1. In this meta-analysis, researchers found that a high-sensitivity cardiac troponin T (hs-cTnT) assay along with a nonischemic electrocardiogram (ECG) could be used to classify 30.6% of 9241 adults arriving at the emergency department (ED) for possible cardiac-related chest pain as low-risk for acute myocardial infarction (AMI).
2. This suggests that an hs-cTnT concentration below the detection limit along with a nonischemic ECG could help to rule out a sizeable proportion of patients, which may assist in enabling safe discharge to outpatient earlier than in current practice.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Of patients arriving at the ED with chest pain that may be cardiac-related, only 10% to 20% are diagnosed with AMI. An hs-cTnT assay can detect low concentrations of troponin more reliably and may be used to quickly rule out AMI. However, findings across multiple studies need to be validated before these assays can be used to safely discharge additional patients beyond current practice. This meta-analysis sought to test if an hs-cTnT concentration below the detection limit (<0.005 ug/L) along with a nonischemic electrocardiogram (ECG) could be used to rule out AMI in adults arriving at the ED with chest pain. In this study of 11 cohorts, 30.6% of 9241 patients evaluated with both of these methods were found to be at low risk of AMI, with no deaths of any low-risk patients. This suggests that an hs-cTnT concentration below the detection limit along with a nonischemic ECG could help to rule out a sizeable proportion of patients, which may assist in enabling safe discharge to outpatient earlier than in current practice.
A strength of this meta-analysis is that cohorts were clinically and geographically diverse. Limitations of the study include a small study number and that 9 included studies had a high risk of bias due to missing data or non-random patient selection. There was also heterogeneity in the timing and methods of troponin test reference standards as well as variations in AMI risk and prevalence across studies.
In-Depth [meta-analysis]: In this study, researchers reviewed data from MEDLINE and EMBASE from 1 January 2008 (when the hs-cTnT assay was made available) to 14 December 2016. After selecting for reports that met the study criteria and contacting investigators for data, 11 cohorts were found for inclusion in this meta-analysis. This analysis of 11 cohort studies found that of 9241 patients, 30.6% were categorized as low risk. Of these low-risk patients, 0.5% had AMI. Secondary outcomes measured were major adverse cardiac event (MACE) and death within 30 days. MACE data was obtained from 8 cohorts (n = 8059) and showed that there were 21 MACEs after the index test (hs-cTnT and ECG) result was negative. Within the 30-day follow-up period, 1.3% of patients died, but none of these were low-risk patients. The sensitivity of classifying risk for AMI and 30-day MACEs ranged from 87.5% to 100% and 87.9% to 100%, respectively.
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