, and 4. In conclusion, application of a risk score to patients without troponin increase or ST deviation identified a high-risk group with prognosis similar to that of patients with troponin increase or ST depression and affords a practical classification for the full spectrum of non-ST-elevation chest pain.

Distribution of Coronary Artery Disease and Relation to Mortality in Asymptomatic Hemodialysis Patients

BACKGROUND

Long-term dialysis patients have a high incidence of myocardial infarction and cardiovascular death, but the incidence of coronary artery disease (CAD) in asymptomatic patients, distribution of coronary obstruction, and relationship between lesion location and mortality are unknown.

METHODS

We studied 67 asymptomatic hemodialysis patients who volunteered for coronary angiography. Coronary stenoses of 50% or greater were documented, and the location of each within the proximal, midportion, or distal segment of the coronary vessel was recorded. Patients were followed up until death or renal transplantation. Cox proportional hazards regression was performed to analyze the relationship of lesion location with mortality.

RESULTS

Obstructive CAD was common. Twenty-eight subjects (41.7%) had 50% or greater stenosis in at least 1 epicardial vessel, and 19 subjects (28.5%) had evidence of CAD within the proximal third of an epicardial vessel. After a median follow-up of 2.7 years, the presence of proximal CAD was associated with a marked increase in risk of death (adjusted hazard ratio, 3.14; 95% confidence interval, 1.34 to 7.33; P = 0.008) and was associated more strongly with mortality than multivessel disease or left anterior descending disease.

CONCLUSION

CAD is common in asymptomatic dialysis patients, and stenoses frequently are located within the proximal coronary arteries, where they are associated with markedly increased risks of death. Additional studies are needed to determine whether proximal disease is a modifiable risk factor for cardiovascular mortality in dialysis patients.

Cardiovascular Biomarkers in CKD: Pathophysiology and Implications for Clinical Management of Cardiac Disease

Cardiovascular disease (CVD) is a major cause of morbidity and mortality in patients with all forms of chronic kidney disease (CKD). The underlying pathological state is caused by a complex interplay of traditional and nontraditional risk factors that results in atherosclerosis, arteriosclerosis, and altered cardiac morphological characteristics. This multifactorial disease introduces new challenges in predicting and treating patients with CVD sufficiently early in the course of CKD to positively alter patient outcome. Asymptomatic individuals with progressive CVD are a group of patients that deserve focused attention because early detection and intervention may provide the best opportunity for improved outcome. However, identifying CVD in asymptomatic patients with CKD or end-stage renal disease remains a significant hurdle in the management of these patients. Recently, a number of cardiovascular biomarkers were identified as predictors of patient outcome in individuals with CVD and, with additional research, may be used to guide the early diagnosis of and therapy for CVD in patients with CKD. This review examines the pathophysiological characteristics and potential clinical role of these novel cardiovascular biomarkers in risk stratification, risk monitoring, and selection of preventive therapies for patients with CKD.

Meta-analysis of ischemia-modified albumin to rule out acute coronary syndromes in the emergency department

BACKGROUND

Because of possible adverse outcomes, many of the >6 million annual emergency department (ED) patients with suspected acute coronary syndromes (ACS) undergo extensive evaluations. To minimize medical errors, chest pain evaluations are structured to identify accurately nearly 100% of patients with ACS. This is at a cost of negative evaluation rates that can exceed 90%. Ischemia-modified albumin (IMA), a serum biomarker with a high negative predictive value (NPV) at ED presentation, may exclude ACS. Our objective was to perform a meta-analysis of IMA use for ACS risk stratification.

METHODS

By computer literature search and communication with authors of unpublished information, all IMA data were considered. This analysis included studies if they reported IMA results from an ED presentation for suspected ACS. We defined a negative triple prediction test (TPT) as a nondiagnostic electrocardiogram, negative troponin, and negative IMA.

RESULTS

Eight studies of >1800 patients met the entry criteria. The TPT sensitivity and NPV for acute ACS were 94.4% and 97.1% and, for longer-term outcomes, were 89.2% and 94.5%, respectively.

CONCLUSIONS

A negative TPT of a nondiagnostic electrocardiogram, negative troponin, and negative IMA has a high NPV for excluding ACS in the ED.

The impact of the ESC/ACC redefinition of myocardial infarction and new sensitive troponin assays on the frequency of acute myocardial infarction

BACKGROUND

The prevalence of acute myocardial infarction (AMI) has increased due to the recent definitions, but the magnitude of this effect using contemporary highly sensitive troponin assays is unclear. The objective of this study is to compare the diagnosis of AMI using a contemporary troponin I (cTnI) biomarker and the 2003 American Heart Association (AHA) case definition with diagnoses made using the 1994 World Health Organization MONICA definition.

METHODS

Contemporary troponin I measurements were performed with the Beckman Coulter AccuTnI assay (Chaska, MN) on plasma specimens originally assayed in 1996 for creatine kinase (CK)-MB mass from 486 emergency department patients presenting within 24 hours of onset of symptoms suggestive of cardiac ischemia.

