Prognostic significance of troponin T elevation in patients without chest pain

Prognostic implications of detectable cardiac troponin I below the 99th percentile in patients admitted to an emergency department without acute coronary syndrome

Background:

Detectable troponin below the 99th percentile may reflect an underlying cardiac abnormality which might entail prognostic consequences. This study aimed to investigate the prognosis of patients admitted to an emergency department (ED) with detectable troponin below the 99th percentile reference limit who did not present with an acute coronary syndrome (ACS).

Methods:

We analysed the clinical data of all consecutive patients admitted to the ED during the years 2012 and 2013 in whom cardiac troponin was requested by the attending clinician (cTnI Ultra Siemens, Advia Centaur). Patients with troponin below the 99th percentile of the reference population (40 ng/L) and who did not have a diagnosis of ACS were selected, and their mortality was evaluated in a 2-year follow-up.

Results:

A total of 2501 patients had a troponin level below the reference limit, with 43.9% of those showing detectable levels (>6 ng/L and <40 ng/L). Patients with detectable levels were elderly and had a higher prevalence of cardiovascular history and more comorbidities. The total mortality in the 2-year follow-up was 12.4% in patients with detectable troponin and 4.5% in patients with undetectable troponin (p<0.001). In the Cox multivariate regression analysis, the detectable troponin was an independent marker of mortality at 2 years (HR 1.62, 95% CI 1.07–2.45, p=0.021).

Conclusions:

Detectable troponin I below the 99th percentile is associated with higher mortality risk at 2-year follow-up in patients admitted to the ED who did not present with ACS.

Outcomes of non-acute coronary syndrome patients discharged from the emergency department with troponin positivity

BACKGROUND

Cardiac troponin elevation portends a worse prognosis in diverse patient populations. The significance of troponin elevation in patients discharged from emergency departments (EDs) without inpatient admission is not well known.

METHODS

Patients without a diagnosis of acute coronary syndrome discharged from two EDs between April 1, 2006, and December 31, 2007, with an abnormal cardiac troponin (troponin positive [TP]) were compared to a troponin-negative (TN) cohort matched for age, sex, and primary discharge diagnosis. Outcomes were obtained by linking with a regional ED and a provincial vital statistics database and adjusted for the following: estimated glomerular filtration rate, do-not-resuscitate status, history of coronary artery disease, Canadian Triage and Acuity Scale, and left ventricular hypertrophy on electrocardiography. The primary outcome was a composite of death or admission to hospital within 1 year.

RESULTS

Our total cohort (n  =  344) consisted of 172 TP and 172 TN patients. In the univariate analysis, TP patients had a higher rate of the primary outcome (OR 3.2, 95% CI 2.1-5.0, p < 0.001) and both of its components (p < 0.001). After adjusting for covariates, positive troponin remained an independent predictor of the primary outcome (OR 2.1, 95% CI 1.3-3.4, p  =  0.005) and inpatient admission (OR 2.0, 95% CI 1.2-3.4, p  =  0.006). There was no significant difference in death (OR 1.3, 95% CI 0.6-2.9, p  =  0.5) after adjustment.

CONCLUSIONS

A positive troponin assay during ED stay in discharged patients is an independent marker for risk of subsequent admission. Our findings suggest that the prognostic power of an abnormal troponin extends to patients discharged from the ED.

Measurement of high-sensitivity troponin T in noncardiac medical intensive care unit patients. Correlation to mortality and length of stay

OBJECTIVES

To assess the frequency, magnitude, and prognostic significance of elevations in cardiac troponin T in noncardiac critically ill patients, including elevations at levels below the limit of detection of traditional assays.

METHODS

Using a high-sensitivity assay, we measured troponin T (high-sensitivity troponin T [hsTnT]) in 451 unique patients within 12 hours of their admission to a noncardiac medical intensive care unit. Outcomes of patients, grouped by hsTnT level, were compared.

RESULTS

Overall, 98% of the study patients had detectable levels of hsTnT (>3 ng/L), and 33% had levels above the diagnostic cutoff of a traditional fourth-generation cardiac troponin T assay. Patient groups with higher hsTnT levels had markedly higher rates of in-hospital mortality (P < .001) and longer stays in the hospital and intensive care unit (P < .01).

CONCLUSIONS

In noncardiac critically ill patients, cardiac troponin T elevations are common but often at levels undetectable by traditional assays. hsTnT elevations predict a more complex clinical course and an increased risk of death.

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.