Evaluation of QRS dispersion and its association withtachyarrhythmia events in patients with implantedcardiac resynchronization therapy defibrillator device

Introduction: Heart 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. Methods: 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. Results: 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. Conclusion: 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.