Adverse Outcomes 30 Days After Emergency Department Evaluation for Myocardial Infarction Determined Solely by High Sensitivity Troponin I Values for a 1-Hour Rule-Out/Rule-In Acute Myocardial Infarction Algorithm
Nowak RM, McCord J, Christenson RH, Jacobsen G, Apple F, Limkakeng A, Peacock WF, and DeFilippi C. 5 Adverse Outcomes 30 Days After Emergency Department Evaluation for Myocardial Infarction Determined Solely by High Sensitivity Troponin I Values for a 1-Hour Rule-Out/Rule-In Acute Myocardial Infarction Algorithm. Ann Emerg Med 2019; 74(4):S3.
Ann Emerg Med
Study Objectives: High sensitivity cardiac troponin I (hs-cTnI) rapid evaluations for acute myocardial infarction (AMI) are being approved/used in the United States (US). Our objective was to determine the efficacy of the 1-hour AMI rule-out/rule-in hs-cTnI algorithm zone placements for all enrolled patients in the High Sensitivity Cardiac Troponin I in the US (HIGH-US) study for determining 30-day adverse outcomes. Methods: This was a secondary analysis of a prospective multi-center observational study (HIGH-US). Consenting adults presenting with any suspicion by the treating emergency physician for AMI were enrolled. The baseline and 1-hour plasma samples obtained were later batch analyzed in 5 core laboratories using the Siemens Atellica hs-cTnI assay (combined sex 99th % 45.0 ng/L). AMI diagnosis was independently adjudicated using all 30-day clinical materials available. All enrolled subjects were followed up at 30 days by telephone and review of their medical records. Adverse outcomes reported are all cause death and post discharge AMI. Results: A total of 2505 patients were enrolled in 29 US medical centers with 2113 qualifying for a validation of the 1-hour algorithm. Subject median age was 56 years (interquartile range 48-65), 1313 (56.0%) were males with 1313 (56.0%) white and 939 (40.0%) black patients. There were 1065 (50.4%) patients ruled-out with a NPV of 99.7% and sensitivity of 98.7% (95% CI: 99.2-99.9 and 96.3-99.6 respectively) using a baseline hs-cTnI value < 3ng/L or baseline value < 6ng/L and a delta 1 hour value < 3ng/L. Additionally there were 265 (12.6%) individuals ruled-in with a PPV of 69.4% and specificity of 95.7% (95% CI: 63.6-74.7 and 94.7-96.5 respectively) using a baseline hs-cTnI value > 120 ng/L or a delta 1 hour value ≥ 12ng/L. The remaining 783 (37.1%) patients placed in the continue evaluations zone had a prevalence of adjudicated AMI of 5.6% (95% CI 4.2-7.5). The 30-day rate of death or AMI was low (2, 0.02%) for ruled-out patients, higher (16, 2.1%) for those placed in the continued evaluations zone and highest (13, 4.8%) for ruled-in subjects (p<0.001). Kaplan Meyer generated curves showed that these adverse outcome rates gradually increased over the 30-day time period (figure). All adverse outcomes were determined independently of the ECG interpretations or the application of any clinical risk stratification score calculations. Conclusion: Patients ruled-out for AMI using a 1-hour US validated hs-cTnI algorithm have a very low 30-day rate of death or AMI without consideration of their ECG interpretations or the use of any clinical risk stratification score calculations. Further studies are needed to determine what additional value, if any, the ECG and the use of a clinical risk stratification score are for patients with low 1-hour hs-cTnI values in predicting short term outcomes. Patients placed in the continued evaluations and the ruled-in zones after the 1-hour evaluation using hs-cTnI values have significantly higher 30-day adverse outcomes. Strategies are needed to decrease the adverse clinical outcomes of patients who are not ruled-out for AMI within 1 hour of ED evaluation. [Figure presented]