title: Indexes of temporal myocardial repolarization dispersion and sudden cardiac death in heart failure: any difference?
abstract: BACKGROUND
  The QT variability index, calculated between Q- and the T-wave end (QTend VI), is an index of temporal myocardial repolarization lability associated with sudden cardiac death (SCD) in chronic heart failure (CHF). Little is known about temporal variability in the other two temporal myocardial repolarization descriptors obtained from Q-Tpeak and Tpeak -Tend intervals. We therefore investigated differences between these indexes in patients with CHF who died suddenly and in those who survived with a left ventricular ejection fraction (LVEF) ≤35% or >35%.
  
  
  RESULTS
  We selected 127 ECG and systolic blood pressure (SPB) recordings from outpatients with CHF all of whom had been followed up for 30 months. We calculated RR and SPB variability by power spectral analysis and QTend VI, QTpeak VI, Tpeak Tend VI. We then subdivided data patients into three groups SCD, LVEF ≤ 35%, and LVEF > 35%. The LVEF was higher in the SCD than in the LVEF ≤ 35% group, whereas no difference was found between the SCD and LVEF > 35% groups. QTend VI, QTpeak VI, and Tpeak Tend VI were higher in the SCD and LVEF ≤ 35% groups than in the LVEF > 35% group. Multivariate analysis detected a negative relationship between all repolarization variability indexes, low frequency obtained from RR intervals and LVEF.
  
  
  CONCLUSIONS
  Our data show that variability in the first (QTpeak VI) and second halves of the QT interval (Tpeak -Tend VI) significantly contributes to the QTend VI in patients with CHF. Further studies should investigate whether these indexes might help stratify the risk of SCD in patients with a moderately depressed LVEF.
authors.affiliation: Department of Cardiovascular, Respiratory, Nephrologic, and Geriatric Sciences, Sapienza University of Rome, 00185 Rome, Italy. gianfranco.piccirillo@uniroma1.it
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Piccirillo
authors.forename: Pietro
authors.initials: P
authors.lastname: Rossi
authors.forename: Marilena
authors.initials: M
authors.lastname: Mitra
authors.forename: Raffaele
authors.initials: R
authors.lastname: Quaglione
authors.forename: Annalaura
authors.initials: A
authors.lastname: Dell'Armi
authors.forename: Daniele
authors.initials: D
authors.lastname: Di Barba
authors.forename: Damiana
authors.initials: D
authors.lastname: Maisto
authors.forename: Andrea
authors.initials: A
authors.lastname: Lizio
authors.forename: Francesco
authors.initials: F
authors.lastname: Barillà
authors.forename: Damiano
authors.initials: D
authors.lastname: Magrì
mesh_terms: D000368:Aged; D016757:Death, Sudden, Cardiac / Q000209:etiology*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006333:Heart Failure / Q000150:complications* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies