title: A new method of filtering T waves to detect hidden P waves in electrocardiogram signals.
abstract: OBJECTIVE
  A correct identification of the P wave is crucial for the diagnosis of narrow QRS tachycardias. This is sometimes difficult because atrial activity is hidden in the T wave. The aim of this study is to evaluate the usefulness of a T wave filtering technique based on wavelet transformation to identify atrial activity.
  
  
  RESULTS
  Forty-two patients with narrow QRS tachycardias and regular atrial activity were studied. A surface electrocardiogram (ECG), intra-atrial recording, and the T wave filtering ECG were compared simultaneously to check the accuracy of the filtering system in detecting atrial activity. The sensitivity of the T wave filtering and P wave detection algorithm was 85.8% [95% confidence interval (CI): 81.2-89.4%] and the specificity was 89.4% (95% CI: 87.1-91.4%), with a global accuracy of 88.5% (95% CI: 86.5-90.3%). The expert cardiologist's accuracy in distinguishing between atrioventricular nodal reentry tachycardia and atrioventricular reentry tachycardia was 75% in the surface ECG vs. 100% in the ECG with the T wave filtering process (P<0.01).
  
  
  CONCLUSIONS
  T wave filtering based on wavelet transformation improves the capacity of the surface ECG to identify atrial activity in cases of regular narrow QRS supraventricular tachycardias.
authors.affiliation: Institut Català de Ciències Cardiovasculars, Hospital de la Santa Creu i Sant Pau, Pavelló del Convent, Sant Antoni Maria Claret, and Universidad Politécnica de Catalunya, 167, 08025 Barcelona, Spain.
authors.forename: Diego
authors.initials: D
authors.lastname: Goldwasser
authors.forename: Antonio
authors.initials: A
authors.lastname: Bayés de Luna
authors.forename: Guillem
authors.initials: G
authors.lastname: Serra
authors.forename: Roberto
authors.initials: R
authors.lastname: Elosúa
authors.forename: Enrique
authors.initials: E
authors.lastname: Rodriguez
authors.forename: José M
authors.initials: JM
authors.lastname: Guerra
authors.forename: Concepción
authors.initials: C
authors.lastname: Alonso
authors.forename: Xavier
authors.initials: X
authors.lastname: Viñolas Prat
mesh_terms: D000465:Algorithms; D003937:Diagnosis, Differential; D004562:Electrocardiography / Q000379:methods*; D006325:Heart Atria / Q000503:physiopathology; D006801:Humans; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000175:diagnosis / Q000503:physiopathology; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000503:physiopathology*