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

Identification of important genes associated with acute myocardial infarction using multiple cell death patterns

Acute myocardial infarction (AMI) is a global health threat, and programmed cell death (PCD) plays a crucial role in its occurrence and development. In this study, integrated bioinformatics tools were used to explore new biomarkers and therapeutic targets in AMI. Thirteen types of PCD-related genes were identified through literature review, KEGG, and GSEA pathways. Gene expression matrices and clinical data from AMI patients and healthy controls were obtained from the GEO database. Statistical analysis in R identified 377 differentially expressed genes in AMI patients. Intersection analysis between the differentially expressed genes and PCD-related genes revealed 24 genes positively correlated with immune cells such as Neutrophils and Monocytes, while negatively correlated with T cells CD4 memory resting and Plasma cells. Unsupervised clustering analysis divided patients into two groups (C1 and C2) based on the expression levels of these 24 genes. GSVA analysis showed that C2 patients were more active in pathways related to maintaining normal cell morphology and promoting phagocytosis, suggesting a lower programmed cell death rate and a higher tendency to maintain cell survival. Two hub genes, TNFAIP3 and TP53INP2, were identified through LASSO regression analysis and SVM-RFE, and were validated using an external dataset and RT-qPCR、Western blot and ELISA analysis. These hub genes showed significantly higher expression and protein secretion levels in AMI patients compared to healthy individuals. Overall, regulating and controlling PCD, particularly through the identified hub genes, TNFAIP3 and TP53INP2, may provide new therapeutic strategies for improving the prognosis of AMI patients and preventing heart failure.

The use of cardiac troponins and B-type natriuretic peptide in COVID-19

Coronavirus disease 2019 (COVID-19) is still challenging health care systems worldwide. Over time, it has become clear that respiratory disease is not the only important entity as critically ill patients are also more prone to develop complications, such as acute cardiac injury. Despite extensive research, the mainstay of treatment still relies on supportive care and targeted therapy of these complications. The development of a prognostic model which helps clinicians to diverge patients to an appropriate level of care is thus crucial. As a result, several prognostic markers have been studied in the past few months. Among them are the cardiac biomarkers, especially cardiac troponins T/I and brain natriuretic peptide, which seem to have important prognostic values as several reports have confirmed their strong association with adverse clinical outcomes and death. The use of these biomarkers as part of a prognostic tool could potentially result in more precise risk stratification of COVID-19 patients and divergence to an adequate level of care. However, several caveats persist causing international guidelines to still recommend in favour of a more conservative approach to cardiac biomarker testing for prognostic purposes.

Identification and analysis of key genes associated with acute myocardial infarction by integrated bioinformatics methods

BACKGROUND

Acute myocardial infarction (AMI) is a common disease leading threat to human health around the world. Here we aimed to explore new biomarkers and potential therapeutic targets in AMI through adopting integrated bioinformatics tools.

METHODS

The gene expression Omnibus (GEO) database was used to obtain genes data of AMI and no-AMI whole blood. Furthermore, differentially expressed genes (DEGs) were screened using the "Limma" package in R 3.6.1 software. Functional and pathway enrichment analyses of DEGs were performed via "Bioconductor" and "GOplot" package in R 3.6.1 software. In order to screen hub DEGs, the STRING version 11.0 database, Cytoscape and molecular complex detection (MCODE) were applied. Correlation among the hub DEGs was evaluated using Pearson's correlation analysis.

RESULTS

By performing DEGs analysis, 289 upregulated and 62 downregulated DEGs were successfully identified from GSE66360, respectively. And they were mainly enriched in the terms of neutrophil activation, immune response, cytokine, nuclear factor kappa-B (NF-κB) signaling pathway, IL-17 signaling pathway, and tumor necrosis factor (TNF) signaling pathway. Based on the data of protein-protein interaction (PPI), the top 10 hub genes were ranked, including interleukin-8 (CXCL8), TNF, N-formyl peptide receptor 2 (FPR2), growth-regulated alpha protein (CXCL1), transcription factor AP-1 (JUN), interleukin-1 beta (IL1B), platelet basic protein (PPBP), matrix metalloproteinase-9 (MMP9), toll-like receptor 2 (TLR2), and high affinity immunoglobulin epsilon receptor subunit gamma (FCER1G). What's more, the results of correlation analysis demonstrated that there was positive correlation between the 10 hub DEGs.

CONCLUSION

Ten DEGs were identified as potential candidate diagnostic biomarkers for patients with AMI in present study. However, further experiments are needed to confirm the functional pathways and hub genes associated with AMI.

CUPRAC-Reactive Advanced Glycation End Products as Prognostic Markers of Human Acute Myocardial Infarction

Cardiovascular disorders, especially acute coronary syndromes, are among the leading causes of mortality worldwide, and advanced glycation end products (AGEs) are associated with cardiovascular disease and serve as biomarkers for diagnosis and prediction. In this study, we investigated the utility of AGEs as prognostic biomarkers for acute myocardial infarction (AMI). We measured AGEs in serum samples of AMI patients (N = 27) using the cupric ion reducing antioxidant capacity (CUPRAC) method on days 0, 2, 14, 30, and 90 after AMI, and the correlation of serum AGE concentration and post-AMI duration was determined using Spearman's correlation analysis. Compared to total serum protein, the level of CUPRAC reactive AGEs was increased from 0.9 to 2.1 times between 0-90 days after AMI incident. Furthermore, the glycation pattern and Spearman's correlation analysis revealed four dominant patterns of AGE concentration changes in AMI patients: stable AGE levels (straight line with no peak), continuous increase, single peak pattern, and multimodal pattern (two or more peaks). In conclusion, CUPRAC-reactive AGEs can be developed as a potential prognostic biomarker for AMI through long-term clinical studies.

