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Updated: Jul 2, 2025
Real-Time Cardiac Mapping with a Noninvasive Imageless Electrocardiographic Imaging System
Published on: April 11, 2025
Personalized cardiac resynchronization therapy guided by real-time electrocardiographic imaging for patients with
Mark T K Tam1, Alex C K Au1, Joseph Y S Chan1
1Division of Cardiology, Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong SAR, China.
Background:
Patients with heart failure and a non-left bundle branch block (non-LBBB) QRS pattern have a limited response to biventricular pacing (BVP).
Objective:
A personalized cardiac resynchronization therapy (CRT) implantation approach guided by real-time electrocardiographic imaging (ECGi) was studied.
Methods:
Twenty patients with left ventricular ejection fraction (LVEF) ≤ 35%, QRS duration ≥ 120 ms, and non-LBBB [13 (65%) with right bundle branch block and 7 (35%) with intraventricular conduction delay] were recruited. During CRT implantation, right atrial, right ventricular, coronary sinus, His-bundle, and/or left bundle leads were inserted. The total activation time (TAT) with different pacing combinations were measured in real time during implantation by ECGi. The configuration producing the shortest TAT was chosen. Clinical response was defined as ≥1 New York Heart Association class improvement. Echocardiographic response was defined as left ventricular end-systolic volume reduction ≥ 15% and/or LVEF improvement ≥ 10% at 6 months.
Results:
After ECGi-guided CRT implantation, LVEF improved from 26% ± 6% to 34% ± 11% (P < .01) and New York Heart Association class improved from 3.0 ± 0.5 to 2.0 ± 0.6 (P < .01). Both clinical and echocardiographic response rates were 70%. The ECGi approach resulted in better acute electrical resynchronization over BVP as measured by TAT reduction (40% vs 14%; P < .01). The percentage of TAT reduction was found to be a strong predictor for echocardiographic response (area under the curve for the receiver operating characteristic curve 0.91; 95% confidence interval 0.78-1.00). A strong positive correlation between percentage TAT reduction and percentage LVEF improvement (Pearson R = 0.70; P = .001) was found.
Conclusion:
ECGi-guided CRT implantation in patients with non-LBBB generates superior acute electrical resynchronization compared with BVP and is associated with favorable clinical and echocardiographic outcomes.
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