title: Improvements in ECG accuracy for diagnosis of left ventricular hypertrophy in obesity.
abstract: The electrocardiogram (ECG) is the most commonly used tool to screen for left ventricular hypertrophy (LVH), and yet current diagnostic criteria are insensitive in modern increasingly overweight society. We propose a simple adjustment to improve diagnostic accuracy in different body weights and improve the sensitivity of this universally available technique.
  
  
  
  Overall, 1295 participants were included-821 with a wide range of body mass index (BMI 17.1-53.3 kg/m(2)) initially underwent cardiac magnetic resonance evaluation of anatomical left ventricular (LV) axis, LV mass and 12-lead surface ECG in order to generate an adjustment factor applied to the Sokolow-Lyon criteria. This factor was then validated in a second cohort (n=520, BMI 15.9-63.2 kg/m(2)).
  
  
  
  When matched for LV mass, the combination of leftward anatomical axis deviation and increased BMI resulted in a reduction of the Sokolow-Lyon index, by 4 mm in overweight and 8 mm in obesity. After adjusting for this in the initial cohort, the sensitivity of the Sokolow-Lyon index increased (overweight: 12.8% to 30.8%, obese: 3.1% to 27.2%) approaching that seen in normal weight (37.8%). Similar results were achieved in the validation cohort (specificity increased in overweight: 8.3% to 39.1%, obese: 9.4% to 25.0%) again approaching normal weight (39.0%). Importantly, specificity remained excellent (>93.1%).
  
  
  
  Adjusting the Sokolow-Lyon index for BMI (overweight +4 mm, obesity +8 mm) improves the diagnostic accuracy for detecting LVH. As the ECG, worldwide, remains the most widely used screening tool for LVH, implementing these findings should translate into significant clinical benefit.
authors.affiliation: Radcliffe Department of Medicine, Division of Cardiovascular Medicine and University of Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK.
authors.forename: Oliver J
authors.initials: OJ
authors.lastname: Rider
authors.affiliation: Radcliffe Department of Medicine, Division of Cardiovascular Medicine and University of Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK Division of Cardiology, Department of Medicine Research, University of Capetown, South Africa.
authors.forename: Ntobeko
authors.initials: N
authors.lastname: Ntusi
authors.affiliation: Radcliffe Department of Medicine, Division of Cardiovascular Medicine and University of Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK.
authors.forename: Sacha C
authors.initials: SC
authors.lastname: Bull
authors.affiliation: Chris Hani Baragwanath Hospital, Soweto & University of Witwatersrand, Johannesburg, South Africa.
authors.forename: Richard
authors.initials: R
authors.lastname: Nethononda
authors.affiliation: Radcliffe Department of Medicine, Division of Cardiovascular Medicine and University of Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Ferreira
authors.affiliation: St Vincent's Hospital, Sydney, Australia.
authors.forename: Cameron J
authors.initials: CJ
authors.lastname: Holloway
authors.affiliation: Radcliffe Department of Medicine, Division of Cardiovascular Medicine and University of Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK.
authors.forename: David
authors.initials: D
authors.lastname: Holdsworth
authors.affiliation: Radcliffe Department of Medicine, Division of Cardiovascular Medicine and University of Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK.
authors.forename: Masliza
authors.initials: M
authors.lastname: Mahmod
authors.affiliation: Radcliffe Department of Medicine, Division of Cardiovascular Medicine and University of Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK.
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Rayner
authors.affiliation: Radcliffe Department of Medicine, Division of Cardiovascular Medicine and University of Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK.
authors.forename: Rajarshi
authors.initials: R
authors.lastname: Banerjee
authors.affiliation: Radcliffe Department of Medicine, Division of Cardiovascular Medicine and University of Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK.
authors.forename: Saul
authors.initials: S
authors.lastname: Myerson
authors.affiliation: Radcliffe Department of Medicine, Division of Cardiovascular Medicine and University of Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK.
authors.forename: Hugh
authors.initials: H
authors.lastname: Watkins
authors.affiliation: Radcliffe Department of Medicine, Division of Cardiovascular Medicine and University of Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, UK.
authors.forename: Stefan
authors.initials: S
authors.lastname: Neubauer
mesh_terms: D000200:Action Potentials; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006339:Heart Rate; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications* / Q000175:diagnosis; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012815:Signal Processing, Computer-Assisted