RESULTS

In a subgroup of 258 patients with 2 specimens drawn at least 6 hours apart (the AHA "adequate set of biomarkers"), AMI prevalence using CK-MB was 19.4% (95% CI 15.0-24.7) based on MONICA and 19.8% (15.4-25.1) based on the AHA case definition using the criterion for change of > or = 20% between specimens. Using cTnI as the biomarker of choice, under the AHA definition, the prevalence increased to as high as 35.7% (30.1-41.7, a relative increase of 84%, P < .001) using the 99th percentile cutoff. In 121 patients with a lower index of suspicion and without the requisite 6-hour interval between measurements, positivity increased from 5% with CK-MB by MONICA up to 12% to 16% with cTnI by AHA.

CONCLUSIONS

A highly sensitive contemporary cTnI assay used with the AHA case definition results in a 62% to 84% increase in the frequency of AMI diagnosis compared with MONICA criteria.

Biomarkers in acute cardiac disease: the present and the future

The use of biomarkers to aid diagnosis and treatment is increasing rapidly as genomics and proteomics help us expand the number of markers we can use and as an improved understanding of the pathophysiology of cardiac disease guides their use. However, as with all rapidly expanding fields, there is the risk of excessive enthusiasm unless we are circumspect about the data that guide the clinical use of these new tools. This review focuses first on how to use troponin, which at present is the best validated of the new markers, and will hopefully provide insight into how to use this biomarker more productively by distinguishing subsets of patients and by providing an understanding of the meaning of elevations in various clinical situations. The review then discusses the use as well as the knowledge gaps associated with emerging biomarkers such as B-type natriuretic peptide and C-reactive protein, which are increasingly moving toward more productive clinical use. Finally, it reflects on some of the large number of markers that are still in development.

Use of biomarkers in the emergency department and chest pain unit

The use of biomarkers of cardiac injury in the emergency department (ED) and observation unit settings has several nuances that are different and, therefore, worthy of its own set of use guidelines. The markers that are used, however, are the same. The primary marker of choice continues to be cardiac troponin (Tn). Other markers that have been used because of the need in the ED for rapid triage have been myoglobin and fatty acid binding protein. In addition, some centers still prefer less sensitive and less specific markers such as creatine kinase myocardial band (CK-MB). More recently, a push has occurred to develop markers of ischemia, such as ischemia modified albumin (IMA),to determine which patients have ischemia, even in the absence of cardiac injury. As troponin assays become more sensitive and method for use becomes better understood, the use of these other markers are being relegated to lesser and lesser roles. Markers of ischemia are useful, but at present, despite some enthusiasm, are not ready for routine use. Before describing the recommendations for clinical use of biomarkers in the ED, a basic understanding of some of the science and measurement issues related to these analytes is helpful.

Combined prognostic utility of ST segment in lead aVR and troponin T on admission in non-ST-segment elevation acute coronary syndromes

Many studies have shown that ST-segment depression is a strong predictor of poor outcomes in patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACSs); however, lead aVR was not considered in these studies. The present study examined the prognostic usefulness of the 12-lead electrocardiogram in combination with biochemical markers in 333 patients with NSTE-ACS. ST-segment deviation of > or =0.5 mm was considered clinically significant. Coronary angiography was performed a median of 3 days after admission in all patients. The primary end point was the composite of death, myocardial infarction, and urgent revascularization at 90 days. ST-segment elevation in lead aVR (odds ratio 13.8, 95% confidence interval 1.43 to 100.9, p = 0.03) and increased troponin T (odds ratio 7.9, 95% confidence interval 1.22 to 123.8, p = 0.04) were the only independent predictors of restricted events (death or myocardial infarction) at 90 days. ST-segment elevation in lead aVR (odds ratio 12.8, 95% confidence interval 4.80 to 33.9, p < 0.0001) and increased troponin T (odds ratio 2.03, 95% confidence interval 1.20 to 4.29, p = 0.04) were also the only independent predictors of adverse events (death, myocardial infarction, or urgent revascularization) at 90 days. When ST-segment status in lead aVR was combined with troponin T, patients with ST-segment elevation in lead aVR and increased troponin T had the highest rates of left main or 3-vessel coronary disease (62%) and 90-day adverse outcomes (47%). In conclusion, our findings suggest that ST-segment status in lead aVR combined with troponin T on admission is a simple and useful clinical tool for early risk stratification in patients with NSTE-ACS.

The new definition of myocardial infarction and the impact of troponin determination on clinical practice

OBJECTIVE

To discuss the more controversial clinical and laboratory aspects in the application of the new biochemical diagnostic standard for myocardial infarction, 4 years after its introduction, and to make some suggestions, which could allow for a more realistic application of the new definition in the current clinical practice.

METHODS

Studies published in the last 4 years in the most important cardiology and laboratory medicine journals (including proceedings of the international meetings), discussing advantages and limits of the new definition of myocardial infarction, were reviewed and pertinent data were discussed and compared with similar information available in literature.

