Elevated cardiac troponin levels do not predict adverse outcomes in hospitalized patients without clinical manifestations of acute coronary syndromes

Use of Admission Troponin in Critically Ill Medical Patients

Serum troponin I (TnI) is a sensitive marker of cardiac injury. A relation between elevated TnI and mortality has been suggested. In this retrospective chart review of 221 patients admitted to the medical intensive care unit (MICU) during a 6-month period, the authors studied the use of admission TnI levels in predicting mortality in MICU-admitted patients. Data retrieved included demographics, admission diagnosis, troponin, electrocardiogram, Acute Physiology and Chronic Health Evaluation (APACHE) II score, echocardiogram, requirements for mechanical ventilation and vasopressor support, development of multiorgan failure, mortality, and discharge disposition. There were 132 patients for whom TnI level was sent within 24 hours of admission; these patients comprised the study group. The median age was 70 years; 59% were female. The mean APACHE II score was 22. Troponin I was positive in 31% of patients (median level, 0.4 Ug/L; range 0-358 Ug/L). The hospital mortality was 39%. Positive TnI showed a weak association with intensive care unit (ICU) mortality ( P= .049) but not with overall mortality. There was no significant correlation between admission TnI concentration and APACHE II score ( P= .33), administration of vasopressor medications ( P= .115), or development of multiorgan failure ( P= .64). The authors concluded that there is no benefit in obtaining a routine admission troponin level in MICU patients when an acute coronary event is not suspected.

[Acute coronary syndrome in acute stroke]

BACKGROUND

Elevated troponin levels are commonly found in patients with acute stroke and approximately 60 % of stroke patients suffer from an accompanying coronary artery disease. Troponin release can be caused either by an acute thrombotic myocardial infarction or by insufficient coronary perfusion due to neurocardiogenic causes like blood pressure or heart rate variability without thrombotic coronary occlusion. Due to the often unclear pathological cause of troponin release and the risk of secondary hemorrhage during dual antiplatelet therapy, the determination of the best time point for coronary diagnostics and therapy in stroke patients is a common challenge in clinical daily routine.

MATERIALS AND METHODS

Based on the current literature, we describe a potential diagnostic and therapeutic approach in stroke patients with increased troponin levels.

RESULTS

First, the probability of an acute thrombotic myocardial infarction should be evaluated based on clinical, laboratory, and electrocardiographic parameters. In case of suspected myocardial infarction, a diagnostic coronary angiography/CT angiography should be performed and dual antiplatelet therapy should be given depending on the intracranial bleeding risk. In patients with high risk of intracranial bleeding, thrombus aspiration and balloon dilatation should be considered.

CONCLUSION

In patients with acute stroke and elevated troponin levels, a thorough diagnostic workup is necessary to estimate the probability for a thrombotic myocardial infarction and to prevent cardiac and neurologic complications.

Clinical utility and prognostic significance of measuring troponin I levels in patients presenting to the emergency room with atrial fibrillation

BACKGROUND

The clinical significance of mildly elevated troponins in patients presenting to the emergency room (ER) with atrial fibrillation (AF) is not well understood.

HYPOTHESIS

We hypothesized that mildly elevated troponin in these patients is associated with adverse cardiovascular outcomes.

METHODS

In a multi-center, retrospective study, 662 patients with AF were divided into 3 groups based on troponin levels: group 1, mildly elevated; group 2, normal; and group 3, troponin not measured. Primary outcome was the combined endpoint of all-cause mortality and myocardial infarction (MI) at one year.

RESULTS

Levels of TnI were measured in 503 (76%) patients. They were elevated in 220 patients (33%, group 1; mean, 0.56 ng/mL), normal in 283 patients (43%, group 2), and not measured in 159 patients (24%, group 3). Significantly more cardiac testing was done at index hospitalization in group 1 (50%) compared with groups 2 and 3 (28% and 29%, P ≤ 0.001) and in the following year (29%, vs 20% and 17%, P = 0.02). Group 1 had more positive tests (62%) compared with groups 2 and 3 (25% and 43%, P ≤ 0.001). Group 1 had a significantly higher occurrence of the primary endpoint (22%, vs 10% and 15%, P = 0.002), driven primarily by a higher incidence of MI in group 1 (7%, vs 1% and 2%, P = 0.001).

