A laboratory score at presentation to rule-out serious cardiac outcomes or death in patients presenting with symptoms suggestive of acute coronary syndrome

Background We evaluated whether a low high-sensitivity cardiac troponin (hs-cTn) cutoff combined with glucose, red cell distribution width (RDW), and the estimated glomerular filtration rate (eGFR) can be used to rule-out a serious cardiac outcome or death in patients presenting with symptoms suggestive of acute coronary syndrome (ACS). Methods: This was a prospective observational emergency department (ED) study enrolling consecutive patients presenting with symptoms suggestive of ACS (ClinicalTrials.gov: NCT01994577). The primary outcome was a 7 day composite of myocardial infarction, unstable angina, decompensated congestive heart failure, serious ventricular cardiac arrhythmia, or death. A laboratory score combining glucose, RDW, eGFR with hs-cTnT (Roche) or hs-cTnI (Abbott) was compared to hs-cTn alone using the limit of detection (LoD; hs-cTnT < 5 ng/l/ hs-cTnI < 2 ng/l) as the cutoff. A benchmark of > 99% sensitivity was used to assess the laboratory panel with hs-cTn versus the LoD alone to identify low-risk patients suitable for discharge. Results: A total of 1095 patients (n = 267 composite-outcomes) had measurements of glucose, RDW, eGFR, hs-cTnT, and hs-cTnI at presentation. Applying the hs-cTn LoD alone as the cutoff missed 5 composite-outcomes (sensitivity = 98.1%), however the addition of the laboratory panel to the hs-cTn LoD increased the sensitivity to > 99% with approximately 10% of the population identified as low-risk. The percentage of low-risk patients was increased to 15% (1 composite-outcome missed) when employing a low measurable hs-cTnI cutoff with the laboratory panel (laboratory score < 2 points). Conclusion: A laboratory score with hs-cTn may identify low-risk patients suitable for ED discharge at presentation.