title: Screening entire health system ECG databases to identify patients at increased risk of death.
abstract: BACKGROUND
  Current methods to identify patients at higher risk for sudden cardiac death, primarily left ventricular ejection fraction ≤35%, miss ≈80% of patients who die suddenly. We tested the hypothesis that patients with elevated QRS-scores (index of myocardial scar) and wide QRS-T angles (index abnormal depolarization-repolarization relationship) have high 1-year all-cause mortality and could be further risk stratified with clinical characteristics.
  
  
  RESULTS
  We screened all 12-lead ECGs over 6 months at 2 large hospital systems and analyzed clinical characteristics and 1-year mortality. Patients with ECGs obtained in hospital areas with known high mortality rates were excluded. At the first hospital, QRS-score ≥5 and QRS-T angle ≥105° identified 8.0% of patients and was associated with an odds ratio of 2.79 (95% confidence interval, 2.10-3.69) for 1-year mortality compared with patients below both ECG thresholds (13.9% versus 5.5% death rate). Left ventricular ejection fraction was >35% in 82% of the former group of patients, and addition of ECG measures to left ventricular ejection fraction increased the discrimination of death risk (P<0.0001). At the second hospital, the odds ratio was 2.42 (1.95-3.01) for 1-year mortality (8.8% versus 3.8%). Adjustment for patient characteristics eliminated interhospital differences. Multivariable adjusted odds ratio combining data from both hospitals was 1.53 (1.28-1.83). Increasing heart rate and chronic renal impairment further predicted mortality.
  
  
  CONCLUSIONS
  Screening hospital ECG databases with QRS-scoring and QRS-T angle analysis identifies patients with high 1-year all-cause mortality and predominantly preserved left ventricular ejection fraction. This approach may represent a widely available method to identify patients at increased risk of death.
authors.affiliation: Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food & Drug Administration, Silver Spring, MD.
authors.forename: David G
authors.initials: DG
authors.lastname: Strauss
authors.forename: Nathan
authors.initials: N
authors.lastname: Mewton
authors.forename: Richard L
authors.initials: RL
authors.lastname: Verrier
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Nearing
authors.forename: Francis E
authors.initials: FE
authors.lastname: Marchlinski
authors.forename: Tony
authors.initials: T
authors.lastname: Killian
authors.forename: John
authors.initials: J
authors.lastname: Moxley
authors.forename: Larisa G
authors.initials: LG
authors.lastname: Tereshchenko
authors.forename: Katherine C
authors.initials: KC
authors.lastname: Wu
authors.forename: Raimond
authors.initials: R
authors.lastname: Winslow
authors.forename: Christopher
authors.initials: C
authors.lastname: Cox
authors.forename: Peter M
authors.initials: PM
authors.lastname: Spooner
authors.forename: João A C
authors.initials: JA
authors.lastname: Lima
mesh_terms: D000328:Adult; D000368:Aged; D016208:Databases, Factual; D016757:Death, Sudden, Cardiac / Q000453:epidemiology* / Q000517:prevention & control; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012372:ROC Curve; D018570:Risk Assessment; D013318:Stroke Volume
keywords: arrhythmias, cardiac; death; electrocardiography; fibrosis; mass screening