RESULTS AND CONCLUSIONS

Although the exact status of implementation of the new definition of myocardial infarction cannot yet be known, the trend toward such recommendation is evolving significantly, even if at different rates in different countries. To make the transition smoother, major educational efforts are required to disseminate the conceptual reasoning behind the new guidelines. On the other hand, more knowledge is needed for some relevant issues, such as the different analytical performance of cardiac troponin assays or the prognostic significance of biomarker changes after a percutaneous coronary intervention.

The significance of elevated troponin T in patients with nondialysis-dependent renal insufficiency: a validation with coronary angiography

BACKGROUND

Patients with elevated troponin are at high risk of adverse outcomes, future cardiac events, and are more likely to have hemodynamically significant coronary artery stenoses. Elevated troponin T (cTnT) in patients with poor renal function portends a poor prognosis; however, findings of significant coronary artery disease (CAD) by coronary angiography have not been demonstrated in patients with poor renal function and elevated cTnT.

HYPOTHESIS

The purpose of this study was to correlate the angiographic findings of patients with elevated cTnT with respect to renal function in patients with nondialysis-dependent renal insufficiency.

METHODS

We retrospectively identified 342 patients with elevated cTnT who underwent coronary angiography in the setting of acute coronary syndrome. Patients were divided into poor (< 40 ml/min) and normal (> 40 ml/min) renal function by measuring their glomerular filtration rate. Our primary outcome was CAD stenosis, defined as epicardial stenosis > or = 70%. Secondary outcomes were rates of contrast nephropathy, initiation of hemodialysis, revascularization, length of stay (LOS), and in-hospital mortality.

RESULTS

There was no significant difference in the prevalence of CAD between patients who had positive cTnT with poor renal function versus patients with positive cTnT and normal renal function (87.1 vs. 89.7%, p = 0.54). This finding persisted after stratifying by age. Patients with impaired renal function had a higher mortality, longer LOS, and a higher rate contrast nephropathy requiring hemodialysis.

CONCLUSION

The association between elevated cTnT and significant CAD stenosis does not vary with renal function.

Predictors of left main or three-vessel disease in patients who have acute coronary syndromes with non-ST-segment elevation

To identify an early, simple, noninvasive predictor of left main (LM) or 3-vessel disease (3-VD), we retrospectively studied clinical variables on admission in 310 patients with acute coronary syndromes with non-ST-segment elevation. Univariate analysis indicated that many factors were related to LM/3-VD. Multivariate analysis showed that ST-segment elevation in lead aVR of >/=0.5 mm was the strongest predictor of LM/3-VD, followed by positive troponin T (odds ratio 19.7, p <0.001, and odds ratio 3.08, p = 0.048, respectively). ST-segment elevation in lead aVR of >/=0.5 mm and positive troponin T identified LM/3-VD with sensitivities of 78% and 62%, specificities of 86% and 59%, positive predictive values of 57% and 26%, and negative predictive values of 95% and 87%, respectively (p <0.05). Our findings suggest that in patients with non-ST-segment elevation acute coronary syndromes, ST-segment elevation in lead aVR of >/=0.5 mm and positive troponin T on admission (especially the former) are useful predictors of LM/3-VD.

Prognostic implications of elevated troponin in patients with suspected acute coronary syndrome but no critical epicardial coronary disease: a TACTICS-TIMI-18 substudy

OBJECTIVES

The purpose of this study is to determine whether there is clinical significance to elevated troponin I in patients with suspected acute coronary syndromes (ACS) with non-critical angiographic coronary stenosis.

BACKGROUND

Elevation of troponin in patients admitted with ACS symptoms with non-critical coronary artery disease (CAD) may result from coronary atherothrombosis not evident using standard angiography or from other ischemic and non-ischemic causes that may confer increased risk for future events.

METHODS

Patients with ACS enrolled in the Treat Angina With Aggrastat and Determine Cost of Therapy With Invasive or Conservative Strategy-Thrombolysis In Myocardial Infarction (TACTICS-TIMI)-18 were included. Of 2,220 patients enrolled in the trial, 895 were eligible. Patients were divided into four groups according to troponin status on admission and presence of significant angiographic stenosis. Baseline brain natriuretic peptide (BNP) and C-reactive protein (CRP) were obtained on all patients.

RESULTS

The median troponin I levels were 0.71 ng/ml in patients with CAD compared with 0.02 ng/ml in patients without CAD (p <0.0001). Troponin-positive patients with or without angiographic CAD had higher CRP and BNP levels compared with troponin-negative patients (p <0.01 for both). The rates of death or reinfarction at six months were 0% in troponin-negative patients with no CAD, 3.1% in troponin-positive patients with no CAD, 5.8% in troponin-negative patients with CAD, and 8.6% in troponin-positive patients with CAD (p=0.012).

CONCLUSIONS

Elevated troponin in ACS is associated with a higher risk for death or reinfarction, even among patients who do not have significant angiographic CAD. The mechanisms conferring this adverse prognosis merit further study.

