title: Prognostic Significance of Premature Ventricular Contractions without Obvious Heart Diseases Determined by Standard 12-Lead Electrocardiography Considering their Morphology.
abstract: BACKGROUND
  Although ventricular premature contraction (VPC) commonly arises in subjects with and without heart diseases, the prognosis of VPC has remained controversial and the effect of their morphology on mortality has not been fully determined in subjects without obvious heart diseases. The objective of this study was to assess the morphologic effect of VPC on mortality.
  
  
  METHODS
  Japanese atomic bomb survivors (n = 6685) underwent baseline health examinations and standard 12-lead electrocardiogram (ECG) between January 1990 and December 1991. Of these, we extracted data from 5,685 (67.1% women) subjects who had neither heart diseases nor electrocardiographic abnormalities at baseline. Among them, we identified 131 VPC cases using standard 12-lead ECG and classified them into left bundle branch block (LBBB) type (n = 74), right bundle branch block (RBBB) type (n = 21), and undetermined type (n = 36) according to their morphology. These subjects were followed up until December 2008; we compared all-cause, cardiac and coronary heart disease (CHD) mortality rates using multivariate Cox regression analysis between those with and without VPC.
  
  
  RESULTS
  No VPCs were associated with all-cause and cardiac mortality, but the LBBB type was significantly associated with CHD mortality (hazard ratio, 2.73; 95% confidence interval, 1.11-6.73) after controlling for age, sex, smoking status, alcohol consumption, and underlying diseases.
  
  
  CONCLUSIONS
  Among Japanese atomic bomb survivors without obvious heart diseases, LBBB-type VPC was associated with increased CHD mortality. Larger studies are needed to confirm the effect of morphology as it might help to predict the risk.
authors.affiliation: Department of Clinical Studies, Radiation Effects Research Foundation, Nagasaki, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Haruta
authors.affiliation: Department of Clinical Studies, Radiation Effects Research Foundation, Nagasaki, Japan.
authors.forename: Masazumi
authors.initials: M
authors.lastname: Akahoshi
authors.affiliation: Department of Clinical Studies, Radiation Effects Research Foundation, Nagasaki, Japan.
authors.forename: Ayumi
authors.initials: A
authors.lastname: Hida
authors.affiliation: Department of Clinical Studies, Radiation Effects Research Foundation, Nagasaki, Japan.
authors.forename: Nobuko
authors.initials: N
authors.lastname: Sera
authors.affiliation: Department of Clinical Studies, Radiation Effects Research Foundation, Nagasaki, Japan.
authors.forename: Misa
authors.initials: M
authors.lastname: Imaizumi
authors.affiliation: Department of Clinical Studies, Radiation Effects Research Foundation, Nagasaki, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Ichimaru
authors.affiliation: Departments of Statistics, Radiation Effects Research Foundation, Hiroshima, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Nakashima
authors.affiliation: Clinical Studies, Radiation Effects Research Foundation, Hiroshima, Japan.
authors.forename: Ikuno
authors.initials: I
authors.lastname: Takahashi
authors.affiliation: Clinical Studies, Radiation Effects Research Foundation, Hiroshima, Japan.
authors.forename: Waka
authors.initials: W
authors.lastname: Ohishi
authors.affiliation: Department of Cardiovascular Medicine, Course of Medical and Dental Sciences, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Satoki
authors.initials: S
authors.lastname: Fukae
authors.affiliation: Department of Cardiovascular Medicine, Course of Medical and Dental Sciences, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Maemura
mesh_terms: D000368:Aged; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D054043:Nuclear Weapons; D011379:Prognosis; D012307:Risk Factors; D017741:Survivors / Q000706:statistics & numerical data; D018879:Ventricular Premature Complexes / Q000175:diagnosis*
keywords: arrhythmia; epidemiology; mortality