Fragmented QRS is associated with intraventricular dyssynchrony and independently predicts nonresponse to cardiac resynchronization therapy—Systematic review and meta-analysis

Background: Fragmented QRS (fQRS) is postulated to be associated with ventricular dyssynchrony and might be able to predict a nonresponse to cardiac resynchronization therapy (CRT) implantation. In this systematic review and meta-analysis, we aim to assess whether fQRS can be a marker of intraventricular dyssynchronies in patients with ischemic and nonischemic cardiomyopathy and whether it is an independent predictor of nonresponse in patients receiving CRT. Methods: We performed a comprehensive search on topics that assesses fQRS and its association with intraventricular dyssynchrony and nonresponse to CRT up until September 2019. Results: Fragmented QRS is associated with intraventricular dyssynchrony (OR 10.34 [3.39, 31.54], p <.001; I²: 80% with sensitivity 76.8%, specificity 77%, LR+ 3.3, and LR− 0.3). Subgroup analysis showed that fQRS is associated with intraventricular dyssynchrony in patients with narrow QRS complex (OR 20.92 [12.24, 35.73], p <.001; I²: 0%) and nonischemic cardiomyopathy (OR of 19.97 [12.12, 32.92], p <.001; I²: 0%). Fragmented QRS was also associated with a higher time-to-peak myocardial sustained systolic (Ts-SD) (OR 15.19 [12.58, 17.80], p <.001; I²: 0% and positive Yu index (OR 15.61 [9.07, 26.86], p <.001; I²: 0%). Fragmented QRS has a pooled adjusted OR of OR of 1.70 [1.35, 2.14], p <.001; I²: 62% for association with a nonresponse to CRT. QRS duration is found to be higher in nonresponders group mean difference −8.54 [−13.38, −3.70], p <.001; I²: 70%. Conclusion: Fragmented QRS is associated with intraventricular dyssynchrony and is independently associated with nonresponse to cardiac resynchronization therapy.