Multi-biomarker risk stratification of N-terminal pro-B-type natriuretic peptide, high-sensitivity C-reactive protein, and cardiac troponin T and I in end-stage renal disease for all-cause death

BACKGROUND

In patients with end-stage renal disease (ESRD), the ability of single and multiple biomarker monitoring to predict adverse outcomes has not been well established. This study determined the prognostic value of multiple biomarkers for all-cause death over 2 years in 399 ESRD patients.

METHODS

The risk of all-cause death was determined by use of multiple biomarkers based on concentrations for a reference population (normal) and cutoffs based on tertile distributions in the ESRD group. Biomarkers studied included N-terminal pro-B-type natriuretic peptide (NT-proBNP), high-sensitivity C-reactive protein (hsCRP; Dade Behring and Roche assays), and cardiac troponin T (cTnT; Roche) and I (cTnI; Dade Behring and Beckman Coulter assays). Relative risks of death were estimated and survival curves computed.

RESULTS

A total of 101 deaths occurred during 594 patient-years of follow-up. Increased NT-proBNP concentrations were not predictive of death on the basis of the normal cutoffs. However, tertile analysis of NT-proBNP was significantly predictive of death and had a ROC area under the curve equivalent to or better than any of the other biomarkers. Biomarkers independently predictive of survival were hsCRP (P <0.001, either assay), cTnT (P <0.05), and cTnI (Dade, P <0.05). Two-year mortality rates were 6% (n = 45) with normal hsCRP, cTnI, and cTnT concentrations; 19% (n = 173) with increased hsCRP or cTnT and normal cTnI; 44% (n = 160) with both hsCRP and cTnT increased and normal cTnI; 61% (n = 21) with increased cTnI (Dade) or 47% (n = 74) with increased cTnI (Beckman) regardless of hsCRP or cTnT concentrations. Defined by the normal cutoffs, increased concentrations of biomarkers were present in various proportions of the 399 patients with ESRD: NT-proBNP, 99%; hsCRP, 46% (both Roche and Dade assays); cTnT, 85%; cTnI, 19% (Beckman assay) and 5% (Dade assay).

CONCLUSIONS

Although mechanisms likely vary for causation, increased plasma hsCRP, cTnT, and cTnI above the cutoffs for our reference (normal) population were all independently predictive of subsequent death in ESRD patients. Tertile analysis for NT-proBNP also demonstrated prognostic value.

Predictors of short-term outcome in acute chest pain without ST-segment elevation

BACKGROUND

Management of acute chest pain in the emergency room constitutes a challenge.

METHODS

Seven hundred and one consecutive patients were evaluated by clinical history (chest pain score and risk factors), ECG, troponin I and early (<24 h) exercise testing in low risk patients (n=165). A composite end-point (recurrent unstable angina, acute myocardial infarction or cardiac death) was recorded during hospital stay or in ambulatory care settings for patients discharged after early exercise testing.

RESULTS

The end-point occurred in 122 patients (17%). Multivariate analysis identified the following predictors: chest pain score > or =11 points (OR=1.8, 2-2.8, 95% CI, P=0.007), age > or =68 (OR 1.6, 1.1-2.4 CI 95%, P=0.03), insulin-dependent diabetes mellitus (OR 1.9, 1.1-3.4 CI 95%, P=0.02), a history of coronary surgery (OR 3.3, 1.5-7.2 CI 95%, P=0.003), ST-segment depression (OR 1.9, 1.2-3.0 CI 95%, P=0.009) and troponin I elevation (OR 1.6, 1.1-2.5, CI 95%, P=0.05). ST-segment depression produced a high end-point increase (31 vs. 13%, P=0.0001). Troponin I elevation increased the risk in the subgroup without ST-segment depression (20 vs. 11%, P=0.006) but did not further modify the risk in the subgroup with ST depression (31 vs. 28%, ns). Nevertheless, the negative ECG and troponin I subgroup showed a non-negligible end-point rate (16% when pain score > or =11 or 7% when pain score <11, P=0.004). Finally, no patient with a negative exercise test presented events compared to 7% of those with a non-negative test (RR=2.5, 2.1-3.1 95% CI, P=0.01).

CONCLUSIONS

Emergency room evaluation of chest pain should not focus on a single parameter; on the contrary, the clinical history, ECG, troponin and early exercise testing must be globally analysed.

Evaluation and risk stratification of acute coronary syndromes using a low cut-off level of cardiac troponin T, combined with CK-MB mass determination

OBJECTIVES

To study the usefulness of combined cardiac Troponin T (cTnT) and CK-MB mass determinations in risk stratification of acute coronary syndromes.

DESIGN AND METHODS

Blood samples for cTnT and CK-MB mass were collected at arrival and 4, 8, and 12-24 later in 301 consecutive patients with recent acute chest pain (ACP). Data were also collected for cardiac events.