Elevated CK-MB with a normal troponin does not predict 30-day adverse cardiac events in emergency department chest pain observation unit patients

BACKGROUND

Prior studies indicate that an elevated creatinine kinase (CK)-MB imparts poor prognosis in patients with acute coronary syndrome despite a normal troponin. Its prognosis in the undifferentiated chest pain observation unit (CPU) population remains undefined.

OBJECTIVE

To compare rates and predictors of 30-day adverse cardiac events in 2 cohorts (CK ±/MB+ vs. normal [CK ±/MB-]) in low-moderate-risk CPU patients.

METHODS

Consecutive CPU patients were followed in a retrospective cohort study for primary outcome (acute coronary syndrome, percutaneous transluminal coronary angioplasty, coronary artery bypass graft, abnormal stress test, cardiac hospitalization, or death within 30 days) by using standardized chart reviews and national death registry. Exclusions were: those aged 30 years or younger, positive troponin, ischemic electrocardiogram, hemodynamic instability, heart failure, or dialysis.

RESULTS

Between January 2006 and April 2009, 2979 patients were eligible, of which 350 excluded and 2629 analyzed. MB+ compared with normal patients were more likely to be: older (mean, 53.4 ± 14 vs. 51.5 ± 12 years; P = 0.04); male (71% vs. 40%; P = 0.01); renal insufficient (5% vs. 2%; P = 0.01); hypertensive (50% vs. 44%; P = 0.04); dyslipidemic (44% vs. 33%; P = 0.01) obese (55% vs. 43%; P = 0.01); and with known coronary artery disease (14% vs. 5%; P < 0.01). Composite adverse events were 213 (8%) and did not significantly differ for either initial MB+ vs. normal (9.1%, 8.0%; odds ratio, 1.1, 0.7-1.9) or serial MB+ vs. normal (7.5%, 7.4%; odds ratio, 1.0, 0.5-1.8). In a multiple logistic regression model, male sex, diabetes, and prior CAD predicted adverse events, whereas CK-MB along with race, hypertension, smoking, dyslipidemia, family history, and obesity did not.

CONCLUSIONS

Elevated CK-MB does not add value to serial troponin testing in low-moderate-risk CPU patients.

Isolated creatine kinase-MB rise with normal cardiac troponins: a strange occurrence with difficult interpretation

A 37-year-old man is admitted to the hospital for retrosternal chest pain lasting more than 30  min and nonspecific ECG findings. Serial assays of cardiac biomarkers reveal an isolated elevation of creatine kinase-MB and negative troponin levels. A coronary angiography shows normal vessels in the presence of a Thrombolysis in Myocardial Infarction (TIMI) 2 flow. How should this patient be managed and treated? Is it a myocardial infarction? We here provide a review of the relevant literature and suggest that such a strange condition, for which several explanations are possible, involves a worse prognosis than for normal creatine kinase-MB and troponins.

The clinical significance of cardiac troponins in medical practice

Troponins are regulatory proteins that form the cornerstone of muscle contraction. The amino acid sequences of cardiac troponins differentiate them from that of skeletal muscles, allowing for the development of monoclonal antibody-based assay of troponin I (TnI) and troponin T (TnT). Along with the patient history, physical examination and electrocardiography, the measurement of highly sensitive and specific cardiac troponin has supplanted the former gold standard biomarker (creatine kinase-MB) to detect myocardial damage and estimate the prognosis of patients with ischemic heart disease. The current guidelines for the diagnosis of non-ST segment elevation myocardial infarction are largely based on an elevated troponin level. The implementation of these new guidelines in clinical practice has led to a substantial increase in the frequency of myocardial infarction diagnosis. Automated assays using cardiac-specific monoclonal antibodies to cardiac TnI and TnT are commercially available. They play a major role in the evaluation of myocardial injury and prediction of cardiovascular outcome in cardiac and non-cardiac causes. In this review we discuss the clinical applications of cardiac troponins and the interpretation of elevated levels in the context of various clinical settings.

Ischemia-modified albumin levels predict long-term outcome in patients with acute myocardial infarction. The French Nationwide OPERA study

BACKGROUND

Little is known about the capacity of ischemia-modified albumin (IMA) plasma concentration to predict long-term cardiac outcome in patients with established acute myocardial infarction (AMI). Because IMA is a marker of ischemia rather than myocardial cell damage, we hypothesized that IMA plasma levels could provide additional prognostic value to classic clinical and biological risk markers in patients with AMI. Therefore, we investigated the predictive value of plasma IMA in patients with AMI enrolled in the French Nationwide OPERA study.

