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.