A-002 Novel Mindray High Sensitivity Cardiac Troponin I Assay for Single Sample Rule Out of Myocardial Injury: MERITnI Study

Abstract Background We determined the efficacy of a high sensitivity (hs) cardiac troponin I (hs-cTnI) assay for a newly derived 0-hour rule-out concentration for myocardial injury. Methods Consecutive, emergency department patients undergoing serial hs-cTnI heparin plasma testing (on the Mindray CL1200i analyzer) on clinical indication of ischemic symptoms were studied in the ‘Mindray hs-cTnI Assay Analytical and Clinical Evaluation for the Diagnosis and RIsk Assessment of Myocardial InfarctIon’ (MERITnI) trial. The primary safety outcome was the composite of cardiac death and myocardial infarction (MI) at 30 days or myocardial injury at index. The analyses were completed both including and excluding patients with MI at index. Results In the entire cohort of 1556 patients (60.7% male, 43.3% White, 45.8% Black. 34.8% chest pain), 26.9 % patients had at least one hs-cTnI >sex-specific 99th percentile, defined as myocardial injury. 2.7% had type 1 MI, 2.7% type 2 MI, and 21.5% non-MI myocardial injury. Once MIs were excluded, there were 1470 patients (60.7% male, 43.0% White, 46.0% Black, 33.7% chest pain), 22.7% with non-MI myocardial injury. Single-sample MI rule-out in the 1556 patients using a normal ECG plus an optimized hs-cTnI of <2 ng/L ruled out 14% of patients, with a sensitivity of 99.1% (CI 98.2- 100%) and a NPV of 98.1% (CI 96.3- 99.9%). Four patients were missed. Rule out findings by sex and race were as follows: male 10.1% (2 missed patients), female 19.5% (2 missed patients), White 16.6% (1 missed patient), and Black 10.3% (3 missed patients). Single-sample MI rule-out in the 1470 patients using a normal ECG plus an optimized hs-cTnI of <4 ng/L ruled out 29.0% of patients, with a sensitivity of 98.8% (CI 98.1-100%) and a negative predictive value of 99.1% (CI 98.1-100%). Four patients were missed. Rule out findings by sex and race were as follows: male 24.7% (2 missed patients), female 35.7% (2 missed patients), White 31.8% (2 missed patients), and Black 25.9% (2 missed patients). Conclusion The novel Mindray CL1200i hs-cTnI assay enabled safe and early rule out of myocardial injury at a low concentration in a diverse, inner-city patient cohort utilizing a single sample rule out protocol, including early (<2 hour) presenters.