METHODS

Plasma concentrations of IMA and other cardiac biomarkers (troponin, C-reactive protein, B-type natriuretic peptide) were measured within 24 hours of hospital admission in 471 patients hospitalized with an AMI (defined using European Society of Cardiology/American College of Cardiology criteria). Patients' characteristics, cardiovascular risk factors and treatments, and clinical outcomes were recorded. Univariate and multivariable predictors of cardiac outcome in-hospital and at 1 year were identified.

RESULTS

The primary composite end point (death, resuscitated cardiac arrest, recurrent myocardial infarction or ischemia, heart failure, stroke) occurred in 75 (15.6%) patients in-hospital and in 144 (30.6%) at 1 year: 40% of patients in the highest IMA quartile (>104 IU/mL) reached the end point compared with 20% in the lowest (<83 IU/mL) by 1 year. Multivariable logistic regression analysis identified 4 independent predictors of composite end point at 1 year: plasma concentrations of IMA (P = .01), brain natriuretic peptide (P = .001), heart failure (P = .005), and age (P = .003).

CONCLUSIONS

In patients with AMI, IMA measured within 24 hours is a strong and independent predictor of cardiac outcome at 1 year and may help identify those requiring more aggressive medical management.

National impact of the troponin diagnostic standard on the prevalence and prognosis of acute myocardial infarction in older persons

BACKGROUND

Consensus guidelines from the American College of Cardiology, the American Heart Association, and the European Society of Cardiology have made cardiac troponin central to the diagnosis of acute myocardial infarction (AMI). Although multiple studies have shown that the troponin diagnostic standard facilitates the identification of new AMI cases in the general population, and that elevations of troponin are associated with poor prognosis, questions remain regarding the impact of the troponin diagnostic standard on the prevalence and prognosis of AMI in older persons.

METHODS

Nationwide samples of eligible Medicare beneficiaries aged > or =65 years who were hospitalized (n = 71,120) with a primary discharge diagnosis of AMI between April 1998 and March 1999 (baseline cohort) or July 2000 and June 2001 (remeasurement cohort) were evaluated. The analysis was restricted to patients with clinically confirmed AMI who underwent testing for both CK-MB and troponin.

RESULTS

The majority of these patients (71.0%) were both CK-MB- and troponin-positive, but 17.8% were diagnosed with AMI based solely on positive troponin levels. Combining the CK-MB or both groups as a reference and troponin as a design variable to fit Cox proportional hazards models, troponin-only-positive patients had an unadjusted risk ratio (RR) of 1.14 (95% confidence interval [CI], 1.07-1.22) for the 30-day mortality and RR of 1.09 (95% CI, 1.03-1.15) for the 3-year mortality. However, after adjusting for patient demographics, clinical characteristics, physician specialties, and hospitals characteristics, troponin-only-positive patients had similar risk for early- and long-term mortality as the other 2 groups; the risk-adjusted RR for 30-day mortality was 0.96 (95% CI, 0.89-1.02) and for 3-year mortality was 0.95 (95% CI, 0.90-1.00).

CONCLUSION

The widespread application of cardiac troponins results in a substantial increase in AMI diagnoses in older patients. Contrary to the prevailing wisdom that troponin-only-positive AMIs are smaller "infarctlets" and likely to have better prognosis, older persons with troponin-only AMIs are at similar risk for early and long-term mortality compared with those with CK-MB-positive AMIs. Therefore, nationwide efforts should focus on the unique characteristics of this emerging patient population so as to improve quality of care provided to this high-risk cohort of patients with AMI.

Transcranial Doppler ultrasonography predicts cardiovascular events after TIA

Background

Transient ischemic attack (TIA) patients are at high vascular risk. We assessed the value of extracranial (ECD) and transcranial (TCD) Doppler and duplex ultrasonography to predict clinical outcome after TIA.

Methods

176 consecutive TIA patients admitted to the Stroke Unit were recruited in the study. All patients received diffusion-weighted imaging, standardized ECD and TCD. At a median follow-up of 27 months, new vascular events were recorded.

Results

22 (13.8%) patients experienced an ischemic stroke or TIA, 5 (3.1%) a myocardial infarction or acute coronary syndrome, and 5 (3.1%) underwent arterial revascularization. ECD revealed extracranial ≥ 50% stenosis or occlusions in 34 (19.3%) patients, TCD showed intracranial stenosis in 15 (9.2%) and collateral flow patterns due to extracranial stenosis in 5 (3.1%) cases. Multivariate analysis identified these abnormal ECD and TCD findings as predictors of new cerebral ischemic events (ECD: hazard ratio (HR) 4.30, 95% confidence interval (CI) 1.75 to 10.57, P = 0.01; TCD: HR 4.73, 95% CI 1.86 to 12.04, P = 0.01). Abnormal TCD findings were also predictive of cardiovascular ischemic events (HR 18.51, 95% CI 3.49 to 98.24, P = 0.001).

Conclusion

TIA patients with abnormal TCD findings are at high risk to develop further cerebral and cardiovascular ischemic events.

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.

Unexpected mortality in patients discharged from the emergency department following an episode of nontraumatic chest pain

BACKGROUND

Chest pain is the second most common presenting complaint seen in the emergency department. Following evaluation in the emergency department, many of these patients are discharged with a diagnosis of nonspecific chest pain. Our hypothesis is that this group of patients has a high prevalence of ischaemic heart disease.