CONCLUSIONS

Troponin levels are routinely checked in a majority of patients presenting to the emergency department with AF. Even mildly elevated TnI is associated with a greater incidence of coronary artery disease on diagnostic testing and a higher 1-year incidence of MI.

Cardiac complications in acute ischemic stroke

Introduction

To characterize cardiac complications in acute ischemic stroke (AIS) patients admitted from an urban emergency department (ED).

Methods

Retrospective cross-sectional study evaluating AIS patients admitted from the ED within 24 hours of symptom onset who also had an echocardiogram performed within 72 hours of admission.

Results

Two hundred AIS patients were identified with an overall in-hospital mortality rate of 8% (n = 16). In our cohort, 57 (28.5%) of 200 had an ejection fraction less than 50%, 35 (20.4%) of 171 had ischemic changes on electrocardiogram (ECG), 18 (10.5%) of 171 presented in active atrial fibrillation, 21 (13.0%) of 161 had serum troponin elevation, and 2 (1.1%) of 184 survivors had potentially lethal arrhythmias on telemetry monitoring. Subgroup analysis revealed higher in-hospital mortality rates among those with systolic dysfunction (15.8% versus 4.9%; P = 0.0180), troponin elevation (38.1% versus 3.4%; P < 0.0001), atrial fibrillation on ECG (33.3% versus 3.8%; P = 0.0003), and ischemic changes on ECG (17.1% versus 6.1%; P = 0.0398) compared with those without.

Conclusion

A proportion of AIS patients may have cardiac complications. Systolic dysfunction, troponin elevation, atrial fibrillation, or ischemic changes on ECG may be associated with higher in-hospital mortality rates. These findings support the adjunctive role of cardiac-monitoring strategies in the acute presentation of AIS.

The twilight zone of troponins

Since its introduction into the clinical environment in the early nineties, the cardiac enzyme troponin has significantly changed the way we diagnose and manage acute coronary syndromes. Troponin I is a biochemical marker of myocardial injury with a high level of specificity and sensitivity. It has been demonstrated that as ischaemia progresses, troponin I is degraded predictably into smaller and smaller fragments that can be detected in the blood-stream. This may eventually allow more accurate determination of the duration of ischaemia and the likelihood of myocardial salvage and recovery.

Increases of cardiac troponin in conditions other than acute coronary syndrome and heart failure

BACKGROUND

Although cardiac troponin (cTn) is a cornerstone marker in the assessment and management of patients with acute coronary syndrome (ACS) and heart failure (HF), cTn is not diagnostically specific for any single myocardial disease process. This narrative review discusses increases in cTn that result from acute and chronic diseases, iatrogenic causes, and myocardial injury other than ACS and HF.

CONTENT

Increased cTn concentrations have been reported in cardiac, vascular, and respiratory disease and in association with infectious processes. In cases involving acute aortic dissection, cerebrovascular accident, treatment in an intensive care unit, and upper gastrointestinal bleeding, increased cTn predicts a longer time to diagnosis and treatment, increased length of hospital stay, and increased mortality. cTn increases are diagnostically and prognostically useful in patients with cardiac inflammatory diseases and in patients with respiratory disease; in respiratory disease cTn can help identify patients who would benefit from aggressive management. In chronic renal failure patients the diagnostic sensitivity of cTn for ACS is decreased, but cTn is prognostic for the development of cardiovascular disease. cTn also provides useful information when increases are attributable to various iatrogenic causes and blunt chest trauma.

SUMMARY

Information on the diagnostic and prognostic uses of cTn in conditions other than ACS and heart failure is accumulating. Although increased cTn in settings other than ACS or heart failure is frequently considered a clinical confounder, the astute physician must be able to interpret cTn as a dynamic marker of myocardial damage, using clinical acumen to determine the source and significance of any reported cTn increase.

Prognostic significance of troponin T elevation in patients without chest pain

Increased cardiac troponin with chest pain is important for the diagnosis, triage, and treatment of patients in the emergency department. However, the use of troponin for the diagnosis and triage of patients without chest pain is poorly established. The aim of this study was to determine 30-day and 1-year mortality and morbidity of troponin T increases in patients without chest pain. This retrospective study compared 92 hospitalized patients without (study group) and 91 patients with chest pain (control group), followed up for 1 year. Study group patients had troponin T >0.04 microg/L, normal creatine kinase or creatine kinase-MB fraction <5%, and no electrocardiographic ischemia. Excluded were high-risk patients with end-stage kidney disease, those with left ventricular ejection fraction <40%, and the critically ill. Outcome variables included 30-day and 1-year death, myocardial infarction, unstable angina, and coronary revascularization rates. Thirty-day (13.0% vs 4.4%; p = 0.032) and 1-year (33% vs 4.6%; p <0.001) mortality rates were significantly higher in the study group, whereas myocardial infarction, unstable angina, and revascularization were infrequent. In conclusion, patients with increased troponin T and no chest pain had a high mortality rate and required careful follow-up.

