BACKGROUND: We aimed to assess the diagnostic utility of the Dimension EXL LOCI High-Sensitivity Troponin I (hs-cTnI-EXL) assay. METHODS: This multicenter study included patients with chest discomfort presenting to the emergency department. Diagnoses were centrally and independently adjudicated by two cardiologists using all available clinical information. Adjudication was performed twice including serial measurements of high-sensitivity cardiac troponin (hs-cTn) I-Architect (primary analysis) and serial measurements of hs-cTnT-Elecsys (secondary analysis) in addition to the clinically used (hs)-cTn. The primary objective was to assess and compare the discriminatory performance of hs-cTnI-EXL, hs-cTnI-Architect and hs-cTnT-Elecsys for acute myocardial infarction (MI). Furthermore, we derived and validated a hs-cTnI-EXL-specific 0/1h-algorithm. RESULTS: Adjudicated MI was the diagnosis in 204/1454 (14%) patients. The area under the receiver operating characteristics curve for hs-cTnI-EXL was 0.94 (95%CI, 0.93-0.96), and comparable to hs-cTnI-Architect (0.95; 95%CI, 0.93-0.96) and hs-cTnT-Elecsys (0.93; 95%CI, 0.91-0.95). In the derivation cohort (n = 813), optimal criteria for rule-out of MI were <9ng/L at presentation (if chest pain onset >3h) or <9ng/L and 0h-1h-change <5ng/L, and for rule-in ≥160ng/L at presentation or 0h-1h-change ≥100ng/L. In the validation cohort (n = 345), these cut-offs ruled-out 56% of patients (negative predictive value 99.5% (95%CI, 97.1-99.9), sensitivity 97.8% (95%CI, 88.7-99.6)), and ruled-in 9% (positive predictive value 83.3% (95%CI, 66.4-92.7), specificity 98.3% (95%CI, 96.1-99.3)). Secondary analyses using adjudication based on hs-cTnT measurements confirmed the findings. CONCLUSIONS: The overall performance of the hs-cTnI-EXL was comparable to best-validated hs-cTnT/I assays and an assay-specific 0/1h-algorithm safely rules out and accurately rules in acute MI. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov number, NCT00470587.

Cardiovascular Research Institute Basel and Department of Cardiology University Hospital Basel University of Basel Basel Basel Switzerland

Cardiovascular Research Institute Basel and Department of Cardiology University Hospital Basel University of Basel Basel Basel Switzerland; Department of Cardiac Surgery University Hospital Basel University of Basel Basel Basel Switzerland; GREAT network Basel Basel Switzerland

Cardiovascular Research Institute Basel and Department of Cardiology University Hospital Basel University of Basel Basel Basel Switzerland; Department of Cardiology Heart Center Leipzig University of Leipzig Leipzig Saxony Germany

Cardiovascular Research Institute Basel and Department of Cardiology University Hospital Basel University of Basel Basel Basel Switzerland; Emergency Department University Hospital Zurich Zurich Zurich Switzerland

Cardiovascular Research Institute Basel and Department of Cardiology University Hospital Basel University of Basel Basel Basel Switzerland; GREAT network Basel Basel Switzerland

Cardiovascular Research Institute Basel and Department of Cardiology University Hospital Basel University of Basel Basel Basel Switzerland; GREAT network Basel Basel Switzerland; Critical Care Research Group and the University of Queensland Brisbane Queensland Australia

Cardiovascular Research Institute Basel and Department of Cardiology University Hospital Basel University of Basel Basel Basel Switzerland; GREAT network Basel Basel Switzerland; Division of Cardiology Vancouver General Hospital University of British Columbia Vancouver British Columbia Canada

Cardiovascular Research Institute Basel and Department of Cardiology University Hospital Basel University of Basel Basel Basel Switzerland; GREAT network Basel Basel Switzerland; Division of Internal Medicine University Hospital Basel University of Basel Basel Basel Switzerland

Cardiovascular Research Institute Basel and Department of Cardiology University Hospital Basel University of Basel Basel Basel Switzerland; GREAT network Basel Basel Switzerland; Division of Internal Medicine University Hospital Basel University of Basel Basel Basel Switzerland; BHF University Centre for Cardiovascular Science University of Edinburgh Edinburgh UK

Cardiovascular Research Institute Basel and Department of Cardiology University Hospital Basel University of Basel Basel Basel Switzerland; University Center of Cardiovascular Science and Department of Cardiology University Heart and Vascular Center Hamburg University Medical Center Hamburg Eppendorf Hamburg Hamburg Germany

Department of hematology and Blood Bank University Hospital Basel University of Basel Basel Basel Switzerland

Emergency Department Kantonsspital Liestal Liestal Liestal Switzerland

Emergency Department Kantonsspital Luzern Luzern Luzern Switzerland

Emergency Department University Hospital Zurich Zurich Zurich Switzerland

GREAT network Basel Basel Switzerland; 2nd Department of Cardiology School of Medicine with the Division of Dentistry in Zabrze Medical University of Katowice Silesian Poland

GREAT network Basel Basel Switzerland; Emergency Department Hospital Clinic Barcelona Catalonia Spain

GREAT network Basel Basel Switzerland; Servicio de Urgencias Hospital Clínico San Carlos Madrid Madrid Spain

Institute of Laboratory Medicine County Hospital Aarau Aarau Aarau Switzerland

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ClinicalTrials.gov
NCT00470587