title: QRS duration and QRS fractionation on surface electrocardiogram are markers of right ventricular dysfunction and atrialization in patients with Ebstein anomaly.
abstract: BACKGROUND
  Ebstein anomaly is a rare and heterogeneous congenital heart defect affecting the tricuspid valve and right ventricular (RV) myocardium. Few studies have analysed the electrocardiographic features of Ebstein anomaly and none has addressed correlations with disease severity.
  
  
  METHODS
  Patients with Ebstein anomaly who had undergone electrocardiography and cardiac magnetic resonance (CMR) within 6 weeks between 2001 and 2009 were included. Exclusion criteria were: associated congenital cardiac defect, previous RV myoplasty and/or reduction surgery, class I anti-arrhythmic drug therapy, and paced/pre-excited QRS. Standard electrocardiogram (ECG) findings were correlated with CMR-based RV measures and clinical profile.
  
  
  RESULTS
  The mean age of the 63 study patients was 22 ± 13 years. An RV conduction delay (rsR' pattern in right precordial leads) was present in 45 patients (71%). The QRS duration correlated with anatomic RV diastolic volume (r = +0.56, P < 0.0001) and inversely with RV ejection fraction (EF; r = -0.62, P < 0.0001). The presence of QRS fractionation predicted greater atrialized RV volume (80 ± 31 vs. 45 ± 37 mL/m(2), P < 0.001). Normal QRS duration was associated with smaller anatomic RV diastolic volume (150 ± 57 vs. 256 ± 100 mL/m(2); P < 0.0001), higher RV EF (48 ± 6 vs. 34 ± 14%; P < 0.0001), higher oxygen consumption (VO(2)) at cardiopulmonary exercise (25.8 vs. 21.8 mL/kg/min, P = 0.05) and lower incidence of oxygen desaturation with exercise (25 vs. 65%, P = 0.02).
  
  
  CONCLUSIONS
  Delayed and prolonged depolarization of the RV is common in patients with Ebstein anomaly. The QRS duration is a marker of RV enlargement and dysfunction. QRS fractionation is associated with a greater atrialized RV volume. A preserved surface ECG identifies a subset of patients with Ebstein anomaly with mild morphological and functional abnormalities and better clinical profile.
authors.affiliation: Department of Cardiology, Children's Hospital Boston, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Egidy Assenza
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: Valente
authors.forename: Tal
authors.initials: T
authors.lastname: Geva
authors.forename: Dionne
authors.initials: D
authors.lastname: Graham
authors.forename: Francesca Romana
authors.initials: FR
authors.lastname: Pluchinotta
authors.forename: Francesca
authors.initials: F
authors.lastname: Romana Pluchinotta
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Sanders
authors.forename: Camillo
authors.initials: C
authors.lastname: Autore
authors.forename: Massimo
authors.initials: M
authors.lastname: Volpe
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Landzberg
authors.forename: Frank
authors.initials: F
authors.lastname: Cecchin
mesh_terms: D002306:Cardiac Volume; D004437:Ebstein Anomaly / Q000175:diagnosis* / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D006325:Heart Atria / Q000503:physiopathology; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D018497:Ventricular Dysfunction, Right / Q000175:diagnosis*; D020257:Ventricular Remodeling; D055815:Young Adult