3303Classification of patients with acute chest pain by analytical benchmarks and subsequent management recommendations - A comparison of three highly-sensitivity troponin assays in the ROMICAT trials

Background

Concordance of different highly-sensitive troponin (hsTn) assays in stratifying acute chest pain (ACP) patients according to analytical benchmarks and subsequent emergency department (ED) management recommendations are unknown.

Methods

We included patients enrolled in the ROMICAT (Rule Out Myocardial Infarction/Ischemia Using Computer-Assisted Tomography) I and II trials (n=624; 39.1% female; 52.8±10.0 years), who presented to the ED and were referred to further non-invasive diagnostic testing. In ROMICAT I, blood was obtained at 4 hours, and in ROMICAT II at ED presentation, and at 2 and 4 hours and was tested with three state-of-the-art hsTn assays (Roche Diagnostics, Elecsys 2010; Abbott ARCHITECT i2000SR; Siemens Diagnostics, HsVista). In a per sample analysis, we compared the concordance of assays for analytic benchmarks (below the level of detection (LOD)/LOD to 99th percentile/99th percentile to myocardial infarction (<LOD], ><LOD], >MI)/above MI). In a per patient analysis of serial hsTn testing in ROMICAT II, we determined concordance of management recommendations (rule out/observe/rule in) based on 2015ESC guidelines, results of coronary CT angiography and stress myocardial perfusion, and adjudicated endpoints of ACS.

Results

Overall, only 34.4% (353/1027) of samples were classified into the same benchmark category by all assays (table 1). In a per patient analysis, all assays agreed on the same of management recommendation in 25.3% (49/242) patients after the 1st hsTn, mostly driven by differences in discharge (6.6%, 21.1%, and 61.2%; respectively; all p<0.001). The concordance of management recommendations improved significantly to 67.4% (163/242; p<0.001) after the 2nd hsTn measurement but the final agreement for “observe” and “rule in” remained limited (13/90 and 5/18). Among patients in whom discharge was recommended, at least 18.8% (range: 18.8–21.0% across assays) had a positive imaging/stress test and at least 2.9% (range: 2.9–3.4%) had ACS.

Table 1. Classification of measurements from three hsTn assays in 1027 samples of patients with ACP according to analytical benchmarks <LOD LOD – 99th %tile* 99th %tile* – AMI** AMI**< Roche Elecsys, n (%) 578 (56.3) 328 (31.9) 95 (9.3) 26 (2.5) Abbott ARCHITECT, n (%) 176 (17.1) 788 (76.7) 14 (1.7) 49 (4.8) Siemens Vista, n (%) 96 (9.4) 861 (83.9) 33 (3.2) 37 (3.6) *Assay specific 99th percentiles; **as per ESC 2015 guidelines.

Conclusion

Differences in hsTn assay concordance for analytical benchmarks and subsequent ED management recommendations in patients with ACP are substantial raising concerns about the lack of uniform management.

Acknowledgement/Funding

Fulbright Visiting Student Researcher Grant

Troponin testing after cardiac surgery

Single biomarker measurements can predict outcome after cardiac surgery. and may assist in decision making about diagnostic and therapeutic steps following surgery. Although comparative data are relatively lacking some data exist to suggest that among markers of myocardial necrosis, results from cardiac troponin (cTn) measurement may be superior for risk prediction after cardiac surgery to those from the MB isoenzyme of CK (CK-MB). Loss of cardiac troponins from necrotic myocardium is not replenished through re-expression of genes that might increase protein synthesis, and release of cTn appears to represent irreversibly damaged myocardium. Not every cardiac surgical procedure is associated with the same degree of cTn elevation and forms of cardioprotection may im-portantly affect concentrations of cTn after coronary artery bypass grafting. Similarly, less cardiac injury may occur depending on the form of anesthesia used during surgery. Great caution must be exercised when utilizing cTnT or cTnI for diagnosis of post-cardiac surgery regional acute myocardial infarction: in this context clinical factors must be applied at the risk of a false diagnosis. On the other hand, concentrations of both cTnT and cTnI have repeatedly and unequivocally been shown to be prognostic for delayed recov-ery, intensive care unit utilization, as well as short- and longer-term mortality following cardiac surgery.