title: Prevalence of mechanical dyssynchrony in heart failure patients with different QRS durations.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) has emerged as an established therapy for congestive heart failure. However, up to 30% of patients fail to respond to CRT despite prolonged QRS.
  
  
  OBJECTIVE
  This study aimed at defining the prevalence of interventricular and intraventricular dyssynchrony in heart failure patients with different QRS durations.
  
  
  METHODS
  A total of 123 consecutive patients with severe heart failure (LVEF < 35% and NYHA class III-IV) were prospectively evaluated using 12-lead electrocardiogram and complete echocardiographic examination including tissue Doppler imaging.
  
  
  RESULTS
  According to the QRS duration, 56 patients had a QRS duration < or = 120 ms (Group 1), 33 patients had a QRS duration between 120 and 150 ms (Group 2), and 34 patients had a QRS duration > or = 150 ms (Group 3). Intraventricular dyssynchrony was present in 36% of Group 1 patients, in 58% of Group 2 patients, and in 79% of Group 3 patients (P < 0.000). Linear regression demonstrated a weak relation between QRS and intraventricular dyssynchrony. A greater proportion of patients with interventricular dyssynchrony was observed in Group 3 or Group 2 compared to patients with normal QRS duration (32% in Group 1 vs. 51.5% in Group 2 vs. 76.5% in Group 3, P < 0.000). Linear regression demonstrated a significant relation between QRS duration and interventricular mechanical delay.
  
  
  CONCLUSIONS
  Although both interventricular and intraventricular dyssynchrony increased with the increasing QRS duration, the correlation between intraventricular mechanical and electrical dyssynchrony was weak. The lack of intraventricular dyssynchrony in a fraction of patients with standard CRT indication by QRS duration may provide us insight into the nonresponders rates.
authors.affiliation: Department of Pacemaker and Electrophysiology, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Mellat Park, Tehran, Iran. majid.haghjoo@gmail.com
authors.forename: Majid
authors.initials: M
authors.lastname: Haghjoo
authors.forename: Ataallah
authors.initials: A
authors.lastname: Bagherzadeh
authors.forename: Amir Farjam
authors.initials: AF
authors.lastname: Fazelifar
authors.forename: Zahra Ojaghi
authors.initials: ZO
authors.lastname: Haghighi
authors.forename: Maryam
authors.initials: M
authors.lastname: Esmaielzadeh
authors.forename: Abolfath
authors.initials: A
authors.lastname: Alizadeh
authors.forename: Zahra
authors.initials: Z
authors.lastname: Emkanjoo
authors.forename: Anita
authors.initials: A
authors.lastname: Sadeghpour
authors.forename: Niloofar
authors.initials: N
authors.lastname: Samiei
authors.forename: Maryam Moshkani
authors.initials: MM
authors.lastname: Farahani
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Sadr-Ameli
authors.forename: Majid
authors.initials: M
authors.lastname: Maleki
authors.forename: Fereidoun
authors.initials: F
authors.lastname: Noohi
mesh_terms: D000704:Analysis of Variance; D016009:Chi-Square Distribution; D018618:Echocardiography, Doppler, Color; D004554:Electric Countershock; D004562:Electrocardiography; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D016896:Treatment Outcome