title: Relationship between QRS duration and left ventricular dyssynchrony in patients with end-stage heart failure.
abstract: BACKGROUND
  Patients with end-stage heart failure and a wide QRS complex are considered candidates for cardiac resynchronization therapy (CRT). However, 20% to 30% of patients do not respond to CRT. Lack of left ventricular dyssynchrony may explain the nonresponse. Accordingly, we evaluated the presence of left ventricular dyssynchrony using tissue Doppler imaging (TDI) in 90 consecutive patients with heart failure.
  
  
  RESULTS
  Ninety patients with severe heart failure (left ventricular ejection fraction <35%, New York Heart Association class III-IV) were prospectively evaluated. Based on QRS duration, 30 consecutive patients with a narrow QRS complex were included (QRS duration <or=120 ms), 30 patients with an intermediate QRS duration (120-150 ms), and 30 patients with a wide QRS complex (>150 ms). All patients underwent TDI to assess left ventricular dyssynchrony. Extensive left ventricular dyssynchrony was defined as an electromechanical delay on TDI between the septum and lateral wall, the so-called septal-to-lateral delay, of >60 ms. Severe dyssynchrony was observed in 27% of patients with narrow QRS complex, 60% with intermediate QRS duration, and 70% with wide QRS complex. No relation existed between QRS duration and septal-to-lateral delay.
  
  
  CONCLUSIONS
  From 30% to 40% of heart failure patients with QRS duration >120 ms do not exhibit left ventricular dyssynchrony, which may explain the nonresponse to CRT. Alternatively, 27% of patients with heart failure and a narrow QRS complex show significant left ventricular dyssynchrony and may be candidates for CRT.
authors.affiliation: Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Gabe B
authors.initials: GB
authors.lastname: Bleeker
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Schalij
authors.forename: Sander G
authors.initials: SG
authors.lastname: Molhoek
authors.forename: Harriette F
authors.initials: HF
authors.lastname: Verwey
authors.forename: Eduard R
authors.initials: ER
authors.lastname: Holman
authors.forename: Eric
authors.initials: E
authors.lastname: Boersma
authors.forename: Paul
authors.initials: P
authors.lastname: Steendijk
authors.forename: Ernst E
authors.initials: EE
authors.lastname: Van Der Wall
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: Bax
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial / Q000379:methods; D015150:Echocardiography, Doppler / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000209:etiology* / Q000628:therapy; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011300:Preoperative Care; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D013223:Statistics as Topic; D018487:Ventricular Dysfunction, Left / Q000150:complications* / Q000175:diagnosis* / Q000628:therapy