title: Cardiac resynchronization therapy in patients with a narrow QRS complex.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effects of cardiac resynchronization therapy (CRT) in heart failure patients with narrow QRS complex (<120 ms) and evidence of left ventricular (LV) dyssynchrony on tissue Doppler imaging (TDI).
  
  
  BACKGROUND
  Cardiac resynchronization therapy is beneficial in selected heart failure patients with wide QRS complex (> or =120 ms). Patients with narrow QRS complex are currently not eligible for CRT, and the potential effects of CRT are not well studied.
  
  
  METHODS
  Thirty-three consecutive patients with narrow QRS complex and 33 consecutive patients with wide QRS complex (control group) were prospectively included. All patients needed to have LV dyssynchrony > or =65 ms on TDI, New York Heart Association (NYHA) functional class III/IV heart failure, and LV ejection fraction < or =35%.
  
  
  RESULTS
  Baseline characteristics, particularly LV dyssynchrony, were comparable between patients with narrow and wide QRS complex (110 +/- 8 ms vs. 175 +/- 22 ms; p = NS). No significant relationship was observed between baseline QRS duration and LV dyssynchrony (r = 0.21; p = NS). The improvement in clinical symptoms and LV reverse remodeling was comparable between patients with narrow and wide QRS complex (mean NYHA functional class reduction 0.9 +/- 0.6 vs. 1.1 +/- 0.6 [p = NS] and mean LV end-systolic volume reduction 39 +/- 34 ml vs. 44 +/- 46 ml [p = NS]).
  
  
  CONCLUSIONS
  Cardiac resynchronization therapy appears to be beneficial in patients with narrow QRS complex and severe LV dyssynchrony on TDI, with similar improvement in symptoms and comparable LV reverse remodeling to patients with wide QRS complex. The current results need confirmation in larger patient cohorts.
authors.affiliation: Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Gabe B
authors.initials: GB
authors.lastname: Bleeker
authors.forename: Eduard R
authors.initials: ER
authors.lastname: Holman
authors.forename: Paul
authors.initials: P
authors.lastname: Steendijk
authors.forename: Eric
authors.initials: E
authors.lastname: Boersma
authors.forename: Ernst E
authors.initials: EE
authors.lastname: van der Wall
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Schalij
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: Bax
mesh_terms: D000368:Aged; D002303:Cardiac Output, Low / Q000150:complications / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial; D004562:Electrocardiography; D005260:Female; D006331:Heart Diseases / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012720:Severity of Illness Index; D016896:Treatment Outcome; D018608:Ultrasonography, Doppler; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy; D020257:Ventricular Remodeling