Short-Term Atrial Pacing and Hemodynamics After Cardiac Surgery

Inclusion Criteria: * Patients aged 18 years or older * Cardiac surgery under CPB (coronary artery bypass grafting, valve replacement or repair, or combined procedures) * Placement of epicardial atrioventricular pacing wires during surgery * Placement of a Swan-Ganz catheter intraoperatively * Signed informed consent Exclusion Criteria: * Emergency surgery * Patients with an internal pacemaker * History of permanent atrial fibrillation * Complete atrioventricular block upon weaning from CPB * Junctional rhythm upon weaning from CPB * Sinus rhythm \< 50 bpm upon weaning from CPB * Failure of atrial or dual-chamber pacing (patients paced in ventricular mode VVI) * Contraindication to Swan-Ganz catheter placement * Hemodynamic instability defined by significant bleeding or tamponade requiring surgical re-intervention, or the need for escalating doses of vasopressors (Norepinephrine \> 1 μg/kg/min, Dobutamine \> 10 μg/kg/min)