Clinical validation of a point of care whole blood high sensitive cardiac troponin I assay: a prospective real time study on 3306 consecutive presentations with suspected acute coronary syndrome

Introduction A point of care (POC) high sensitive cardiac troponin (hs-cTn) can improve early discharge and rule-in for suspected acute coronary syndrome (ACS) but large-scale prospective studies assessing clinical performance of whole blood POC troponin in the emergency department (ED) are lacking. Methods This was a preplanned nested cohort study of the MACROS trial, a randomised controlled study of the ESC 0-1 versus 0-3 hour pathway for suspected ACS. As well as central laboratory hs-cTn sampling all patients had real time whole blood (WB) sampling for Quidel TriageTrue POC hs-cTn I by non-laboratory operators at presentation and at 1 or 3 hours according to randomisation. The hs-cTn T (Roche, elecsys) biomarker was used for all clinical decisions. Subsequent event adjudication was undertaken in a blinded fashion using Abbott allinity hs-cTn I. The performance of the POC hs-cTn I assays was assessed using prespecified, and previously published criteria for single sample rule-out (SSRO) and the ESC 0-1 hour and 0-3 hour pathway. The clinical endpoints were by adjudicated type 1 or 2 MI (4th universal definition) and major adverse cardiac events (MACE), defined as adjudicated type 1 MI, cardiovascular death and urgent coronary revascularisation at 30 days. Results 3306 presentations in 3163 patients recruited from 2 large EDs in North England form the study population. The mean age was 59 years, 1755 (53.4%) were male, 206 (6.2%) an index type 1 MI and 237 (7.2%) had a MACE within 30 days. The median time, from blood sampling to result, for Quidel TriageTrue POC hs-cTn I and central laboratory hs-cTnT was 29 and 79 minutes respectively. Safety for SSRO, both for index MI and MACE at 30 days, for TriageTrue POC hs-cTn I (table) was equivalent to central laboratory troponins but the clinical efficiency (% cohort rule-out) was greater. Performance of triage true POC hs-cTn I in both the ESC 0-1 and 0-3 hour pathway was impressive, demonstrating rule-out of >60% and rule-in of approximately 10% with safety parameters similar to central laboratory hs-cTnT. The figure illustrates classification and performance metrics for MACE at 30 days in the 0-1 hour pathway Conclusion This is the first large prospective multicentre study that comprehensively determines clinical performance of POC hs-cTn I assay, when analysed in real time in ED. Triagetrue POC hs-cTn I has equivalent clinical performance to central laboratory hs-cTns but with a much faster turn-around time.