Role of fragmented QRS complex in the prognosis of patients undergoing cardiac resynchronization therapy. A new red flag to look for?

Abstract Introduction Cardiac resynchronization therapy (CRT) has demonstrated to reduce mortality and hospitalization for heart failure in selected patients with heart failure with reduced ejection fraction (HFrEF). However, there is a significant percentage of readmissions for heart failure (HF) after implantation. In the recent years, several biomarkers and electrocardiographic findings possibly related with prognosis in this group of patients have been identified. Fragmentation of QRS complex (fQRS) has been related with worse prognosis in various cardiac diseases, but the evidence in patients undergoing CRT is limited. Purpose The objective of this study is to evaluate if the presence of pre-implantation fragmented QRS complex has a prognostic role in patients undergoing cardiac resynchronization therapy in terms of hospitalization for HF. Methods Consecutive patients undergoing CRT were prospectively included from October 2009 to December 2022. Demographic clinical, electrocardiographic and echocardiographic variables were recorded. Prospective follow-up variables were collected from electronic clinical records and telephone interview. Fragmentation of the QRS complex was defined by the presence of different RSR′ patterns including an additional R-wave (R′), notching of the R-wave and S-wave or the presence of more than 1R′ in two contiguous leads corresponding to a main coronary artery territory. Results 244 patients were included. Mean age at the implantation of the device was 71.8 years (standard deviation, SD ±9.8 years), 79.5% were male and 40.2% were diabetic. Mean LVEF was 24.9% (SD ±8.9) and the aetiology was non-ischaemic in 50.8% of the patients and ischaemic in 49.2%. 40.2% had prior history of acute myocardial infarction. Pre-implantation fragmented QRS complex was found in 58.6% of the patients and mostly in inferior leads of the surface ECG. Mean QRS duration was 157.9ms and 82.0% had left-bundle branch block morphology. CRT with defibrillator implantation was performed in 71.4% of the patients. The median follow-up time was 27.4 month. After device implantation, mean LVEF was 33.2% and 76.6% presented NYHA class I-II. During this period, 28.7% of the patients died. Additionally, 29.1% of the patients presented at least one hospitalization for heart failure (HF), 22.5% with fQRS and 6.6% without fQRS. A multivariate survival study using Cox regression showed that the presence of pre-implantation fQRS was an independent predictor of HF h