Myocardial stress in patients with acute cerebrovascular events

Signs of myocardial involvement are common in patients with acute cerebrovascular events. ST segment deviations, abnormal left ventricular function, increased N-terminal pro-brain natriuretic peptide (NT-proBNP), prolonged QT interval, and/or raised troponins are observed in up to one third of the patients. The huge majority of these findings are fully reversible. The changes may mimic myocardial infarction, but are not necessarily identical to coronary thrombosis. Based on the literature these signs may represent an acute catecholamine release provoked by the cerebrovascular catastrophe itself and not coronary thrombosis. However, all patients with signs of cardiac involvement during acute cerebrovascular events should receive a cardiological follow-up in order to exclude concomitant ischemic heart disease.

Prognostic value of SPECT myocardial perfusion imaging in patients with elevated cardiac troponin I levels and atypical clinical presentation

BACKGROUND

We determined the prognostic value of myocardial perfusion imaging (MPI) in patients with atypical clinical presentations and unexpected elevation of cardiac troponin I (cTnI) levels.

METHODS AND RESULTS

In 156 consecutive patients with atypical presentations for acute coronary syndromes (ACS) and elevated cTnI levels undergoing MPI within 30 days, rates of all-cause mortality (100% follow-up; median follow-up, 611 days) and 6-month cardiac death and nonfatal myocardial infarction (96% follow-up; median follow-up, 167 days) were determined. The mean age of the patients was 68 +/- 14 years. The majority of the study cohort (96%) was at low to intermediate clinical risk for ACS (Thrombolysis in Myocardial Infarction score for unstable angina/non-ST-segment elevation myocardial infarction <5). The overall event rate was high, with 45 deaths (28.8%). There were 13 cardiac deaths/nonfatal myocardial infarctions in 6 months (8.3%). A normal MPI result was associated with a high event-free survival rate, whereas an abnormal MPI result was associated with a 3-fold and 7-fold higher risk of all-cause mortality and 6-month cardiac events, respectively. An abnormal MPI result was an independent predictor of all-cause death.

CONCLUSIONS

In patients with cTnI elevation and a low to intermediate risk for ACS, a normal MPI result portends a good prognosis. Patients with abnormal MPI results have a higher 6-month cardiac event rate and a worse survival rate.

Prevalence and clinical significance of an elevated cardiac troponin I in patients presenting to the Emergency Department without chest pain

BACKGROUND

Cardiac troponins are currently measured in patients presenting with chest pain. Little is known about routinely measured cardiac troponins in patients presenting without chest pain. The aim of this study was to determine the prevalence and clinical significance of an elevated cardiac troponin I (cTnI) in patients presenting to the Emergency Department without chest pain.

METHODS

During a 6-month period, we routinely measured cTnI in all patients presenting to the internist, neurologist, or lung specialist for reasons other than chest pain. We followed patients with an elevated cTnI for 1 year and determined mortality and incidence of non-fatal myocardial infarction, percutaneous coronary intervention (PCI), and coronary artery bypass grafting (CABG).

RESULTS

cTnI was elevated in 41 out of 1130 patients (3.6%). Patients with an elevated cTnI were older (78 vs. 62 years) and more often admitted to the hospital (95% vs. 78%) than those with a normal cTnI. Twenty-six patients (63%) with an elevated cTnI died within 1 year. Approximately 50% of these deaths were cardiac-related. Two patients (4.9%) suffered a non-fatal myocardial infarction, while no patient underwent PCI or CABG during follow-up.

CONCLUSION

Routinely measured cTnI is seldom elevated in a general population of patients presenting to the Emergency Department without chest pain. Patients with an elevated cTnI are, on the average, 16 years older than those with a normal level. An elevated cTnI is clearly associated with an unfavorable outcome.

