title: Archeological Echocardiography: Digitization and Speckle Tracking Analysis of Archival Echocardiograms in the HyperGEN Study.
abstract: BACKGROUND
  Several large epidemiologic studies and clinical trials have included echocardiography, but images were stored in analog format and these studies predated tissue Doppler imaging (TDI) and speckle tracking echocardiography (STE). We hypothesized that digitization of analog echocardiograms, with subsequent quantification of cardiac mechanics using STE, is feasible, reproducible, accurate, and produces clinically valid results.
  
  
  METHODS
  In the NHLBI HyperGEN study (N = 2234), archived analog echocardiograms were digitized and subsequently analyzed using STE to obtain tissue velocities/strain. Echocardiograms were assigned quality scores and inter-/intra-observer agreement was calculated. Accuracy was evaluated in: (1) a separate second study (N = 50) comparing prospective digital strain versus post hoc analog-to-digital strain, and (2) in a third study (N = 95) comparing prospectively obtained TDI e' velocities with post hoc STE e' velocities. Finally, we replicated previously known associations between tissue velocities/strain, conventional echocardiographic measurements, and clinical data.
  
  
  RESULTS
  Of the 2234 HyperGEN echocardiograms, 2150 (96.2%) underwent successful digitization and STE analysis. Inter/intra-observer agreement was high for all STE parameters, especially longitudinal strain (LS). In accuracy studies, LS performed best when comparing post hoc STE to prospective digital STE for strain analysis. STE-derived e' velocities correlated with, but systematically underestimated, TDI e' velocity. Several known associations between clinical variables and cardiac mechanics were replicated in HyperGEN. We also found a novel independent inverse association between fasting glucose and LS (adjusted β = -2.4 [95% CI -3.6, -1.2]% per 1-SD increase in fasting glucose; P < 0.001).
  
  
  CONCLUSIONS
  Archeological echocardiography, the digitization and speckle tracking analysis of archival echocardiograms, is feasible and generates indices of cardiac mechanics similar to contemporary studies.
authors.affiliation: Division of Cardiology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Frank G
authors.initials: FG
authors.lastname: Aguilar
authors.affiliation: Division of Cardiology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Senthil
authors.initials: S
authors.lastname: Selvaraj
authors.affiliation: Division of Cardiology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Eva E
authors.initials: EE
authors.lastname: Martinez
authors.affiliation: Division of Cardiology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Katz
authors.affiliation: Division of Cardiology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Lauren
authors.initials: L
authors.lastname: Beussink
authors.affiliation: Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Kwang-Youn A
authors.initials: KY
authors.lastname: Kim
authors.affiliation: Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Jie
authors.initials: J
authors.lastname: Ping
authors.affiliation: Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Laura
authors.initials: L
authors.lastname: Rasmussen-Torvik
authors.affiliation: Division of Cardiology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Amita
authors.initials: A
authors.lastname: Goyal
authors.affiliation: Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Jin
authors.initials: J
authors.lastname: Sha
authors.affiliation: Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Marguerite R
authors.initials: MR
authors.lastname: Irvin
authors.affiliation: Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Donna K
authors.initials: DK
authors.lastname: Arnett
authors.affiliation: Division of Cardiology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Sanjiv J
authors.initials: SJ
authors.lastname: Shah
mesh_terms: D000703:Analog-Digital Conversion; D057225:Data Mining / Q000379:methods; D004452:Echocardiography / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D011873:Radiology Information Systems / Q000458:organization & administration*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000503:physiopathology*
keywords: epidemiology; speckle tracking echocardiography; strain; ventricular mechanics