title: Electrocardiographic Markers and the Left Ventricular Ejection Fraction have Cumulative Effects on Risk of Sudden Cardiac Death.
abstract: OBJECTIVE
  To assess potential improvement in SCD risk prediction by adding selected risk markers from the 12-lead ECG to measurement of the left ventricular ejection fraction (LVEF).
  
  
  BACKGROUND
  Novel strategies to improve risk stratification for sudden cardiac death (SCD) are needed. Given the modest odds associated with most individual risk markers, combining multiple markers may be a useful approach.
  
  
  METHODS
  From the ongoing Oregon Sudden Unexpected Death Study, SCD cases with pre-event LVEF available were compared to matched control subjects with coronary artery disease. Resting heart rate, QRS duration (QRSD), and JTc intervals were measured from archived ECGs prior and unrelated to the SCD event. Independent odds of SCD for individual and combined ECG markers were calculated.
  
  
  RESULTS
  SCD cases (n= 317; 67.9 ± 12.9 years) were more likely than controls (n=317; 67.9 ± 12.8 years) to have LVEF ≤ 35% (26% vs. 11%). Mean heart rate, QRSD, and JTc were significantly higher in cases (all p<0.0001). In adjusted analyses, higher heart rate [OR 2.6 (1.8 - 3.7)], QRSD [OR 1.5 (1.0 - 2.5)] and JTc [OR 2.3 (1.6 - 3.4)] were independently associated with SCD. When ECG markers were combined, SCD odds progressively increased with one [OR 3.4 (2.1 - 5.4)] and ≥ 2 elevated markers [OR 6.3 (3.3 - 12.1)]. Addition of ECG markers to an adjusted model with LVEF improved discrimination (C statistic 0.724 vs. 0.642) and net reclassification (by 22.7%) (p<0.0001).
  
  
  CONCLUSIONS
  Combining selected 12-lead ECG markers with LVEF improves SCD risk prediction, and warrants further investigation in prospective studies.
authors.affiliation: Heart Institute, Cedars-Sinai Medical Center, Los Angeles CA.
authors.forename: Kyndaron
authors.initials: K
authors.lastname: Reinier
authors.affiliation: Heart Institute, Cedars-Sinai Medical Center, Los Angeles CA.
authors.forename: Kumar
authors.initials: K
authors.lastname: Narayanan
authors.affiliation: Heart Institute, Cedars-Sinai Medical Center, Los Angeles CA.
authors.forename: Audrey
authors.initials: A
authors.lastname: Uy-Evanado
authors.affiliation: Heart Institute, Cedars-Sinai Medical Center, Los Angeles CA.
authors.forename: Carmen
authors.initials: C
authors.lastname: Teodorescu
authors.affiliation: Heart Institute, Cedars-Sinai Medical Center, Los Angeles CA.
authors.forename: Harpriya
authors.initials: H
authors.lastname: Chugh
authors.affiliation: Department of Preventive Medicine, University of Southern California.
authors.forename: Wendy J
authors.initials: WJ
authors.lastname: Mack
authors.affiliation: Department of Pathology, Oregon Health and Science University, Portland OR.
authors.forename: Karen
authors.initials: K
authors.lastname: Gunson
authors.affiliation: Department of Emergency Medicine, Oregon Health and Science University, Portland OR.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Jui
authors.affiliation: Heart Institute, Cedars-Sinai Medical Center, Los Angeles CA.
authors.forename: Sumeet S
authors.initials: SS
authors.lastname: Chugh
keywords: ejection fraction; electrocardiogram; risk; sudden cardiac death