RESULTS

Combined cardiac mortality/nonfatal myocardial infarction over a period of 15 months was lowest in patients with <0.04 microg/l cTnT and -<5.0 microg/l CK-MB mass intermediate in those with elevated cTnT but normal CK-MB mass and highest when both markers were elevated, in absence of early reperfusion.

CONCLUSION

The use of a low cut-off point of cTnT, combined wit CK-MB mass determination, offers a good strategy for risk stratification of ACP patients.

The prognostic value of markers of inflammation in patients with troponin T-negative chest pain before discharge from the emergency department

PURPOSE

To assess the prognostic value of markers of inflammation for rule-out purposes in patients admitted to the emergency department with troponin T-negative chest pain.

METHODS

Patients presenting to the emergency department within 6 hours of symptom onset and who had a normal or nondiagnostic electrocardiogram were eligible. The standard rule-out protocol, which included serial creatine kinase and creatine kinase-MB measurements, was applied, and markers of inflammation (C-reactive protein, erythrocyte sedimentation rate, and total white blood cell count and differential count) were measured. The study group comprised patients with negative serial troponin T results (<0.06 microg/L) who were discharged home after unstable coronary artery disease was ruled out. Endpoints during the 6-month follow-up were cardiac death, myocardial infarction, or rehospitalization for unstable angina.

RESULTS

A total of 382 troponin T-negative patients were discharged, of whom 2 died, 2 had a myocardial infarction, and 7 were rehospitalized for unstable angina. A positive C-reactive protein test result (>0.3 mg/dL) was associated with future clinical events (hazard risk [HR] = 4.5; 95% confidence interval [CI]: 1.2 to 17.0; P = 0.03), as was a positive test (>13 mm/h) for erythrocyte sedimentation rate (HR = 5.6; 95% CI: 1.5 to 22.2; P = 0.01). Patients with positive results for both tests were at highest risk of clinical events (9.3%) compared with patients with other combinations of test results (1.1% to 2.1%; HR = 7.5; 95% CI: 2.2 to 25.5; P = 0.001).

CONCLUSION

The combination of C-reactive protein and erythrocyte sedimentation rate had prognostic value in patients with troponin T-negative chest pain and a normal or nondiagnostic electrocardiogram in whom unstable coronary artery disease was ruled out.

Prognostic value of isolated troponin elevation across the spectrum of chest pain syndromes

The risk of death or recurrent myocardial infarction (MI) in patients with chest pain and baseline isolated troponin elevation is unclear. To determine the early and short-term risk of death or MI associated with isolated troponin elevation across a spectrum of chest pain syndromes, we used baseline creatine kinase (CK)-MB and troponin data from the Platelet IIb/IIIa Antagonism for the Reduction of Acute Coronary Syndrome Events in a Global Organization Network (PARAGON) B troponin substudy, the Global Utilization of Strategies To Open Occluded Coronary Arteries (GUSTO) IIa troponin substudy, and the Chest Pain Evaluation by Creatine Kinase-MB, Myoglobin, and Troponin I (CHECKMATE) study. Patients were grouped into 1 of 4 categories based on marker status (troponin-positive/CK-MB-positive, troponin-positive/CK-MB-negative, troponin-negative/CK-MB-positive, or troponin-negative/CK-MB-negative). The adjusted odds of death or MI occurring at 24 hours and 30 days was assessed by baseline marker status using multivariable logistic regression, with the group negative for both markers used as the reference. Patients who were positive for both markers had the highest odds of the 24-hour and 30-day end point. The adjusted odds of the 30-day end point for patients with isolated troponin elevation were 1.3 (95% confidence interval 0.7 to 2.3) and 4.8 (95% confidence interval 1.4 to 16.0) for high- and low-risk patients, respectively. The risk for 24-hour and 30-day death or MI with isolated positive CK-MB results was lower than with isolated positive troponin results, and it was not significantly greater than if the 2 markers were negative. For patients with high- and low-risk chest pain, baseline troponin elevation without CK-MB elevation was associated with increased risk for early and short-term adverse outcomes. This suggests that these patients should be admitted to the hospital and monitored in either an intensive care or step-down unit.

[Risk stratification using combined ECG, clinical, and biochemical assessment in patients with chest pain without ST-segment elevation. How long should we wait? ]

INTRODUCTION

We use clinical, ECG, and biochemical data to stratify risk in patients with chest pain without ST segment elevation. However, the prognostic performance of these studies in relation to time from onset of symptoms is unknown.

PATIENTS AND METHOD

In a single-center, prospective study, 321 consecutive patients who had been admitted in the emergency room with a suspected acute coronary syndrome without ST segment elevation were included in the study. Blood samples were collected for CK, CK-MB mass, myoglobin, and cardiac troponin T analysis 6, 12 and 18 hours after the onset of pain and other clinical and ECG data were recorded. Univariate and multivariate analysis was used to identify independent prognostic predictors 6 and 12 hours after the onset of chest pain.

