title: Delayed intrinsicoid deflection of the QRS complex is associated with sudden cardiac arrest.
abstract: BACKGROUND
  Prolongation of initial ventricular depolarization on the 12-lead electrocardiogram (ECG), or delayed intrinsicoid deflection (DID), can indicate left ventricular hypertrophy (LVH). The possibility that this marker could convey distinct risk of sudden cardiac arrest (SCA) has not been evaluated.
  
  
  OBJECTIVE
  To evaluate the association of DID and SCA in the community.
  
  
  METHODS
  In the ongoing prospective, population-based Oregon Sudden Unexpected Death Study (Oregon SUDS; catchment area approximately 1 million), SCA cases were compared to geographic controls with no SCA. Archived ECGs (closest and unrelated to SCA event for cases) were evaluated for the presence of DID, defined as ≥0.05 second in leads V5 or V6. Left ventricular (LV) mass and function were evaluated from archived echocardiograms.
  
  
  RESULTS
  SCA cases (n = 272, 68.7 ± 14.6 years, 63.6% male) as compared to controls (n = 351, 67.6 ± 11.4 years, 63.3% male) were more likely to have DID on ECG (28.3% vs. 17.1%, P = .001). DID was associated with increased SCA odds (odds ratio [OR] 1.92; 95% confidence interval [CI] 1.31-2.81; P = .001), but showed poor correlation with LV mass and echocardiographic LVH (kappa 0.13). In multivariate analysis adjusted for clinical and ECG markers, reduced LV ejection fraction, and echocardiographic LVH, DID remained an independent predictor of SCA (OR 1.82; 95% CI 1.12-2.97; P = .016). Additionally, in a sensitivity analysis restricted to narrow QRS, DID and ECG LVH by voltage were each independently associated with SCA risk.
  
  
  CONCLUSIONS
  DID was associated with increased SCA risk independent of echocardiographic LVH, ECG LVH, and reduced LV ejection fraction, potentially reflecting unique electrical remodeling that warrants further investigation.
authors.affiliation: The Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California.
authors.forename: Navid
authors.initials: N
authors.lastname: Darouian
authors.affiliation: The Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California.
authors.forename: Kumar
authors.initials: K
authors.lastname: Narayanan
authors.affiliation: The Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California.
authors.forename: Aapo L
authors.initials: AL
authors.lastname: Aro
authors.affiliation: The Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California.
authors.forename: Kyndaron
authors.initials: K
authors.lastname: Reinier
authors.affiliation: The Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California.
authors.forename: Audrey
authors.initials: A
authors.lastname: Uy-Evanado
authors.affiliation: The Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California.
authors.forename: Carmen
authors.initials: C
authors.lastname: Teodorescu
authors.affiliation: Oregon Health and Science University, Portland, Oregon.
authors.forename: Karen
authors.initials: K
authors.lastname: Gunson
authors.affiliation: Oregon Health and Science University, Portland, Oregon.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Jui
authors.affiliation: The Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California,. Electronic address: sumeet.chugh@cshs.org.
authors.forename: Sumeet S
authors.initials: SS
authors.lastname: Chugh
mesh_terms: D000368:Aged; D016757:Death, Sudden, Cardiac / Q000453:epidemiology / Q000209:etiology*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000150:complications / Q000503:physiopathology*; D015994:Incidence; D008297:Male; D016017:Odds Ratio; D009922:Oregon / Q000453:epidemiology; D011379:Prognosis; D011446:Prospective Studies; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: Arrhythmia; Electrocardiography; Intrinsicoid deflection; Left ventricular hypertrophy; Sudden cardiac death