CardiacResynchronization Therapy Defibrillator,
QRS dispersionHeart failure (HF) is one of the major problems of health system in the countries. In a subgroup of these patients, cardiac resynchronization therapy defibrillator (CRT-D) improves the quality of life by enhancing the function of the left ventricle (LV) and preventing of arrhythmias. The present study intends to discuss the effect of CRT-D on the QRS dispersion, as a predisposing factor to arrhythmias. 45 patients treated with CRT-D during 2012-2015 were enrolled in this study. QRS dispersion in various V-V delays was measured and its association with the incidence of arrhythmias, at least six months after insertion, was assessed.The results showed that QRS dispersion in the intrinsic mode was significantly lower than the other modes of the CRT-D device (P < 0.001). Besides, it was revealed that mean QRS duration in the intrinsic mode had a higher association with arrhythmic events than max QRS duration. QRS dispersion after CRT-D implantation had a significant increase compared to the intrinsic mode. However, it did not correlate with the arithmetic events. Further decrease in the duration of QRS after CRT-D implantation improved arrhythmias.QRS dispersion after CRT-D implantation is not an indicative of arrhythmia risk, and a decrease in the duration of QRS had a more significant effect on the incidence of arrhythmias.