Assay Imprecision and 99th-Percentile Reference Value of a High-Sensitivity Cardiac Troponin I Assay

Abstract

We undertook a performance evaluation and determination of the 99th-percentile reference value for the Siemens cTnI-Ultra with a fully characterized population that had undergone noninvasive cardiac imaging. Permission for the study was obtained from the local research ethics committee. Participants >45 years of age were randomly selected from the practice lists of 7 representative local community practices; 1392 individuals from the general population were invited. Demographic data were collected from the participants by questionnaire. Heart rate and blood pressure measurements (mean of 2 readings) and spirometry, electrocardiography, and echocardiography evaluations were performed. For measurements of fasting serum glucose, creatinine, and cardiac troponin, venous blood was collected into Becton Dickinson serum separator tubes and centrifuged. The serum was removed and stored at −70 °C. Frozen samples were thawed to room temperature, mixed, and centrifuged before analysis. The left ventricular ejection fraction was calculated quantitatively with Simpson’s apical biplane method (1). The left ventricular mass was calculated with the Devereux-modified American Society of Echocardiography equation(2). Valvular regurgitation and stenosis were assessed qualitatively on a 5-point scale. Diastolic heart failure …