METHODS

This was a prospective follow-up study of mortality in 786 patients who presented to an emergency department in the UK with an episode of nontraumatic chest pain and were discharged without further inpatient assessment. Observed mortality was compared with expected mortality in age-matched and sex-matched local population.

RESULTS

The observed mortality of the study group was consistently higher than expected throughout the study period. The 5-year mortality rates for men and women under the age of 65 years were more than double the expected rates for the local population [relative risk of 2.1 (95% confidence interval: 1.4-2.8) and 2.6 (1.4-3.8), respectively]. This increase was less marked in male and female patients aged 65 years or more [relative risk of 1.2 (0.9-1.5) and 1.5 (1.2-1.8), respectively]. Ischaemic heart disease accounted for almost 50% of male deaths in the study group. This compared with an expected rate of less than 30% of male deaths in the local population. An excess of cardiac deaths was not seen in women.

INTERPRETATION

Patients discharged from the emergency department following an episode of acute chest pain have significantly reduced 5-year survival. We conclude that further evaluation of this group to establish the prevalence of risk factors is important to support the strategic implementation of appropriate prevention programmes.

Sex and racial differences in outcomes and guideline-based management of troponin-only-positive acute myocardial infarction in older persons

Multiple studies have shown sex and racial differences in the management and outcomes of ischemic heart disease, but whether these sex and racial disparities persist in patients with troponin-only-positive acute myocardial infarction (AMI) is unknown. The authors evaluated a nationwide sample of eligible Medicare beneficiaries, 65 years or older, who were hospitalized (N=71,120) with a primary discharge diagnosis of AMI. Analysis was restricted to patients with troponin-only-positive AMI (n=5897) and was substratified into 4 groups: white men, white women, nonwhite men, and nonwhite women. The authors found that the traditional sex and racial disparities in the evidence-based medication prescriptions for ischemic heart diseases resolved in this cohort of older patients. Similarly, in settings of equal care, sex and race seem to have no impact on the outcomes for older patients with troponin-only-positive AM.

Biochemical markers of myocardial injury

The serum markers of myocardial injury are used to help in establishing the diagnosis of myocardial infarction. The older markers like aspartate amino-transferase, creatine kinase, lactate dehydrogenase etc. lost their utility due to lack of specificity and limited sensitivities. Among the currently available markers cardiac troponins are the most widely used due to their improved sensitivity specificity, efficiency and low turn around time. Studies have shown that cardiac troponins should replace CKMB as the diagnostic 'gold standard' for the diagnosis of myocardial injury. The combination of myoglobin with cardiac troponins has further improved the accuracy in the diagnosis of acute coronary syndromes and thereby reducing the hospital stay and patients' money. Among the other new markers of early detection of myocardial damage, heart fatty acid binding protein, glycogen phosphorylase BB and myoglobin/carbonic anhydrase III ratio seem to be the most promising. But the search for the most ideal marker of myocardial injury is still on.

Validation and refinement of scores to predict very early stroke risk after transient ischaemic attack

BACKGROUND

We aimed to validate two similar existing prognostic scores for early risk of stroke after transient ischaemic attack (TIA) and to derive and validate a unified score optimised for prediction of 2-day stroke risk to inform emergency management.

METHODS

The California and ABCD scores were validated in four independent groups of patients (n=2893) diagnosed with TIA in emergency departments and clinics in defined populations in the USA and UK. Prognostic value was quantified with c statistics. The two groups used to derive the original scores (n=1916) were used to derive a new unified score based on logistic regression.

FINDINGS

The two existing scores predicted the risk of stroke similarly in each of the four validation cohorts, for stroke risks at 2 days, 7 days, and 90 days (c statistics 0.60-0.81). In both derivation groups, c statistics were improved for a unified score based on five factors (age >or=60 years [1 point]; blood pressure >or=140/90 mm Hg [1]; clinical features: unilateral weakness [2], speech impairment without weakness [1]; duration >or=60 min [2] or 10-59 min [1]; and diabetes [1]). This score, ABCD(2), validated well (c statistics 0.62-0.83); overall, 1012 (21%) of patients were classified as high risk (score 6-7, 8.1% 2-day risk), 2169 (45%) as moderate risk (score 4-5, 4.1%), and 1628 (34%) as low risk (score 0-3, 1.0%).

IMPLICATIONS

Existing prognostic scores for stroke risk after TIA validate well on multiple independent cohorts, but the unified ABCD(2) score is likely to be most predictive. Patients at high risk need immediate evaluation to optimise stroke prevention.

Discordant Cardiac Biomarkers: Frequency and Outcomes in Emergency Department Patients With Chest Pain

STUDY OBJECTIVE

We evaluate associations between pairs of discordant cardiac biomarkers (positive MB band of creatine kinase [CKMB] with negative creatine kinase, positive CKMB with negative cardiac troponin, and positive troponin with negative CKMB) and the presence of acute coronary syndromes in emergency department (ED) chest pain patients.

