title: Assessment of QT-measurement accuracy using the 12-lead electrocardiogram derived from EASI leads.
abstract: The purpose of the present study is to assess QT-interval measurements from the EASI 12-lead electrocardiogram (ECG) as compared with the standard 12-lead ECG. The QT interval was automatically determined in simultaneously recorded standard and EASI 12-lead ECGs, using a validated wavelet-based delineator. The agreement between the 2 sets of measurements was quantified both on a lead-by-lead basis and a multilead basis with global definitions of QRS onset and T-wave end. The results show that the agreement between QT-interval measurements from the 2 lead systems is acceptable, with negligible mean differences and with correlation coefficients ranging from 0.91 to 0.98 depending on the lead studied. Although the SD shows a clear dependence on the selected lead (ranging from 9.2 to 26.4 milliseconds), differences are within the accepted tolerances for automatic delineation. In a few patients, large differences were found, mainly because of changes in morphology present in both lead systems. QT intervals measured by the multilead approach were considerably more stable than single-lead measurements and resulted in a much better agreement between the 2 lead systems (correlation coefficient, 0.98; QT difference, 1.1 +/- 9.8 milliseconds). Thus, the EASI 12-lead ECG may be used for reliable QT monitoring when the multilead delineation approach is adopted.
authors.affiliation: Aragon Institute of Engineering Research, Universidad de Zaragoza, 50015 Zaragoza, Aragon, Spain. jpmart@unizar.es
authors.forename: Juan Pablo
authors.initials: JP
authors.lastname: Martínez
authors.forename: Pablo
authors.initials: P
authors.lastname: Laguna
authors.forename: Salvador
authors.initials: S
authors.lastname: Olmos
authors.forename: Olle
authors.initials: O
authors.lastname: Pahlm
authors.forename: Jonas
authors.initials: J
authors.lastname: Pettersson
authors.forename: Leif
authors.initials: L
authors.lastname: Sörnmo
mesh_terms: D003936:Diagnosis, Computer-Assisted / Q000295:instrumentation* / Q000706:statistics & numerical data*; D004562:Electrocardiography / Q000295:instrumentation* / Q000706:statistics & numerical data*; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis*; D015588:Observer Variation; D010818:Practice Patterns, Physicians'; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome