title: Characterization of the observe zone of the ESC 2015 high-sensitivity cardiac troponin 0h/1h-algorithm for the early diagnosis of acute myocardial infarction.
abstract: OBJECTIVE
  The novel high-sensitivity cardiac troponin (hs-cTn) 0h/1h-algorithm substantially improves the early triage of patient's assigned "rule-out" or "rule-in" of acute myocardial infarction (AMI), while diagnostic uncertainty remains in that 25-30% of patients assigned to "observe". We aimed to better characterize these patients.
  
  
  METHODS
  In a prospective multicenter diagnostic study, we applied the hs-cTnT 0h/1h-algorithm in 2213 unselected patients presenting with symptoms suggestive of AMI to the emergency department. The final diagnosis was adjudicated by two independent cardiologists using all available information. Survival at 720-days was the prognostic endpoint. Findings were validated using a hs-cTnI 0h/1h-algorithm.
  
  
  RESULTS
  Twenty-four percent (n=523) of patients were assigned to "observe" by the hs-cTnT 0h/1h-algorithm. These patients differed significantly in multiple characteristics from "rule-out" and "rule-in" patients: they were older, in 75% male, and very often (57%) had pre-existing coronary artery disease (CAD). Diagnostic uncertainty for the presence of an AMI/UA was high. Only 39% of patients were suitable for coronary computed tomography angiography (CCTA). The most common final adjudicated diagnoses were non-cardiac disease (38%), non-coronary cardiac disease (24%), unstable angina (UA, 21%), and AMI (15%). Absolute hs-cTnT-changes within 3h had the highest diagnostic accuracy for AMI (AUC 0.86). Cumulative 720-day survival rate was 86%, which was significantly lower as compared to "rule-out" (p<0.001) and comparable to "rule-in" (p=ns). Findings were similar for the hs-cTnI "observe" zone.
  
  
  CONCLUSIONS
  "Observe" patients are typically elderly men with pre-existing CAD and high long-term mortality. Absolute hs-cTn-changes within 3h, functional stress imaging and coronary angiography are the key diagnostic modalities.
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland; GREAT network.
authors.forename: Thomas
authors.initials: T
authors.lastname: Nestelberger
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland; GREAT network.
authors.forename: Karin
authors.initials: K
authors.lastname: Wildi
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland; GREAT network.
authors.forename: Jasper
authors.initials: J
authors.lastname: Boeddinghaus
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland; GREAT network.
authors.forename: Raphael
authors.initials: R
authors.lastname: Twerenbold
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland; GREAT network.
authors.forename: Tobias
authors.initials: T
authors.lastname: Reichlin
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland; GREAT network.
authors.forename: Maria Rubini
authors.initials: MR
authors.lastname: Giménez
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland; GREAT network.
authors.forename: Christian
authors.initials: C
authors.lastname: Puelacher
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland; GREAT network.
authors.forename: Cedric
authors.initials: C
authors.lastname: Jaeger
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland; GREAT network.
authors.forename: Karin
authors.initials: K
authors.lastname: Grimm
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland.
authors.forename: Zaid
authors.initials: Z
authors.lastname: Sabti
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland.
authors.forename: Petra
authors.initials: P
authors.lastname: Hillinger
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland.
authors.forename: Nikola
authors.initials: N
authors.lastname: Kozhuharov
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland; GREAT network.
authors.forename: Jeanne
authors.initials: J
authors.lastname: du Fay de Lavallaz
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland.
authors.forename: Florentina
authors.initials: F
authors.lastname: Pinck
authors.affiliation: GREAT network; Emergency department, Hospital Clinic, Barcelona, Catalonia, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Lopez
authors.affiliation: GREAT network; Emergency department, Hospital Clinic, Barcelona, Catalonia, Spain.
authors.forename: Emilio
authors.initials: E
authors.lastname: Salgado
authors.affiliation: GREAT network; Emergency department, Hospital Clinic, Barcelona, Catalonia, Spain.
authors.forename: Òscar
authors.initials: Ò
authors.lastname: Miró
authors.affiliation: Department of Emergency Medicine, University Hospital Basel, Switzerland.
authors.forename: Roland
authors.initials: R
authors.lastname: Bingisser
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland; Department of Emergency Medicine, University Hospital Basel, Switzerland.
authors.forename: Jens
authors.initials: J
authors.lastname: Lohrmann
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Osswald
authors.affiliation: Department of Cardiology, University Hospital Basel, Switzerland; Cardiovascular Research Institute Basel (CRIB), University Hospital Basel, Switzerland; GREAT network. Electronic address: christian.mueller@usb.ch.
authors.forename: Christian
authors.initials: C
authors.lastname: Mueller
mesh_terms: D000368:Aged; D000465:Algorithms; D015415:Biomarkers / Q000097:blood; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D038622:Internationality; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000175:diagnosis*; D011446:Prospective Studies; D013997:Time Factors; D020107:Troponin T / Q000097:blood*
chemical_list: D015415:Biomarkers; D020107:Troponin T
keywords: Acute myocardial infarction; Diagnostic algorithm; High-sensitivity cardiac troponin