Abstract Body (Do not enter title and authors here): Introduction:
Epicardial atrial pacing (EAP) is selectively used in cardiac surgery, but its routine postoperative application lacks robust supporting evidence.

Objectives:
To compare in-hospital clinical outcomes in patients undergoing cardiac surgery with and without epicardial atrial pacing.

Methods:
We conducted a retrospective cohort study at a high-complexity community hospital in Argentina, including adult patients who underwent cardiac surgery. Patients were divided into two groups: those who received EAP (EAP group) and those who did not (control group). Preoperative data included age and comorbidities. Intraoperative and postoperative variables such as inotrope use, surgery type, complications, and length of stay were recorded. Multivariate logistic regression was used to identify independent predictors of EAP use. Model performance was evaluated with the Hosmer-Lemeshow test and ROC curve.

Results:
A total of 305 patients were analyzed: 156 in the EAP group and 149 in the control group. The EAP group was older (mean 68 ± 9.5 vs. 64 ± 12 years; p < 0.001), with no other significant differences in baseline characteristics. Intraoperative inotrope use was more frequent in the EAP group: norepinephrine (64.1% vs. 45.6%; p = 0.02), dobutamine (13.5% vs. 6%; p = 0.047), and milrinone (16% vs. 8.1%; p = 0.05). Postoperatively, norepinephrine use remained higher in the EAP group (48.1% vs. 32.9%; p = 0.010), but no differences were found in complications, mortality, or length of stay. In multivariate analysis, age (p = 0.005) and intraoperative inotrope use (p = 0.008) were independent predictors of EAP use. Postoperative inotrope use was included in the model as a confounder (p = 0.161). The model showed moderate discrimination (ROC = 0.67; Hosmer-Lemeshow p = 0.30).

Conclusions:
Routine epicardial atrial pacing following cardiac surgery was not associated with improved in-hospital clinical outcomes. While its primary indication remains postoperative rhythm disturbances, its use may be justified in selected patients—particularly older individuals or those requiring intraoperative inotropic support—based on clinical judgment. Importantly, the procedure demonstrated a favorable safety profile.