During pacemaker implantation, the atrial lead is commonly positioned in the right atrium. However, this pacing location can be problematic because it may disrupt physiological atrial activation, leading to atrial dyssynchrony. Such dyssynchrony has been associated with an increased risk of atrial fibrillation and its related complications.

To mitigate atrial dyssynchrony, pacing of the Bachmann's bundle region has emerged as an alternative strategy. Bachmann's bundle is the principal interatrial conduction pathway, and pacing at this site may help preserve physiological atrial activation. Several studies have suggested that pacing in this region can significantly reduce the incidence of new-onset atrial fibrillation and heart failure in selected populations.

To date, however, robust data from large cohorts regarding the feasibility of Bachmann's bundle area pacing and the factors associated with successful implantation remain limited. To address this gap, we established the Bachstim cohort study, aimed at determining the success rate of Bachmann's bundle area pacing and identifying the clinical and procedural factors associated with its feasibility.

Inclusion Criteria:

• Cardiac pacemaker with atrial lead indication

Exclusion Criteria:

• patients < 18 years old
• pregnancy of breast feeding

The study population will include all patients with an indication for cardiac pacemaker implantation requiring an atrial lead, in whom Bachmann's bundle area pacing is planned. Patients with age inferior to 18 years old will be excluded.