Prevalence of mechanical dyssynchrony in heart failure patients with different QRS durations.
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.
Haghjoo
Majid
M
Department of Pacemaker and Electrophysiology, Rajaie Cardiovascular Medical and Research Center, Iran University of Medical Sciences, Mellat Park, Tehran, Iran. majid.haghjoo@gmail.com
Bagherzadeh
Ataallah
A
Fazelifar
Amir Farjam
AF
Haghighi
Zahra Ojaghi
ZO
Esmaielzadeh
Maryam
M
Alizadeh
Abolfath
A
Emkanjoo
Zahra
Z
Sadeghpour
Anita
A
Samiei
Niloofar
N
Farahani
Maryam Moshkani
MM
Sadr-Ameli
Mohammad Ali
MA
Maleki
Majid
M
Noohi
Fereidoun
F
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