METHODS

This was a secondary analysis of a prospective registry. Data were obtained from the multicenter Internet Tracking Registry of Acute Coronary Syndromes, which included 17,713 ED visits for possible acute coronary syndrome between June 1999 and August 2001. First visits and first ED cardiac biomarker results from the 9 sites, 8 in the United States and 1 in Singapore, were included. Subjects were excluded for incomplete information or an initial ECG consistent with ST-segment elevation myocardial infarction. Acute coronary syndrome was defined by diagnosis-related group code indicating myocardial infarction, positive invasive or noninvasive diagnostic testing, revascularization, or death during hospitalization or within 30 days.

RESULTS

Of 8,769 eligible patients, 1,614 (18.4%) had acute coronary syndrome. The CKMB and cardiac troponin results were discordant in 7% of patients (CKMB+/cardiac troponin-, 4.9%, CKMB-/cardiac troponin+ 2.1%), whereas increased CKMB with normal creatine kinase levels occurred in 239 (3.1%) patients. The unadjusted odds ratios with 95% confidence intervals for acute coronary syndrome in patients with and without discordant markers were: CKMB+/CK- 5.7 (4.4-7.4), CKMB+/CK+ 4.4 (3.6-5.2), CKMB-/cTn+ 4.8 (3.4-6.8), CKMB+/cTn- 2.2 (1.7-2.8), CKMB+/cTn+ 26.6 (18.0-39.3). For the group with cardiac troponin, the reference category was negative troponin and negative CKMB; for the group with creatine kinase, the reference category was negative CKMB but either a positive or negative creatine kinase.

CONCLUSION

Among the spectrum of ED patients with chest pain, an increased CKMB level with a normal creatine kinase level identifies patients at increased risk for acute coronary syndrome. Similarly, an increased troponin level regardless of CKMB level and an increased CKMB level regardless of troponin level identify patients at higher risk for acute coronary syndrome than those with uniformly normal cardiac biomarker levels. Our data suggest that discordant cardiac biomarkers may identify patients at increased risk for acute coronary syndrome.

Detected troponin elevation is associated with high early mortality after lung resection for cancer

Background

Myocardial infarction can be difficult to diagnose after lung surgery. As recent diagnostic criteria emphasize serum cardiac markers (in particular serum troponin) we set out to evaluate its clinical utility and to establish the long term prognostic impact of detected abnormal postoperative troponin levels after lung resection.

Methods

We studied a historic cohort of patients with primary lung cancer who underwent intended surgical resection. Patients were grouped according to known postoperative troponin status and survival calculated by Kaplan Meier method and compared using log rank. Parametric survival analysis was used to ascertain independent predictors of mortality.

Results

From 2001 to 2004, a total of 207 patients underwent lung resection for primary lung cancer of which 14 (7%) were identified with elevated serum troponin levels within 30 days of surgery, with 9 (64%) having classical features of myocardial infarction.

The median time to follow up (interquartile range) was 22 (1 to 52) months, and the one and five year survival probabilities (95% CI) for patients without and with postoperative troponin elevation were 92% (85 to 96) versus 60% (31 to 80) and 61% (51 to 71) versus 18% (3 to 43) respectively (p < 0.001).

T stage and postoperative troponin elevation remained independent predictors of mortality in the final multivariable model. The acceleration factor for death of elevated serum troponin after adjusting for tumour stage was 9.19 (95% CI 3.75 to 22.54).

Conclusion

Patients with detected serum troponin elevation are at high risk of early mortality with or without symptoms of myocardial infarction after lung resection.

Non-ST Segment Elevation Acute Coronary Syndromes: A Comprehensive Review

As the non-ST segment elevation acute coronary syndromes (NSTEACS) include unstable angina pectoris (UAP) and the non-ST segment elevation myocardial infarction (NSTEMI), acute diagnosis and risk stratification can often prove challenging. This review will cover guidelines and strategies for risk assessment, contemporary approaches to acute patient management as well as recommendations for timing of specialist referral.

The association between hyperglycaemia and elevated troponin levels on mortality in acute coronary syndromes

Diabetes is associated with increased cardiovascular morbidity and mortality. We studied the relationship between hyperglycaemia, troponin I concentrations and one-year mortality in 498 subjects admitted to hospital with an acute coronary syndrome. The proportion of deaths was higher in those with hyperglycaemia (random glucose > 11.1 mmol/L) compared to those without (27% and 12%, respectively, Chi-squared test = 9.84, p=0.002). There was a difference in troponin I concentration on admission between those patients who were alive and dead (median and interquartile range 0.14 [0 to 3.90] and 2.98 [0.23 to 18.53] respectively, p<0.001) and the risk of death was elevated in those with a myocardial infarction compared to those without (relative risk = 1.85, 95% confidence intervals 1.55 to 2.21). Despite adherence to guidelines for the management of acute coronary syndromes, the presence of hyperglycaemia confers a significant long-term mortality disadvantage.

