Effectiveness of dynamic atrioventricular optimization in CRT patients across different physiological conditions

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Abstract Background Recent studies suggest that atrioventricular delay (AVD) optimization can play a key role in QRSd narrowing in patients treated with cardiac resynchronization therapy (CRT) , thus improving outcomes. For this purpose, device-based algorithms have been developed. These algorithms continuously monitor the patient’s intrinsic AVD and dynamically adjust the pacing AVD to allow fusion of the left ventricle pacing with intrinsic right ventricle depolarization. AVD optimization is usually performed in a single patient condition, i.e. at rest, and in a single operating scenario of the device, i.e. during atrial sensing. Purpose This study aims to compare QRS narrowing after AVD optimization in patients treated with CRT, during moderate exertion, and during atrial pacing. Methods This is a prospective, non-randomized, non-blinded, multicenter study. The study population consisted of patients in sinus rhythm, PR interval < 350 ms, and rest rate < 100 bpm. Patients were assessed for AVD optimization with SyncAV, selecting the offset (i.e. 10 to 40% AVD) that resulted in the shortest QRS duration (QRSd). Subsequently, patients performed moderate physical activity using a bicycle ergo-meter while a surface ECG was collected. QRSd was assessed once patients achieved a heart rate over 20 bpm to baseline heart rate and during a programmed increase in atrial pacing. Results 20 patients (mean age 70 ± 9.6 years; 50% male) underwent CRT-D implantation, the mean baseline PR interval was 178 ± 26 ms, QRSd 162 ± 21 ms, and left ventricular ejection fraction (LVEF) 29 ± 4%. AVD optimization was conducted at rest using SyncAV, yielding a median optimal offset of 20% (IQR: 15%–22.5%). Optimized SyncAV resulted in a 20% QRSd reduction compared to intrinsic (157.5 ± 24.1 ms to 125.9 ± 15.8 ms, p < 0.05) and an 8% reduction compared to biventricular (BiV) pacing with fixed AVD (p = 0.13). During exercise, heart rate increased by 23% (65.5 ± 9.1 bpm to 84.9 ± 14.4 bpm, p < 0.05), with a mean QRSd reduction of 19% using SyncAV compared to intrinsic (157.8 ± 26.1 ms to 127.7 ± 17.4 ms, p < 0.05). Also, during atrial pacing, SyncAV showed a 13% QRSd reduction compared to intrinsic (150.0 ± 23.0 ms to 130.1 ± 18.8 ms, p < 0.05). No significant differences were found in QRSd across rest, exercise, and atrial pacing conditions with optimized SyncAV, suggesting consistent benefit in QRS narrowing regardless patients heart rate and device operating scenario. Conclusions AVD optimization using SyncAV reduced QRS duration compared to intrinsic conduction and BiV pacing with fixed AVD, both at rest and during exercise and atrial pacing. These findings suggest that device-based algorithms effectively enhance ventricular synchrony and boosts CRT-D efficacy across various physiological conditions. This optimization may contribute to improved clinical outcomes, supporting its use as a valuable tool to personalize CRT-D therapy.

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