Does a lower diagnostic threshold of sensitive plasma troponin I assay improve clinical outcomes of patients with chest pain?

Abstract

In the study by Mills et al. [3] consecutive patients admitted to the Royal Infirmary of Edinburgh for a chest pain of suspected cardiac origin were enrolled. For each patient included, the value of troponin I concentrations on admission, 12 h after symptom onset, or both had to be available. Patients with non-cardiac (respiratory, gastrointestinal, or musculo-skeletal) chest pain or those for whom follow-up was not possible were excluded. The study was divided into two phases (validation and implementation), performed 1 year apart, each one enrolled different groups of patients. Although throughout the study the same test was performed (Abbott Architect assays), in the validation phase the original diagnostic threshold of troponin concentration of C0.20 ng/mL was used, whereas in the implementation phase the revised threshold of C0.05 ng/ mL was considered. Patients of both phases were then stratified into three groups based on the peak values of plasma troponin concentrations (\0.05 ng/mL; between 0.05 and 0.19 ng/mL; C0.20 ng/mL). The main outcomes were MI recurrences and deaths at 1 year. 2,092 patients with suspected acute coronary syndrome (ACS) were included in the study, 1,038 in validation and 1,054 in implementation phase. Regarding the clinical management, in the validation phase, patients with troponin concentrations between 0.05 and 0.19 ng/mL were less likely to be referred to a cardiologist (44 vs. 93%), to receive dual antiplatelet therapy (27 vs. 80%) or be subjected to revascularization (17 vs. 59%) (p 0.001 for all comparisons) than patients with troponin concentration of C0.20 ng/mL. In the implementation phase, the management of patients with troponin values between 0.05 and 0.19 ng/mL improved when compared to validation phase (cardiology referral 74 vs. 44%; dual antiplatelet therapy 58 vs. 27%; coronary angiography procedure 46 vs. 20%; p 0.001 for all comparisons). Patients included during the validation phase had a median follow-up of 453 days. In this group, those with troponin concentrations between 0.05 and 0.19 ng/mL had higher probability of death at 12 months (25%) or new hospitalization for MI (31%) compared with patients with troponin \0.05 ng/mL (4 and 5%, respectively) and troponin C0.20 (13 and 18%, respectively). From validation to implementation phase, 29% increase in the frequency of diagnosis of MI was observed. F. Perego (&) Medicina III, ‘‘Luigi Sacco’’ Hospital, University of Milan, via G.B. Grassi 74, 20154 Milan, Italy e-mail: francescap.p@libero.it