title: Non-dipolar content of the T-wave as a measure of repolarization inhomogeneity in ST-elevation myocardial infarction.
abstract: The non-dipolar content of the T-wave, i.e. the component of the signal, which cannot be explained by a dipolar model, has been suggested as a measure of the local repolarization inhomogeneity. Our purpose was to study the non-dipolar content of the T-wave during the initial course of ST-elevation myocardial infarction (STEMI), when local repolarization inhomogeneity presumably is markedly increased. Twelve-lead ECG was semicontinuously collected in 211 patients with STEMI, treated with a thrombolytic agent. The T-wave was processed by principal component analysis. The absolute and relative T-wave residues were used as measures of the non-dipolar content. The median values for each hour and for the entire monitoring time were computed. Changes in the parameters were closer studied in two windows, 0-10 respectively, 11-24 h after start of ECG-monitoring. The median of the absolute T-wave residue during the entire monitoring period was 25 000 units in the STEMI-group and 13 500 units in the comparison group. The median for hour 1 was 36 500 units and 28 800 units for hour 2. The decrease was greater in patients with >or=50% resolution of the ST-elevation at 60 min. The moment of change, identified by cumulative sum-method, showed no correlation to the time for 50% ST-resolution. We conclude, that patients with thrombolysed STEMI have an increased non-dipolar content of the T-wave. Resolution of the ST-elevation is associated with a decrease. The increased non-dipolar content reflects a property of the repolarization phase, which is related to but separated from the ST-elevation.
authors.affiliation: Department of Cardiology, Heart Centre, University Hospital, Umeå, Sweden. milos.kesek@comhem.se
authors.forename: Milos
authors.initials: M
authors.lastname: Kesek
authors.forename: Erik
authors.initials: E
authors.lastname: Bjorklund
authors.forename: Tomas
authors.initials: T
authors.lastname: Jernberg
authors.forename: Bertil
authors.initials: B
authors.lastname: Lindahl
authors.forename: Joel
authors.initials: J
authors.lastname: Xue
authors.forename: Anders
authors.initials: A
authors.lastname: Englund
mesh_terms: D000368:Aged; D000787:Angina Pectoris / Q000503:physiopathology; D015986:Confounding Factors, Epidemiologic; D004562:Electrocardiography; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use; D006329:Heart Conduction System / Q000187:drug effects / Q000503:physiopathology*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy / Q000503:physiopathology*; D015203:Reproducibility of Results; D012737:Sex Factors; D013548:Sweden / Q000453:epidemiology; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D005343:Fibrinolytic Agents