title: Detection of transient regional myocardial ischemia using body surface Delta map in patients referred for myocardial perfusion imaging--a pilot study.
abstract: BACKGROUND
  The diagnosis of transient regional myocardial ischemia (TRMI) in patients presenting with stable chest pain is a challenge. Exercise Tolerance Test (ETT) is no longer recommended in most cases due to its flaws. Alternative tests are more expensive and less readily available. The BSM Delta map is an intuitive color display of digitally subtracted ST-segment shift derived from two 80-electrode BSM recordings at baseline and at peak stress, and has shown promise as a tool for detection of TRMI.
  
  
  OBJECTIVE
  The purpose of this pilot study was to assess the feasibility of BSM Delta map as a tool to detect TRMI using dobutamine stress ECG gated single-photon emission computed tomography myocardial perfusion imaging (MPI) as a reference.
  
  
  METHODS
  Forty consecutive patients were recruited who were referred for MPI with a history of angina-like symptoms. The BSM Delta map was derived from two 80-electrode body surface mapping system recordings carried out simultaneously with MPI at (a) baseline and (b) peak dobutamine stress. Standard 12-lead ECGs were also recorded at the same time points.
  
  
  RESULTS
  The mean patient age was 68±7.1years, and 52% (21/40) were female. Using MPI as the reference the sensitivity of BSM Delta map was 82% (9/11) and specificity was 86% (25/29) (95% CI 0.688-0.992), positive likelihood ratio 5.93 (95% CI 2.29-15), negative likelihood ratio 0.21 (95% CI 0.06-0.75). The sensitive of the 12-lead ECG was 36% (4/11) and specificity was 76% (22/29) (95% CI 0.356-0.767), positive likelihood ratio 1.51 (95% CI 0.55-4.15), negative likelihood ratio 0.84 (95% CI 0.51-1.37). BSM Delta map is more sensitive and specific (McNemar's chi-square test p=0.03 (95% CI, 0.448-0.924). The PPV and NPV for BSM Delta map were 69% (9/13) and 93% (25/27) respectively, compared with 36% (4/11) and 76% (22/29) for 12-lead ECG.
  
  
  CONCLUSIONS
  This pilot study confirms the feasibility of using Delta map in this context and suggests that it has promising diagnostic accuracy and is superior to the 12-lead ECG. It could potentially represent a clinically suitable screening tool for TRMI in patients presenting with stable chest pain, since it is near patient and requires little specialist training for acquisition and interpretation. A larger clinical study is now required.
authors.affiliation: Wessex Cardiac Unit, Southampton University Hospital, Southampton, UK; Faculty of Medicine, University of Southampton, Southampton, UK. Electronic address: mehmoodzeb@hotmail.com.
authors.forename: Mehmood
authors.initials: M
authors.lastname: Zeb
authors.forename: Florence
authors.initials: F
authors.lastname: Garty
authors.forename: Nirmala
authors.initials: N
authors.lastname: Nagaraj
authors.forename: Wendy
authors.initials: W
authors.lastname: Bannister
authors.forename: Paul
authors.initials: P
authors.lastname: Roderick
authors.forename: Simon
authors.initials: S
authors.lastname: Corbett
authors.forename: John
authors.initials: J
authors.lastname: Morgan
authors.forename: Nick
authors.initials: N
authors.lastname: Curzen
mesh_terms: D000368:Aged; D000465:Algorithms; D018780:Body Surface Potential Mapping / Q000379:methods*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D017202:Myocardial Ischemia / Q000175:diagnosis*; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Body surface mapping; Diagnostic imaging; ECG; Myocardial perfusion imaging; Regional myocardial ischemia