title: Implication of QRS prolongation and its relation to mechanical dyssynchrony in idiopathic dilated cardiomyopathy in childhood.
abstract: We explored the role of QRS prolongation (>or=120 ms) and its relation to mechanical dyssynchrony and outcomes in childhood idiopathic dilated cardiomyopathy (IDC). A total of 89 patients <or=18 years old diagnosed as having IDC (21 days to 26 years of follow-up) were investigated. In 20 survivors with residual left ventricular (LV) dysfunction, mechanical (interventricular and intra-LV) dyssynchrony was assessed. The SD of time from the beginning of QRS prolongation to peak systolic contraction was measured in 12 LV segments by tissue Doppler imaging. A cut-off value >32.6 ms was used to define intra-LV dyssynchrony. The 1- and 5-year survivals were 70% and 53%, respectively. Requirement of intravenous inotropes at follow-up (hazard ratio 3.10) and initial LV ejection fraction (hazard ratio 0.95) were major prognostic factors. QRS prolongation, primarily left bundle branch block, was identified in 16 patients (18%) and tended to increase the risk of requiring inotropes. Moreover, none of those with QRS prolongation regained normal cardiac function at follow-up. Two patients with QRS prolongation showed marked improvement in cardiac function after cardiac resynchronization therapy. Mechanical dyssynchrony was noted in all patients with QRS prolongation and in 8% (interventricular) or 38% (intra-LV) of those without. In conclusion, QRS prolongation was common in childhood IDC and was possibly associated with persistent LV dysfunction and worse cardiac outcome. Mechanical (inter- and intraventricular) dyssynchrony was highly prevalent in those with QRS prolongation and was still often observed in those without.
authors.affiliation: Department of Pediatrics, National Taiwan University Hospital, Taipei, Taiwan; Heart Failure Center, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Chun-An
authors.initials: CA
authors.lastname: Chen
authors.forename: Cheng-Hui
authors.initials: CH
authors.lastname: Hsiao
authors.forename: Jou-Kou
authors.initials: JK
authors.lastname: Wang
authors.forename: Ming-Tai
authors.initials: MT
authors.lastname: Lin
authors.forename: En-Ting
authors.initials: ET
authors.lastname: Wu
authors.forename: Shuenn-Nan
authors.initials: SN
authors.lastname: Chiu
authors.forename: Hsin-Hui
authors.initials: HH
authors.lastname: Chiu
authors.forename: Mei-Hwan
authors.initials: MH
authors.lastname: Wu
mesh_terms: D000293:Adolescent; D002311:Cardiomyopathy, Dilated / Q000188:drug therapy* / Q000453:epidemiology / Q000503:physiopathology; D002316:Cardiotonic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007275:Injections, Intravenous; D008297:Male; D009017:Morbidity / Q000639:trends; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D013624:Taiwan / Q000453:epidemiology; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left / Q000187:drug effects / Q000502:physiology
chemical_list: D002316:Cardiotonic Agents