Abstract 20: Are We Ready for High(er) Sensitivity Troponin Assays? The Positive Predictive Value of a Contemporary Troponin Assay for Acute Myocardial Infarction

Abstract

Background: Patients with elevated troponin (cTn) in the absence of Acute Myocardial Infarction (AMI) present a diagnostic dilemma: they at high risk of adverse cardiac events, yet there is little evidence on how they should be managed clinically. In recent years, greater sensitivity of cTn assays and less selective use of cTn in clinical practice have led to a greater number of non-AMI patients with elevated troponin. The exact scope of the problem in routine clinical practice is not known, as published estimates of troponin’s positive predictive value (PPV) for AMI range from 15% to 70%. We sought to define troponin’s PPV for AMI at our institution and examine both process and outcome measures for AMI and non-AMI patients. Methods: In a retrospective cohort analysis of patients evaluated at the University of Colorado Hospital, we identified 5,903 hospital encounters between January 1, 2017 and October 6, 2018 in which patients were found to have an elevated serum troponin level (>0.04 ng/mL, Siemens Advia Centaur Tnl-Ultra). We used ICD-10 codes, billing diagnosis related groups (DRGs), or inclusion in the NCDR® ACTION Registry® to identify patients with a diagnosis of AMI. Patients not captured by one of these diagnoses were categorized as non-AMI. We then compared AMI and non-AMI patients according to the primary outcome of 100-day mortality. Secondary outcomes and process measures were also examined. Results: Out of 5,903 hospital encounters in which elevated cTn was detected, 730 were associated with any diagnosis of AMI (PPV 12.4%). The PPV was lower for individual AMI diagnosis groups. The primary outcome of 100-day mortality was observed in 10.3% of AMI patients versus 20.5% of non-AMI patients (p < 0.001). AMI patients also had significantly shorter hospitalizations, higher rates of inpatient echocardiography and higher rates of P2Y12 inhibitor therapy (Table 1). Conclusion: The PPV of a contemporary troponin assay for AMI was 12.4% in routine clinical practice at a tertiary care academic hospital. Concordant with prior studies, non-AMI patients had worse outcomes. With high-sensitivity troponin (hsTn) assays poised to increase the prevalence of non-AMI troponin elevation, guidance is needed regarding the appropriate use of hsTn as well as the evaluation and treatment of non-ACS patients.