Myocardial infarction redefined: impact on case-load and outcome of patients with suspected acute coronary syndrome and nondiagnostic ECG at presentation

Risk stratification of chest pain (CP) is still debated. Objective of this study was to evaluate the performance of a risk stratification model for patients with suspected acute coronary syndrome (ACS) and nondiagnostic ECG at presentation, in whom the occurrence of myocardial infarction was either diagnosed following traditional (t-MI) or the recently redefined (r-MI) criteria. First-line 6-h work-up categorized 3068 patients with suspected ACS and nondiagnostic ECG into low-risk for short-term coronary events, intermediate-risk who entered second-line work-up, and high-risk. Intermediate-risk patients with positive second-line work-up and high-risk patients were considered for urgent coronary angiography. Angina, non-fatal MI, sudden death, and revascularization constituted composite end-point (CE) for in-hospital and 6-month outcome. ACS incidence was 16%; r-MI increased by 62% the diagnosis of MI over t-MI. Among 2024 discharged low-risk patients, 12 (0.6%) had non-fatal CE at 6 months. ACS was diagnosed in 19% of 503 intermediate-risk and 96% of 389 high-risk patients. Among ACS patients, in-hospital CE occurred in 14% of t-MI, 7% of r-MI, and 9% of unstable angina (UA) patients (t-MI vs. r-MI and t-MI vs. UA: p<0.05, for both); 6-month CE occurred in 23%, 16% and 12% of t-MI, r-MI and UA, respectively (t-MI vs. UA: p<005). Sensitivity, specificity and accuracy were high both for diagnostic (97%, 98%, 99%, respectively) and treatment (83%, 98%, 97%, respectively) strategy. Risk stratification, and categorization according to traditional or redefined MI and UA criteria allow safe allocation of resources in CP patients with suspected ACS and nondiagnostic ECG at presentation because outcome is accurately predicted.

Bare metal stent restenosis is not a benign clinical entity

BACKGROUND

Restenosis after percutaneous coronary intervention (PCI) has been thought to present in a stable manner as exertional angina. However, the presentation of in-stent restenosis (ISR) is not well-studied. We hypothesized that a substantial proportion of bare metal ISR presents as acute coronary syndromes. We aimed to characterize the severity of the clinical presentation of ISR.

METHODS

We searched our PCI database for all cases of PCI for bare metal ISR occurring between May 1999 and September 2003. Multivessel interventions were excluded. In-stent restenosis presentation was classified into three categories: (1) myocardial infarction (MI), (2) unstable angina requiring hospitalization before angiography, and (3) exertional angina. Routine angiographic screening after initial stent placement was not performed, so ISR episodes were clinical, rather than angiographic, ISR.

RESULTS

We identified 1186 cases of bare metal ISR in 984 patients. Median age was 63, 72% were male, and 36% had diabetes. Of the ISR episodes, 9.5% presented as acute MI (7.3% as non-ST-segment elevation MI and 2.2% as ST-segment elevation MI), 26.4% as unstable angina requiring hospitalization before angiography, and 64.1% as exertional angina.

CONCLUSIONS

More than one third of bare metal ISR episodes presented as MI or unstable angina requiring hospitalization. The acuity of the clinical presentation of bare metal ISR appears to be more severe than has been previously thought. Aggressive efforts, such as drug-eluting stents to decrease the incidence of unstable angina due to bare metal ISR, are warranted.

Prognostic factors in patients with minor troponin-I elevation but without acute myocardial infarction

OBJECTIVES

Although cardiac troponin I is widely used as a marker for myocardial infarction, its minor elevations are also observed in other clinical situations, and the prognostic factors in such clinical settings have not been well established. The aim of this study was to identify predictors of mortality in patients with minor troponin elevations without an acute myocardial infarction.

METHODS

We consecutively enrolled 134 patients from the emergency department with a peak troponin I level greater than the lower limit of detectability (0.04 ng/ml) but less than the 10% coefficient of variation cutoff value for diagnosis of myocardial infarction (0.26 ng/ml). These patients had chest pain or nonspecific symptoms of a circulatory abnormality but lacked the traditional features of an acute myocardial infarction. End point was defined as death from all causes. Cox regression analysis was used to test relations between clinical and biochemical variables and the outcome.

RESULTS

During the follow-up of 7.6+/-7.4 months, 12 patients died. Age, log creatine kinase myocardial isoform, and log C-reactive protein were found to be significantly correlated with death. After adjusting for possible confounders in the multivariate model, age (hazard ratio 1.09, confidence interval 1.02-1.16, P=0.012), log creatine kinase myocardial isoform (hazard ratio 13.11, confidence interval 2.01-85.52, P=0.007), and log C-reactive protein (hazard ratio 1.64, confidence interval 1.02-2.56, P=0.041) were identified as independent predictors of mortality.

CONCLUSIONS

Creatine kinase myocardial isoform and C-reactive protein levels and age can be integrated to risk-stratify patients with minor troponin I elevation for reasons other than acute myocardial infarction.

The diagnostic and prognostic impact of the redefinition of acute myocardial infarction: lessons from the Global Registry of Acute Coronary Events (GRACE)

BACKGROUND

The impact and prognostic value of the redefinition of myocardial infarction (MI) with more sensitive markers have not been evaluated prospectively in a large, less selected population with acute coronary syndrome (ACS).

METHODS

We evaluated the attack and case-fatality rates of MI based on initial and/or peak creatine kinase (CK), creatine kinase-MB (CK-MB), and cardiac troponin (the upper limit of normal [ULN] was defined according to the local hospital's standard) in a prospective observational registry of 26,267 patients with ACS admitted to 106 hospitals in 14 countries.

