Sex-specific diagnostic cut-offs may improve the test characteristics of high-sensitivity troponin assays for the diagnosis of myocardial infarction (MI). The objective of this study was to quantify test characteristics of sex-specific cut-offs of a single, high-sensitivity cardiac troponin T (hs-cTnT) assay for 7-day MI in patients with chest pain.

This observational cohort study included consecutive emergency department (ED) patients with suspected cardiac chest pain from four Canadian EDs who had an hs-cTnT assay performed within 60 minutes of ED arrival. The primary outcome was MI at 7 days. We quantified test characteristics (sensitivity, negative predictive value [NPV], likelihood ratios and proportion of patients ruled out) for multiple combinations of sex-specific, rule-out cut-offs. We calculated the net reclassification index compared to universal rule-out cut-offs.

In 7,130 patients (3,931 men and 3,199 women), the 7-day MI incidence was 7.38% among men and 3.78% among women. Optimal sex-specific cut-offs (<8 ng/L for men and <7 ng/L for women) had a 98.5% sensitivity for MI and ruled out MI in 55.8% of patients. This would enable an absolute increase in the proportion of patients who were able to be ruled out with a single hs-cTnT of 13.2% to 22.2%, depending on the universal rule-out concentration used as a comparator.

Sex-specific hs-cTnT cut-offs for ruling out MI at ED arrival may improve classification performance, enabling more patients to be safely ruled out at ED arrival. However, differences between sex-specific and universal cut-off concentrations are within the variation of the assay, limiting the clinical utility of this approach. These findings should be confirmed in other data sets.

Not all patients with suspected acute coronary syndrome (ACS) receiving cardiac troponin (cTn) testing present to the emergency department (ED) with cardiac chest pain. Since elderly patients (age ≥70) have increased morbidity and mortality associated with ACS, complaints other than cardiac chest pain may justify cTn testing. Our primary objective was to characterize the population of ED patients who receive cTn testing. The secondary objective was to determine if elderly patients underwent cTn testing for different presenting complaints than their younger counterparts.

We created an electronic database including Canadian Emergency Department Information Systems (CEDIS) presenting complaints, age, sex, disposition, and Canadian Triage Acuity Scale (CTAS) score, for patients who received cTn testing in three Canadian EDs during 2011. We analyzed the data for patient characteristics and sorted by age (<70 and ≥70) for further analysis.

In the 15,824 included patients, the average age was 66 (51%<70; 51% female). The most common presenting complaints were cardiac chest pain (n=3,267) and shortness of breath (n=2,266). The elderly underwent cTn testing for significantly (p<0.0001) different complaints than their younger counterparts. They more commonly presented with generalized weakness (n=898), whereas younger patients more frequently had abdominal pain (n=576).

Cardiac chest pain and shortness of breath are presenting complaints in one-third of patients undergoing ED cTn testing. The majority of patients undergoing cTn testing did not have typical ACS symptoms. Half of all cTn testing in the ED is on the elderly, who present with different complaints than their younger counterparts.

Emergency department (ED) patients with symptoms of cardiac ischemia often require a second cardiac troponin (cTn) measurement to rule out non–ST elevation myocardial infarction. We measured the total turnaround time and the component event times following the ordering of the second cTn level to ED discharge to identify root causes of delays.

We reviewed a random sample of ED discharges following a second normal cTn measurement and recorded associated event times. The central tendency of time intervals is reported as median and mean number of minutes with interquartile ranges (IQRs) and 95% confidence intervals, respectively.

From 9,656 eligible cases, we randomly selected 226 for data collection. The median number of minutes for each event are as follows: from ordering the second cTn measurement to the time of ED discharge was 90 minutes (IQR 65–120); for blood collection from the time the collection was ordered for was 0 minutes (IQR 212–0); from blood collection to the time the blood was transported to the laboratory was 9 minutes (IQR 2–19); laboratory process duration was 44 minutes (IQR 39–52); from when the results were available to the time the patient was discharged was 30 minutes (IQR 15–52).

For ED patients discharged following two normal cTn levels, the laboratory processing time and time from the result being available to the time of ED discharge represent the longest modifiable time periods to reduce ED length of stay.