Implementation of high sensitivity cardiac troponin T measurement in the emergency department

High-sensitivity versus conventional troponin in the emergency department for the diagnosis of acute myocardial infarction

Introduction

Recently, newer assays for cardiac troponin (cTn) have been developed which are able to detect changes in concentration of the biomarker at or below the 99th percentile for a normal population. The objective of this study was to compare the diagnostic performance of a new high-sensitivity troponin T (HsTnT) assay to that of conventional cTnI for the diagnosis of acute myocardial infarction (AMI) according to pretest probability (PTP).

Methods

In consecutive patients who presented to our emergency departments with chest pain suggestive of AMI, levels of HsTnT were measured at presentation, blinded to the emergency physicians, who were asked to estimate the empirical PTP of AMI. The discharge diagnosis was adjudicated by two independent experts on the basis of all available data.

Results

A total of 317 patients were included, comprising 149 (47%) who were considered to have low PTP, 109 (34%) who were considered to have moderate PTP and 59 (19%) who were considered to have high PTP. AMI was confirmed in 45 patients (14%), 22 (9%) of whom were considered to have low to moderate PTP and 23 (39%) of whom were considered to have high PTP (P < 0.001). In the low to moderate PTP group, HsTnT levels ≥ 0.014 μg/L identified AMI with a higher sensitivity than cTnI (91%, 95% confidence interval (95% CI) 79 to 100, vs. 77% (95% CI 60 to 95); P = 0.001), but the negative predictive value was not different (99% (95% CI 98 to 100) vs. 98% (95% CI 96 to 100)). There was no difference in area under the receiver operating characteristic (ROC) curve between HsTnT and cTnI (0.93 (95% CI 0.90 to 0.98) vs. 0.94 (95% CI 0.88 to 0.97), respectively).

Conclusions

In patients with low to moderate PTP of AMI, HsTnT is slightly more useful than cTnI. Our results confirm that the use of HsTnT has a higher sensitivity than conventional cTnI.

Comparison of prognostic value of high-sensitivity and conventional troponin T in patients with non-ST-segment elevation acute coronary syndromes

BACKGROUND

The impact of high-sensitivity troponin assays on risk stratification of patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS) is unknown.

METHODS

The study included 447 patients with NSTE-ACS. Cardiac troponin T (TnT) was measured with conventional and high-sensitivity assays, in parallel, using the same plasma sample. The primary end-point was 4-year mortality.

RESULTS

The use of cut-off of 0.014 μg/L of high-sensitivity TnT (hs-TnT) instead of 0.01 μg/L of the conventional (cTnT) increased proportion of non-ST-segment elevation myocardial infarction (NSTEMI) patients by 33% (from 201 to 268 patients). Re-classified patients from unstable angina to NSTEMI had similar 4-year mortality compared to patients with NSTEMI by both assays: 16 deaths (25.1%) among 67 re-classified patients versus 47 deaths (23.6%) among patients diagnosed with NSTEMI by both assays; odds ratio=1.03, 95% confidence interval [CI] 0.53-1.97; P=0.933). The Cox model identified hsTnT (hazard ratio=2.59, 95% CI 1.22-5.50; P=0.013 for hsTnT>0.014μg/L versus hsTnT ≤ 0.014 μg/L) as an independent correlate of 4-year mortality. hsTnT significantly improved prediction of the four-year mortality (relative integrated discrimination improvement 8.2%, P=0.005).

CONCLUSIONS

The use of hsTnT instead of cTnT increased the proportion of patients with NSTEMI among patients with NSTE-ACS and significantly improved risk stratification regarding long-term mortality.

High-sensitivity troponin assays in the evaluation of patients with acute chest pain in the emergency department

Evaluating patients with acute chest pain presenting to the emergency department remains an ongoing challenge. The spectrum of etiologies in acute chest pain ranges from minor disease entities to life-threatening diseases, such as pulmonary embolism, acute aortic dissection or acute myocardial infarction (MI). The diagnosis of acute MI is usually made integrating the triad of patient history and clinical presentation, readings of 12-lead ECG and measurement of cardiac troponins (cTn). Introduction of high-sensitivity cTn assays substantially increases sensitivity to identify patients with acute MI even at the time of presentation to the emergency department at the cost of specificity. However, the proportion of patients presenting with cTn positive, non-vascular cardiac chest pain triples with the implementation of new sensitive cTn assays increasing the difficulty for the emergency physician to identify those patients who are at need for invasive diagnostics. The main objectives of this mini-review are 1) to discuss elements of disposition decision made by the emergency physician for the evaluation of chest pain patients, 2) to summarize recent advances in assay technology and relate these findings into the clinical context, and 3) to discuss possible consequences for the clinical work and suggest an algorithm for the clinical evaluation of chest pain patients in the emergency department.