RESULTS

The addition of cardiac troponin-positive status to CK status as a criterion for the diagnosis of MI resulted in as many as 1 in 4 additional patients meeting the redefined criteria. Compared with patients without elevated levels of CK and cardiac troponin, the crude odds for dying during hospitalization were significantly higher for patients with elevated troponin but not CK levels of greater than or equal to the ULN (odds ratio [OR] 2.2, 95% CI 1.6-2.9), those without CK levels >2 times the ULN (OR 2.8, 95% CI 2.2-3.5), and those with nonelevated levels of CK-MB (OR 2.1, 95% CI 1.4-3.2). The addition of cardiac troponin-positive status significantly increased the multivariable-adjusted odds for hospital death in patients with CK < or =2 times the ULN (OR 1.6, 95% CI 1.2-2.1) but not for patients without elevated levels of CK or CK-MB.

CONCLUSIONS

The prognostic value of cardiac troponin, beyond that supplied by CK status or important baseline characteristics, assists in the identification of patients with ACS who are at increased risk for death.

Chest pain unit concept: rationale and diagnostic strategies

Each year in the United States, over 8 million patients present to the emergency department(ED) with complaints of chest discomfort or other symptoms consistent with possible acute coronary syndrome (ACS). While over half of these patients are typically admitted for further diagnostic evaluation, fewer than 20% are diagnosed with ACS. With hospital beds and inpatient resources scarce, these admissions can be avoided by evaluating low- to moderate-risk patients in chest pain units. This large, undifferentiated patient population represents a potential high-risk group for emergency physicians requiring a systematic approach and specific ED resources. This evaluation is required to appropriately determine if a patient is safe to be discharged home with outpatient follow-up versus requiring admission to the hospital for monitoring and further testing.

Acute coronary syndromes in the emergency department: diagnostic characteristics, tests, and challenges

Failure to diagnose patients who have acute coronary syndromes (ACSs)-either acute myocardial infarction (AMI) or unstable angina pectoris (UAP)-who present to the emergency department (ED) remains a serious public health issue. Better understanding of the pathophysiology of coronary artery disease has allowed the adoption of a unifying hypothesis for the cause of ACSs: the conversion of a stable atherosclerotic lesion to a plaque rupture with thrombosis. Thus, physicians have come to appreciate UAP and AMI as parts of a continuum of ACSs. This article reviews the state of the art regarding the diagnosis of ACSs in the emergency setting and suggests reasons why missed diagnosis continues to occur, albeit infrequently.

Frequency and Clinical Implications of Discordant Creatine Kinase-MB and Troponin Measurements in Acute Coronary Syndromes

OBJECTIVES

We sought to evaluate the association between discordant cardiac marker results and in-hospital mortality and treatment patterns in patients with non-ST-segment elevation acute coronary syndromes (NSTE ACS).

BACKGROUND

Creatine kinase-MB (CK-MB) and cardiac troponins (cTn) are often measured concurrently in patients with NSTE ACS. The significance of discordant CK-MB and cTn results is unknown.

METHODS

Among 29,357 ACS patients in the CRUSADE initiative who had both CK-MB and cTn measured during the first 36 hours, we examined relationships of four marker combinations (CK-MB-/cTn-, CK-MB+/cTn-, CK-MB-/cTn+, and CK-MB+/cTn+) with mortality and American College of Cardiology/American Heart Association guidelines-recommended acute care.

RESULTS

The CK-MB and cTn results were discordant in 28% of patients (CK-MB+/cTn-, 10%; CK-MB-/cTn+, 18%). In-hospital mortality was 2.7% among CK-MB-/cTn- patients; 3.0%, CK-MB+/cTn-; 4.5%, CK-MB-/cTn+; and 5.9%, CK-MB+/cTn+. After adjustment for other presenting risk factors, patients with CK-MB+/cTn- had a mortality odds ratio (OR) of 1.02 (95% confidence interval [CI] 0.75 to 1.38), those with CK-MB-/cTn+ had an OR of 1.15 (95% CI 0.86 to 1.54), and those with CK-MB+/cTn+ had an OR of 1.53 (95% CI 1.18 to 1.98). Despite variable risk, patients with CK-MB+/cTn- and CK-MB-/cTn+ were treated similarly with early antithrombotic agents and catheter-based interventions.

CONCLUSIONS

Among patients with NSTE ACS, an elevated troponin level identifies patients at increased acute risk regardless of CK-MB status, but an isolated CK-MB+ status has limited prognostic value. Recognition of these risk differences may contribute to more appropriate early use of antithrombotic therapy and invasive management for all cTn+ patients.

Stress testing and troponin in unstable coronary syndromes: the status trial-clinical outcomes and resource use

Cardiac troponins are markers used to diagnose acute myocardial infarction, but their value in guiding management in low- to intermediate-risk patients is not well established. Using a randomized design, the authors compared a strategy using stress testing with blinded troponins vs a troponin I-guided strategy for risk stratification and management of 241 patients with intermediate-risk unstable angina. Fewer stress-tested patients required coronary care unit admission and repeat hospitalization for acute coronary syndrome, at a lower cost. There was no significant difference in rates of death and myocardial infarction due to acute coronary syndrome at 6 months' follow-up. For patients with intermediate-risk acute coronary syndrome, stress testing is as safe as, and more cost-effective than, a troponin I-guided strategy. Patients with marginal troponin I elevations can safely undergo stress testing. Further studies combining stress testing and a troponin I-guided strategy are warranted.

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.

Diagnostic potential of phosphorylated cardiac troponin I as a sensitive, cardiac-specific marker for early acute coronary syndrome: Preliminary report

BACKGROUND

Cardiac troponin I (cTnI) has low sensitivity in the early hours of acute coronary syndrome (ACS). For patients with early ACS symptoms, we determined the diagnostic potential of an immunoassay for phosphorylated cTnI (PO(4)-cTnI).

METHODS

In a prospective study of 61 emergency department patients with suspected ACS, we compared a novel plasma immunoassay for PO(4)-cTnI to cTnI overall and in a subgroup with symptoms < or =4 h duration (n = 31). Admission PO(4)-cTnI and cTnI assays (thresholds determined by ROC curve) were analyzed in a blinded fashion against the clinical, ECG and coronary angiographic diagnosis of ACS.

RESULTS

Overall, PO(4)-cTnI sensitivity was significantly higher than cTnI (82% vs. 50%, respectively, P < 0.05) and PO(4)-cTnI specificity was 81% (n = 61). Addition of PO(4)-cTnI to cTnI improved sensitivity to 91% vs. 50% for cTnI alone (P < 0.001). In the < or =4 h subgroup (n = 31), PO(4)-cTnI sensitivity was significantly higher than cTnI (79% vs. 26%, respectively, P < 0.01) and PO(4)-cTnI specificity was 75%. In the same < or =4 h subgroup, addition of PO(4)-cTnI to cTnI improved sensitivity to 84% vs. 26% for cTnI alone (P = 0.001).

CONCLUSIONS

The results suggest that PO(4)-cTnI, alone or in combination with cTnI, warrants further investigation as a sensitive, cardiac-specific diagnostic tool for early ACS.

Artificial Neural Network Models for Prediction of Acute Coronary Syndromes Using Clinical Data From the Time of Presentation

STUDY OBJECTIVE

Clinical and ECG data from presentation are highly discriminatory for diagnosis of acute coronary syndromes, whereas definitive diagnosis from serial ECG and cardiac marker protein measurements is usually not available for several hours. Artificial neural networks are computer programs adept at pattern recognition tasks and have been used to analyze data from chest pain patients with a view to developing diagnostic algorithms that might improve triage practices in the emergency department. The aim of this study is to develop and optimize artificial neural network models for diagnosis of acute coronary syndrome, to test these models on data collected prospectively from different centers, and to establish whether the performance of these models was superior to that of models derived using a standard statistical technique, logistic regression.

METHODS

The study used data from 3,147 patients presenting to 3 hospitals with acute chest pain. Data from hospital 1 were used to train the models, which were then tested on independent data from the other 2 hospitals. From 40 potential factors, variables were selected according to the logarithm of their likelihood ratios to produce models using 8, 13, 20, and 40 factors. Identical data were used for logistic regression and artificial neural network models. Calibration and performance were assessed, the latter using receiver operating characteristic (ROC) curve analysis.

RESULTS

Although the performance of artificial neural network models generally increased with increasing numbers of factors, this was insignificant. The 13-factor model was therefore used for the rest of the study owing to its marginally improved calibration over the smallest model. Area under the ROC curve (with standard error) was 0.97 (0.006). The overall sensitivity and specificity of this model for acute coronary syndrome diagnosis using the training data was 0.93. ROC curves for logistic regression and artificial neural network models applied to data from the 3 hospitals were identical. For the 13-factor artificial neural network model tested on data from hospitals 2 and 3, area under the ROC curves (standard error) were 0.93 (0.006) and 0.95 (0.009), respectively. Investigation of the performance of the artificial neural network models throughout the range of predicted probabilities showed that they were well calibrated.

CONCLUSION

This study confirms that artificial neural networks can offer a useful approach for developing diagnostic algorithms for chest pain patients; however, the exceptional performance and simplicity of the logistic model militates in favor of logistic regression for the present task. Our artificial neural network models were well calibrated and performed well on unseen data from different centers. These issues have not been addressed in previous studies. However, and unlike in previous studies, we did not find the performance of artificial neural network models to be significantly different from that of suitably optimized logistic regression models.

Using biomarkers to assess risk and consider treatment strategies in non-ST-segment elevation acute coronary syndromes

Since the first biomarker of myocardial necrosis was described in 1954, cardiac-specific biomarkers have been increasingly identified. This, coupled with dramatic evolution in assay technology and resultant highly sensitive assays, has rendered a remarkable transformation in the medical use of biomarkers. Initially used to aid in diagnosis of myocardial infarction, newer biomarkers of inflammation, plaque instability, and ischemia may complement biomarkers of necrosis by providing tools to diagnose impending myocardial necrosis before irreversible damage occurs, and offering additional information for risk stratification. Importantly, biomarkers of different processes may be combined to enhance risk stratification above that of any single marker.

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.