ABSTRACT
BACKGROUND: High-sensitivity cardiac troponin T (hs-cTnT) blood concentrations were shown to exhibit a diurnal rhythm, characterized by gradually decreasing concentrations throughout daytime, rising concentrations during nighttime and peak concentrations in the morning. We aimed to investigate whether this also applies to (h)s-cTnI assays and whether it would affect diagnostic accuracy for acute myocardial infarction (AMI). METHODS: Blood concentrations of cTnI were measured at presentation and after 1â¯h using four different cTnI assays: three commonly used sensitive (s-cTnI Architect, Ultra and Accu) and one experimental high-sensitivity assay (hs-cTnI Accu) in a prospective multicenter diagnostic study of patients presenting to the emergency department with suspected AMI. These concentrations and their diagnostic accuracy for AMI (quantified by the area under the curve (AUC)) were compared between morning (11â¯p.m. to 2â¯p.m.) and evening (2â¯p.m. to 11â¯p.m.) presenters. RESULTS: Among 2601 patients, AMI was the final diagnosis in 17.6% of patients. Concentrations of (h)s-cTnI as measured using all four assays were comparable in patients presenting in the morning versus patients presenting in the evening. Diagnostic accuracy for AMI of all four (h)s-cTnI assays were high and comparable between patients presenting in the morning versus presenting in the evening (AUC at presentation: 0.90 vs 0.93 for s-cTnI Architect; 0.91 vs 0.94 for s-cTnI Ultra; 0.89 vs 0.94 for s-cTnI Accu; 0.91 vs 0.94 for hs-cTnI Accu). CONCLUSIONS: Cardiac TnI does not seem to express a diurnal rhythm. Diagnostic accuracy for AMI is very high and does not differ with time of presentation. CLINICAL TRIAL REGISTRATION: NCT00470587, http://clinicaltrials.gov/show/NCT00470587.
Subject(s)
Circadian Rhythm/physiology , Myocardial Infarction/blood , Myocardial Infarction/diagnostic imaging , Troponin I/blood , Aged , Biomarkers/blood , Female , Follow-Up Studies , Humans , Male , Middle Aged , Prospective StudiesABSTRACT
OBJECTIVE: To validate the National Institute for Health and Care Excellence (NICE) recommended algorithms for high-sensitivity troponin (hsTn) assays in adults presenting with chest pain. METHODS: International post hoc analysis of three prospective, observational studies from tertiary hospital emergency departments. The primary endpoint was cardiac death or acute myocardial infarction (AMI) within 24â hours of presentation, and the secondary endpoint was major adverse cardiac events (MACE) at 30â days. RESULTS: 15% of patients were diagnosed with non-ST elevation myocardial infarction (MI) on admission. The hsTnI algorithm classified 2506/3128 (80.1%) of patients as 'ruled out' with 50 (2.0%) missed MI. 943/3128 (30.1%) of patients had a troponin I level below the limit of detection on admission with 2 (0.2%) missed MI. For the hsTnT algorithm, 1794/3374 (53.1%) of patients were 'ruled out' with 7 (0.4%) missed MI. 490/3374 (14.5%) of patients had a troponin T below the limit of blank on admission with no MI. MACE at 30â days occurred in 10.7% and 8.5% of patients 'ruled out' defined by the hsTnI and hsTnT algorithms, respectively. CONCLUSIONS: The NICE algorithms could identify patients with low probability of AMI within 2â hours; however, neither strategy performed as predicted by the NICE diagnostic guidance model. Additionally, the rate of MACE at 30â days was sufficiently high that the algorithms should only be used as one component of a more extensive model of risk stratification. TRIAL REGISTRATION NUMBER: ACTRN12611001069943, NCT00470587; post-results.
