title: Q wave area for stratification of global left ventricular infarct size: comparison to conventional ECG assessment using Selvester QRS-score.
abstract: OBJECTIVE
  Left ventricular (LV) infarct size is a prognostic determinant after acute myocardial infarction (AMI). ECG data have been used to measure infarct size, but conventional approaches use multiparametric algorithms that have limited clinical applicability. This study tested a novel ECG approach - based solely on Q wave area - for calculation of LV infarct size.
  
  
  METHODS
  Serial 12-lead ECGs were performed in AMI patients. Computerized software was used to quantify Q wave area (summed across surface ECG leads) and Selvester QRS-score components. ECG analysis was compared to the reference of myocardial infarct size quantified by delayed enhancement cardiac magnetic resonance.
  
  
  RESULTS
  Overall, 158 patients underwent ECG during early (4±0.4) and follow-up (29±5 days) post-AMI time points. Selvester QRS-score and Q wave area increased stepwise with LV infarct size (P<0.001). Whereas both methods manifested marked increases at a threshold of 10% LV infarction, magnitude was greater for Q wave area (>2.5-fold) than Selvester QRS-score (<two-fold). In receiver operating characteristic analysis, Q wave area (area under the curve=0.83-0.86) and Selvester QRS-score (0.82-0.87) manifested similar performance in relation to a 10% infarct cutoff. When Selvester QRS-score and Q wave area thresholds were selected to optimize sensitivity, both methods yielded similar negative predictive value (Q wave area: 89-91%, Selvester QRS-score: 92-94%) although specificity was higher for Q wave area (44-45 vs. 17-25%; P≤0.01).
  
  
  CONCLUSIONS
  Q wave area provides an index for stratification of LV infarct size that performs similarly to conventional ECG assessment via the Selvester QRS-score for exclusion of large infarction.
authors.affiliation: aDepartment of Medicine, Greenberg Cardiology Division, Weill Cornell Medical College, New York, New York bDuke University School of Medicine, Durham, North Carolina, USA.
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Weinsaft
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Kochav
authors.forename: Anika
authors.initials: A
authors.lastname: Afroz
authors.forename: Peter M
authors.initials: PM
authors.lastname: Okin
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D019540:Area Under Curve; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006352:Heart Ventricles / Q000473:pathology*; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000473:pathology; D009206:Myocardium / Q000473:pathology*; D011237:Predictive Value of Tests; D011379:Prognosis; D012372:ROC Curve; D012042:Registries; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors