title: Calculating Cornell voltage from nonstandard chest electrode recording site in the Reasons for Geographic And Racial Differences in Stroke study.
abstract: BACKGROUND
  To minimize participants' burden and the need for disrobing, a 7-lead electrocardiogram (ECG) recording using a single mid-sternal chest lead was recorded at the initial stages of The REasons for Geographic And Racial Differences in Stroke (REGARDS) study. Electrocardiogram-detected left ventricular hypertrophy (ECG-LVH) by Cornell voltage (RaVL + S-wave amplitude in V(3) [SV(3)]) cannot be assessed from this method because of the absence of V(3). We examined the possibility that the S-wave amplitude in the mid-sternal lead (SV) could be used as a surrogate for SV(3).
  
  
  METHODS
  The REGARDS study is a US national study where 7-lead ECGs were performed in 8,330 (29%) participants and standard 12-lead EGCs were performed in 20 811 (71%). Cornell voltage was calculated as the sum of aVL amplitude + SV (in the 7-lead group) or SV(3) (in the 12-lead group). Logistic regression analysis was used to examine and compare the magnitude of the association between the LVH risk factors with ECG-LVH in both groups, and Cox proportional hazards analysis was used to examine and compare the hazard ratios of overall mortality and cardiovascular mortality associated with ECG-LVH in both groups.
  
  
  RESULTS
  Regardless of the Cornell voltage calculation method, ECG-LVH was significantly associated with LVH risk factors; and with the exception of sex, there was no evidence of a difference in the magnitude of the association. ECG-LVH from both approaches were significantly and similarly associated with both all-cause and cardiovascular mortality.
  
  
  CONCLUSIONS
  ECG-LVH by Cornell voltage calculated from a 7-lead ECG (using SV in the formula) has demographic and clinical associations that are similar to that calculated from a standard 12-lead ECG (using SV(3)). In epidemiologic studies recording 7-lead ECG, SV could be used as an alternative to SV(3) in the Cornell voltage formula.
authors.affiliation: Department of Epidemiology and Prevention, Wake Forest University School of Medicine, 2000 West First St.,Winston-Salem, NC 27104, USA. esoliman@wfubmc.edu
authors.forename: Elsayed Z
authors.initials: EZ
authors.lastname: Soliman
authors.forename: George
authors.initials: G
authors.lastname: Howard
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Prineas
authors.forename: Leslie A
authors.initials: LA
authors.lastname: McClure
authors.forename: Virginia J
authors.initials: VJ
authors.lastname: Howard
mesh_terms: D015897:Comorbidity; D004562:Electrocardiography / Q000379:methods* / Q000706:statistics & numerical data*; D006801:Humans; D015995:Prevalence; D044469:Racial Groups / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D020521:Stroke / Q000175:diagnosis* / Q000453:epidemiology*; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis* / Q000453:epidemiology*