title: Usefulness of Q waves on ECG for the prediction of contractile reserve after acute myocardial infarction.
abstract: BACKGROUND
  Controversy exists regarding the significance of pathological 'Q' waves on electrocardiography (ECG) following established acute myocardial infarction (AMI) in predicting non-viable myocardium.
  
  
  OBJECTIVE
  The aim of the study was to ascertain the reliability of 'Q' waves on ECG to predict myocardial viability following AMI.
  
  
  METHODS
  176 patients underwent both ECG and DSE, at a mean of 4.9 days post AMI. Non-viability on ECG and DSE was defined as mentioned below. Both ECG and DSE were used to evaluate 352 (176 anterior and 176 inferior) myocardial territories for viability.
  
  
  RESULTS
  The positive predictive value and the negative predictive value of 'Q' waves on ECG to predict non-viable myocardium were 43% and 85% respectively. The sensitivity for ECG to detect non-viable myocardium was rather low for both anterior and inferior 'Q' waves (64% and 65% respectively), and, the specificity was as well not high enough (72% for anterior and 69% for inferior).
  
  
  CONCLUSIONS
  The presence of extensive 'Q' waves does not predict non-viable myocardium. Whereupon, absence of 'Q' waves predicts the presence of viable myocardium for inferior territory but this is relatively less reliable for anterior territory. Myocardial viability should be sought in patients with extensive 'Q' waves and in unclear anterior territories.
authors.affiliation: Cardiac Research, Department of Cardiology, Northwick Park Hospital, Harrow HA1 3UJ, Middlesex University, London, United Kingdom.
authors.forename: Anil Kumar
authors.initials: AK
authors.lastname: Taneja
authors.affiliation: Cardiac Research, Department of Cardiology, Northwick Park Hospital, Harrow HA1 3UJ, Middlesex University, London, United Kingdom.
authors.forename: Sajad
authors.initials: S
authors.lastname: Hayat
authors.affiliation: Cardiac Research, Department of Cardiology, Northwick Park Hospital, Harrow HA1 3UJ, Middlesex University, London, United Kingdom.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Swinburn
authors.affiliation: Cardiac Research, Department of Cardiology, Northwick Park Hospital, Harrow HA1 3UJ, Middlesex University, London, United Kingdom. Electronic address: roxysenior@cardiac-research.org.
authors.forename: Roxy
authors.initials: R
authors.lastname: Senior
mesh_terms: D004562:Electrocardiography / Q000379:methods / Q000592:standards*; D006801:Humans; D009200:Myocardial Contraction / Q000502:physiology*; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000503:physiopathology*; D011237:Predictive Value of Tests; D011446:Prospective Studies