Abstract
The importance of intra-ventricular conduction delay (IVCD), the incidence of new IVCD and its relationship to outcomes in heart failure and reduced ejection fraction (HFrEF) are not well studied. We addressed these questions in the PARADIGM-HF and ATMOSPHERE trials. The risk of the primary composite outcome of cardiovascular death or heart failure hospitalization and all-cause mortality were estimated by use of Cox regression according to baseline QRS duration and morphology in 11 861 patients without an intracardiac device. At baseline, 1789 (15.1%) patients had left bundle branch block (LBBB), 524 (4.4%) right bundle branch block (RBBB), 454 (3.8%) non-specific IVCD, 2588 (21.8%) 'mildly abnormal' QRS (110-129 ms) and 6506 (54.9%) QRS <110 ms. During a median follow-up of 2.5 years, the risk of the primary composite endpoint was higher among those with a wide QRS, irrespective of morphology: hazard ratios (95% confidence interval) LBBB 1.36 (1.23-1.50), RBBB 1.54 (1.31-1.79), non-specific IVCD 1.65 (1.40-1.94) and QRS 110-129 ms 1.35 (1.23-1.47), compared with QRS duration <110 ms. A total of 1234 (15.6%) patients developed new-onset QRS widening ≥130 ms (6.1 per 100 patient-years). Incident LBBB occurred in 495 (6.3%) patients (2.4 per 100 patient-years) and was associated with a higher risk of the primary composite outcome [hazard ratio 1.42 (1.12-1.82)]. In patients with HFrEF, a wide QRS was associated with worse clinical outcomes irrespective of morphology. The annual incidence of new-onset LBBB was around 2.5%, and associated with a higher risk of adverse outcomes, highlighting the importance of repeat electrocardiogram review. ClinicalTrials.gov Identifier NCT0083658 (ATMOSPHERE) and NCT01035255 (PARADIGM-HF).
Highlights
Intra-ventricular conduction delay (IVCD), with a left bundle branch block (LBBB) morphology, results in a dyssynchronous electrical activation sequence of the heart.[1]
Outcomes according to baseline QRS duration and morphology: The primary composite outcome of HF hospitalization or cardiovascular death occurred in 1543 (24%) of patients with QRS
In adjusted Cox regression analyses, this corresponded to significantly increased risk for those with QRS 110-129 ms (HR 1.35; 95% CI 1.23, 1.47), any QRS ≥130 ms (HR 1.44; 95% CI 1.32, 1.57), ns IVCD (HR 1.65; 95% CI 1.40, 1.94), RBBB (HR 1.54; 95% CI 1.31, 1.79) and LBBB (HR 1.36; 95% CI 1.23, 1.50)
Summary
Intra-ventricular conduction delay (IVCD), with a left bundle branch block (LBBB) morphology, results in a dyssynchronous electrical activation sequence of the heart.[1]. Very little is known about the incidence and clinical consequences of new-onset QRS widening in patients with HFrEF.[8, 9] This information is important as a new diagnosis of IVCD may be of prognostic importance and may identify an indication for CRT. In the present study we examined the prognostic importance of prevalent and incident QRS widening to a duration of ≥130 ms using data from two HFrEF trials which included a broad spectrum of ambulatory patients receiving contemporary therapy.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
