title: Increased QT variability in young asymptomatic patients with beta-thalassemia major.
abstract: BACKGROUND
  Despite recent progress in iron chelation therapy, sudden cardiac death due to malignant ventricular arrhythmias remains a vexing, clinical problem in patients with beta-thalassemia major (TM). In this study we assessed whether the major indices of QT variability, emerging tools for risk stratification of sudden cardiac death, differ in young asymptomatic patients with TM and healthy persons.
  
  
  METHODS
  Thirty patients with TM and 30 healthy control subjects underwent a 5-min electrocardiography recording to calculate the following variables: QT variance (QT(v)), QT(v) normalized for mean QT (QTVN) and QT variability index (QTVI). All subjects also underwent a two-dimensional and Doppler echocardiography study and magnetic resonance imaging (MRI) to determine cardiac and hepatic T2* values.
  
  
  RESULTS
  No differences were observed in clinical and conventional echo-Doppler findings in healthy control subjects and patients with TM whereas QT(v), QTVN and QTVI values were significantly higher in patients than those in controls (QT(v), P < 0.001; QTVN, P < 0.05 and QTVI, P < 0.001) and cardiac T2* and hepatic MRI T2* values were significantly lower in patients with TM (P < 0.001). The indices of temporal QT variability correlated significantly with MRI data.
  
  
  CONCLUSIONS
  Young asymptomatic patients with TM have increased cardiac repolarization variability as assessed by QT variability indices, probably due to cardiac iron deposition. These easily assessed, non-invasive markers could be used to identify increased myocardial repolarization lability early in asymptomatic patients with TM.
authors.affiliation: Dipartimento di Scienze Cardiovascolari, Respiratorie e Morfologiche, Policlinico Umberto I, Università La Sapienza, Rome, Italy. damiano.magri@libero.it
authors.forename: Damiano
authors.initials: D
authors.lastname: Magrì
authors.forename: Susanna
authors.initials: S
authors.lastname: Sciomer
authors.forename: Francesco
authors.initials: F
authors.lastname: Fedele
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Gualdi
authors.forename: Emanuele
authors.initials: E
authors.lastname: Casciani
authors.forename: Pellegrina
authors.initials: P
authors.lastname: Pugliese
authors.forename: Anna
authors.initials: A
authors.lastname: Losardo
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Ferrazza
authors.forename: Eleonora
authors.initials: E
authors.lastname: Pasquazzi
authors.forename: Erika
authors.initials: E
authors.lastname: Schifano
authors.forename: Marzia
authors.initials: M
authors.lastname: Magnanti
authors.forename: Sabrina
authors.initials: S
authors.lastname: Matera
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Marigliano
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Piccirillo
mesh_terms: D000293:Adolescent; D000328:Adult; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000473:pathology; D015150:Echocardiography, Doppler; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007501:Iron / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D020379:Risk Adjustment; D017086:beta-Thalassemia / Q000150:complications / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*
chemical_list: D007501:Iron