RESULTS

Five variables were independent predictors of the recurrence of ischemia. The model correctly classified 82% of the patients. Age, history of coronary artery disease, prolonged chest pain at rest in the preceding 15 days, pain, ST-segment changes with pain, and cardiac troponin T in excess of 0.1 ng/m 12 hours after the onset of chest pain were identified by logistic regression. A similar model was analyzed at 6 hours, after changing the cutoff point for cardiac troponin T. Cardiac troponin T was considered positive with values of 0.04 ng/ml 6 hours after the onset of chest pain.

CONCLUSIONS

More than 80% of the patients admitted to the emergency room with chest pain without ST segment elevation can be correctly classified for new ischemic recurrences using clinical, ECG, and biochemical parameters 6 hours after the onset of pain.

Outcomes of patients presenting with acute coronary syndromes and negative Troponin-T

The aim of the study was to compare need for revascularization and clinical course between troponin-positive and troponin-negative patients with unstable angina pectoris defined as class IIIB according to Braunwald classification.

METHODS

The study group consisting of 104 patients was divided into troponin-positive (28 patients) and troponin-negative (76 patients) subgroups. Per study design all patients underwent coronary angiography. The subgroups were compared in regard to angiographic status and consequently the need for revascularization. Additionally, major adverse cardiac events (MACE) consisting of death, myocardial infarction, in-hospital revascularization during 30-days follow-up were assessed in subgroups.

RESULTS

In 58 (76%) patients with negative troponin test, the angiographically significant coronary artery stenosis was shown. Major adverse cardiac events were similar in both groups. Regardless of the initial TnT status, in both groups revascularizations (percutaneous or surgical) were performed with high frequency (89 versus 72%, P=NS).

CONCLUSION

In patients with unstable angina in class IIIB according to Braunwald classification, the negative cardiac troponin test did not exclude severe coronary artery disease, which in the majority of patients required revascularization without any additional non-invasive testing for ischemia. Therefore, we postulate that patients with clinically evident unstable angina (IIIB) should be referred to early invasive assessment despite negative troponin T screening.

Prognostic value of predischarge dobutamine stress echocardiography in chest pain patients with a negative cardiac troponin T

OBJECTIVES

We prospectively studied the prognostic value of predischarge dobutamine stress echocardiography (DSE) in low-risk chest pain patients with a normal or nondiagnostic electrocardiogram (ECG) and a negative serial troponin T.

BACKGROUND

Noninvasive stress testing is recommended before discharge or within 72 h in patients with low-risk chest pain. The prognostic value of immediate DSE has not been studied in a blinded, prospective fashion.

METHODS

Patients presenting at the emergency room within 6 h of symptom onset and a normal or nondiagnostic ECG were eligible. Dobutamine stress echocardiography was performed after unstable coronary artery disease was ruled out by a standard rule-out protocol and a negative serial troponin T; the occurrence of any new wall motion abnormality was considered positive. Results were kept blinded. End points were cardiac death, myocardial infarction, rehospitalization for unstable angina or revascularization.

RESULTS

In total, 377 patients were included. There were 2 deaths, 2 myocardial infarctions, 8 rehospitalization for unstable angina, and 10 revascularizations at six-month follow-up. The end points occurred in 8/26 (30.8%) patients with a positive versus 14/351 (4.0%) patients with a negative DSE (odds ratio, 10.7; 95% confidence interval, 4.0 to 28.8; p < 0.0001). By multivariate analysis, DSE remained a predictor of end points (p < 0.0001).

CONCLUSIONS

A predischarge DSE had important, independent prognostic value in low-risk, troponin negative, chest pain patients.

Troponin T and quantitative ST-segment depression offer complementary prognostic information in the risk stratification of acute coronary syndrome patients

OBJECTIVES

Our primary objective was to examine the prognostic relationship between baseline quantitative ST-segment depression (ST) and cardiac troponin T (cTnT) elevation. The secondary objectives were to: 1) examine whether ST provided additional insight into therapeutic efficacy of glycoprotein IIb/IIIa therapy similar to that demonstrated by cTnT; and 2) explore whether the time to evaluation impacted on each marker's relative prognostic utility.

BACKGROUND

The relationship between the baseline electrocardiogram (ECG) and cTnT measurements in risk-stratifying patients presenting with acute coronary syndromes (ACS) has not been evaluated comprehensively.

METHODS

The study population consisted of 959 patients enrolled in the cTnT substudy of the Platelet IIb/IIIa Antagonism for the Reduction of Acute coronary syndrome events in a Global Organization Network (PARAGON)-B trial. Patients were classified as having no ST (n = 387), 1 mm ST (n = 433), and ST > or =2 mm (n = 139). Forty-percent (n = 381) were classified as cTnT-positive based on a definition of > or =0.1 ng/ml.

RESULTS

Six-month death/(re)myocardial infarction rates were 8.4% among cTnT-negative patients with no ST and 26.8% among cTnT-positive patients with ST > or =2 mm. On ECGs done after 6 h of symptom onset, ST > or =2 mm was associated with higher risk compared to its presence on ECGs done earlier (odds ratio [OR] 7.3 vs. 2.1). In contrast, the presence of elevated cTnT within 6 h of symptom was associated with a higher risk of adverse events compared with elevations after 6 h (OR 2.4 vs. 1.5).

