title: [The QTc interval and its dispersion in hypertrophic myocardiopathy--its relation to complex ventricular arrhythmias and the effect of anti-arrhythmia agents].
abstract: The aim of the present study was to evaluate, in patients with hypertrophic cardiomyopathy (HCM): 1. The relation of rate corrected QT interval (QTc) and of QTc interlead variability (QTc dispersion) to complex ventricular arrhythmias (CVA); 2. The effects of amiodarone (Am), beta-blockers (beta B) and calcium antagonists (CA) on QTc and on QTc dispersion. Surface 12 leads ECG was analysed in 55 patients with HCM (39 +/- 12 years, 32 males). All patients were in sinus rhythm, without bundle branch block. Maximum (max), minimum (min) and mean QTc values were considered. QTc dispersion was calculated as: a) max QTc - min QTc (max-min); b) dispersion index (DI) = standard deviation of QTc/mean QTcx100. Patients groups were defined accordingly to: 1--the absence (group A1-35 patients) or the presence (group A2-20 patients) of CVA on 24 hours Holter monitoring; II--absence of cardioactive medication (group B1-20 patients) versus monotherapy with Am (group B3-10 patients), or beta B (group B4-15 patients), or CA (group B5-10 patients). Age, gender, type of HCM (asymmetric versus concentric) and echocardiographic fractional shortening were not different in the studied groups.
  
  
  RESULTS
  [table: see text]
  
  
  CONCLUSIONS
  1. Maximum QTc interlead QTc dispersion are increased in patients with HCM that show CVA on Holter monitoring; 2. Amiodarone prolongs QTc but reduces QTc dispersion, while beta-blockers and calcium antagonists do not significantly change neither the duration nor the dispersion of ventricular repolarization.
authors.affiliation: Serviço de Cardiologia, Hospital de Santa Marta, Lisboa.
authors.forename: M J
authors.initials: MJ
authors.lastname: Sousa
authors.forename: J
authors.initials: J
authors.lastname: Aranha
authors.forename: C
authors.initials: C
authors.lastname: Cotrim
authors.forename: L
authors.initials: L
authors.lastname: Sousa
authors.forename: A
authors.initials: A
authors.lastname: Sequeira
authors.forename: R M
authors.initials: RM
authors.lastname: Soares
authors.forename: J
authors.initials: J
authors.lastname: Abreu
authors.forename: L
authors.initials: L
authors.lastname: Bernardes
authors.forename: R
authors.initials: R
authors.lastname: Gracias
authors.forename: S
authors.initials: S
authors.lastname: Salomão
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000188:drug therapy*; D002121:Calcium Channel Blockers / Q000627:therapeutic use; D002312:Cardiomyopathy, Hypertrophic / Q000175:diagnosis / Q000188:drug therapy*; D016009:Chi-Square Distribution; D004562:Electrocardiography / Q000187:drug effects* / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D006352:Heart Ventricles; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D000319:Adrenergic beta-Antagonists; D000889:Anti-Arrhythmia Agents; D002121:Calcium Channel Blockers
vernacular_title: Intervalo QTc e sua dispersão na miocardiopatia hipertrófica--relação com arritmias ventriculares complexas e efeito dos fármacos anti-arrítmicos.