Immediate Electrophysiological Effects of Different Atrial Pacing Sites on P-Wave Characteristics

Prospective Within-Subject Evaluation of Immediate Electrophysiological Effects of Multiple Atrial Pacing Sites on Atrial Activation and P-Wave Morphology

This is a prospective, single-center, non-randomized, within-subject interventional study. The purpose is to compare the immediate effects of different atrial pacing sites on atrial electrical activation, as reflected by P-wave characteristics on surface electrocardiography (ECG).

During pacemaker implantation, short-term pacing will be performed sequentially at multiple predefined atrial sites, including the right atrial appendage (RAA), atrial septum, Bachmann's bundle (BB) area, and posterosuperior bundle (PSB) regions. ECG parameters will be recorded at each site to evaluate differences in P-wave duration and morphology.

Atrial pacing site plays a key role in determining atrial activation sequence and interatrial synchrony. Conventional right atrial appendage (RAA) pacing has been associated with delayed and non-physiological atrial activation, whereas alternative sites such as the atrial septum and Bachmann's bundle (BB) may better preserve physiological conduction.Posterosuperior bundle (PSB) pacing has recently been proposed as a novel physiological atrial pacing strategy.

This study is designed to evaluate the acute electrophysiological effects of different atrial pacing sites within the same individual. During routine pacemaker implantation, sequential short-term pacing will be performed at predefined atrial sites (RAA, atrial septum, BB area, high PSB, and low PSB), with simultaneous 12-lead ECG recording.

The primary objective is to compare P-wave duration across pacing sites. Secondary analyses include P-wave morphology and polarity. The study aims to identify the atrial pacing site that most closely approximates physiological atrial activation and to provide mechanistic insights to guide optimal site selection.

Inclusion Criteria:

• Age ≥18 years
• Sinus rhythm at baseline
• Indication for permanent pacemaker implantation with planned atrial lead placement
• Willing and able to provide written informed consent

Exclusion Criteria:

• Long-standing persistent or permanent atrial fibrillation, or prior atrioventricular node ablation
• Prior cardiac implantable electronic device (CIED) requiring revision, replacement, or upgrade
• Indication for implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D)
• Significant valvular heart disease, cardiomyopathy, or prior cardiac surgery
• Angina or acute myocardial infarction within 3 months before enrollment
• Chronic use of antiarrhythmic drugs
• Severe hepatic or renal dysfunction, or other serious systemic diseases
• Participation in another clinical study that may interfere with the objectives of this study