382 The impact of paced ECG duration on CRT-P upgrade outcomes: an observational study
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Authors
Bett, Poppy
Basquill, Olivia
Furniss, Guy
Issue Date
2026-06-09
Type
Article
Language
en
Keywords
Wessex Classification Subject Headings::Cardiology
Alternative Title
Abstract
Background Upgrading from dual-chamber pacemakers (DDD) to cardiac resynchronisation therapy pacemakers (CRT-P) can significantly improve left ventricular (LV) function in selected patients. However, the predictive role of electrophysiological features, including QRS duration and morphology, and the presence of atrial fibrillation (AF), remains unclear.
Purpose We aimed to assess (1) whether post-upgrade QRS narrowing correlates with left ventricular ejection fraction (LVEF) response, and (2) whether baseline paced QRS duration predicts the degree of LVEF improvement after CRT-P upgrade.
Methods We conducted a retrospective, single-centre analysis of 71 patients who underwent DDD-to-CRT-P upgrades between 2018 and 2024. Complete echocardiographic and electrocardiographic data were available for 66 patients (mean age 79 years; 68% male). Changes in LVEF and paced QRS duration were compared before and after upgrade. Patients were classified as ‘Responders’ (≥10% LVEF improvement) or ‘Poor Responders’ (<10%). Subgroup analyses examined baseline QRS duration (<130 ms, 130–170 ms, >170 ms) and its relationship with LVEF change.
Results ‘Responders’ (n = 48) demonstrated significantly greater QRS narrowing than ‘Poor Responders’ (n = 18). Mean ΔQRS was −43.6ms ±23.3 in ‘Responders’ vs −27.8ms ± 22.6 in ‘Poor Responders’ (t = −2.50, p = 0.018). Greater post-upgrade QRS reduction was associated with more pronounced LVEF improvement.
Baseline QRS duration was not a statistically significant predictor of response (F = 0.23, p = 0.9), although patients with intermediate QRS durations (130–170 ms) had the largest mean LVEF gain (15.5%). Among 66 patients, 22 had permanent Atrial Fibrillation (AF). AF was slightly more prevalent in weak responders (44% vs. 29%; R = −0.13), indicating a modest, non-significant trend toward reduced response in AF patients.
Conclusion In patients undergoing DDD-to-CRT-P upgrade, greater ΔQRS was strongly associated with superior LVEF improvement. While baseline QRS duration was not a statistically significant predictor, intermediate durations may confer optimal benefit. The potential role of QRS morphology as an electrophysiological marker of CRT-P response warrants further study.
Description
Citation
Bett P, Basquill O, Furniss G382 The impact of paced ECG duration on CRT-P upgrade outcomes: an observational studyHeart 2026;112:A17.