Prognostic value of low-level cardiac troponin-I elevations in patients without definite acute coronary syndromes

BACKGROUND

Low-level cardiac troponin-I (cTn-I) elevations predict adverse cardiovascular outcomes in patients with definite acute coronary syndromes (ACS), as defined by the presence of chest pain accompanied by ischemic electrocardiographic changes. However, their prognostic value in other clinical situations remains unclear.

METHODS

We studied 366 patients with suspected myocardial infarction (MI) but without definite ACS, including 57 patients with low-level cTn-I elevations (1.0 to 3.0 ng/mL) and 309 patients with cTn-I <1.0 ng/mL. All cTn-I measurements were made with the Dade Stratus II analyzer. We determined the adjusted 1-year risk of nonfatal MI or death from coronary heart disease (CHD death) in each group by using Cox proportional hazards models.

RESULTS

Among patients with cTn-I elevations between 1.0 and 3.0 ng/mL, 6 (11%) had a nonfatal MI or CHD death at 1 year compared with 12 (4%) patients in the cTn-I <1.0 ng/mL group [hazard ratio (HR), 3.5; 95% CI, 1.4 to 8.8]. After adjusting for baseline clinical characteristics, cTn-I levels between 1.0 and 3.0 ng/mL remained strongly associated with nonfatal MI or CHD death (adjusted HR, 3.4; 95% CI, 1.3 to 9.4). This association persisted even in the 215 patients who presented without chest pain (adjusted HR, 4.3; 95% CI, 1.4 to 13).

CONCLUSIONS

Low-level cTn-I elevations identify a subset of patients at increased risk for future cardiovascular events, even when obtained outside the context of definite ACS or presentation with chest pain.

Derivation of the San Francisco Syncope Rule to predict patients with short-term serious outcomes

STUDY OBJECTIVE

The causes of syncope are usually benign but are occasionally associated with significant morbidity and mortality. We derive a decision rule that would predict patients at risk for short-term serious outcomes and help guide admission decisions.

METHODS

This prospective cohort study was conducted at a university teaching hospital and used emergency department (ED) patients presenting with syncope or near syncope. Physicians prospectively completed a structured data form when evaluating patients with syncope. Serious outcomes (death, myocardial infarction, arrhythmia, pulmonary embolism, stroke, subarachnoid hemorrhage, significant hemorrhage, or any condition causing a return ED visit and hospitalization for a related event) were defined at the start of the study. All patients were followed up to determine whether they had experienced a serious outcome within 7 days of their ED visit. Univariate analysis was performed with chi2 and nonparametric techniques on all predictor variables. kappa Analysis was performed on variables requiring interpretation. Variables with kappa more than 0.5 and a P value less than.1 were analyzed with recursive partitioning techniques to develop a rule that would maximize the determination of serious outcomes.

RESULTS

There were 684 visits for syncope, and 79 of these visits resulted in patients' experiencing serious outcomes. Of the 50 predictor variables considered, 26 were associated with a serious outcome on univariate analysis. A rule that considers patients with an abnormal ECG, a complaint of shortness of breath, hematocrit less than 30%, systolic blood pressure less than 90 mm Hg, or a history of congestive heart failure has 96% (95% confidence interval [CI] 92% to 100%) sensitivity and 62% (95% CI 58% to 66%) specificity. If applied to this cohort, the rule has the potential to decrease the admission rate by 10%.

CONCLUSION

The San Francisco Syncope Rule derived in this cohort of patients appears to be sensitive for identifying patients at risk for short-term serious outcomes. If prospectively validated, it may offer a tool to aid physician decision making.

[Cardiac troponin I and T: specific biomarkers of cardiomyocyte]

PURPOSE

Cardiac troponin I and troponin T have replaced creatine kinase MB (CK-MB) for the diagnosis of cardiomyocyte necrosis. Cardiac specificity of these new markers leads to a change in our practice.

CURRENT KNOWLEDGE AND KEY POINTS

Following necrosis, intracellular proteins are released into blood. This easy concept overlaps a biological complexity since troponins are released as complexes leading to various cut-off values depending on the assay used, as least for cardiac troponin I. The increase in both specificity and analytical sensitivity of these markers reached to propose a new definition of myocardial infarction. The diagnosis of acute coronary syndrome is a clinical based diagnosis, the use of troponin contributing to their classification. Finally, pathological processes leading to cardiac injury may induce an increase in the cardiac troponin level.

FUTURE PROSPECTS AND PROJECTS

Troponin standardization is a challenge for the near future leading to better follow-up of patients and comparison between cohorts.