CONCLUSIONS

Quantitative ST and cTnT status are complementary in assessing risk among ACS patients and both should be employed to determine prognosis and assist in medical decision making.

Predictive value of cardiac troponin I and T for subsequent death in end-stage renal disease

BACKGROUND

This study determined the prevalence of increased cardiac troponin I (cTnI) and T (cTnT) in end-stage renal disease (ESRD) patients and whether an increased troponin was predictive of death.

METHODS AND RESULTS

Serum was obtained from 733 ESRD patients and measured for cTnI and cTnT. Relative risks were estimated using Cox proportional hazards regressions univariately and adjusted for age, time on dialysis, and coronary artery disease. Kaplan-Meier curves compared time to event data between groups. Greater percentages of patients had an increased cTnT versus cTnI at each cutoff, as follows: 99th percentile, 82% versus 6%; 10% coefficient of variation, 53% versus 1.0%; and receiver operator characteristic, 20% versus 0.4%. Increased versus normal cTnT was predictive of increased mortality using all cutoffs and only above the 99th percentile for cTnI. Two-year cumulative mortality rates increased (P<0.001) with changes in cTnT from normal (<0.01 microg/L, 8.4%) to small (> or =0.01 to <0.04 microg/L, 26%), moderate (> or =0.04 to <0.1 microg/L, 39%), and large (> or =0.1 microg/L, 47%) increases. Two-year mortalities were 30% for cTnI <0.1 microg/L and 52% if > or =0.1 microg/L. Univariate and adjusted relative risks of death associated with elevated (>99th percentile) cTnT were 5.0 (CI, 2.5 to 10; P<0.001) and 3.9 (CI, 1.9 to7.9; P<0.001) and cTnI were 2.0 (CI, 1.3 to 3.3; P=0.008) and 2.1 (CI, 1.3 to 3.3; P=0.007). Age, coronary artery disease, and time on dialysis were also independent predictors of mortality.

CONCLUSIONS

Increases in cTnT and cTnI in ESRD patients show a 2- to 5-fold increase in mortality, with a greater number of patients having an increased cTnT.

Value of a single troponin T at the time of presentation as compared to serial CK-MB determinations in patients with suspected myocardial ischemia

BACKGROUND

Prior studies with cardiac markers have focused predominantly on subjects presenting to the emergency department with chest pain or unstable angina, and have relied on serial markers for the diagnosis of acute myocardial infarction. We evaluated the diagnostic utility of a single cardiac troponin T (cTnT) determination at the time of presentation as compared to serial creatine kinase (CK) MB determinations in a broad spectrum of patients with suspected myocardial ischemia.

METHODS

A total of 267 consecutive patients presenting to the emergency department with suspected myocardial ischemia had a single, blinded cTnT determination drawn at the time of presentation to the emergency department in addition to routine serial electrocardiographic and CK-MB determinations.

RESULTS

The specificity (93.7% vs. 87.1%; p<0.05) and positive predictive value (80.0% vs. 69.4%; p<0.05) of a single cTnT determination were superior to that of serial CK-MB determinations without compromising sensitivity. Forty-six percent of patients with confirmed myocardial infarction and an abnormal cTnT at presentation had a normal initial CK-MB determination. Conversely, 20% of patients without acute coronary syndromes had an abnormal CK-MB determination in the setting of a normal cTnT. The initial cTnT was abnormal in all patients with confirmed myocardial infarction and a symptom duration of at least 3.5 h.

CONCLUSIONS

In a heterogeneous population of patients with suspected myocardial ischemia, the initial cTnT determination drawn at the time of presentation is a powerful diagnostic tool that, when used in context with symptom duration, allows for more rapid and accurate triage of patients than serial CK-MB determinations.

Diagnosis of myocardial injury by biochemical markers: problems and promises

The role of biochemical markers in the diagnosis of acute coronary syndromes has increased considerably in the past decade. The World Health Organization previously defined acute myocardial infarction as a combination of at least 2 of 3 components: symptoms consistent with acute myocardial infarction, electrocardiogram changes diagnostic of acute myocardial infarction, and an enzyme pattern with classic rise and fall. Measurement of creatine kinase and its MB fraction by various assays was the gold standard for the diagnosis. Troponins are more specific and sensitive markers for myocardial injury, and their increasing utilization has resulted in a broadening of the definition of acute myocardial infarction to incorporate high-risk acute coronary syndromes. Previously, traditional enzyme evaluation left patients with small amounts of cellular death undiagnosed; these patients were categorized as having unstable angina or, worse, noncardiac chest pain. Newer markers now identify these patients as a subgroup at high risk for cardiac death or cardiac events. Newer therapeutic interventions and a more invasive strategy have been shown to improve outcomes in this high-risk subgroup. Increased specificity has also reduced the number of patients who undergo extensive, expensive, and invasive evaluations for noncardiac syndromes due to false elevations of traditional markers. This article comprehensively reviews the evolution of biochemical markers for the diagnosis of acute myocardial infarction, addressing their promise for improving delivery of care and outcomes and their technical and diagnostic pitfalls.

