Sensitivity of undetectable level of high-sensitivity troponin T at presentation in a large non-ST-segment elevation myocardial infarction cohort of early presenters.

BACKGROUND: We aimed to evaluate the diagnostic sensitivity for myocardial infarction (MI) when using an undetectable level of high-sensitivity cardiac troponin T (hs-cTnT < 5 ng/L) at presentation combined with a non-ischemic electrocardiogram (ECG), to rule out MI in a non-ST-segment elevation MI (NSTEMI) cohort presenting ≤2 h from symptom onset. We also aimed to compare baseline characteristics and 30-day outcome in NSTEMI patients presenting with and without hs-cTnT < 5 ng/L. METHODS: All patients admitted to five centers in Sweden 2011-2015, after the introduction of hs-cTnT, who presented ≤2 h from symptom onset and received a final diagnosis of NSTEMI, were identified through the SWEDEHEART registry. These data and data of hs-cTnT levels were verified in the hospitals' medical records. The registry provided baseline and outcome data. RESULTS: Twenty-four (2.6%) of 911 NSTEMI patients presented with hs-cTnT < 5 ng/L. In patients presenting >1-≤2 h from symptom onset the sensitivity for MI when combining hs-cTnT and ECG was 99.4% (95% CI 98.4%-99.8%). In patients presenting ≤1 h, and in patients aged ≤65 years without prior MI, the sensitivity was insufficient. NSTEMI patients presenting with hs-cTnT < 5 ng/L were younger and had less often a prior MI. A total of 62.5 vs. 63.5% of the NSTEMI patients presenting with and without hs-cTnT < 5 ng/L underwent revascularization within 30 days and 4.5 and 3.2% died respectively. CONCLUSIONS: Hs-cTnT < 5 ng/L at presentation combined with a non-ischemic ECG may be used to rule out MI in patients presenting as early as >1 h from symptom onset with a sufficient sensitivity.