title: Abnormal electrocardiographic QRS transition zone and risk of mortality in individuals free of cardiovascular disease.
abstract: OBJECTIVE
  We examined the prognostic significance of abnormal electrocardiographic QRS transition zone (clockwise and counterclockwise horizontal rotations) in individuals free of cardiovascular disease (CVD).
  
  
  RESULTS
  A total of 5541 adults (age 53 ± 10.4 years, 54% women, 24% non-Hispanic black, 25% Hispanic) without CVD or any major electrocardiogram (ECG) abnormalities from the US Third National Health and Nutrition Examination Survey were included in this analysis. Clockwise and counterclockwise horizontal rotations were defined from standard 12-lead ECG using Minnesota ECG Classification. Mortality and cause of death were assessed through 2006. At baseline, 282 participants had clockwise rotation and 3500 had counterclockwise rotation. During a median follow of 14.6 years, 1229 deaths occurred of which 415 were due to CVD. In multivariable-adjusted Cox proportional hazard analysis and compared with normal rotation, clockwise rotation was significantly associated with increased risk of all-cause mortality {hazard ratio (HR) [95% confidence interval (CI)]: 1.43 (1.15-1.78); P = 0.002} and CVD mortality [HR (95% CI): 1.61 (1.09, 2.37) P = 0.016]. In contrast, counterclockwise rotation was associated with significantly lower risk of all-cause mortality [HR (95% CI): 0.86 (0.76, 0.97); P = 0.017] and non-significant association with CVD mortality [HR (95% CI): 1.07 (0.86, 1.33); P = 0.549]. These results were consistent in subgroup analysis stratified by age, sex, and race.
  
  
  CONCLUSIONS
  In a diverse community-based population free of CVD and compared with normal rotation, clockwise rotation was associated with increased risk of all-cause and CVD mortality while counterclockwise rotation was associated with lower risk of all-cause mortality and non-significant association with CVD mortality. These findings call for attention to these often neglected ECG markers, and probably call for revising the current definition of normal rotation.
authors.affiliation: Department of Internal Medicine-Cardiology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
authors.forename: Natalie
authors.initials: N
authors.lastname: Bradford
authors.affiliation: Department of Epidemiology and Medicine, Emory University, Atlanta Veterans Affairs Medical Center, Atlanta, GA 30322, USA.
authors.forename: Amit J
authors.initials: AJ
authors.lastname: Shah
authors.affiliation: Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Usoro
authors.affiliation: Department of Internal Medicine-Cardiology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
authors.forename: Wesley K
authors.initials: WK
authors.lastname: Haisty
authors.affiliation: Department of Internal Medicine-Cardiology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA Epidemiological Cardiology Research Center (EPICARE), Department of Epidemiology and Prevention, Division of Public Health Sciences, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157, USA esoliman@wakehealth.edu.
authors.forename: Elsayed Z
authors.initials: EZ
authors.lastname: Soliman
mesh_terms: D001145:Arrhythmias, Cardiac / Q000145:classification / Q000175:diagnosis* / Q000401:mortality*; D003936:Diagnosis, Computer-Assisted / Q000379:methods / Q000706:statistics & numerical data*; D004562:Electrocardiography / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008403:Mass Screening / Q000379:methods / Q000706:statistics & numerical data*; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015996:Survival Rate; D014481:United States / Q000453:epidemiology
keywords: Clockwise rotation; Counterclockwise rotation; Electrocardiogram; Mortality; Transition zone