[Utility of the serum biochemical markers CPK, CPK MB mass, myoglobin, and cardiac troponin T in a chest pain unit. Which marker determinations should be requested and when?]

BACKGROUND

The prognostic value of biochemical markers in relation to time since onset of chest pain was evaluated in an emergency room with a chest pain unit.

METHODS

In a single-center, prospective study we included 321 consecutive patients admitted to the emergency room with suspected unstable angina IIIB and an evolution of less than 12 hours. Blood samples were collected for CPK, CPK MB mass, myoglobin, and cardiac troponin T assays 6, 12, and 18 h after the onset of pain. ROC curve analysis was carried out to compare biochemical markers in terms of cutoff values and time since onset of pain. We determined the relation between prognosis and biochemical markers before and after adjustment for baseline characteristics.

RESULTS

CPK mass and myoglobin showed the maximum sensitivity and specificity for new ischemic recurrences 6 hours after the onset of chest pain with laboratory cutoff values. We had to wait 12 h after the onset of pain for troponin T to be useful using the laboratory cutoff value (0.1 ng/ml). A single determination 6 hours after onset of chest pain of cardiac troponin T above 0.04 ng/ml was the most sensitive and specific marker for new ischemic recurrences.

CONCLUSIONS

A single blood determination of cardiac troponin T 6 hours after the onset of chest pain complete the prognostic stratification in combination with clinical and ECG variables. The best cutoff point of cardiac troponin T, based on univariate and multivariate analysis, was 0.04 ng/ml 6 h after the onset of chest pain.

Elevations in troponin T and I are associated with abnormal tissue level perfusion: a TACTICS-TIMI 18 substudy. Treat Angina with Aggrastat and Determine Cost of Therapy with an Invasive or Conservative Strategy-Thrombolysis in Myocardial Infarction

BACKGROUND

Cardiac troponin T (cTnT) and I elevations are associated with a higher risk of adverse events, a higher incidence of multivessel disease, complex lesions, and visible thrombus in the setting of non-ST elevation (NSTE) acute coronary syndromes (ACS). Other pathophysiological mechanisms underlying troponin elevation remain unclear.

METHODS AND RESULTS

We evaluated the relationship between troponin elevation and tissue level perfusion using the TIMI myocardial perfusion grade (TMPG) in 310 patients with NSTE-ACS 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. TMPG 0/1 ("closed" microvasculature) was observed more frequently in cTnT-positive patients both before (58.1% versus 42.1%; P=0.007) and after percutaneous coronary intervention (55.4% versus 35.6%; P=0.004). cTnT levels were higher among patients with TMPG 0/1 versus patients with TMPG 2/3 (0.50 versus 0.31 ng/mL; P=0.006). cTnT-positive patients were more likely to have thrombus (42.5% versus 29.3%), tighter stenoses (72.0% versus 64.8%), and higher rates of TIMI flow grade 0/1 (15.6% versus 7.0%; all P<0.05). TMPG 0/1 remained independently associated with cTnT elevation (odds ratio, 1.81; P=0.02), even after adjusting for epicardial TIMI flow grade, presence of thrombus, and prior myocardial infarction. TMPG 0/1 flow both before and after intervention was associated with increased risk of death or myocardial infarction at 6 months.

CONCLUSIONS

Similar to what has been observed in the setting of ST-elevation myocardial infarction, abnormal tissue level perfusion is also associated with adverse outcomes in the NSTE-ACS setting. Independent of the presence of thrombus and abnormal flow in the epicardial artery, impaired tissue level perfusion is associated with a 1.8-fold increased risk of cTnT elevation.

Characteristics and prognostic impact of plasma fibrin monomer (soluble fibrin) in patients with coronary artery disease

We measured fibrin monomer (FM), soluble fibrin, as a marker of thrombin activity in plasma samples obtained in parallel with the first two routine samples for cardiac markers in 165 patients with acute chest pain admitted consecutively to our hospital. A reference limit of FM in a healthy population was set at 3.0 mg/l. Elevated plasma FM was observed in 48.8% of patients with acute coronary syndromes, in 42.3% of patients with specific non-coronary disease, in 31.5% of those with stable angina pectoris and in 18.2% of patients with non-specific chest pain. No significant difference was observed between sample 1 and sample 2 in patients not receiving thrombolytic treatment during the sampling period (P = 0.46). In patients with coronary artery disease, FM was significantly related to the level of cardiac troponin T (P = 0.001), but no correlation was observed between the individual plasma FM and cardiac troponin T values. Outcome analysis during the following 30 months after the index event in patients with acute coronary syndromes revealed higher FM levels in those with coronary re-events or death than in patients without new events (P = 0.001). This observation indicates a prognostic potential of FM in risk evaluation of patients with coronary artery disease.