title: ECG-derived spatial QRS-T angle is strongly associated with hypertrophic cardiomyopathy.
abstract: ECG-derived vectorcardiography (VCG) has diagnostic and prognostic value in various diseases. Hypertrophic cardiomyopathy (HCM), a genetic disease with unexplained left ventricular hypertrophy, is one of the most common causes of sudden cardiac death (SCD) in young persons. Genotype positive status is associated with increased risk of systolic dysfunction, heart failure, and (SCD). Herein, we aimed to determine the diagnostic utility of derived VCG parameters in a large cohort of genotyped HCM patients.
  
  
  
  Between 1997 and 2007, genetic testing was performed on 1053 unrelated patients with HCM. Of these, 967 had 12-lead ECGs suitable for computerized derivation of VCG parameters, including the spatial mean and peaks QRS-T angles, spatial ventricular gradient (SVG), spatial QRS, QT, and Tpeak-Tend (TpTe) intervals. ECGs were also evaluated using Seattle ECG criteria. Differences between HCM patients and healthy controls as well as between genotype positive versus genotype negative HCM patients were assessed.
  
  
  
  Spatial peaks (129.3±26.4 vs.30.5±24.2 degrees) and spatial mean QRS-T angles (121.8±38.6 vs. 47.3±27.6 degrees) were significantly higher in patients with HCM than in controls (P<0.001). The spatial peaks and mean QRS-T angles identified 94% and 84% of HCM patients, respectively, while Seattle criteria identified 70.7% of patients (P<0.001). Genotype positive patients had higher spatial mean QRS-T angles, spatial TpTe (P<0.001 respectively), spatial peaks QRS-T angles (P=0.017) and lower SVG (P<0.001) than genotype negative patients.
  
  
  
  ECG-derived spatial QRS-T angles can differentiate patients with HCM from controls and could provide a better tool than traditional Seattle criteria. Clinical usefulness of VCG to differentiate genotype-negative from genotype-positive patients has yet to be established.
authors.affiliation: Electrophysiology, Milton S. Hershey Medical Center, Hershey, USA; Clinical Sciences, Lund University, Lund, Sweden.
authors.forename: Daniel
authors.initials: D
authors.lastname: Cortez
authors.affiliation: Karolinska University Hospital and Karolinska Institute, Stockholm, Sweden; Nicollier-Schlegel SARL, Trélex, Switzerland.
authors.forename: Todd T
authors.initials: TT
authors.lastname: Schlegel
authors.affiliation: Department of Cardiovascular Medicine, Mayo Clinic, MN, USA; Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, MN, USA; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, MN, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ackerman
authors.affiliation: Department of Cardiovascular Medicine, Mayo Clinic, MN, USA; Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, MN, USA; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, MN, USA. Electronic address: Bos.Martijn@mayo.edu.
authors.forename: J Martijn
authors.initials: JM
authors.lastname: Bos
mesh_terms: D000328:Adult; D000465:Algorithms; D002312:Cardiomyopathy, Hypertrophic / Q000175:diagnosis* / Q000453:epidemiology*; D003936:Diagnosis, Computer-Assisted / Q000379:methods* / Q000706:statistics & numerical data; D004562:Electrocardiography / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008910:Minnesota / Q000453:epidemiology; D015995:Prevalence; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014672:Vectorcardiography / Q000379:methods* / Q000706:statistics & numerical data
keywords: Genotype; HCM; Seattle criteria; Vectorcardiography